Rodentia

Question 1

A recent study evaluated the digestive physiology of the capybara.

What is the scientific name of the capybara?

Describe the GI anatomy.

What are the mechanisms of colonic separation?

How do they differ and what species use which method?

Answer 1

Kiani, A., Clauss, M., Ortmann, S., Vendl, C., Congdon, E. R., Herrera, E. A., … & Schwarm, A. (2019). Digestive physiology of captive capybara (Hydrochoerus hydrochaeris). Zoo biology, 38(2), 167-179.

Abstract: The capybara (Hyrdochoerus hydrochaeris), the largest living rodent, probably has a mucus-trap colonic separation mechanism. To test this hypothesis, we measured the mean retention time of a solute marker (MRT-solute), 2 mm (MRT-2mm), 10 mm (MRT-10mm), and 20 mm (MRT-20mm) particle markers and nutrient digestibility in adult captive capybaras (27-52 kg body mass, 2-11 yr). In addition, total gut fill and selectivity factor (MRT-solute/MRT-2 mm) were calculated and mean faecal particle size and metabolic fecal nitrogen of captive capybaras were compared to those of free-ranging specimens. Finally, we also measured methane production in one animal. The MRT-2mm (29.2 ± 8.2 hr) was different (p<0.01) from MRT-solute (37.0 ± 13.1 hr), MRT-10 mm (36.5 ± 8.2 hr), and MRT-20mm (35.1 ± 9.6 hr). The selectivity factor (1.25 ± 0.30) was in the range considered typical for a mucus-trap colonic separation mechanism. The estimated total gut fill was 1.5 ± 0.37% and 1.73 ± 0.25% of BM calculated from the results of the 2-mm and 10-mm particle markers, respectively. The CH4 emission was 13.7 L/day. Captive capybaras had greater mean fecal particle size (0.44 ± 0.06 v 0.29 ± 0.05 mm, P<0.001) and metabolic fecal nitrogen (65.5 ± 3.91 v 46.8 ± 10.5%, p<0.001) than free-ranging capybaras. Organic matter digestibility decreased less steeply with increasing dietary crude fiber content in capybaras as compared to published data from rabbits or guinea pigs. Accordingly, the digestive physiology of the capybara is characterized by a comparatively high fiber digestibility, with a mucus-trap colonic separation mechanism, allowing capybaras to thrive on forage-only diets.

• Capybara GI anatomy
  
  • Monogastric animals with voluminous haustrated cecum
  • Cecum is 74% of total GIT on a dry matter basis, about 7% of BW
  • High methane produces – equivalent to ruminants
  • Colon has a colonic groove suggesting this species uses a mucus-trap CSM
  • Third molar with multiple transverse enamel ridges effectively reduces particle size (50% of particles in feces were less than 0.25 mm)
• Colonic separation mechanisms
  
  • Wash-back – lagamorphs – microbes and other small particles are washed back into the cecum by fluid
  • Mucus-trap – hystricomorph rodents – microbes and small particles are trapped in a colonic groove and moved back from the proximal colon into the cecum
  • Cecotrophy occurs with these mechanisms to save microbial protein – has been documented in capybaras
• M&M – offered feeds with hay particles of 2, 10, 20 mm lengths with metal markers which was measured in the feces
• Secondary marker excretion peaks confirm cecotrophy

Take home: They can be maintained on forage only diets – still need vitamin C

Question 2

A recent study described the morphology and ophthalmic evaluation of the agouti eye.

What is unique about the fundic exam of the agouti eye?

What is the function of teh harderian gland in rodent adnexa?

Answer 2

Tavares-Somma, A., Seabra, N., Moore, B. A., Sato, M., Lange, R. R., & Montiani-Ferreira, F. (2017). The eye of the azara’s agouti (dasyprocta azarae): morphological observations and selected ophthalmic diagnostic tests. Journal of Zoo and Wildlife Medicine, 48(4), 1108-1119.

Abstract: The purpose of this study was to carry out a descriptive investigation of the Azara’s agouti (Dasyprocta azarae) eye and to establish reference values of select ophthalmic diagnostic tests and physiologic parameters. A total of 19 healthy agoutis were used. Select ophthalmic diagnostic tests were performed, including Schirmer tear test type I (STTI), analysis of the conjunctival bacterial microflora, corneal esthesiometry, and tonometry. B-mode ultrasonic biometry, fundus photography, optical coherence tomography, and gross and histologic analysis of two eyes were also performed. Reference range parameters found for the ocular diagnostic tests were esthesiometry, 4.50 ± 0.36 cm (0.7 ± 0.01 g/mm²); tonometry, 11.61 ± 0.44 mm Hg; palpebral fissure length, 1.70 ± 0.25 mm; STTI, 9.73 ± 0.47 mm/min; corneal thickness, 0.8 ± 0.003 mm; anterior chamber depth, 1.71 ± 0.07 mm; lens thickness, 5.03 ± 0.05 mm; vitreous chamber depth, 5.12 ± 0.01 mm; and globe axial length, 14.02 ± 0.01 mm. A paurangiotic, retinal, vascular pattern with a conspicuous pigment-laden optic disc was observed. The most frequent bacteria isolated were nonhemolytic Streptococcus sp. (36.84%), followed by Enterobacter harfinia (31.58%) and Escherichia coli (28.95%). No significant differences between genders or between left and right eyes were found for any of the results. Gross and histologic evaluation of two eyes confirmed the presence of melanocytic pigment granules between optic nerve fibers. The diagnostic values and the morphologic observations described here provide a reference to veterinarians to aid in the diagnosis of ocular disease.

• Long cilia project ventrally from the superior eyelid.
• Have a vestigial third eyelid similar to chinchilla, capybara, American beavers.
• Circular pupil consistent with other rodents.
• Retina – Paurangiotic vascular pattern, same as chinchilas, capybaras.
  
  • Rat – Holangiotic retinal pattern.
• Most striking finding – Pigmented spot in the center of the optic disc, first report in any species in a nonpathologic state.
• STT generally higher vs chinchillas, rabbits.
• Large amount of porphyrin in tears.
  
  • Harderian gland – Function not well understood; lubrication, gonadal regulation through merocrine secretion, involvement in circadian rhythm of pineal serotonin. Porphyrins abundant in some rodent harderian gland secretions. Controlled by parasympathetic innervation, increased production with stress.
• Mean IOP lower vs other rodents.
• Agoutis have a higher corneal sensitivity and greater larimal production vs GP and chinchillas.

Takeaway: Agoutis have central optic nerve head pigmentation (the only species known that has this).

Question 3

A recent study evaluated progesterone metabolites in the Siberian flying squirrel.

Describe the progesterone profile throughout pregnancy, parturition, and post-partum.

Answer 3

Shimamoto, T., Suzuki, K. K., Hamada, M., Furukawa, R., Matsui, M., & Yanagawa, H. (2018). Fecal progesterone metabolites in postpartum siberian flying squirrels. Journal of Zoo and Wildlife Medicine, 49(1), 237-241.

Abstract: The Siberian flying squirrel (Pteromys volans) produces up to two litters a year. To deliver second litters in breeding season, P. volans may have a postpartum estrus similarly to that of a variety of small mammals. If this were the case, females would have periods of elevated progesterone levels because of the formation of corpora lutea (CL) after postpartum ovulation. To test this hypothesis, fecal progesterone metabolite dynamics was investigated during lactation in this species using an enzyme immunoassay. In five of the six lactating females, periods of high fecal progesterone metabolite concentration were observed, and, furthermore, progesterone secretion patterns were periodic. Therefore, the source of progesterone during lactation could be arising CL from postpartum ovulation, indicating that ovarian activity was reinitiated after parturition and the CL that formed began secreting progesterone. This study thus showed that P. volans likely has the physiologic potential to mate during lactation.

• Siberian Flying Squirrel – OW flying squirrel – LC conservation
• Goal to evaluate whether postpartum estrus occurs
• Methods - fecal samples collected during latter period of pregnancy and during lactation until offspring began to eat solid food, pulverized fecal samples, used enzyme immunoassay to determine levels
• Results – progesterone rmained high during the latter part of pregnancy and then dramatically declined at parturition, spikes resumed between 2 and 18 days suggested there is a post-partum estrus.

Take Home:

• Siberian flying squirrels have a post-partum estrus – PPE is a time saving mechanism for faster reproductive rates

Question 4

A recent study described common causes of morbidity and mortality in slener-tailed cloud rats.

What is their scientific name?

What was the most common cause of neonatal morbidity & mortality? What is the prognosis with these conditions?

What was the most common cause of adult morbidity and mortality? What other two conditions were common?

Answer 4

Sykes IV, J. M., Wilson, C., & McAloose, D. (2019). Husbandry, morbidity, and mortality of slender‐tailed cloud rats (Phleomys pallidus). Zoo biology, 38(4), 360-370.

Absract: The Wildlife Conservation Society’s Bronx Zoo has been housing and breeding slender‐tailed cloud rats (Phleomys pallidus) since 1985. Records of 82 animals from 1985 to 2013 were reviewed for this study. The animals were kept successfully in small family groups with a single adult male, multiple adult females, and their offspring. Sexual maturity was noted at approximately 2 years of age and gestation length ranged from 52 to 55 days. Animals were fed a diet including a complete commercial pelleted feed, mixed greens, carrot or yam, mixed hard nuts, and locally sourced browse. Medical conditions requiring treatment in neonates were often fatal whereas most medical conditions in adults were survivable. The most common cause of morbidity and mortality in neonates was maternal neglect or trauma (42%, 5/12 antemortem problems; cause of death in 32%, 8/25). The most significant problems in adults were cryptococcal pneumonia and trauma. Cryptococcus sp. was the cause of death in 11 cases (34%, 11/32) and significant comorbidity in an additional three cases. Treatment with antifungal medications was attempted but was unsuccessful in four cases. Many cases of trauma were treated successfully with conservative management or limited intervention. In four cases, treatment was complicated by extensive self‐mutilation after surgical repair of traumatic lesions, which resulted in death or euthanasia. Lymphoplasmacytic thyroiditis was a common postmortem finding in adults (95%, 21/22 for which the thyroid gland was examined histologically). It is unclear if thyroiditis resulted in functional hypothyroidism so the significance of this finding is undetermined.

• Enclosure: vertical and horizontal perches
• Diet: Mazuri rodent chow, Zupreem canned primate, mixed greens, dandelions, carrot, yam, nuts; fruit only for medication administration (had an animal with diabetes in the 90s)
• Reproductively active females at 18-24 months, birth up to 2x/year, gestation 52-55 days, offspring stay attached to teat of the dam
• Neonates eating solid food by 3-4 months, nurse until 6 months
• Male young began to fight with adult males at 12 months
• Comparatively – other animals with predisposition to Cryptococcus include tree shrews, short-eared elephant shrews, koalas

Take home: Cryptococcus was the most common infectious disease of adults; trauma also a major cause of mortality in adults; thyroiditis not uncommon. Neonates – maternal neglect and trauma most common causes of morbidity/mortality.

Question 5

A recent study described hypervitaminosis d in red-rumped agouti.

What is the taxonomy of the red-rumped agouti?

What findings in this case were suggestive of hypervitominosis D?

How was this case managed?

What was the ultimate outcome?

Answer 5

Anderson, K. M., Lewandowski, A., & Dennis, P. M. (2018). Suspected hypervitaminosis d in red-rumped agouti (dasyprocta leporina) receiving a commercial rodent diet. Journal of Zoo and Wildlife Medicine, 49(1), 196-200.

Abstract: An 8 yr, intact male red-rumped agouti (Dasyprocta leporina) was evaluated for weight loss. Examination revealed poor body condition, hypercalcemia, elevated serum 25-hydroxyvitamin D, metastatic calcification of soft tissues, and hyperechoic kidneys. The diet, formulated for laboratory rodents, contained elevated levels of vitamin D3. Histopathology from a female conspecific that died 5 mo prior identified dystrophic mineralization and nephrosclerosis, suggestive of a vitamin D3 toxicity. The male agouti responded well to a dietary reduction in vitamin D3 and calcium. Six months into therapy, progressive renal failure was identified and was further managed with enalapril, phosphorus binders, and dietary manipulation. Suspected vitamin D3 toxicity has been reported in pacas (Cuniculus paca) and agouti and has been linked to exposure to New World primate diets. In this brief communication, an agouti developed suspected hypervitaminosis D after receiving a commercial rodent diet commonly fed to this species in captivity.

• Agouti evaluated for weight loss, arrythmia, calcification of muscle and tendons
• Hypervitaminosis D secondary to a commercial rodent breeder diet (Mazuri rodent breeder)
  
  • Histopathology from conspecific showed dystrophic mineralization suggestive of hypervitD
  • Reducing vitamin D and calcium in diet (50% reduction) ameliorated clinical signs
  • Managed for over a year with ultimate development of renal failure
• New world primate diet (high calcium and vitD) has caused hypervitaminosis D in Pacas

Take home: Hypervitaminosis D occurred secondary to commercial rodent diet in agoutis 🡪 diets should be evaluated for vitamin D

Question 6

A recent study evaluated whether recumbency affects physiologic parameters of black-tailed prarie dogs.

Does it?

Answer 6

Eshar, D., Mason, D., Avni-Magen, N., Kaufman, E., Paz, A., & Beaufrère, H. (2017). Evaluation of the effects of sternal versus lateral recumbency on trends of selected physiologic parameters during isoflurane anesthesia in zoo-housed black-tailed prairie dogs (Cynomys ludovicianus). Journal of Zoo and Wildlife Medicine, 48(2), 388-393.

Abstract: Isoflurane gas anesthesia is often used for immobilization of prairie dogs in field studies, laboratory research, and veterinary clinical purposes. The goals of this prospective study were to evaluate the effects of sternal versus right lateral recumbency on trends of selected physiologic parameters during isoflurane anesthesia in black-tailed prairie dogs (Cynomys ludovicianus). Fourteen adult, zoo-housed black-tailed prairie dogs were tested during the study. Animals were anesthetized using isoflurane and randomly placed in either sternal or right lateral recumbency to evaluate changes in trends of physiologic parameters, measured selectively every 30 min throughout a 60-min anesthesia period. Results were analyzed using linear mixed modeling. Right lateral recumbency resulted in a decrease in anion gap of about 4.6 mEq/L (95% confidence interval [95% CI]: 3.1–6.0, P < 0.001), whereas sternal recumbency resulted in a lower decrease of 2.1 mEq/L (95% CI: 0.7–3.6, P = 0.02). However, the absolute values at the beginning and at the end of the anesthesia time were not significantly different between the right lateral and sternal recumbency (all P > 0.57). Body position did not have any effect on any other variables, and most of the observed physiologic changes were due to the duration of anesthesia. Our results indicate no significant effect on trends of selected physiologic parameters between sternal recumbency and right lateral recumbency during 1 hr of isoflurane anesthesia in black-tailed prairie dogs.

Question 7

A recent study evaluated the intraocular pressures of syrian hamsters.

What are some factors that can affect intraocular pressure? What drugs may affect it?

When were the highest and lowest IOPs documented in these hamsters?

How did the ketamine-xylazine combination affect their IOPs?

Answer 7

Rajaei, S. M., Mood, M. A., Paryani, M. R., & Williams, D. L. (2017). Effects of diurnal variation and anesthetic agents on intraocular pressure in Syrian hamsters (Mesocricetus auratus). American journal of veterinary research, 78(1), 85-89.

OBJECTIVE To determine effects of diurnal variation and anesthetic agents on intraocular pressure (IOP) in Syrian hamsters (Mesocricetus auratus).

ANIMALS 90 healthy adult Syrian hamsters (45 males and 45 females).

PROCEDURES IOP was measured with a rebound tonometer. In phase 1, IOP was measured in all hamsters 3 times during a 24-hour period (7 am, 3 pm, and 11 pm). In phase 2, hamsters were assigned to 5 groups (18 animals [9 males and 9 females]/group). Each group received an anesthetic agent or combination of anesthetic agents (ketamine hydrochloride, xylazine hydrochloride, diazepam, ketamine-diazepam [KD], or ketamine-xylazine [KX] groups) administered via the IP route. The IOP was measured before (time 0 [baseline]) and 10, 30, 60, 90, 120, and 150 minutes after administration of drugs.

RESULTS Mean ± SD IOP values were 2.58 ± 0.87 mm Hg, 4.46 ± 1.58 mm Hg, and 5.96 ± 1.23 mm Hg at 7 am, 3 pm, and 11 pm, respectively. Mean baseline IOP was 6.25 ± 0.28 mm Hg, 6.12 ± 0.23 mm Hg, 5.75 ± 0.64 mm Hg, 5.12 ± 1.40 mm Hg, and 4.50 ± 1.30 mm Hg for the ketamine, xylazine, diazepam, KD, and KX groups, respectively. A significant decrease in IOP, compared with baseline IOP, was detected in only the KX group at 30, 60, and 90 minutes after drug administration.

CONCLUSIONS AND CLINICAL RELEVANCE Maximum IOP in Syrian hamsters was detected at night. The ketamine-xylazine anesthetic combination significantly decreased IOP in Syrian hamsters.

· IOP

o Can effect IOP - tone of extraocular muscles, closure of the eyelids, retraction of the retractor bulbi muscle, external pressure, intraocular changes, drugs, curvature and thickness of the cornea, corneal and scleral rigidity, time of day, head and body position, and tear film viscosity

o Ketamine increases IOP through constriction of extraocular muscles

o Diazepam decreases IOP

· maximum IOP detected at night and minimum IOP detected in morning

· IOP of hamsters slightly lower than mice and other small rodents

· injection of anesthetic agents alone (ketamine, diazepam, or xylazine) did not cause significant changes in IOP

· ketamine-xylazine combination caused significant decrease in IOP

Question 8

A recent study evaluated the effects of anesthesia on ocular variables in black tailed prairie dogs.

Answer 8

Roberts, J. K., Meekins, J. M., Browning, G. R., Beaufrère, H., & Eshar, D. (2019).

Effects of injectable dexmedetomidine-ketamine-midazolam and isoflurane inhalation anesthetic protocols on ocular variables in captive black-tailed prairie dogs (Cynomys ludovicianus).

American journal of veterinary research, 80(9), 878-884.

OBJECTIVE :To evaluate the effects of injectable dexmedetomidine-ketamine-midazolam (DKM) and iso urane inhalation (ISO) anesthetic protocols on selected ocular variables in captive black-tailed prairie dogs (Cynomys ludovicianus; BTPDs). ANIMALS : 9 zoo-kept BTPDs. PROCEDURES : The BTPDs received dexmedetomidine hydrochloride (0.25 mg/kg, IM), ketamine hydrochloride (40 mg/kg, IM), and midazolam hydrochloride (1.5 mg/kg, IM) or inhalation of isoflurane and oxygen in a randomized complete crossover design (2-day interval between anesthetic episodes). Pupil size, globe position, tear production, and intraocular pressure measurements were recorded at 5, 30, and 45 minutes after induction of anesthesia. For each BTPD, a phenol red thread test was performed in one randomly selected eye and a modified Schirmer tear test I was performed in the other eye. Intraocular pressurewas measured by rebound tonometry. RESULTS : Compared with findings for the DKM protocol, pupil size was smaller at all time points when the BTPDs underwent the ISO protocol. Globe position remained central during anesthesia with the DKM protocol, whereas it varied among central, ventromedial, and ventrolateral positions during anesthesia with the ISO protocol. Tear production and intraocular pressure decreased significantly over time when the BTPDs underwent either protocol. CONCLUSIONS AND CLINICAL RELEVANCE : Results indicated that ophthalmic examination findings for anesthetized BTPDs can be in uenced by the anesthetic protocol used. The DKM protocol may result in more consistent pupil size and globe position, compared with that achieved by use of the ISO protocol. Tear production and intraocular pressure measurements should be conducted promptly after induction of anesthesia to avoid the effect of anesthetic episode duration on these variables.

· Injectable and inhalation anesthesia can have ophthalmological effects: decrease tear production, alter IOP by changing rate of aqueous humor production or outflow or by increasing extraocular muscle tone

Study design : Randomized complete crossover design, 9 BTPDs that received Dexmed (0.25 mg/kg), ketamine (40 mg/kg), midazolam (1.5 mg/kg) IM or isoflurane for 45 mins ; Ocular variables assessed at 5, 40 and 45 mins : pupil diameter, globe position, IOP, tear production (phenol red tear test and modified Schirmer test)

• Mean pupil size sig smaller with ISO protocol, and decreased sig over time with both protocols. Examination of lens and posterior segment challenging
• Globe position in several positions other than central w/ ISO protocol
• Mean phenol red tear test values lower w/ DKM protocol, PRTT and STTI values decreased over time w/ both protocols
  
  • PRTT requires only small volume of tears and short testing time \ better adapted for use in rodents than Schirmer
  • Schirmer tear test modified by cutting each strip in half longitudinally through plastic cover
  • Tear test values in BTPDs and other small rodents usually much lower than in larger mammals. Possibly adaptation to desert/dry environments (fluid conservation) or bc aqueous component of tear that is measured by these test is lower compared to mucus or lipid (more viscous tears could be protective barrier against debris when burrowing)
• No sig dif in IOP btw protocols, decreased sig over time with both

o Equally appropriate for anesthesia when low-normal IOP is desired

Question 9

A recent study evaluated the effects of dexmedetomidine ketamine and midazolam for anesthesia of five-striped palm squirrels?

Describe induciton and recovery with this protocol?

What physiolgoic variables were altered by this protocol?

Was a surgical plane maintained?

Answer 9

Eshar, D., & Beaufrère, H. (2019). Anesthetic effects of dexmedetomidine-ketamine-midazolam administered intramuscularly in five-striped palm squirrels (Funambulus pennantii). American journal of veterinary research, 80(12), 1082-1088.

OBJECTIVE To evaluate efficacy and safety of anesthesia with dexmedetomidine ketamine-midazolam (DKM) in five-striped palm squirrels (Funambulus pennantii).

ANIMALS 8 male squirrels.

PROCEDURES Squirrels were anesthetized with DKM (dexmedetomidine, 0.1 mg/ kg; ketamine hydrochloride, 30 mg/kg; and midazolam, 0.75 mg/kg) administered IM. Atipamezole (0.15 mg/kg) and flumazenil (0.1 mg/kg) were administered IM 40 minutes after induction of anesthesia. Vital signs and responses were recorded every 5 minutes during anesthesia.

RESULTS Anesthetic induction and recovery from anesthesia were rapid and without complications in all squirrels. Median anesthetic induction time was 67.5 seconds (interquartile [25th to 75th percentile] range, 5.5 seconds), and mean ± SD recovery time after drug reversal was 147 ± 79 seconds. Heart rate, respiratory rate, and rectal temperature significantly decreased during the anesthetic period. All squirrels became hypothermic by 40 minutes after induction. The righting reflex was absent during the 40-minute anesthetic period in all squirrels, with variable responses for the palpebral reflex, jaw tone, forelimb withdrawal reflex, and hind limb withdrawal reflex. Only 2 of 8 squirrels had loss of the limb withdrawal reflex in both the forelimbs and hind limbs from anesthetic induction to 25 minutes after induction. CONCLUSIONS AND CLINICAL RELEVANCE DKM appeared to provide safe and effective anesthesia in five-striped palm squirrels, but oxygen and thermal support were indicated. At the doses administered, deep surgical anesthesia was not consistently achieved, and anesthetic depth of individual squirrels must be determined before surgical procedures are performed in palm squirrels anesthetized with this drug combination.

• Species used- Five-striped palm squirrels (Funambulus pennantii) = northern palm squirrels = rodents in the family Sciuridae
  
  • Used commonly in research for endocrinology studies
• Objective of the study was to find an alternative to inhalation drug due to risk of waste gases being inhaled by researchers during mask induction
  
  • Chose DKM due to previous studies in prairie dogs
• All squirrels were stable throughout the perianesthetic period and had no adverse effects related to anesthesia during or after conclusion of the study
• Heart rate, respiratory rate and temperature all lower during anesthesia than at baseline- strongly recommend
• Induction and recovery times were brief
• Protocol lasts about 40 minutes
• Did NOT provide a consistent surgical plane of anesthesia- additional drugs or increased doses needed for painful procedures

Question 10

A recent study compared the anesthetic effects of alfaxalone-ketamine-dexmedetomidine to alfaxalone-butorphanol-midazolam in naked mole rats.

What is the scientific name of the naked mole rat?

How did induction vary between the two protocols?

What physiologic parameters differed between the two protocols?

Answer 10

Eshar, D., Huckins, G. L., Shrader, T. C., & Beaufrère, H. (2019). Comparison of intramuscular administration of alfaxalone-ketamine-dexmedetomidine and alfaxalone-butorphanol-midazolam in naked mole-rats (Heterocephalus glaber). American journal of veterinary research, 80(12), 1089-1098.

OBJECTIVE : To compare anesthetic effects of alfaxalone-ketamine-dexmedetomidine (AKD) and alfaxalone- butorphanol-midazolam (ABM) in naked mole-rats (Heterocephalus glaber).

ANIMALS: 20 naked mole-rats.

PROCEDURES: Naked mole-rats received AKD (alfaxalone, 2 mg/kg; ketamine, 20 mg/kg; and dexmedetomidine, 0.02 mg/kg; n = 10) or ABM (alfaxalone, 2 mg/kg; butorphanol, 2 mg/kg; and midazolam, 1 mg/kg; 9) IM; 1 animal was removed from the study. Atipamezole (1 mg/kg) and flumazenil (0.1 mg/kg) were administered 40 minutes after anesthetic induction (defined as loss of the righting reflex) with AKD and ABM, respectively. Heart rate, respiratory rate, oxygen saturation, and reflexes were recorded every 5 minutes.

RESULTS: The ABM group had significantly longer median times for induction and recovery than the AKD group. Administration of ABM resulted in significantly lower respiratory rates than administration of AKD from time of anesthetic induction to 10 minutes after induction. Respiratory rate significantly decreased in the AKD group from 10 minutes after induction through the end of the anesthetic period but did not change over time in the ABM group. Males had higher respiratory rates in both groups. Loss of the righting reflex was still evident 40 minutes after induction in both groups. In the AKD group, all tested reflexes were absent from 10 to 40 minutes after induction; the ABM group had variable reflexes that recovered within individual animals over time.

CONCLUSIONS AND CLINICAL RELEVANCE: Both AKD and ABM provided effective immobilization in naked mole-rats, but AKD appeared to provide more consistent and deeper anesthesia, compared with administration of ABM.

Background: Naked mole rats have lower basal metabolic rates so extrapolation from rodent data is not recommended. Need wide safety margin. Alfaxalone more predictable for anesthesia (rather than just sedation) when given in combo.

• AKD group had a significantly shorter and more consistent recovery after administration of the reversal agent
• Combinations provided more satisfactory results than alfaxalone alone (compared to previous studies)
• Recommended that the dose of alfaxalone administered IM should not exceed 5 mg/kg (0.05 mL) at each injection site (did not exceed in study)
  
  • Much lower dose in combination than when used alone
• Induction time for both drug combinations less than mean induction time for Ansell mole-rats and giant mole-rats anesthetized with ketamine-xylazine
  
  • Higher ketamine dose in this study than in others
• AKD had shorter recovery - more advantageous than ABM (esp in field settings)
• Duration of ax can’t be determined as reversals given 40min after induction regardless
• Differences in withdrawal responses between the fore and hind limbs of the ABM group→ both the fore and hind limbs should be used to determine the plane of anesthesia before application of invasive or pain-inducing procedures
• Naked mole rats compared to humans can have a left-ward shift in the oxygenation curve → pulse oximetry measurements could possibly overestimate blood oxygenation
• Combinations rather than alfaxalone alone can reduce adverse effects in other spp, no adverse effects of alfaxalone noted in this study beyond RR decrease

Take home points: Both AKD and ABM provided sufficient levels of anesthesia for exam +/- surgical plane

Question 11

A recent study evaluated the effects of echocardiographic variables and plasma cardiac troponin I conccentrations in prarie dogs receiving either dexmedetomidine-ketamine-midazolam or isoflurane anesthesia.

How did the echocardiographic variables differ between the prototocols?

How did cardiac troponin I levels vary between the protocols?

A similar study in chinchillas resulted with what echocardiographic changes?

What other physiologic parameters changed with DKM over iso?

Answer 11

Ross, E., Thomason, J. D., Browning, G. R., Beaufrère, H., & Eshar, D. (2019). Comparison of the effects of a dexmedetomidine-ketamine-midazolam anesthetic protocol versus isoflurane inhalation anesthesia on echocardiography variables and plasma cardiac troponin I concentration in black-tailed prairie dogs (Cynomys ludovicianus). American journal of veterinary research, 80(12), 1114-1121.

ABSTRACT:

• OBJECTIVE To compare the effects of a dexmedetomidine-ketamine-midazolam (DKM) anesthetic protocol versus isoflurane inhalation anesthesia on echocardiographic variables and plasma cardiac troponin I (cTnI) concentration in black-tailed prairie dogs (BTPDs; Cynomys ludovicianus).
• ANIMALS Nine 6-month-old sexually intact male captive BTPDs.
• PROCEDURES Each BTPD was randomly assigned to be anesthetized by IM administration of dexmedetomidine (0.25 mg/kg), ketamine (40 mg/kg), and midazolam (1.5 mg/kg) or via inhalation of isoflurane and oxygen. Three days later, each BTPD underwent the alternative anesthetic protocol. Echocardiographic data and a blood sample were collected within 5 minutes after initiation and just prior to cessation of each 45-minute-long anesthetic episode.
• RESULTS Time or anesthetic protocol had no significant effect on echocardiographic variables. For either protocol, plasma cTnI concentration did not differ with time. When administered as the first treatment, neither anesthetic protocol significantly affected plasma cTnI concentration. However, with regard to findings for the second treatments, plasma cTnI concentrations in isoflurane-treated BTPDs (n = 4; data for 1 animal were not analyzed because of procedural problems) were higher than values in DKM-treated BTPDs (4), which was suspected to be a carryover effect from prior DKM treatment.
• CONCLUSIONS AND CLINICAL RELEVANCE The DKM and isoflurane anesthetic protocols did not have any significant effect on echocardiographic measurements in the BTPDs. Increases in plasma cTnI concentration during the second anesthetic episode were evident when BTPDs underwent the DKM anesthetic protocol as the first of the 2 treatments, suggestive of potential myocardial injury associated with that anesthetic protocol. Clinicians should consider these findings, especially when evaluating BTPDs with known or suspected cardiac disease. (Am J Vet Res 2019;80:1114–1121)
• DKM combination partially reversible and may be more helpful in field situations and to reduce inhalant risk to staff
• Echocardiographic variables in prairie dogs with isoflurane previously performed
• Cardiac troponin I is an inhibitory subunit of troponin and is a cardiac-specific marker for myocardial injury in many species

STUDY DESIGN: Prospective study using nine 6mo old male prairie dogs. Randomized crossover design and each animal underwent anesthesia on 2 occasions (gas and DKM IM) 3 days apart, 45 mins each (gas or reversal given). Each animal received a bouls of LRS SC after each anesthetic. No supplemental oxygen provided. Blood sample collected within 5 mins of induction and just prior to reversal (at 45min). Echocardiograms performed within 5 mins of induction and prior to reversal.

• No complications or adverse effects related to anesthesia
• 4 underwent DKM first and 5 underwent isoflurane first, then reversed 3d later. One animal was excluded from study after 2^nd study
• No influence of time on cTnI concentrations in comparing the T0 and T45 measurements. The cTNI concentration was significantly higher when prairie dogs underwent isoflurane second time. Indicating possible carryover effect from initial treatment of DKM.
• No significant effect of time on echocardiographic variables within each protocol or between the two protocols. No notable chamber enlargement, vessel dilation or valve regurg noted
• Significantly lower SpO2 at time 5-25min in the DKM protocol compared to isoflurane.
• Currently no reported echocardiographic reference ranges for nonanesthetized prairie dogs, but the measurements in this study were similar to those previously collected using isoflurane
• In a chinchilla study that compared dexmed-ketamine protocols and echocardiographic findings, there was a significant change between anesthesia and conscious measurements (reduced cardiac output, larger L ventricular volume). In this study no changes in echocardiographic values were detected between both methods. Conscious prairie dog echocardiographic findings have not previously been collected
• Mean baseline value for healthy prairie dogs cTnI concentration may be 0.2ng/mL; near zero concentrations may reflect inadequate sensitivity of the assay
• Increase in plasma cTNI concentrations 3 days after DKM anesthesia- human cTnI peaks at 12-24hrs after myocardial damage, which then has a second increase 2-4 days later (biphasic release)
• Dog study indicated sedation with a2 agonist and breathing room air can develop hypoxemia. Possible this occurred in this study, though vasoconstriction may also account for the drop in spO2 noted.
• cTN1 elevations indicate myocardial disease but do not indicate cause. Prognostic if persistently elevated
• >1ng/mL indicative of severe myocardial insult in small animals, consistent with that found in the DKM cases in prairie dogs
• Should provide supplemental oxygen for animals receiving DKM protocols, as well as a longer washout period (over 3d) between anesthesias

TAKE HOME: DKM and inhalant anesthesia is safe in use for prairie dogs and does not affect echocardiographic findings. Use oxygen and do not re-anesthetize in less than 3 days if using DKM protocols

Question 12

A recent study evaluated the leptospira species in nonhuman primates and free-ranging rodents in Brazil.

What rodent species is the main carrier of leptospirosis?

What environmental factors enhance survival outside the host?

What species of rodents were evaluated? How prevalent was leptospiral seroprevalence?

What serovar was most commonly identified?

How prevalent was leptospiral serorpevalence in the nonhuman primates evaluated?

Answer 12

LEPTOSPIRA SPECIES STATUS OF CAPTIVE NONHUMAN PRIMATES AND FREE-RANGING RODENTS AT THE BARRANQUILLA ZOO, COLOMBIA, 2013

Danielle Woolf, DVM, Carlos Sanchez, DVM, MSc, Viviana Gonzalez-Astudillo, BVSc, MNR, PhD, Mauricio Navarro, DVM, MSc, PhD, Cristian Camilo Tapia, DVM, Mo´nica Franco, DVM, Javier Andre´s Bustamante, MS, Miryam Astudillo, MS, and Jean Mukherjee, DVM, Dipl, ACVM, PhD

Journal of Zoo and Wildlife Medicine 51(4): 780–788, 2020

Abstract: Leptospirosis is a zoonotic disease with worldwide distribution caused by pathogenic Leptospira spp. Pathogenic Leptospira spp. are shed in urine of infected hosts and transmitted via ingestion of contaminated food or water, inoculation, inhalation of aerosolized urine, and absorption through mucous membranes. Leptospirosis is of particular concern in tropical and subtropical regions such as Barranquilla, Colombia. Recent reports indicate that in Barranquilla, rodents, dogs, and humans have a high leptospiral seroprevalence; and amongst zoo mammals, nonhuman primates have a high prevalence of Leptospira spp. infection. We therefore sought to determine whether primates in captivity at the Barranquilla Zoo were exposed to Leptospira spp. and whether there was a probable causal transmission link between the primates and peridomestic rodents. Samples were collected from 29 captive nonhuman primates, 15 free-ranging rats (Rattus rattus), and 10 free ranging squirrels (Sciurus granatensis). Serum samples from primates, rats, and squirrels were evaluated via microagglutination test (MAT) vs 24 reference Leptospira serovars. Blood and urine from the primates and kidney tissue from the rats and squirrels were cultured in Ellinghausen-McCullough-Johnson-Harris (EMJH) medium and polymerase chain reaction (PCR) of lipL32 was performed to determine whether active infection was present. Leptospiral seroprevalence was found to be 66.7% (10/15) in rats, 60% (6/10) in squirrels, and 6.9% (2/29) in neotropical primates. Ateles hybridus and Ateles fusciceps had positive titers to serogroups Cynopteri and Ictohaemorrhagiae, respectively. Of the rodents that had antibodies against Leptospira spp., 90% of the rats and 66.7% of the squirrels corresponded to the serovar australis. Interestingly, all animals were culture and PCR negative, indicating Leptospira spp. exposure in the absence of current infection. While their status as maintenance hosts needs to be investigated further, this is the first study to show leptospiral seropositivity in red-tailed squirrels (S. granatensis).

Importance: high. Zoonosis

Background

· Leptospirosis

o World’s most widely distributed zoonosis→ classified as a neglected infectious disease

o Caused by pathogenic serovars of a bacterial spirochete: genus Leptospira

-Infects most mammalian sp

o Untreated, leptospirosis → leads to kidneys/liver failure, and +/- death in primates

• Chronic infection of the proximal renal tubules

o Rodents → widely distributed reservoirs or maintenance hosts of leptospira

o Increased rainfall, humidity, and temperature→ enhance survival of Leptospira outside of a host→ increased prevalence of disease in tropical / subtropical

o Black rats (Rattus rattus) are carriers

o Limited data available on squirrels as a host species for Leptospira spp.

o Leptospirosis → endemic in Colombia

Study design

· Purpose: To better understand the role of peridomestic rodents with regard to transmission of Leptospira spp. to captive nonhuman primates in a leptospirosis endemic region

o Drinking water source and animal origin, were also investigated

· N=29 healthy, captive neotropical primates at the Barranquilla Zoo

o Blood (venipuncture) and urine (cystocentesis) collected

· N=25 free-ranging rodents (15 black rats and 10 redtailed squirrels) from local wild population within the zoo grounds

o Blood and euthanized → harvesting both kidneys

· Microscopic agglutination test (MAT)

o Seropositive animals were identified using the MAT→ sera samples tested against a panel of 24 Leptospira spp. antigens

· Leptospira culture

o Blood and urine from primates and kidney from rodents were cultured in Ellinghausen McCullough-Johnson-Harris (EMJH) media

· DNA extraction and PCR identification of LipL32

o Macerated kidney

Results

· Seroprevalence: 7% captive non-human primates, 67% black rats, and 60.0% red-tailed squirrels

· Leptospiral seroprevalence was lower in primates compared w/ rats and squirrels during

o Not different w/ respect to age or sex

· 2 nonhuman primates seropositive (icterohaemorrhagiae)

o None clinically ill

o No relationship between seropositivity & drinking water source

· 2/3 black rats seropositive

o Serovar shermani, australis, djasiman, and hurtsbridge

· 2/3 serum samples from red-tailed squirrels seropositive

o Serovar tarassovi, panama, australis, and mini

· None of the cultured samples had of spirochetes

· None of the samples were positive for LipL32 on PCR

Discussion

· 2 rodent species, black rats and red-tailed squirrels included in study

o Black rats are known maintenance hosts of the icterohaemorrhagiae and copenhagen serovars within the region

o Other squirrel species have been shown to be potential hosts elsewhere

· Most rodents sampled were seropositive against serovar australis

o None of the primates were seropositive for australis

o This serovar is reported in ill humans

o Red-tailed squirrels may act as reservoirs

· Serovar icterohaemorrhagiae is known to be harbored by rodents within the region

· Pathogenic Leptospira spp. are known to survive and remain infectious long-term within the environment—in wet soil a minimum of 43 days and in freshwater a minimum of 20 months

Question 13

A recent study evaluated the pathological conditions of the endangered Amargosa vole.

What is their scientific name?

What was the etiology of their tail infections?

What metabolic conditions were observed in these animals?

What GI issues were most common?

What urinary findings were common?

What were the most common parasites observed?

Answer 13

Foley, J., Allan, N., Pesapane, R., Johnson, A., Woods, L., Brignolo, L., … & Imai, D. M. (2020). Disease and pathological conditions of an endangered rodent, microtus californicus scirpensis, in a captive-rearing facility and in the wild. Journal of Zoo and Wildlife Medicine, 50(4), 758-768.

Abstract: Causes of morbidity and mortality and a survey of infectious disease agents were collated from wild and colony-raised endangered Amargosa voles (Microtus californicus scirpensis). Six voles from the wild and 295 voles in the captive-breeding colony were included in the study upon identification of an infectious agent during screening, identification of clinical signs of disease, or finding a pathological condition or infectious agent on necropsy. Findings included 28 significant or incidental pathological conditions of seven organ systems and 19 parasitic, viral, bacterial, or fungal agents. Several voles captured in the wild had fungal osteomyelitis of the tail that disseminated systemically in a vole brought from the wild to the colony and may have been caused by a Penicillium sp. Three voles reintroduced from the colony to the wild experienced inanition and subsequent severe hepatic and moderate renal tubular lipidosis. The most common significant pathological conditions in colony- reared voles were chronic interstitial nephritis with proteinosis; cardiomyopathy; trichobezoars that, in intestines or cecocolic junctions, sometimes induced local rupture or infarction with peritonitis; multifocal gastrointestinal ulceration and colibacillosis; acute renal tubular necrosis or nephritis; sepsis; hepatic and renal lipidosis; molar apical elongation sometimes progressing to invasion of the calvarium; and mammary tumors. Uncommon diagnoses included intervertebral disc disease; microvascular dysplasia; and multifocal bacterial abscessation. Common or clinically important infectious agents included Demodex sp. mites in hair follicles, Demodex sp. in esophageal mucosa, and an outbreak of tropical rat mites thought to have been introduced via the straw bedding; gastrointestinal Helicobacter sp.; attaching and effacing Escherichia coli; and Citrobacter braakii, a possible zoonotic bacterium. This survey of species-specific diseases and pathogens was possible because the established health surveillance program that is part of the species recovery plan allowed for monitoring of voles throughout the duration of their natural life spans in captivity.

• Armagosa vole – Mojave desert vole that became endangered when its single marsh dried up and the ecosystem collapsed – captive colony maintained at Davis – can live up to 32 months
• Integument – demodex
• Alimentary – trichobezoars & molar apical elongation
• Repro – mucometra, mastitis
• Urinary – degenerative interstitial nephritis most finding, urolithiasis
  
  • Hepatic & renal lipidosis when voles reintroduced from wild and they don’t eat
• Cardiomyopathy
• Neoplasia – tumors of mammary glands and trophoblastic tissue
• Fungal infections – myroides infections in wild voles

Take home: Most common issues – demodex, trichobezoars, molar apical elongation, chronic nephritis, fungal infection tails

Question 14

A recent study evaluated the effect of black-tailed prairie dogs on the transmission of pathogens within ecological communities.

What is the scientific name of the black-tailed prairie dog?

Why is this species significant ecologically.

What did this study collect and evaluate?

What bacterial pathogens were identified? Did this vary in sites without prairie dogs?

What parasites were identified? Did this vary in sites without prairie dogs?

Answer 14

Zapata-Valdés, C., Avila-Flores, R., Gage, K., Holmes, J., Montenierri, J., Kosoy, M., & Suzán, G. (2018). Mammalian hosts, vectors, and bacterial pathogens in communities with and without black-tailed prairie dogs (Cynomys ludovicianus) in northwestern Mexico. Journal of Wildlife Diseases, 54(1), 26-33.

Abstract: The presence of keystone species can influence disease dynamics through changes in species diversity and composition of vector and host communities. In this study, we compared 1) the diversity of small mammals; 2) the prevalence, abundance, and intensity of arthropod vectors; and 3) the prevalence of Yersinia pestis, Francisella tularensis, and Bartonella spp. in vectors, between two grassland communities of northern Sonora, Mexico, one with (La Mesa [LM]) and one without (Los Fresnos [LF]) black-tailed prairie dogs (Cynomys ludovicianus). The mammal community in LF exhibited higher species richness and diversity than LM, and species composition was different between the two communities. Flea species richness, prevalence, abundance, and intensity, were higher in LM than in LF. The most abundant fleas were Oropsylla hirsuta and Pulex simulans, and C. ludovicianus was the host with the highest flea intensity and richness. There was no serologic evidence for the presence of Y. pestis and F. tularensis in any community, but Bartonella spp. was present in 18% of the total samples. Some specificity was observed between Bartonella species, flea species, and mammal species. Although prairie dogs can indirectly affect the diversity and abundance of hosts and vectors, dynamics of vector-borne diseases at these spatial and temporal scales may be more dependent on the vector and pathogen specificity.

• Prairie dogs – keystone spp in NA grasslands.
  
  • Influence structure and composition of plant and animal communities, modify physical and chemical properties of soils, change nutrient cycle dynamics.
  • Affect distribution of other mammals, changes dynamics of infectious disease spread. Zoonotic agents – plague, tularemia, bartonellosis.
• This study – compared two mammal communities of Mexico – one with black-tailed PD, one without, in relation to diversity of small mammals, prevalence, abundance, intensity of arthropod vectors, prevalence of Y. pestis, F. tularensis, Bartonella spp.
• Counted/collected fleas, blood samples, assessed mammal communities.
• Flea prevalence much higher where PD present (LM).
  
  • Also higher prevalence and abundance in grasslands vs shrublands (only in community with PD).
• Serologic evidence of Y. pestis, F. tularensis not found; only Bartonella spp ~18%. Not significant between PD and no PD sites.
  
  • In general – F. tularensis transmitted primarily by ticks, no ticks in this study.
• Only hooded skunk shared two spp of fleas with PD in LM; cactus mouse and gray fox shared one spp flea with BP.

Takeaway: BTPD keystone spp, fleas higher where they are present, not correlated to plague or tularemia in this study; Bartonella detected.

Answer 15

Poulsen, A., Fritz, H., Clifford, D. L., Conrad, P., Roy, A., Glueckert, E., & Foley, J. (2017). Prevalence and potential impact of Toxoplasma gondii on the endangered amargosa vole (Microtus californicus scirpensis), California, USA. Journal of wildlife diseases, 53(1), 62-72.

Abstract: We investigated the prevalence of Toxoplasma gondii in 2011–15 to assess its potential threat on the endangered Amargosa vole (Microtus californicus scirpensis) in California, US. Surveillance was simultaneously performed on populations of syntopic rodent species. We detectedantibodies to T. gondii in sera from 10.5% of 135 wild-caught Amargosa voles; 8% of 95 blood samples were PCR-positive for the T. gondii B1 gene, and 5.0% of 140 sympatric rodent brain samples were PCR-positive. Exposure to T. gondii did not change the probability that an animal would be recaptured in the field study. Behavioral response to domestic cat (Felis catus) and bobcat (Lynx rufus) urine was evaluated in five nonendangered Owens Valley voles (Microtus californicus vallicola) as surrogates for Amargosa voles and seven uninfected controls. Voles showed mild attraction to mouse urine and had neutral reactions to domestic cat urine whether or not infected. Time spent near bobcat urine was approximately twice as high in infected than in uninfected voles (although not statistically significant). The presence of T. gondii in wild Amargosa vole and sympatric rodent populations may hinder the endangered Amargosa vole population’s ability to recover in the wild.

• Amargosa vole may maintain T. gondii in nature and represent a stressor to Amargosa vole population health
  
  • Infection can cause abortion and altered behavior that increases risk of predation
• Toxoplasma gondii is a zoonotic protozoan, infecting 30–40% of humans causing birth defects and miscarriages
  
  • Only sexually reproduces in felines, including cats (Felis catus) and bobcats (Lynx rufus)
  • Oocysts in felid feces may remain viable for months to years
  • Infection leads to formation of latent tissue cysts in muscle and brain – transmitted through tissue consumption
  • Transplacental transmission is also a major route in small mammals
• Toxoplasma gondii causes reduced aversion to felids in some rodents 🡪 form of parasite-increased trophic transmission (PITT)
• Goal: determine T. gondii prevalence, if infected voles exhibit attraction to felids, and determine if natural infection reduces vole survival
  
  • Owens Valley voles were surrogates and administered T.gondi oocysts and response to bobcat or domestic cat urine, mouse urine, or control (fig 2) evaluated
• Prevalence in voles was 10%
  
  • Possibly higher if brain could be tested (more likely to be positive than blood)
  • Only area with bobcat sighting did not have T. gondii
  • Voles living farther from buildings had lower exposure suggesting pet cats having an effect
• Data suggests no reaction to domestic cat or bobcat urine and an attraction to house mouse urine, regardless of infection status
  
  • Lack of effect may be affected by oocyst dose or use of a proxy species
• Data suggests possibility of attraction to bobcat urine (but not statistically significant)
  
  • Time spent near bobcat urine was approximately twice as high in infected than in uninfected
  • Reason for response difference between domestic and bobcats is not clear

Take home: T. gondii prevalence of 10% in Amargosa voles and possible attraction to bobcat urine seen in experimental trials

Question 16

A recent study descrbied bayliscascaris larva migrans in North American Beavers.

What is the scientific name of the North American beaver?

How were these beaver affected by B. procyonis?

What lesions were seen on necropsy?

What are some possible treatments for this parasite?

Answer 16

Desprez, I., Yabsley, M. J., Fogelson, S. B., Hicks, J. A., Barber, R., Sladakovic, I., … & Mayer, J. (2017). Baylisascaris procyonis larva migrans in two captive north american beavers (castor canadensis). Journal of Zoo and Wildlife Medicine, 48(1), 232-236.

Abstract: Baylisascaris procyonis larva migrans was diagnosed in two North American beavers (Castor canadensis) belonging to a zoological park in Clarke County, Georgia. Both beavers presented with neurological signs. One beaver died naturally and despite attempted treatment, the other beaver was euthanatized because of severe clinical signs and poor prognosis. Histologic evaluation of the beavers revealed evidence of parasitic migration characterized by several lesions, including eosinophilic granulomas in various organs, as well as necrotizing eosinophilic and lymphoplasmacytic to granulomatous polioencephalitis, leukoencephalitis and cervical leukomyelitis. This represents the first confirmed case of B. procyonis larva migrans in beaver and the first non-raccoon (Procyon lotor) host in the southeastern United States. This report highlights the need for clinicians and diagnosticians to consider baylisascariasis in animals with compatible clinical signs. Preventative measures should be considered for captive animals, because early diagnosis of B. procyonis is challenging, and treatment is often unrewarding.

· Baylisascaris procyonis

o Intestinal nematode of raccoons, fatal larva migrans in other species

o Intermediate host – commonly rodents

· First confirmed cases of B. procyonis larva migrans in beaver

o Signs – behavior change, vestibular signs, ataxia

o Necropsy lesions - eosinophilic granulomas in various organs, necrotizing eosinophilic and lymphoplasmacytic to granulomatous polioencephalitis, leukoencephalitis and cervical leukomyelitis

· Possible treatments for larval migrans

o Anthelmintics, corticosteroids

o Fenbendazole or albendazole

Question 17

A recent study described ear mite infestation in Patagonian cavies.

What rodents are in the family caviidae?

describe teh anatomy and natural history of the patagonian cavy.

What is the scientific name fo teh ear mite? What are its natural hosts? What is its defining morphology?

How can this be treated?

Answer 17

da Cruz, C. L., Alpino, T., & Kottwitz, J. (2017). Recurrent ear mite (Otodectes cynotis) infestation in three related groups of Patagonian cavies (Dolichotis patagonum). Journal of Zoo and Wildlife Medicine, 48(2), 484-490.

Abstract: Two of three groups of Patagonian cavies (Dolichotis patagonum) contracted Otodectes cynotis infestations after exposure to mite-infested feral cats. Otodectes cynotis infestations were initially identified in 9 of 10 cavies in group 1. Multiple feral cats with O. cynotis infestations were observed in the vicinity of the Patagonian cavies and were subsequently removed. The Patagonian cavies were initially treated with ivermectin (0.4 mg/kg s.q.) every 2 wk, but ivermectin was discontinued after the third treatment due to injury to one of the Patagonian cavies during capture. Sixteen months after initial treatment, clinical signs of scratching the pinnae, hemorrhagic lesions on the ear margins, head shaking, and O. cynotis mites in the auricular canal were again noted in all Patagonian cavies in group 1. Repeated administration of ivermectin (0.4 mg/kg s.q. every 2 wk for three treatments) failed to eliminate the mites in two of the Patagonian cavies. Selamectin administered (20 mg/kg, topically between the shoulder blades) to all Patagonian cavies eliminated the mite infestation after a single application. The Patagonian cavies remained O. cynotis mite free for 2 yr, until males (group 2) and females (group 3) were separated for population control. Three months after separation, 8 of the 12 females in group 3 again were infestated with O. cynotis mites. Feral cats with O. cynotis infestations were again noted in the vicinity of group 3. A single dose of selamectin applied topically eliminated all mites in all treated Patagonian cavies. Group 2 was not exposed to feral cats and remained mite free.

• Patagonian cavy – one of the largest rodents.
• Caviidae also includes capybaras, domestic guinea pigs.
  
  • Patagonian cavies – Longer ears, short tail, relatively long limbs for running.
  • Native to only Argentina.
  • Opportunistic browsers.
  • Live in large groups up to 70, communal burrows.
  • Shared denning may contribute to spread of parasites.
• Otodectes cynotis – nonburrowing, surface-living mite of family Psoroptidae.
  
  • Infestation of external acoustic meatus of dogs, cats. Feed on epidermal debris.
  • Highest prevalence in stray and feral cats. Very itchy. Live up to 12 days in environment.
  • First report of this parasite in an herbivorous species except one WTD report.
  • Specific morphologic characteristics – merging of long apodemes extending from the coxae of legs 1 and 2; females with suckers only on legs 1, 2; males with suckers on legs 1-4; fourth leg of female very small relative to others.
    
    • Allow for positive ID by microscopic evaluation alone.
    • Compared to Chorioptes spp mites:
      
      • Much shorter, nonmerging apodemes extending from coxae of legs 1 and 2; females with suckers on legs 1, 2, 4, with smaller sucker on leg 4, with fourth leg of females as long as the other legs.
      • Distinctly angular lobes on the caudal end of the body, not the more rounded caudal body shape observed on the Patagonian cavies.
• Selamectin – Arthropod death by stimulating release of gamma-amino butyric acid at presynaptic neurons. Transdermal absorption. In this case series used rabbit dose (20 mg/kg topically between shoulders).

Takeaway: Otodectes cynotis ear mites can infect cavies from feral cats, use selemectin to tx.

Question 18

A recent paper described a urethral diverticulum and urolithiasis in a female guinea pig.

How did this guines pig present nad how was it diagnosed?

What procedure was performed in this guinea pig?

What are the most common stone types on guinea pigs?

Answer 18

Journal of the American Veterinary Medical Association 2017; 251: 1313-1317

URETHRAL DIVERTICULUM AND UROLITHIASIS IN A FEMALE GUINEA PIG (CAVIA PORCELLUS)

Parkinson, Lily; Hausmann, Jennifer C; Hadie, Robert J; Mickelson, Megan A; Sladky, Kurt K. Reviewed by SP

CASE DESCRIPTION

A 5-year-old sexually intact female guinea pig was evaluated because of mild dysuria and a subcutaneous mass located cranioventral to the urogenital openings.

CLINICAL FINDINGS

Non–contrast-enhanced CT and surgical exploration of the distal aspect of the urethra revealed a urethral diverticulum with an intraluminal urolith. Analysis revealed that theurolithwascomposed of calcium carbonateand struvite.

TREATMENT AND OUTCOME

The urolith was surgically removed and ablation of the urethral diverticulumwas attempted. Approximately3 months later, the guinea pig was reevaluated for masses in the perineal region, andpositive-contrasturethrocystographyrevealed2 uroliths present in the same diverticulum. Uroliths were manually expressed with the patient under general anesthesia. Approximately 2 weeks later,urethroplastywas performed to create anenlarged stoma with the diverticulum,therebypreventing urine from poolingin the diverticulum and potentiallyreducing the risk of future urolith formation. The urethroplasty site healed well withno reported complicationsor evidence of urolith recurrence 6 months after surgery.

CLINICAL RELEVANCE

Urolithiasis is common in guinea pigs, and urethral diverticulum and intraluminal urolithformation should be considered as apotential differential diagnosis for a subcutaneous mass along the distal aspect of the urethra. Creation ofa urethral stomafrom aurethral diverticulum via urethroplasty achieved a successful outcome in this patient.

Key points:

· Urethroplasty

o Goal: prevent urine accumulation to prevent future predisposition to uroliths

o Pros: Reduces risk of stricture

o Cons: general anesthesia and risk of urethral stricture post-op

o Pass 5 Fr red rubber into urethra and diverticulum (A)

o Midline incision from cranial aspect of urethral stoma to diverticulum

o Incised urethral mucosa and diverticulum, appose edges to perineal skin (B)

· Histopathology of urethral diverticulum tissue

o Dense collagenous connective tissue, keratinizing stratified squamous epithelium with multifocal erosions and replaced with serocellular crust of degenerate neutrophils and cellular debris

· Urolithiasis in guinea pigs

o #1 calcium carbonate, #2 struvite

o Median age of 3 YO

o No known definitive cause

· Urethral diverticulum: uncommon, described in rabbits, swine and humans

o Congenital or acquired

o Unclear of etiology in this case- did diverticulum collect urine sedimentàuroltih OR urolith àurethral strictureàprogressive dilation of urethra and eventual diverticulum

· Unique genital anatomy- simplifies surgical approach, makes urethroplasty best option in female GP’s

o 3 external openings in females (anus, urethra and vagina)

Take home: urethroplasty successful in preventing further urolith formation for 6 mos, and should be considered a viable option for similar cases

Question 19

A recent study described the distribution and seasonal variation of lgungan virus in bank voles.

What type of virus is Ljungan virus/. What types of diseases may this be associated with?

How prevalent was this virus?

Were there any groups that showed different prevalences?

Answer 19

Fevola, C., Rossi, C., Rosà, R., Nordström, Å., Ecke, F., Magnusson, M., … & Hauffe, H. C. (2017). Distribution and seasonal variation of Ljungan virus in bank voles (Myodes glareolus) in Fennoscandia. Journal of wildlife diseases, 53(3), 552-560.

ABSTRACT: Ljungan virus (LV) is a picornavirus originally isolated from Swedish bank voles (Myodes glareolus) in 1998. The association of LV with human disease has been debated ever since, but fundamental data on the ecology of the virus are still lacking. Here we present results of the first intensive study on the prevalence of LV in bank voles trapped in Fennoscandia (Sweden and Finland) from 2009–12 as determined by PCR. Using an LV-specific real-time reverse transcriptase PCR, LV was detected in the liver of 73 out of 452 (16.2%) individuals and in 13 out of 17 sampling sites across Sweden and Finland (mean per site prevalence 16%, SE 3%, range 0–50%). We found more infected animals in autumn compared to spring, and lighter and heavier individuals had a higher prevalence than those with intermediate body masses. The result that LV prevalence is also lower in heavier (i.e., older) animals suggests for the first time that LV infection is not persistent in rodents.

• Ljungan virus (LV, also called Parecho-virus B) is a positive-sense RNA virus belonging to the family Pircornaviridae, first isolated in bank voles in Sweden in 1998
  
  • May be associated with human diseases including myocarditis, type 1 diabetes, and fetal pathologies
  • Role of LV in these syndromes remains controversial and role of rodent reservoirs is unknown
• Goal was to present prevalence of LV viral RNA in bank voles in Fennoscandia (Sweden and Finland)
  
  • 452 voles were live trapped, and livers tested using PCR for LV RNA
• LV detected in 16.2% of voles and 76% of sampling sites
  
  • Range is striking with 0-50% among study sites (previously reported in limited number of voles)
• Higher prevalence in LV in autumn
  
  • Possible explanations include chronic infections leading to vole mortality 🡪 reducing spring numbers OR voles may clear LV infection with LV antibodies disappearing or decreasing to undetectable levels
    
    • Little is known about LV kinetics
  • Host social behavior could cause 🡪 high contact rate during reproductive season (march-sept) may promote pathogen spread

Lighter and heavier animals show lower LV prevalence

• Result for lighter animals expected since juvenile rodents have low pathogen prevalence – limited contact and not had time to be infected
• Lower prevalence in heavier (older) animals suggests for the first time that LV infection is not persistent in rodents

Take home: LV has higher prevalence than previously thought with 16.2% of individuals sampled and 0-50% range, higher prevalence of LV in autumn

Question 20

A recent study established the hematologic and biochemical values of eastern gray squirrels.

How were these animals sedated for blood collection?

How did blood values differ from other rodents?

Answer 20

Ratliff, C., Kingsley, L., Kusmierczyk, J., Gentry, J., Russell, K. E., & Heatley, J. J. (2019). Hematologic and biochemical values of the juvenile eastern gray squirrel (sciurus carolinensis). Journal of Zoo and Wildlife Medicine, 50(3), 644-649.

Abstract: Venous blood samples were collected from 64 apparently healthy juvenile Eastern gray squirrels (Sciurus carolinensis) after sedation with midazolam at the Wildlife Center of Texas located in Houston, Texas, during 2012. Blood gas (pH, PCO2, PO2, base excess, bicarbonate, oxygen saturation), electrolyte (sodium, potassium), biochemical (total CO2, ionized calcium, glucose), and hematologic parameters (hematocrit, hemoglobin, complete blood count) were determined using the i-STAT point-of-care analyzer. Sex did not affect any analyte. All squirrels recovered uneventfully and were successfully rehabilitated and released. Most values were as expected based on comparison to other young rodent species. These analyte data for healthy juvenile Eastern gray squirrels may be useful in assessment of Eastern gray squirrel population health and management and treatment of individual squirrels presented in need of medical care.

• Goal of study- provide reference interval data from rehabbing EGS + preliminary data regarding sedation protocol
• Prospective: collected samples from juvie EGS (4-6 wks, n - 64) that presented to wildlife rehab center
• Sedation - midazolam ~1.2 mg/kg IM - sedation evaluated based on acceptance of manual restraint
• Results similar to those previously published in other similar species
  
  • Glu & TS had less variability - attributed to standardized diet/environment of rehabbed squirrels
  • First time iCa values assessed and published - can help evaluate for nutritional hyperparathyroidism (though values in disease unknown)
  • Sedation was effective and may be preferable to ISO due to iso’s effects on blood gas analysis
    
    • Decrease pH and resp acidosis previously seen in prairie dogs
  • Increased WBC vs wild caught adults, may be age related or associated with rehab setting
  • No effect of sex or body mass on analytes

TAKE HOME:

Blood analytes including blood gas, and basic biochem and hematology can be useful in assessment of juvenile EGS presenting in need of medical care. Midazolam can be used successfully in juvie ground squirrels for blood collection.

Question 21

A recent study evaluated echocardiography in nonsedated free ranging agouti.

What is the scientic name of the agouti?

What parameters varied based on size of the animals?

What animal has similar echocardiographic measurements?

Answer 21

Sousa, M. G., Lucina, S. B., Camacho, R. R., Przydzimirski, A. C., & Lange, R. R. (2020). Transthoracic echocardiography in nonsedated, free-ranging healthy agoutis (dasyprocta azarae). Journal of Zoo and Wildlife Medicine, 50(4), 903-909.

Abstract: Most of the agouti species are kept in captivity, including the species Dasyprocta azarae. These animals are of zootechnical interest and, in addition, they can potentially be used as experimentation models because of their physical characteristics and possibility of manipulation. Therefore, the purpose of this study was to investigate the feasibility of the echocardiographic exam in nonsedated agoutis and to determine the normal reference ranges for the standard transthoracic echocardiographic parameters in healthy, adult, free-ranging agoutis found in an urban wood and intended for scientific investigations. Most of the echocardiographic parameters evaluated were similar to what has already been described for other rodent species such as rabbits or the Dasyprocta primnolopha agoutis. Based on the information compiled in this study, echocardiographic examination is feasible in awake adult, free-ranging agoutis. The results obtained from the morphologic and hemodynamic evaluation of the heart can help in future studies, either involving the clinical aspects or considering the potential use of these animals as an experimental model.

STUDY DESIGN: Captured 23 agoutis in wildlife park and completed echocardiograms on them after health assessment.

• Avg HR 183bpm, tables listing the normal measurements using M-mode, B-mone and Doppler echocardiography
• No difference between body weight and cardiac morphology in most measurements except in measurement of left ventricular free wall thickness at end-systole and left atrial diameter
  
  • Lower in agoutis <2.8kg compared to >3.1kg
• Noted a higher La:Ao ratio, aortic and pulmonic flow velocities in agoutis than in rabbits
  
  • Suspect due to unsedated study design compared to rabbit studies

TAKE HOME: Echocardiography measurements similar to that of rabbits, aside from having higher La:Ao ratio, aortic and pulmonic flow velocities

Question 22

A recent study evaluated echocardiography in black-rumped agouti.

How did heart rate compare to other similarly sized small mammals?

Were there differences based on sex?

How did the left ventricular chamber differ from other small mammals?

Answer 22

das Neves Diniz, A., Pessoa, G. T., da Silva Moura, L., de Sousa, A. B., Sousa, F. D. C. A., de Sá Rodrigues, R. P., … & Alves, F. R. (2017). Echocardiographic findings of bidimensional mode, M-mode, and Doppler of clinically normal black-rumped agouti (Dasyprocta prymnolopha, Wagler 1831). Journal of Zoo and Wildlife Medicine, 48(2), 287-293.

Abstract: The black-rumped agouti (Dasyprocta prymnolopha, Wagler 1831) is currently under intense ecologic pressure, which has resulted in its disappearance from some regions of Brazil. Echocardiography is widely used in veterinary medicine but it is not yet part of the clinical routine for wild animals. The objective of the present study was to assess the applicability of the echocardiographic exam in nonanesthetized agouti and to establish normal reference values for echocardiographic measurements in bidimensional mode (2D), M-mode, and Doppler for this species, and a lead II electrocardiogram was simultaneously recorded. Twenty agouti were used in this study. All the echocardiographic measurements were positively correlated with weight (P , 0.05), and there were no significant differences between sexes (P . 0.05). Blood flow velocities in the pulmonary and aortic artery ranged from 67.32–71.28 cm/sec and 79.22–101.84 cm/sec, respectively. The isovolumic relaxation time was assessed in all the animals and ranged from 38.5 to 56.6 ms. The maximum value for the nonfused E and A waves and the Et and At waves was 158 beats/min for both. The results obtained for the morphologic and heart hemodynamic measurements can guide future studies and help in the clinical management of these animals in captivity.

• Agouti is a small rodent of the Dasyprocta genus, important component of the Brazilian biome and under ecologic pressure
  
  • No reports of cardiac disease in Dasyprocta species
  • Only small exotic animals previously studied with echocardiography are rabbits and ferrets
• Goal: perform echocardiographic examinations in nonanaesthetized black-rumped agouti and establish reference values for echocardiographic measurements
  
  • 20 agoutis physically restrained under R lateral recumbency
  • Agoutis are regularly restrained and are less resistant to restraint 🡪 remained calm during manual restraint
• HR observed for the agouti was measured from the systolic pulse of the aortic flow (140.4–199.1 beats/min)
  
  • HR range in the present study was considerably lower than that of non-anesthetized rabbits but was similar to anesthetized rabbits
  • Likely related to the influence of the sympathetic (causing reflex tachycardia) and vagal tone (reflex bradycardia)
  • In this study, unlike with rabbits, agoutis are regularly handled minimizing these responses 🡪 supported by no elevated peaks in blood pressure seen
  • Minimal influence of restraint stress makes the results more reliable and approximate to the cardiologic parameters
• No difference between sexes for all of the parameters assessed
  
  • Similar to rabbits WHILE ferrets showed difference in sex but was likely more secondary to size variation than sex
  • Weight in this study was not significantly different between males and females
• L ventricular chamber dimensions were considerably greater, for both the systolic and diastolic measurements than guinea pigs, rabbits, and ferrets
• Shortening fraction values were similar to those reported for nonanesthetized ferrets and were greater than anesthetized ferrets
• Proper alignment for doppler was possible in this study favoring an insonation angle less than 20^o
• Transvalvular flows were very sensitive to HR
  
  • ↑HR caused the fusion of E and A waves (also observed in rabbits) 🡪 diastolic function evaluation was possible in 40% of agoutis
• IVRT is an indirect measure of ventricular relaxation frequently used in echocardiography
  
  • IVRT was consistent with little variability for agoutis in study with strong positive HR correlation
    
    • In contrast to humans, dogs, and cats which show negative correlation

Aorta and left atrium diameters were strongly correlated

• LA : Ao ratio were similar to those reported in rabbits, guinea pigs, and dogs

Take home: First reported echocardiographic data on agoutis

Question 23

A recent study evaluated the conjunctival microflora of the persian squirrel

What were the four most common bactiera isolated?

Are these bacteria commonly isolated in other rodent/lagomorph eyes?

Answer 23

Faghihi, H., Aftab, G., Rajaei, S. M., & Arfaee, F. (2018). Evaluation of conjunctival microbiota in clinically normal persian squirrels (sciurus anomalus). Journal of Zoo and Wildlife Medicine, 49(3), 794-797.

Abstract: This study aimed to evaluate the bacterial flora in the conjunctival fornix of clinically normal Persian squirrels (Sciurus anomalus). Forty healthy Persian squirrels of equal gender distribution with similar ages (approximately 2 yr) were used for this study. A total of 80 conjunctival swabs were taken from both the right and left eyes of each squirrel for aerobic and anaerobic bacterial identification. A slit-lamp examination was conducted and no external ocular disease was identified. From 80 normal eyes, Staphylococcus spp. comprised the most frequently isolated organism (83%), while Corynebacterium spp. were the second most frequently isolated bacteria (56%), followed by Streptococcus spp. (53%), Chlamydia spp. (33%). Mycoplasma spp. (30%), Pseudomonas spp. (23%), Escherichia coli spp. (12.5%), Enterococcus spp. (7%), and Micrococcus spp. (4%) were also isolated. The most frequently isolated bacteria from the conjunctival fornix of healthy Persian squirrels were Staphylococcus spp. followed by Corynebacterium spp.

• Gram positive most common isolates in normal conjunctiva across species
• Gram positive predominant in this study 🡪 Staphylococcus, Corynebacterium, Streptococcus, Enterococcus, and Micrococcus
  
  • Staphylococcus is most common conjunctival flora across species
• Most isolated gram negative 🡪 Chlamydia, Pseudomonas, and nonhemolytic E. coli
• Female had greater population of bacteria than males

Take home: Gram positive bacteria, esp Staphylococcus, were most commonly detected in Persian squirrel eyes

Question 24

A recent study described teh treatment of dermatophytosis in North American porcupine.

What is the scientific name of the North American porcupine?

What dermatophyte was diagnosed?

How was this treated?

Is this zoonotic?

Answer 24

Hackworth, C. E., Eshar, D., Nau, M., Bagladi-Swanson, M., Andrews, G. A., & Carpenter, J. W. (2017). Diagnosis and successful treatment of a potentially zoonotic dermatophytosis caused by microsporum gypseum in a zoo-housed North American porcupine (Erethizon dorsatum). Journal of Zoo and Wildlife Medicine, 48(2), 549-553.

Abstract: A female North American porcupine (Erethizon dorsatum) was evaluated for a unilateral pedal crusting and alopecic dermatopathy. Fungal culture and histopathology testing revealed Microsporum gypseum dermatophytosis. Treatment with topical miconazole was initiated and then discontinued after 9 days and changed to oral terbinafine. Twenty-eight days after initial examination, clinical signs were improving, and fungal cultures of the front foot, muzzle, and noninfected area along the dorsum were negative for M. gypseum. Visual exams were conducted on a regular basis. Eighty-three days after initial evaluation, clinical signs had completely resolved and repeat fungal cultures were negative. One of the animal’s keepers was suspected to have acquired a dermal fungal infection 3 days after contact with this porcupine, and lesions had resolved after treatment with topical ketoconazole. To the authors’ knowledge, this is the first report of M. gypseum diagnosed and treated in a captive North American porcupine. Veterinary staff and zookeepers should be aware of this potentially zoonotic infection.

Question 25

A recent study evaluated self-injurious behavior in rats.

What are some potential side effects of buprenorphine in rats?

When was self-injurious behavior observed? Was this for all formulations?

Did any of these formulations result in pica?

What formulations resulted in hypoalgesia?

Answer 25

Allen, M., & Johnson, R. A. (2018). Evaluation of self-injurious behavior, thermal sensitivity, food intake, fecal output, and pica after injection of three buprenorphine formulations in rats (Rattus norvegicus). American journal of veterinary research, 79(7), 697-703.

OBJECTIVE To assess effects of buprenorphine hydrochloride (BH), sustained-release buprenorphine (SRB), and high-concentration buprenorphine (HCB) formulations in healthy rats.

ANIMALS 8 Sprague-Dawley rats.

PROCEDURES In a crossover-design study, rats received BH (0.05 mg/kg), SRB (1.2 mg/kg), HCB (0.30 mg/kg), or 5% dextrose solution (0.2 mL/kg), SC, once. Self-injurious behavior [self-biting and cage-biting] and thermal sensitivity (hind limb withdrawal latencies used for hypoalgesia) were assessed prior to injection (time 0) and 1, 4, 8, 12, and 24 hours after injection. Food intake, kaolin intake [pica], and fecal output were measured over 12-hour light and dark periods before and after each treatment. Values were compared among treatments and time points.

RESULTS Self-injurious behavior was detected with all buprenorphine treatments; scores were greater at all time points during the 12 hours after HCB and 24 hours after SRB administration than at time 0. Percentage change in hind limb withdrawal latencies from time 0 was higher with BH and HCB 1 hour after injection than at other time points. Postinjection light-period food intake was higher (BH and HCB) and dark-period food intake was lower (BH, HCB, and SRB), compared with preinjection values for the same treatments. For SRB, postinjection light-period kaolin intake was greater than the preinjection value, and postinjection light- and dark-period kaolin intake was greater than that for other treatments.

CONCLUSIONS AND CLINICAL RELEVANCE Hypoalgesic effects were briefly observed after administration of BH or HCB in healthy rats; adverse effects were detected in some rats with all buprenorphine formulations. Studies comparing effects of BH, SRB, and HCB in rats undergoing surgery or other noxious stimuli are indicated to determine clinical benefits in this species.

o Buprenorphine partial mu opioid agonist.

o Other studies showed buprenorphine hydrochloride administration resulted in stress, pica, reduced food intake, altered locomotor activity, hyperalgesis due to dosing q6-8h.

o SR buprenorphine showed hypoalgesia up to 72h but adverse effects (skin irritation, lethargy, resp depression).

o Kaolin – acacia gum substance safely used to assess pica behavior in rats.

o High conc buprenorphine hypoalgesic up to 14h in cats, but in rats doses only detectable for short duration and was assoc with altered food intake and self-injurious behavior.

· Key points:

o Self-injurious behavior observed with all buprenorphine tx, at all time points for SRB and HCB and 24h after SRB.

o Withdrawal latency of hind limb higher for SRB vs BH at 24h.

§ BH and HCB withdrawal higher at 1 hour post tx compared to other time points.

· Food intake NSD.

· Kaolin intake was higher for SRB vs all other treatments.

· All of the formulations tested have the potential to cause unwanted effects.

§ Self-injurious behavior observed in all rats during the first 8 hours following tx.

§ Significant hypoalgesia observed only with BH and HCB tx, only differed at that 1 hour time point.

· Rats became more active (ate more) during light period of the day for BH and HCB.

Question 26

A recent study evaluated the effects of high concentration buprenorphine in rats.

Were any adverse effects observed?

When was withdrawal latency affected?

What gastrointestinal effects were noted?

Answer 26

Allen, M., Nietlisbach, N., & Johnson, R. A. (2018). Evaluation of self-injurious behavior, food intake, fecal output, and thermal withdrawal latencies after injection of a high-concentration buprenorphine formulation in rats (Rattus norvegicus). American journal of veterinary research, 79(2), 154-162.

OBJECTIVE To evaluate effects of high-concentration buprenorphine (HCB) on self-injurious behavior, food intake, fecal output, and thermal withdrawal latencies in healthy rats.

ANIMALS 8 Sprague-Dawley rats.

PROCEDURES Rats received 4 SC treatments (HCB at 0.075, 0.15, or 0.30 mg/kg [HCB0.075, HCB0.15, and HCB0.30, respectively] or 5% dextrose solution [0.20 mL/kg]) in a randomized, crossover-design study. Self-injurious behavior was assessed for 8 hours after injection. Food intake and fecal output were assessed for predetermined periods before and after treatment and separated into 12-hour light and dark periods for further analysis. Withdrawal latencies were assessed before (time 0) and at predetermined times after injection. Data were compared among treatments and time points.

RESULTS Self-injurious behavior was observed up to 8 hours after injection for all HCB, but not dextrose, treatments. Preinjection food intake and fecal output amounts were similar among groups and higher during the dark period than during the light period. Food intake after all HCB treatments was higher during the light period and lower during the dark period, compared with preinjection results for the same treatments and with postinjection results for dextrose administration. Light-period fecal output was lower after HCB0.15 and HCB0.30 administration, compared with preinjection values for the same treatments and postinjection values for dextrose administration. Percentage change in withdrawal latency was significantly higher than that at time 0 (ie, 0%) for only 1 treatment (HCB0.30) at 1 time point (1 hour after injection).

CONCLUSIONS AND CLINICAL RELEVANCE Although HCB0.30 produced a degree of thermal hypoalgesia in healthy rats, self-injurious behavior and alterations in food intake and fecal output were detected, potentially affecting clinical utility of the treatment.

· HCB at all doses in this study assoc with self-injurious behaviors.

· HCB at 0.30 mg/kg dose only dose to show increased withdrawal latency and only at 1 hour time point.

· Food intake did not differ significantly.

· Fecal output was lower after 0.30 mg/kg HCB vs preinjection for the same treatment, mainly attributed to lower values during the 12-hour light period after tx.

Question 27

A recent study evaluated the pharmacokinetics of buprenorphine in guinea pigs.

What dose did they use?

What two routes were investigated?

How bioavailable was the oral transmucosal route?

How often does buprenorphine in these two routes need to be administered?

Answer 27

Sadar, M. J., Knych, H. K., Drazenovich, T. L., & Paul-Murphy, J. R. (2018). Pharmacokinetics of buprenorphine after intravenous and oral transmucosal administration in guinea pigs (Cavia porcellus). American journal of veterinary research, 79(3), 260-266.

OBJECTIVE To determine pharmacokinetics and sedative effects of buprenorphine after IV and oral transmucosal (OTM) administration in guinea pigs.

ANIMALS 14 male guinea pigs (6 adults for preliminary experiment; eight 8- to 11-week-old animals for primary study).

PROCEDURES A preliminary experiment was conducted to determine an appropriate buprenorphine dose. In the primary study, buprenorphine (0.2 mg/kg) was administered IV or OTM, and blood samples were obtained. The pH of the oral cavity was measured before OTM administration. Sedation was scored for 6 hours on a scale of 0 to 3 (0 = no sedation and 3 = heavy sedation). After a 7-day washout period, procedures were repeated in a crossover manner. Plasma buprenorphine concentration was quantified, and data were analyzed with a noncompartmental pharmacokinetic approach. RESULTS Mean peak plasma buprenorphine concentrations were 46.7 and 2.4 ng/ mL after IV and OTM administration, respectively. Mean time to maximum plasma buprenorphine concentration was 1.5 and 71.2 minutes, and mean terminal half-life was 184.9 and 173.0 minutes for IV and OTM administration, respectively. There was a range of sedation effects (0 to 2) for both routes of administration, which resolved within the 6-hour time frame.

CONCLUSIONS AND CLINICAL RELEVANCE On the basis of pharmacokinetic parameters for this study, buprenorphine at 0.2 mg/kg may be administered IV every 7 hours or OTM every 4 hours to maintain a target plasma concentration of 1 ng/mL. Further studies are needed to evaluate administration of multiple doses and sedative effects in guinea pigs with signs of pain.

· Buprenorphine

o partial µ-opioid receptor agonist

o ceiling effect - increases in dosages do not result in improved analgesia

· buprenorphine 0.2 mg/kg IV or OTM

o mean bioavailability of buprenorphine after OTM administration to guinea pigs was 28.4%

o norbuprenorphine (metabolite of buprenorphine) was not detected in the guinea pigs of the present study

o bup 0.2 mg/kg IV q 7 hours or OTM q 4 hours to maintain target plasma concentration

o Anecdotally substantial sedation after OTM administration at 0.2 mg/kg to diseased or postsurgical guinea pigs

Question 28

A recent study evaluated the pharmacokinetics of enrofloxacin in black tailed prairie dogs.

What is enrofloxacin? What pathogens is it effective for?

Is it a time-dependent or concentration-dependent antibiotic?

How is it excreted adn metabolized?

what dose was used in this study? What routes?

What dose and route are recommended?

Answer 28

Eshar, D., Wright, L. T., McCullough, C. E., & Kukanich, B. (2018). Pharmacokinetics of enrofloxacin and its metabolite ciprofloxacin following single-dose subcutaneous injection in black-tailed prairie dogs (Cynomys ludovicianus). American journal of veterinary research, 79(6), 658-663.

OBJECTIVE To determine plasma concentrations of enrofloxacin and its active metabolite ciprofloxacin following single-dose SC administration to black-tailed prairie dogs (Cynomys ludovicianus).

ANIMALS 8 captive healthy 6-month-old sexually intact male black-tailed prairie dogs.

PROCEDURES Enrofloxacin (20 mg/kg) was administered SC once to 6 prairie dogs and IV once to 2 prairie dogs. A blood sample was collected from each animal immediately before (0 hours) and 0.5, 1, 2, 4, 8, 12, and 24 hours after drug administration to evaluate the pharmacokinetics of enrofloxacin and ciprofloxacin. Plasma enrofloxacin and ciprofloxacin concentrations were quantified with ultraperformance liquid chromatography–mass spectrometry, and noncompartmental pharmacokinetic analysis was performed.

RESULTS Enrofloxacin was biotransformed to ciprofloxacin in the prairie dogs used in the study. For total fluoroquinolones (enrofloxacin and ciprofloxacin), the mean (range) of peak plasma concentration, time to maximum plasma concentration, and terminal half-life after SC administration were 4.90 μg/ mL (3.44 to 6.08 μg/mL), 1.59 hours (0.5 to 2.00 hours), and 4.63 hours (4.02 to 5.20 hours), respectively.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that administration of enrofloxacin (20 mg/kg, SC, q 24 h) in black-tailed prairie dogs may be appropriate for treatment of infections with bacteria for which the minimum inhibitory concentration of enrofloxacin is ≤ 0.5 µg/mL. However, clinical studies are needed to determine efficacy of such enrofloxacin treatment.

· Enrofloxacin

o concentration-dependent fluoroquinolone

o activity against mainly gram-negative and some gram-positive bacteria

o minimal activity against anaerobic bacteria

o possibly somewhat effective for Chlamydia, Mycoplasma (Haemobartonella), Mycobacterium, and Toxoplasma

o primarily excreted through the kidneys

o can also be metabolized by liver

o low protein-binding activity

o high bioavailability

o extended half-life

o good penetration to multiple body tissues

o ciprofloxacin is an active metabolite of enrofloxacin

· Enrofloxacin 20 mg/kg administered SC once to 6 prairie dogs and IV once to 2 prairie dogs

o high parenteral absorption

o large volume of distribution

o T1/2 3-6 hours

o No adverse reactions

o Enrofloxacin 20 mg/kg SC SID would meet the surrogate markers of efficacy (ie, AUC:MIC and CMAX:MIC ratios) for treatment of susceptible bacteria (ie, bacteria for which the enrofloxacin MIC is ≤ 0.5 µg/mL) in black-tailed prairie dogs

Question 29

A recent study described a plague outbreak in gunnison’s prairie dogs despite deltamethrin burrow infusion.

What is the etiologic agent of plague?

How is it transmitted? By what species?

How effective was deltamethrin in reducing vector populations?

Answer 29

Hoogland, John L., et al. “Plague in a colony of Gunnison’s prairie dogs (Cynomys gunnisoni) despite three years of infusions of burrows with 0.05% deltamethrin to kill fleas.” Journal of wildlife diseases 54.2 (2018): 347-351.

ABSTRACT: At Valles Caldera National Preserve in New Mexico, US, infusing Gunnison’s prairie dog (Cynomys gunnisoni) burrows with an insecticide dust containing 0.05% deltamethrin killed fleas which transmit bubonic plague. The reduction in the number of fleas per prairie dog was significant and dramatic immediately after infusions, with a suggestion that the reduction persisted for as long as 12 mo. Despite the lower flea counts, however, a plague epizootic killed .95% of prairie dogs after 3 yr of infusions (once per year). More research is necessary for a better understanding of the efficacy of insecticide dusts at lowering flea counts and protecting prairie dogs from plague

• Prairie dogs are highly susceptible to plague (yersinia pestis)
• Epizootic outbreaks of plague typically kill .95% of residents within infected colonies of all four species of prairie dogs that inhabit the western US
  
  • Transmitted by fleas
• Common species include Oropsylla hirsuta, Oropsylla labis, and Oropsylla tuberculata cynomuris
  
  • In this report they infused Gunnison’s prairie dog (Cynomys gunnisoni) burrows with an insecticide dust containing 0.05% deltamethrin
• Infusions given yearly for 3 years
  
  • The reduction in the number of fleas per prairie dog was significant and dramatic immediately after infusions (given in September)
• flea prevalence in September–October was reduced from 69% to 5% in 2013 and from 55% to 1% in 2014
• Long term reduction in flea intensity, including in juveniles that had not been alive for the infusion
  
  • No adverse effects noted in prairie dog health
  • Despite the lower flea counts, a plague epizootic killed 95% of prairie dogs after 3 yr of infusions
  • Possible that this outbreak was caused by a different mode of transmission (ie aerosol from an infected carcass) or could have been caused by low level of fleas present
• Takeaway: Deltamethrin was effective at reducing the prevalence of fleas in the Gunnison’s prairie dog, but did not prevent an outbreak of yersinia pestis

Question 30

A recent study described resistance to deltamethrin in areas treated to reduce incidence of plague in prairie dogs.

In colonies with resistance, how quickly did flea populations rebound?

How does this affect plague management strategies?

Answer 30

Eads, D. A., Biggins, D. E., Bowser, J., McAllister, J. C., Griebel, R. L., Childers, E., … & Bly, K. (2018). Resistance to deltamethrin in prairie dog (Cynomys ludovicianus) fleas in the field and in the laboratory. Journal of wildlife diseases, 54(4), 745-754.

Abstract: Sylvatic plague poses a substantial risk to black-tailed prairie dogs (Cynomys ludovicianus) and their obligate predator, the black-footed ferret (Mustela nigripes). The effects of plague on prairie dogs and ferrets are mitigated using a deltamethrin pulicide dust that reduces the spread of plague by killing fleas, the vector for the plague bacterium. In portions of Conata Basin, Buffalo Gap National Grassland, and Badlands National Park, South Dakota, US, 0.05% deltamethrin has been infused into prairie dog burrows on an annual basis since 2005. We aimed to determine if fleas (Oropsylla hirsuta) in portions of the Conata Basin and Badlands National Park have evolved resistance to deltamethrin. We assessed flea prevalence, obtained by combing prairie dogs for fleas, as an indirect measure of resistance. Dusting was ineffective in two colonies treated with deltamethrin for >8 yr; flea prevalence rebounded within 1 mo of dusting. We used a bioassay that exposed fleas to deltamethrin to directly evaluate resistance. Fleas from colonies with >8 yr of exposure to deltamethrin exhibited survival rates that were 15% to 83% higher than fleas from sites that had never been dusted. All fleas were paralyzed or dead after 55 min. After removal from deltamethrin, 30% of fleas from the dusted colonies recovered, compared with 1% of fleas from the not-dusted sites. Thus, deltamethrin paralyzed fleas from colonies with long-term exposure to deltamethrin, but a substantial number of those fleas was resistant and recovered. Flea collections from live-trapped prairie dogs in Thunder Basin National Grassland, Wyoming, US, suggest that, in some cases, fleas might begin to develop a moderate level of resistance to deltamethrin after 5–6 yr of annual treatments. Restoration of black-footed ferrets and prairie dogs will rely on an adaptive, integrative approach to plague management, for instance involving the use of vaccines and rotating applications of insecticidal products with different active ingredients.

• Deltamethrin pulicide dust reduces spread of plague by killing fleas.
• Has been used in prairie dog burrows annually in South Dakota – Badlands NP and Conata Basin.
• Study to determine if fleas in these areas have evolved resistance.
• Assessed flea prevalence as indirect measure of resistance.
• Dusting ineffective in two colonies with flea rebound within 1 month of dusting.
• Fleas from dusted colonies exhibited survival rates higher than fleas from sites that had never been dusted.
• Fleas might begin to develop a moderate level of resistance to deltamethrin after several years (5-6) annual treatments.
• Integrative approach to plague management using vaccines, rotating applications of insecticidal products with different active ingredients recommended.

Question 31

A recent study described an outbreak of tropical rat mites in an endangered amargosa vole colony.

What is the scientific name of the tropical rat mite?

What lesions does it cause clinically and histologically?

How was this outbreak managed?

Answer 31

Mantovani, S., Allan, N., Pesapane, R., Brignolo, L., & Foley, J. (2018). Eradication of a tropical rat mite (Ornithonyssus bacoti) infestation from a captive colony of endangered Amargosa voles (Microtus californicus scirpensis). Journal of Zoo and Wildlife Medicine, 49(2), 475-479.

Abstract: Staff at a university laboratory responsible for management of a captive insurance colony of endangered Amargosa voles (Microtus californicus scirpensis) discovered an outbreak of tropical rat mites (Ornithonyssus bacoti) infesting 106 voles. This bloodsucking mesostigmatid mite typically occurs in laboratory settings and can cause weight loss, wounds, or other negative impacts on health. The source of the infestation was likely feral rodents, and the route was suspected to be straw bedding. Twenty-nine of the 106 (27.4%) infested voles developed ulcerated dorsal skin lesions that resolved when treated with topical selamectin. A triad approach was implemented to eradicate the mites, consisting of environmental management, individual animal treatment, and training. Voles were moved individually into a clean room containing only autoclaved materials (including straw), cages were treated with permethrin-impregnated cotton, treatment order was instituted to avoid transferring mites, and voles coming from outside were quarantined. All animals in an infested room were treated with topical selamectin, and personnel were trained on risks and new procedures. No adverse effects from the use of selamectin were identified, and this efficient protocol does not require the long-term use of acaricides. This report documents infestation of an endangered rodent with an exotic parasite, safe use of permethrin and selamectin in this species, and comprehensive management to manage a large infestation.

• Tropical rat mite (Ornithonyssus bacoti) – bloodsucking, zoonotic.
  
  • 8 legs, unsegmented, weakly sclerotized body, three setal pairs on the sternal shield, anal shield with cranially positioned anus, anteroventral keep on trochanter of pedipalp, gnathosoma with four pairs of setae, and a tritosternum.
• Skin lesions – round 0.5-1 cm diameter with raised, reddened edges and central ulceration. Histo showed ulcerative pleocellular dermatitis with lymphocytes, plasma cells, neutrophils, mites in hair follicles. Lesions either from mites or self-trauma.
• One staff person noted similar lesions on herself.
• Eradication: New room, scrubbed weekly for 2 wk with germicidal detergent, fooged room for 10 min with hydrogen peroxide, autoclaved materials, treated voles with selamectin, autoclaved straw in new cages. Permethrin-impregnated cotton balls and systematic decontamination of cages and room surfaces used for another room. Replaced cotton balls once weekly for 8 wks. Shelving dusted with pyrethrin and piperonyl butoxide (Zodiac flea powder). Monthly exams of voles.

Takeaway: Environmental decontamination, treatment of animals, and personnel training the triad approach for successful eradication of mites in this paper. Selemectin safe for voles. TRM is zoonotic.

Question 32

A recent study investigated inducing infertility in norway rats with a liquid bait.

What chemicals were they testing?

How do they function?

What was the effect of these drugs on the fertility of the rats?

How long did these effects last?

What histologic changes were seen in the gonads following this treatment?

Answer 32

Witmer, G. W., Raymond-Whish, S., Moulton, R. S., Pyzyna, B. R., Calloway, E. M., Dyer, C. A., … & Hoyer, P. B. (2017). Compromised fertility in free feeding of wild-caught Norway rats (Rattus norvegicus) with a liquid bait containing 4-vinylcyclohexene diepoxide and triptolide. Journal of Zoo and Wildlife Medicine, 48(1), 80-90.

Abstract: Wild rat pests in the environment cause crop and property damage and carry disease. Traditional methods of reducing populations of these pests involve poisons that can cause accidental exposures in other animals and humans. Fertility management with nonlethal chemicals would be an improved method of rat pest population control. Two chemicals known to target ovarian function in female rats are 4-vinylcyclohexene diepoxide (VCD) and triptolide. Additionally, triptolide impairs spermatogenesis in males. A liquid bait containing no active ingredients (control), or containing triptolide (0.001%) and VCD (0.109%; active) was prepared to investigate the potential use of these agents for wild rat pest population control. Liquid bait was made available to male (n = 8 control; n = 8 active) and female (n = 8 control; n = 8 active) Sprague Dawley rats (Rattus norvegicus) for oral consumption prior to breeding. Whereas, control bait-treated females produced normal-sized litters (10.0 6 1.7 pups/litter), treated females delivered no pups. Wild Norway male (n = 20) and female (n = 20) rats (Rattus norvegicus) were trapped, individually housed, and one group given free access to control bait, one group to active bait. Following three cycles of treatment-matched mating pairs, females consuming control bait (control) produced normal litter sizes (9.73 6 0.73 pups/litter). Females who had consumed active bait (treated) produced no litters on breeding cycles one and two; however, 2 of 10 females produced small litters on the third mating cycle. In a fourth breeding cycle, control females were crossmated with treated males, and treated females were crossmated with control males. In both groups, some dams produced litters, while others did not. The differences in response reflect a heterogeneity in return to cyclicity between females. These results suggest a potential approach to integrated pest management by compromising fertility, and could provide a novel alternative to traditional poisons for reducing populations of wild rat pests.

• Norway rat (Rattus norvegicus) pests cause extensive crop loss, damage infrastructure, and are vectors for several zoonotic diseases
  
  • Most common control is rodenticide but affects nontarget animals AND doesnt cause long-term population reduction due to rapid reproductive rebound of survivors
• Two chemicals known to target ovarian function in female rats are 4-vinylcyclohexene diepoxide (VCD) and triptolide
  
  • VCD causes selective follicle loss by inhibiting the downstream signaling pathway regulated by c-kit in the oocyte 🡪 induces oocyte degeneration
    
    • Since females are born with a set cohort of oocytes 🡪 irreversible loss of follicles 🡪 resulting in ovarian failure
  • Triptolide is a major component in the traditional Chinese medicinal herb, Tripterygium wilfordii, causes lengthened the interval between estrous cycles and enhanced the amount of apoptosis in ovarian secondary follicles and impairs spermatogenesis in males

Goal: liquid bait with combination of VCD and triptolide to assess its effectiveness in wild-caught male and female rats

• Studied previously for 15 days in SD rats 🡪 immediate reversible infertility (triptolide effect) but suspect longer exposure will produce irreversible infertility (VCD effect)
• Rats treated for 50 days

Initial experiment in SD rats to determine effect on litter size

• No pups born to treated dams that mated with treated males AND reduced primordial follicles BUT no difference in large follicles
• No litters likely result of triptolide affecting males and females – with no effect on large follicles, this result could be solely from effect on males

Wild Norway rat fed treated bait

• No litters in the first two breeding cycles AND two smaller litters in the third breeding cycle
• Litters in third cycle likely reflect initial triptolide effect had become reversed once bait withdrawn

Cross breeding of control females + treated males and treated females + control males

• Some dams in both groups had relatively normal litters AND some had no pups
• Suggests that triptolide effect had reversed in some females and males but not in others 🡪 sterility was not permanent
  
  • Fertility had returned more readily in treated females (7/10 litters) than in treated males (5/10 litters)
• Continuous exposure to active bait would be required to cause persistent fertility

Testes/epididymis and ovaries weighed less in treated males and females

• Unhealthy-appearing seminiferous tubules with visibly reduced numbers of spermatozoa histologically
  
  • Direct effect of triptolide targeting epididymal sperm viability and spermatogenesis
• Evidence of destruction of primordial follicles by VCD BUT destruction had not been complete during the exposure time frame 🡪 entire primordial follicle pool needs to be complete for female sterility

Testosterone and estrogen levels were NOT different between two groups

• Reversibility of the triptolide effect may have restored testicular function and follicle development

Conclusion: triptolide effects in males and females caused initial reduction in fertility, which had started to reverse once exposure to active bait had ceased

• VCD had begun to affect primordial follicles in females, however, sterility (irreversible) had not yet been achieved

Take home: VCD/triptolide bait inhibits fertility in both male and female Norway rats for up to 122 days following 50-day exposure

Question 33

A recent study investigated the pharmacokinetics of hydromorphone in guinea pigs.

What dose did they use? What routes were studied?

How bioavailable was the drug IM?

What are some adverse effects of hydromorphone in other species?

How frequently should hydro be administered in guinea pigs?

Answer 33

• Key Points:
  
  • Hydromorphone 0.3 mg/kg IV q 2-3 hours or IM q4-5 hours reaches target conc in guinea pigs, no sedative or adverse effects observed.
  • A plasma hydro concentration between 2-3 ng/mL is expected to have antinociceptive effects in humans and in dogs.
  • High bioavailability and rapid elimination. Could have rapid onset of clinical effects based on time to achieve target plasma concentrations.
  • Bioavailability in this study was reported as > 100% but stated to likely be erroneous.
  • Important to note that the duration of the antinociceptive effect of opioids does not necessarily correlate with plasma drug concentration. Drug concentrations at the receptor level lag behind plasma concentrations.
  • Adverse effects of hydro in other spp – Nausea, vomiting, resp depression, CNS depression, bradycardia. They only evaluated sedation scores in this study, so unknown cardiovascular effects on GP.
• Takeaway: Hydromorphone 0.3 mg/kg IV q 2-3 hours or IM q4-5 hours guinea pigs, no sedation.

Question 34

A recent study evaluated the effects of coinfection of Sin Nobre virus and Bartonella on the immune system of deer mice.

What measure of immune function were they evaluateing?

How did it change with infection in one or the other pathogen?

What is Sin Nombre virus? What disease does it cause? How is it transmitted? What species is the primary reservoir?

What lesions does bartonella typically cause?

Answer 34

Lehmer, E. M., Lavengood, K., Miller, M., Rodgers, J., & Fenster, S. D. (2018). Evaluating the impacts of coinfection on immune system function of the deer mouse (Peromyscus maniculatus) using Sin Nombre virus and Bartonella as model pathogen systems. Journal of wildlife diseases, 54(1), 66-75.

Abstract: Simultaneous infections with multiple pathogens can alter the function of the host’s immune system, often resulting in additive or synergistic morbidity. We examined how coinfection with the common pathogens Sin Nombre virus (SNV) and Bartonella sp. affected aspects of the adaptive and innate immune responses of wild deer mice (Peromyscus maniculatus). Adaptive immunity was assessed by measuring SNV antibody production; innate immunity was determined by measuring levels of C-reactive protein (CRP) in blood and the complement activity of plasma. Coinfected mice had reduced plasma complement activity and higher levels of CRP compared to mice infected with either SNV or Bartonella. However, antibody titers of deer mice infected with SNV were more than double those of coinfected mice. Plasma complement activity and CRP levels did not differ between uninfected deer mice and those infected with only Bartonella, suggesting that comorbid SNV and Bartonella infections act synergistically, altering the innate immune response. Collectively, our results indicated that the immune response of deer mice coinfected with both SNV and Bartonella differed substantially from individuals infected with only one of these pathogens. Results of our study provided unique, albeit preliminary, insight into the impacts of coinfection on immune system function in wild animal hosts and underscore the complexity of the immune pathways that exist in coinfected hosts.

o Animals infected with one pathogen often require less of a secondary pathogen to become coinfected.

§ Infection from first pathogen suppresses immune response of host.

§ Pathogens also may interact in hosts resulting in additive or synergistic morbidity.

· Sin Nombre virus SNV – Hantavirus, SW US.

§ Causes hantavirus pulmonary syndrome in humans, often fatal.

§ Deer mice primary reservoir.

§ Trans through inhalation of particles from urine, saliva, feces.

§ No acute pathology in deer mice. Persistent shedding.

· Bartonella.

§ Bacteremia, granulomatous hepatic lesions, typically mild and short-lived.

§ Humans – cat scratch dz, other pathologies.

· Purpose of study – assessment of adaptive immunity by measuring Ab production, innate immunity by measuring CRP and complement activity in coinfected individuals.

· Deer mice sampled 2012-2013, May-Aug, Colorado US.

· Anesthetized with isoflurane, collected blood, released.

· ELISA to screen for immunoglobulin G Ab (virus-specific).

· PCR for Bartonella.

· Humoral (Ab) response determined by SNV titer.

· Inflammatory immune response assessed by measuring CRP using an ELISA kit.

· Plasma complement activity assessed using bactericidal assay to measure susceptibility of E. coli strains to complement-mediated killing following previous protocols.

Results/Discussion:

· SNV Ab titers higher in SNV infected mice vs coinfected individuals.

· Reproductively active mice had lower SNV Ab titers (both SNV infected and coinfected).

· CRP levels not influenced by body mass, month of year, study site.

· Coinfected mice highest CRP followed by SNV infected mice.

· CRP did not differ between uninfected mice and Bartonella infections.

§ Surprising since CRP activates complement activity.

§ Possible that chronic, relatively benign coinfections with these pathogens cause long-term elevations in CRP that ultimately lead to complement depletion.

§ Bartonella did not generate a detectable immune response.

§ Coinfections with bartonella and other pathogens in other species often result in greater costs to the animal.

§ No definitive explanation for why coinfection increases morbidity in the hosts.

· Nonreproductive females had higher levels of CRP vs nonreproductive males.

· Plasma complement activity – coinfected mice had lowest complement activity.

· No relationship between Ab titer and SNV antigen and complement activity.

· Coinfected deer mice less immunocompetent compared to only SNV infection.

· Ab titers of coinfected less than half of those with only SNV.

· Ab production can vary over course of infection, may have influenced study.

· Immunocompromised deer mice likely to shed greater amounts of infectious pathogens for longer periods, increasing likelihood of transmission to humans.

Question 35

Describe the taxonomy of rodents - what are the seven clades? How do they fit into the traditional three groups?

Describe the unique anatomy of rodents.

What type of teeth do rodents have? Which have bracydont versus elodont molars?

What type of stomach do they have? What species are unable to vomit?

Do they have gallbladders?

Describe the trigonal anal sacs of prarie dogs.

What is unique about the female chinchilla reproductive anatomy?

What type of placentation do rodents have?

Answer 35

Taxonomy, Anatomy, Physiology

• Biology (F8)
  
  • Classification (Box 42-1)
    
    • Clades
      
      • Anomaluropmorpha (scaly-tailed flying squirrels, springhares)
      • Ctenohystrica (gundi, porcupines, guinea pigs)
      • Castoridae (beavers)
      • Geomyoidea (pocket gophers, pocket mice)
      • Myodonta (rats, mice, gerbils)
      • Gliridae (dormice)
      • Sciuroidea (mountain beavers, squirrels, woodchucks)
• Unique anatomy
  
  • Distensible cheek pouches
  • Sensory vibrissae
  • Guinea pigs – 4 front toes, 3 back toes
  • Hamsters, rats, mice – 4 front toes, 5 back toes
  • Hamsters – flank glands (dark brown patches)
  • Teeth
    
    • All rodents have 2 pairs of continuously growing incisors
    • Muridae (mice, rats, hamsters, gerbils), Sciuridae, Castoridae, Erethizontidae, and Myocastoridae – Elodont incisors (continuously growing), brachydont molars (closed-rooted)
    • Hystricomorphs (guinea pigs, chinchillas, degus, NW porcupines, agoutis, etc) – Elodont incisors and molars (all teeth are open-rooted and grow continuously)
      
      • Adapted for abrasive diets
    • Generalized dental formula (total teeth)
      
      • 4 incisors | 0 canines | few premolars | 8-12 molars
  • Simple stomach (some have non-glandular portion or forestomach)
    
    • Cavies, chinchillas, porcupines, voles, beavers, capybaras, lemmings, muscrats, etc. have completely glandular stomachs and are strict herbivores
    • Carnivorous species (water rat) have 75% glandular stomach
    • Strong gastroesophageal sphincter and thin diaphragm prevents vomiting
  • RATS DO NOT HAVE GALL BLADDERS
  • Separate urinary and reproductive orifices in females
  • Most rodents are spontaneous ovulators and polyestrous
  • Chinchillas have 2 cervixes and 2 uterine horns
  • Most males have open inguinal canals, os penis, and prominent accessory sex glands
    
    • Hystrichomorpha – precocial young
    • Sciuromorpha – altricial young
  • Prairie dogs have trigonal anal sacs (papillae beside the anus)
• Physiology
  
  • Biological information Table 42-1, 42-2, 42-3
  • Limited tolerance of high temperatures (no sweat glands)
  • Several species permissively hibernate (hamsters, chipmunks, prairie dogs, woodchucks
  • Some degree of coprophagy/cecotrophy occurs
  • Cavies, chinchillas, porcupines, voles, beavers, capybaras, lemmings, muscrats, etc. have completely glandular stomachs and are strict herbivores
• REPRODUCTION (F8)
  
  • Chemical factors in urine that accelerate and suppress reproduction, express dominance, and serve as cute of genetic compatability in mate choice
  • Larger species reproduce once a year, smaller several times a year
  • Muridae rodents show estrus shortly after parturition
    
    • Breed guinea pigs before 6-7 mo to prevent permanent fusion of pelvic symphisis
  • Many are seasonal breeders and are seasonally polyestrous
  • Pair of large anal scent flands are present in both sexes in beavers- do not confuse with testes
    
    • Os penis should be palpated by inserting a finger into cloacal opening
  • Hystricognati have long gestation and are usually well developed and fully furred
  • Sex by determining anogenital distance, genital papilla is usually more prominent and has a round opening in the male

Unique Features

• Seven clades: three phylogenetic lineages:
  
  • Squirrel-related: Sciuriodea, Gliridae
  • Mouse-related: Anomaluromorpha, Castoridae, Geomyoidae, Myodonta
  • Ctenohystrica
• Dentition: 2 pairs elondont incisors
  
  • Hystricomorphs: all elondont teeth
  • Brachydonts: mice, rats, hamsters, gerbils (still elondont incisors)
  • 4 incisors, no canines, 1-2 premolars, up to 12 molars
• Monogastric, variable degree of hind gut fermentation
  
  • Most are coprophagic or cecotrophicLack gallbladders: rats, gophers
• Unable to vomit: rats, hamsters - muscular sphincter at esophageal-gastric junction
• Caviidae lack enzyme L-gulonolactone oxidase: dietary requirement of Vit C
• Lack sweat glands
• Most ovulate spontaneously, polyestrus
  
  • Chinchilla: 2 cervices with individual uterine horns
  • Imperforate vaginas prior to sexual maturation and during nonbreeding and/or postpartum
  • Discoid, hemochorial placentation
  • Porcupines, agoutis, chinchillas, cavies, capybaras - inguinal testes
  • Well developed accessory sex glands, os penis
  • Prairie dogs: perianal sacs similar to cats and dogs
  • Male beavers: ‘masculine uterus’ persistent paramesonephric ducts resembling uterus
  • Scuirognatha: altricial young
  • Stricognatha: precocial young
• South American rodents (including guinea pigs): unique pulmonary anatomy, large, dilated primitive bronchi and bronchioles
• Nocturnal, some hibernate (woodchucks)

Question 36

Describe the restraint of rodents.

How are they manually restrained?

Describe their anesthesia.

Do they need to be fasted?

Where is vascular access obtained?

What monitoring needs to be performed?

Describe the intubation of guinea pigs and rats.

Answer 36

• Restraint and handling/Anesthesia (F8)
  
  • Manual restraint
    
    • Minimize if possible due to stress, especially in small rodents (that may collapse if too stressed)
    • Rodents have a tendency to bite (hamsters, degus)
    • Grasping gerbils or Australian rodents by the tail may cause degloving/tail slipping
    • Agoutis best manually restrained in a sac
    • Restraint boxes are best for porcupines
  • Chemical restraint/General anesthesia
    
    • Rodents are catecholamine-driven prey species that are easily stressed
    • No fasting required
    • Utilize reversible agents, or agents that allow rapid recovery
    • Anticholinergic medications (atropine, glycopyrrolate)?
      
      • Decreased mucus production
      • Not necessarily needed to pre-treat bradycardia unless indicated
      • Glycopyrrolate does not affect body temperature, blood pressure, or respiration rate, but has been shown to maintain normal HR in rats
      • May alter GI motility, use lower dosages
    • Inhalant anesthesia is most commonly used
      
      • Can pre-oxygenate in a chamber
      • Isoflurane/sevoflurane
      • Intubation is not possible in many species, can intubate some with scope/blind
        
        • Soft palate fused to base of tongue
          
          • Must feed tube through palatal ostium (easily traumatized)
        • Use tight fitting mask
        • V-gels for rabbits are possible
    • Unique pharmaceutical considerations
      
      • Pre-medication (analgesia, sedation) often recommended
      • Midazolam enhances analgesic properties of dexmedetomidine in rats
        
        • Alpha-2 agonists not recommended in compromised rodents
      • Medetomidine + midazolam + fentanyl
        
        • Completely reversible
      • Agouti LS epidural anesthesia has been performed with lidocaine
      • Tramadol (weak mu agonist, weak norepinephrine/serotonin reuptake inhibitor) and gabapentin work synergistically for analgesia in rats
      • Higher dosages of NSAIDs often required in rodents
      • Dental surgical nerve blocks
        
        • Infraorbial, mental, mandibular, maxillary
    • Catheter sites
      
      • IO, IV
        
        • Femoral trochanteric fossa, tibial crest, humerus
        • Cephalic, saphenous, auricular veins
    • Constant monitoring required, crash very quickly
      
      • MONITOR BODY TEMPERATURE – EASILY BECOME HYPOTHERMIC
        
        • Most common complication of rodent surgery
      • Hypoglycemia also contributes to anesthetic morbidity/mortality and slow recoveries

West Ch 66

Primary or obligate nasal breathers

• Upper respiratory disease is common
  
  • Pseudodontoma in prairie dogs, mycoplasmosis in rats

Premedication

• Benzodiazepine, alpha-2 agonist, ketamine
  
  • Produce respiratory depression and bradycardia
  • Midazolam may ameliorate CV effects of dexmed in rats
• Glycopyrrolate - more effective than atropine for maintaining HR in rodents given ketamine/alpha-2 agonist
  
  • May control diffuse salivary secretions in guinea pigs, etc.
• High mortality in rats given yohimbine 20 mg/kg IP
• Porcupines - squeeze cage for IM injection

Venipuncture

• Perineal vein is an option in agoutis and related species

Parenteral Anesthetics

• Alph-2 agonist + ketamine: mild to severe dose-dependent hypotension, bradyarrhythmias, respiratory depression
• Acute reversible lens opacity observed with xylazine and xylazine/ketamine
• Telazol - moderately effective for minor surgery in rats and gerbils
  
  • High dose needed for surgical plane
• Propofol CRI or boluses IV
  
  • Intermediate raet (10 mg/kg/min) had best induction effect vs fast or slow rates
• Alfaxalone - more readily eliminated from males than females, ‘differential clearance’

Inhalant

• Iso - dose-dependent cardiopulmonary depression

Intubation

G pig

• Soft tissue at the base of the tongue is easily traumatized and bleeds profusely from laryngoscope blade
• Soft palate is fused to the base of the tongue
• Entry to the glottis is through the small palatal ostium (also in chinchillas and capybaras)
• Glottis and trachea are small relative to size of the animal
• Prone to airway obstruction from regurgitation or profuse salivary secretions
• Guinea pig intubation - blind or in dorsal with pediatric #0 blade and catheter as ET tube

Rat

• Rigid endoscope or otoscope with #2 ear speculum that has the distal ⅔ of the tip on the right side removed
• Dorsal recumbency on a board with head and neck extended, tongue pulled out
  
  • Slight pressure on ventral surface of the neck may facilitate visualization
• Blind technique also reported
• Local anesthetic on glottis reduces laryngospasm
• Medium-to-moderately large rodents: blind or endoscope-guided

Monitoring

• Corneal reflex is a poor guide to depth
• Fixed and dilated pupil indicates excessive depth
• Anal tone is retained until deep anesthetic levels
• Resting HR based on allometric equation: 241xBW^-0.25
  
  • 20% above or below is abnormal
• Doppler: ventral aspect of tail base, over carotid, femoral, auricular, or heart
• Indirect BP: legs, forearms, tail, ears
• Pulse ox: in rats, accurate at hemoglobin saturation > 70%
• Hypothermia common due to large surface area-to-volume ratio

Free-living large rodents

• Often intraperitoneal radio transmitter implantation surgery

Capybara

• Avoid areas near water as they will retreat to water when threatened
• Ketamine (10 mg/kg) + Xylazine (0.5 mg/kg) was better than telazol +/- levomepromazine
  
  • Telazol lasted 1 hour, longer and better sedation with levomepromazine
• IM telazol (1.5 mg/kg) + medetomidine (7.5 mcg/kg) + butorphanol (0.075 mg/kg) was better than telazol alone or with medetomidine

Beaver

• Ketamine alone (10-15 mg/kg IM) for handling
• Ketamine (25 mg/kg) + diazepam (0.1 mg/kg) IM was safe and effective
  
  • MAP was < 60 mmHg and temp was <35C, respiratory acidemia when ventilating spontaneously (not in controlled)
• Medetomidine (0.05 mg/kg) + ketamine (5 mg/kg) + butorphanol (0.1 mg/kg) + midazolam (0.25 mg/kg)
• Isoflurane or sevoflurane alone

Question 37

What are the poxviruses that affect rodents? Which is OIE reportable?

What are the clinical signs of mousepox? What lesions are present on gross and histo? What are teh inclusion bodies?

What species carry monkeypox? What are the clinical signs in prarie dogs? What about people?

What virus causes squirrel fibromatosis? What species are affected? What are the lesions and inclusion bodies?

What species is the reservoir of parapoxvirus? Which is the clinicall affected species?

Answer 37

Rodent Poxviruses

• Mousepox, Cowpox - Orthopoxviridae *OIE REPORTABLE, ZOONOTIC*, rodent reservoir
  
  • Humans: cutaneous lesions
  • Mousepox: ‘ectromelia’ acutely fatal with minimal lesions, chronic form: crusting face, legs, tail, conjunctivitis
  • Gross: crusting lesions, enlarged swollen friable liver and spleen, splenic fibrosis with recovery, +/- necrosis of kidney, thymus, lymph nodes. Mucosal erosions and hemorrhage of small intestine, urinary bladder, vagina
  • Histo: skin and mucosal lesions - epithelial ballooning degeneration, hyperplasia, erosions with characteristic intraepithelial, intracytoplasmic inclusions bodies. Splenic and hepatocellular necrosis, typically coagulative and multifocal to coalescing
  • Diagnosis: characteristic lesions with viral inclusions, electron microscopy, PCR, virus isolation to confirm strain
• Monkeypox - pet prairie dogs, ZOONOTIC
  
  • 2003 outbreak in prairie dogs in US pet trade, 47 human cases in 6 states, prairie dogs exposed to infected African rodents
  • Fatal in prairie dogs: necrotizing bronchopneumonia, conjunctivitis, glossal ulcers
  • IHC, PCR, electron microscopy
  • Humans: fever, vascular rashes
  • Other rodents affected: rope squirrels, tree squirrels, Gambian giant rats, brush-tailed porcupine, dormice, striped mice
• Squirrel fibroma virus - Leporipoxiviridae, fibromas, fibromatosis of gray squirrels
  
  • Fatal, mainly eastern NA, also red squirrels, a fox squirrel
  • Transmission: biting arthropods (fleas, ticks, mosquitos)
  • Gross and histo similar to Shope fibromas in rabbits (also Leporipoxvirus): multifocal to coalescing tan, firm nodules all parts of body, begins as alopecic nodules, progress to plaque-like pedunculated masses, renomegaly, multiple pulmonary nodules
  • Histo: skin nodules have epidermal hyperplasia with ballooning degeneration of keratinocytes, spongiosis, intracytoplasmic eosinophilic viral inclusions. Pulmonary nodules are adenomatous hyperplasia with viral inclusions. Other lesions include atypical mesenchymal proliferation in liver and seminal vesicles, renal tubular epithelial hyperpasia with viral inclusions
  • Diagnosis: characteristic lesions, PCR or virus isolation
• Parapoxvirus - Red squirrel parapoxvirus, red squirrels in UK and Ireland, severe population declines
  
  • Grey squirrels are likely maintenance host (large % of healthy are positive)
  • Red squirrels: exudative dermatitis with crusting, intracytoplasmic viral inclusions
  • Electron microscopy, PCR

Question 38

What virus causes hepatitis in woodchucks?

Are any other species affected?

What is the pathophysiology?

What are the clinical signs and lesions?

Answer 38

• Woodchuck hepatitis virus (WHV) - Hepadnaviridae
  
  • Animal model for viral hepatitis and hepatocarcinogenicity with Hep B in humans
  • Woodchucks: both sexes, greater than 4 yo.
  • Activated T cells (CD8+) cause cellular and DNA damage creating persistent hepatitis. Viral DNA integrates into host genome at loci containing oncogenes, creating potential for carcinogenic transformation
  • Hepatocellular carcinomas in 100% experimentally infected woodchucks
  • Gross; solitary carcinomas, involve 1 hepatic lobe
  • Histo: differing growth patterns of masses: trabecular, adenoid, or solid, with and without cystic spaces, hemorrhage, and necrosis, atypical bizarre and giant neoplastic cells
  • Adenomas may be present, precursor to carcinoma
  • Remaining hepatic parenchyma: acute and/or chronic hepatitis with neutrophilic to mononuclear inflammation, variable heptocellular degeneration, necrosis, fibrosis, and biliary changes
  • Electron microscopy: definitive
  • Similar virus in Beechey ground squirrels with variable hepatic lesions

Question 39

What are the clinical signs of hamster polyomavirus?

How is it transmitted?

What are the lesions?

What neoplasia has been linked to other polyomaviruses in rodents?

Answer 39

• Hamster polyomavirus (HaPyV) - papovavirus, trichoepitheliomas in Syrian hamsters
  
  • Transmitted via urine, highly contagious, 50% morbidity
  • Early lesions: wart-like growths and alopecic nodules of face and perineum with progression to severe, multifocal to coalescing nodules throughout body.
  • Histo: characteristic skin tumors have multiple islands of basilar to variably differentiated follicular epithelium and abrupt central keratinization with faded nuclear keratinocytes (ghost cells). Rudimentary hairs may be present and follicular rupture may be associated with inflammation.
• Other polyomavirus-associated neoplasms: cutaneous tumors, lymphomas, salivary gland tumors.
  
  • Case of polyomavirus-induced, multicentric lymphoma in 8 wk old Syrian hamster, virus also detected in renal tubular epithelial cells and enterocytes via PCR - some degree of tissue tropism.

Question 40

What coronavirus affects mice?

How is it transmitted?

What are the two syndromes?

What are the lesions?

Answer 40

• Mouse hepatitis (MHV) - Coronaviridae
  
  • Transmission - oronasal.
  • Polytropic and enterotropic disease syndromes
  • Gross: hepatomegaly, splenomegaly, lymphadenomegaly, lymphadenopathy with jaundice and ascites. May be gross intestinal (ileal and cecal) disease - thickened and necrotic mucosa. Liver, spleen, and lymph nodes have multiple coalescing and random white necrotic foci
  • Histo: necrotizing hepatitis with syncytial cells within necrotic foci, demyelination in CNS in immunodeficient mice.
  • Enterotropic disease lesions are age-dependent, villous attenuation and syncytial cell formation with eosinophilic intracytoplasmic inclusion bodies in enterocytes, mesenteric lymph nodes, and endothelial cells. May have granulomatous serositis
  • Diagnosis: histo, IHC, virus isolation, PCR, serology

Question 41

What is the etiologic agent of sendai virus?

How is it transmitted?

What is the pathophysiology?

What infections does it predispose rats to?

What are the lesions it causes?

Answer 41

• Sendai virus infection - Parainfluenza-1; paramyxoviridae
  
  • aerosol inhalation, direct contact, or in utero exposure
  • Targets respiratory epithelium and type II pneumocytes - may impair ciliary activity, predisopses to secondary Mycoplasma pulmonis and other bact infections
  • Gross: dark purple discoloration, atalectasis, consolidation of cranioventral lung lobes, diffuse pulmonary edema. Splenomegaly and lymphadenomegaly common, may cause fetal death in gravid female.
  • Histo: necrotizing rhinitis, laryngotracheitis, bronchitis, bronchointerstitial pneumonia, may see intracytoplasmic and intranuclear inclusion bodies in immunocompromised animals
  • Diagnosis: clinical history, histo, PCR

Question 42

What coronavirus affects rats?

How is it transmitted?

What is the pathophysiology?

What are teh gross and histologic lesions?

Answer 42

• Sialodacryoadenitis - sialodacryoadenitis virus (SDAV), Coronaviridae, specific to rats
  
  • Shed in nasal secretions and/or saliva
  • Infects and replicates in respiratory tract, spreads to salivary and lacrimal glands - secondary lesions of nasopharynx, respiratory tract, and eyes
  • Gross: parotid and submandibular salivary glands, Harderian glands, exorbital glands, and cervical lymph nodes are enlarged, pale, and edematous. Harderian glands may have brown pigmentation correlating to accumulation of porphyrin within acini.
  • Histo: acute necrotizing adenitis, chronic cases have fibrosis and extensive squamous metaplasia of glandular tissue, may be rhinitis, tracheitis, bronchitis, and bronchiolitis.
  • Histo is characteristic and supportive of diagnosis

Question 43

What is the etiologic agent of plague?

How is it transmitted? Who are teh reservoirs? Who are the amplifiers?

What are the three disease forms?

What are the gross and histologic leions?

Answer 43

• Plague - Yersinia pestis, *OIE REPORTABLE, WHO REPORTABLE, ZOONOTIC*
  
  • Transmission by fleas, cats and other predators can contract from ingesting prey and rarely via inhalation
  • Main host types: enzootoci reservoirs (voles, deer mice), epizootic amplifiers (prairie dogs, rats, squirrels)
  • Close to 100% mortality, outbreaks in prairie dog colonies threaten endangered black-footed ferrets (susceptible to disease and prairie dogs are primary food source)
  • Three disease forms
    
    • Bubonic: lymphadenomegaly with abscessation; histo: necrosuppurative lymphadenitis
    • Pneumonic: necrotizing pneumonia with fibrinous pleuritis; histo: necrotizing pneumonia
    • Septicemic: multifocal necrosis of liver, lung, spleen, kidney, eye, brain; histo: multifocal abscessation
  • Gross: multifocal pulmonary hemorrhage, hemorrhagic lymph nodes, erythema of axillary and inguinal skin, splenomegaly, localized hemorrhage and necrosis in dermis and subcutis (suspected site of flea bite)
  • Histo: all lesions contain Gram and Giemsa positive coccobacilli with characteristic bipolar morphology resembling safety pin
  • Culture at a certified, biosecure laboratory. IHC or immunofluorescence can aid diagnosis

Question 44

What is the etiologic agent of pseudotuberculosis?

What rodent species are susceptible?

What are the clinical signs?

Answer 44

• Yersiniosis (Pseudotuberculosis) - Yersinia pseudotuberculsos, Yersinia entercolitica
  
  • Rodents may be carriers, ZOONOTIC
  • Some species susceptible (mice, voles, beavers, muskrats), can be acutely fatal
  • Multifocal necrotizing hepatitis and splenitis and/or fibrinonecrotizing and ulcerative enterocolitis.
  • Agoutis - uniquely susceptible in zoo-settings

Question 45

What is the etiologic agent of tularemia?

What rodents are susceptilbe to disease? Which are subclinical carriers?

What are the clinical signs?

Answer 45

• Tularemia - Francisella tularensis, *OID REPORTABLE, ZOONOTIC*
  
  • Maintained by wild rodents and lagomorphs
  • Disease in many rodents, mice, beavers, muskrats.
  • Voles appear to be subclinical carriers/reservoir
  • Miliary to multifocal and coalescing hepatic necrosis with variable inflammation, depending on chronicity
  • Bacteria weakly gram negative, don’t see on histo, better visualized with ‘special stains’

Question 46

Describe Salmonellosis in Rodents.

What serovars are most common?

What species are particulary susceptible?

What are the gross and histologic lesions?

Answer 46

• Salmonellosis - Salmonella enterica Enteritidis or Typhimurium, ZOONOTIC
  
  • Guinea pigs - septicemia and acute death
  • Other rodents (rats and mice) - diarrhea, abdominal pain, systemic spread
  • Hamsters - ddx for ‘wet tail’ (Lawsonia intracellularis)
  • Gross: cyanosis of mucous membranes, polyserositis with splenomegaly. Hepatic, splenic, and lymph node necrosis, multifocal necrosis and button ulcers in the colon, segmental intestinal infarction
  • Histo: small foci of hepatocellular necrosis, paratyphoid nodules (necrotic debris, variable macrophages, lymphocytes, fewer neutrophils), Kupffer cell hyperplasia, granulomatous hepatitis, splenitis, and lymphadenitis, fibrinonecrotic ileotyphlocolitis, intestinal infarction attributed to vasculitits and thrombosis of mesenteric or mesocolic vessels
  • Culture, histo confirm

Question 47

Rodents are potential reservoirs of what Mycobacterium?

What rodent species are the suspected reservoirs?

Answer 47

• Mycobacteriosis- ZOONOTIC, rarely reported in rodents, may be reservoirs
  
  • Mycobacterium microti - British voles, wood mice, hamsters, Korean and Richardson’s ground squirrels in Spain

Question 48

What Chlamydophila species affect rodents?

What species is commonly affected?

What are teh associated lesions?

Answer 48

• Chlamydophila caviae, C. psittaci - juvenile guinea pigs, ZOONOTIC
  
  • Conjunctivitis, bronchitis, pneumonia, debilitation, death
  • Histo: heterophilic keratoconjunctivitis and uveitis, cranioventral heterophilic pneumonia
  • May be asymptomatic, diagnosis with cytology of ocular discharge and/or PCR, IHC

Question 49

What rodents are susceptible to Bordetella?

What are the gross and histologic lesions?

Answer 49

• Bordetella bronchiseptica - bordetellosis, epizootic pneumonia - guinea pigs, free-ranging squirrels, other immunosuppressed rodents
  
  • Gross: cranioventral pneumonia with multifocal to coalescing, discrete, reddish-gray consolidated regions of multiple lobes, pleuritis. Mucopurulent exudate in nares, nasal passages, trachea, tympanic bullae, often crusting conjunctivitis. Females may have metritis and pyosalpinx
  • Histo: necrotizing and heterophlic bronchopneumonia with obliteration of airways
  • Diagnosis: culture or PCR, rule out predisposing pathogens (adenovirus, Mycoplasma spp.)

Question 50

What species are affected by cilia associated respiratory bacillus?

Coinfection with what other bacteria is common?

What are the lesions seen in rats?

Answer 50

• Ciliated associated respiratory (CAR) bacillus - unclassified bacterium
  
  • Colonizes ciliated respiratory epithelium in rats, mice, rabbits, and other species
  • Synergistic with other respiratory pathogens, coinfections with mycoplasmas reported
  • Rats: suppurative to mucopurulent bronchopneumonia, perivascular and bronchiolar lymphoid hyperplasia, rhinitis, lymphoplasmacytic tracheitis

Question 51

What mycoplasma species affects rodents?

What are the gross and histologic lesions?

What other organ systems may be affected?

Answer 51

• Murine respiratory mycoplasmosis - Mycoplasma pulmonis
  
  • Gross: catarrhal exudate in URT, cranioventral bronchopneumonia, mucopurulent exudate in airways with atelectasis
  • Histo: peribronchial lymphoid cuffing, BALT hyperplasia, neutrophilic bronchopneumonia, type II pneumocyte hyperplasia of alveolar epithelium, emphysema, bronchiectasis is characteristic.
  • Other lesions may include endometritis, salpingitis, perioophoritis
  • Histo can’t differentiate mycoplasma from CAR bacillus
  • Diagnosis: histo, culture, PCR, ELISA

Question 52

WHat rodents are susceptible to pasteurellosis?

Answer 52

• Pasteurellosis - P. multocida
  
  • Young, immunocompromised rodents, direct transmission from dam
  • Strain virulence and species determine lesions
  • Prairie dogs - upper respiratory disease, pneumonia
  • Rats and mice- conjunctivitis more common
  • Hamsters - variable susceptibility

Question 53

What is the etiologic agent of cervical lymphadenitis?

What rodent species is particularly susceptible?

What are teh gross and histologic lesions?

Answer 53

• Cervical lymphadenitis - Streptococcus equi subsp. Zooepidemicus
  
  • Classically described in guinea pigs, associated with coarse food causing oral mucosal lesions, or bite wounds
  • Gross: cervical or submandibular lymph nodes markedly enlarged, containing thick purulent yellow-white to red-gray exudate, may rupture with chronicity
  • Histo: heterophilic lymphadenitis with central necrosis and peripheral fibrosis. Fibineous pleural adhesions in thorax, fibrinosuppurative bronchopneumonia, pleuritis, pericarditis.
  • Chains of G+ cocci in lesions
  • Diagnosis: gross and histo, culture

Question 54

What is the etiologic agent of Tyzzer’s disease?

What rodent species are commonly affected?

What are the three classic gross lesions?

HOw do these cases present?

What are the histologic leisons?

Any special stains recommended?

Answer 54

• Tyzzer’s disease - Clostridium piliforme
  
  • Gerbils, hamsters, spinifex hopping mice, potentially fatal
  • Triad of gross lesions:
    
    • icterus and hepatomegaly
    • military gray foci, congestion, and edema of intestines
    • lymphadenomegaly with edema and hemorrhage
  • Sudden death without clinical disease or lesions in peracute cases
  • Histo: multifocal random to coalescing hepatic necrosis surrounded by hemorrhage, heterophils, macrophages. Hepatocytes at necrotic margins may accumulate characteristic criss-crossed bundles of faintly staining bacilli
  • *Best visualized with silver stains

Question 55

What are the small fungal cysts that are species specific in wild rodents?

What lesions do they produce?

What special stains are used on histo to see them?

Answer 55

• Pneumocystis spp. - thought to be highly host-specific
  
  • Within alveoli and alveolar macrophages: small, eosinophilic, round organisms with small central body, may obliterate alveoli in severe cases, be see interstitial pneumonia
  • Silver stain highlights intralesional/intracellular pneumocystis cysts

Question 56

What rodents are particularly susceptible to Cryptococcus neoformans?

What lesions does this produced?

How are these organisms detected on histo?

Answer 56

• Crytococcosis - Cryptococcus neoformans
  
  • Report of 20% mortality in slender-tailed cloud rats at a zoo over 15 yr period
  • Large, arboreal rodents likely infected by contaminated substrates, may be highly susceptible species
  • No lesions or mild to severe chronic granulomatous pneumonia with or without necrosis and regional lymphadenitis
  • Disseminated disease may have subcutaneous nodules (cryptococcoma) and meningoencephalitis
  • Histo: characteristic fungal yeasts with narrow-based budding
  • GMS: 5-20 um diameter fungal yeasts with distinct thick (5-10 um) nonstaining mucopolysaccharide capsule, best visualized with pAS reaction and mucin stains
  • Culture can confirm

Question 57

What is the etiologic agent of adiaspiromycosis in rodents?

What are the dermatophytes affecting rodents?

What fungus produces suppurative and necrotizing dermatitis that progresses to granulomas and fibrosis in rodents?

Answer 57

• Adiaspiromycosis - Chrysosporium parum, C. crescens (saprophytic fungi) ZOONOTIC
  
  • Inhaled, pulmonary granulomas with fungal spherules and conidia, goes sytemic
  • Immunodiffusion and complement fixation may aid diagnosis
• Other systemic mycoses: Blastomyces dermatitides, histoplasma capsulatum
  
  • Reports in juvenile mice and chinchillas
  • Apparent limited immunity to fungal pathogens in mice
• Dermatophytosis
  
  • Trichophyton mentagrophytes, microsporum canis, M. gypsum, Epidermophyton, cutaneous fungal disease, ZOONOTIC
• Sporothrix schneckii - cutanoues, ZOONOTIC
  
  • Suppurative and necrotizing dermatitis to granulomatous and fibrosing with chronicity
  • PAS-positive yeast within macrophages
  • Cytology of skin scrapes with potassium hydroxide prep - characteristic organisms support diagnosis

Question 58

What is the parasite in rats that produces lymphoplasmacytic and granulomatous hepatitis?

What are the lesions associated with Baylisascaris infection in rodents?

Answer 58

Metazoa

• Capillaria hepatic (Calodium hepaticum) - ZOONOTIC, ubiquitous parasite of Norway and black rats
  
  • Gross: multifocal to coalescing, tortuous, white tracks in liver parenchyma
  • Histo: varying combinations of lymphoplasmacytic and granulomatous inflammatory infiltrates, fibrosis, bioperculate eggs, occasionally adult parasites replace hepatic parenchyma
  • Diagnosis by nematode and/or eggs in liver *NOT fecal exam because eggs only released from liver with carcass decomp or ingestion by predator/cannibalistic conspecific
• Baylisascaris procyonia - fatal visceral larval migrans
  
  • Histo: may see parasite migration in brain with low numbers eosinophils, gliosis, spheroids, rarefaction or necrosis of neuropil

Question 59

What is the most common mite that affects squirrels?

What lesions does it cause?

How is it diagnosed?

Answer 59

Ectoparasites

• Notoedric mange - squirrels
  
  • Mites burrow into stratum corneum - marked hyperkeratosis, patchy alopecia, crusting, lichenification, yellow to gray, predominantly ears, nose, tail, external genitalia, inguinal and perianal regions, and feet
  • Peripheral lymphadenopathy
  • Dx skin scrape and fecal float
  • Histo: marked epidermal hyperplasia with parakeratotic hyperkeratosis forming caps over tunnels containing mites with superficial perivascular eosinophilic dermatitis
  • Secondary bacterial infections

Question 60

What rodents are prone to scurvy?

What enzyme do they lack?

What are the typical clinical signs?

What histologic lesions are present?

Answer 60

• Hypovitaminosis C (scurvy): guinea pigs and some other spp. (capybaras, humans) lack L-gulonolactone oxidase required for L-ascorbic acid production.
  
  • Require dietary Vit C for formation of collagen (hydroxylation of proline/lysine for cross linking of fibrillar collagen)
  • Decreased collagen fibril cross linking - increased fragility of blood cells, cartilage, and osteoid
  • CS: capillary hemorrhage, lack of bone deposition, remodeling, anemia, periarticular hemorrhage, swollen joints esp costochondral junctions (scorbutic lattice), gingival swelling, erythema, hemorrhage, erosion, ulceration, tooth loss.
  • Histo of bone: dilation of metaphyseal blood vessels, irregular columnization and hypertrophy of physeal cartilage, calcification of metaphyseal cartilage with reduced or absent osteoid, microfractures with surrounding and subperiosteal hemorrhage, medullary fibrosis, decreased osteoclastic activity and remodeling.
  • Tooth loss from abnormal odontoblasts and dentin resorption, pulp fibrosis, lack of/abnormal alveolar bone remodeling

Question 61

What rodents are prone to dystrophic mineralization?

Where does it most commonly occur? What other sites may it occur in?

What are the gross and histologic lesions?

Answer 61

• Dystrophic mineralization: guinea pigs, hamsters, free-ranging rats.
  
  • Most often the myocardium, also diaphragm, tongue, liver, kidney, lungs, cornea, aorta
  • Preferential mineralization of the mitochondria
  • Gross: cardiomegaly, chalky to gritty white material and streaking within myocardium
  • Histo: degenerative and/or necrotic myocytes with rupture of sarcolemma, variable and progressive mineralization, variably mature fibrosis, satellite cells frequently hypertrophic

Question 62

What rodents are prone to pregnancy toxemia?

What are the two forms that occur?

What lesions occur as a result?

Answer 62

• Pregnancy toxemia: overweight, pregnant, and lactating female guinea pigs and hamsters
  
  • Occasionally overweight nongravid sows and boars
  • Two forms in guinea pigs
    
    • Fasting type: mobilization of fat stores
    • Circulatory type: gravid uterus compresses aorta, decreasing blood flow to abdominal organs
  • Gross and histo: hepatic lipidosis, fat deposition in renal tubular epithelial cells

Question 63

Urolithiasis is common in what rodent species?

Answer 63

• Urolithiasis: guinea pigs, rats, mice
  
  • High urine pH and calcium concentrations
  • Obstructive urolithiasis in male agoutis resulted in bilateral hydronephosis, bladder rupture, peritonitis

Question 64

What is the pathognomonic lesion for fluorosis in rodents and lagomorphs?

What other lesions occur?

What is one of the first clinical signs seen?

Answer 64

• Fluorosis: guinea pigs, rabbits, rats in contaminated env with petrochemical waste
  
  • Pathognomonic: periosteal hyperostosis along medial metatarsals progresses to mandible, metacarpals, and ribs
  • Brittle, chalky-white bones, pathologic fractures, enamel hypoplasia if present during tooth development: pitting, grooves, discoloration due to oxidation, irregular tooth wear, malocclusion, tooth fractures
    
    • Excessive attrition affects incisors first
    • Ddx for enamel hypoplasia in young Syrian hamsters: Hamster Parvovirus (HaPV) - concurrent testicular hypoplasia and cerebral malacia
  • Histo: ameloblasts (small white osteoblasts) are vacuolated and disorganized, abundant globular dentin and hypomineralization of outer enamel layer

Question 65

What are the lesions associated with cholecalciferol toxicity?

How are most rodents exposed?

What species can develop toxicity if fed the wrong rodent chow?

Answer 65

• Cholecalciferol (Vitamin D) - rodenticide
  
  • Multisystemic mineralization prior to death
  • Naked mole-rats, beavers, and woodchucks do not require dietary Vit D - toxicity can occur if fed rodent chow or diets supplemented with vit D
    
    • Naked mole rats can develop calcinosis cutis and circumscripta
    • Resolution with correction of the diet

Question 66

What are the clotting factors inhibited by anticoagulant rodenticides?

Answer 66

• Anticoagulant rodenticides - warfarin and derivatives
  
  • antagonize Vit K inhibiting production of vit-K dependent clotting factors (I, II, VII, IX, X) - multisystemic hemorrhage, subcutaneous and periarticular hematomas

Question 67

Describe the congenital and genetic diseases of rodents.

What rodents are prone to dystrophic cardiac calcinosis? What are the lesions in these cases?

What rodents are prone to diabetes? What lesions occur? What is a useful diagnostic in these cases?

What rodent species develops polycystic kidney disease?

Answer 67

Congenital/genetic

• Dystrophic cardiac calcinosis: genetic in inbred mouse strains, especially aged
  
  • Cardiac mineralization, gross pinpoint foci to larger irregular crusts of white, gritty material within and overlaying the epicardium
  • Severe cases: extends into mycoardium causing scarring, can also be seen in kidneys and lungs
• Diabetes mellitus: Chinese hamsters - heritable, autosomal recessive
  
  • Hydropic degeneration and degranulation of pancreatic islet B-calls, secondary vascular lesions (arteriosclerosis, glomerulosclerosis)
  • Predisposed to pancreatic adenocarcinomas
  • Serum alpha-2 globulins - useful indicator of risk fo DM
• Polycystic kidney disease: Brazilian agoutis
  
  • Most have no clinical signs, potentially related genetically
  • Range of bilateral renal changes: atrophy, roughened granular cortical surfaces, multiple cysts
  • Histo: cystic dilatation of renal tubules and Bowman’s capsules with mesangial and capsular thickening accompanied by mononuclear interstitial nephritis and fibrosis

Question 68

What rodent species are prone to chronic progressive nephropathy?

What causes this?

What are the characteristic lesions?

How is it diagnosed?

Answer 68

• Chronic progressive nephropathy: rats, mice, naked mole rats, Australian rodents especially sticknest rat
  
  • Unknown pathogenesis, suspect genetic factors
  • Gross: kidney bilaterally pale, enlarged or shrunken with numerous pinpoint to large 1 mm cortical microcysts creating a nodular surface
  • Histo: renal tubules markedly ectatic and tortuous, many contain brightly eosinophilic fluid (proteinosis), range of tubular degeneration, necrosis, and regeneration, occasional tubular hyperplasia and adenoma formation (especially rats), glomeruli variably affected by membranous and/or proliferative changes: thickened basement membranes, sclerosis, obsolescence. Synechiae, dilated Bowman’s capsules, hypertrophied parietal epithelium. Interstitium expanded by lymphoplasmacytic infiltrates with pigment-laden macrophages, mild hemorrhage, edema, often interstitial fibrosis, severe cases can have infarction
  • Diagnosis is based on histology

Question 69

What rodents are prone to cardiomyopathy?

What demographics are more commonly affected?

What lesions are typically present?

Answer 69

• Cardiomyopathy: aged mice, rats, hamsters, especially Syrian hamsters, reported in woodchucks
  
  • Lesion severity increases with age, more common in males
  • May see gross cardiomegaly or no macroscopic changes
  • Histo: multifocal and perivascular lymphoplasmacytic infiltrates with fibrosis, myocyte degeneration, and drop out. Trichome, Movat pentachrome, or other stains highlight fibrosis
  • Syrina hamsters - cardiomyopathy associated spontaneous atrial thrombosis and subsequent fatal coagulopathy. Females affected earlier in life than males

Question 70

What rodents are commonly affected by degenerative joint disease?

What lesions are present in these animals?

Answer 70

• DJD: guinea pigs, especially Duncan-Hartley breed, and Syrian hamsters
  
  • Gross: thickened joint capsules, variable osteophyte formation, roughened cartilage surfaces, eburnation, joint effusion, synovial proliferation, may have crepitus
  • Histo: degeneration, necrosis, and ulceration of articular cartilage, proliferation and fibrosis of synovium and joint capsule, periarticular and periosteal bone formation, remodeling, variable inflammation and hemorrhage within joint spaces

Question 71

What rodents develop amyloidosis more commonly?

What organs are affected?

Answer 71

• Amyloidosis: extracellular accumulation of insoluble protein, typically aged animals, leads to tissue atrophy and dysfunction
  
  • Common in myomorphs (mice, rats, hamsters, gerbils), higher prevalence in females
  • Appears in kidneys, spleen, adrenals, liver, GI lamina propria (mouse)
  • Eosinophilic substance within nasal planum of aged mice was thought to be amyloid but has been shown to consist of collagen and complex carbohydrates produced by nasal gland epithelial cells

Question 72

What rodents are prone to hemosiderosis?

How is this diagnosed?

Answer 72

• Hemosiderosis: accumulation of iron in various tissues, most commonly liver
  
  • 65% of adult naked mole rats in 1 zoo report
  • Gross: bronze liver
  • Histo: zonal to diffuse hepatocellular accumulation of brown granular to globular pigment, most intense in periportal hepatocytes, stains positively with Prussian blue, not refractile with polarized light

Question 73

What rodents are prone to developing stress dermatosis?

What gross and histologic lesions occur?

How is this diagnosed?

Answer 73

• Stress dermatosis (or dermatitis): South American rodents (agouti, acouchis, capybara)
  
  • Alopecic skin lesions and lacerations along lumbosacral spine
  • Possible contributing factors: stress may increase skin fragility, overcrowding with intraspecific aggression, sun exposure, pruritis, and self-mutilation
  • Gross: large patches of alopecia with erythema, excoriated skin, loss of long hairs along dorsum and tail
  • Histo: variable epidermal degeneration, necrosis, erosion/ulceration, associated dermatitis with hemmorhage and edema
  • Diagnosis based on clinical history and absence of parasitic causes, skin scrape, histo

Question 74

What rodent is prone to cystic rete ovarii? Is the ovary itself actually affected?

Answer 74

• Cystic rete ovarii: female guinea pigs
  
  • Arise from rete and compress adjacent ovarian tissue (distinguishing this from other ovarian cysts: bursal cysts, epithelial cysts, follicular cysts, luteal cysts, paraovarian cysts)

Question 75

What rodent is reported to develop trophoblast emboli

What are the associated lesions?

Answer 75

• Trophoblast emboli: incidental, best described in chinchillas
  
  • Predisposed due to hemochorial placentation
  • No gross lesions
  • Histo: intravascular trophoblasts present in lung, uterus, spleen, liver, adrenal, etc. with no associated inflammation
  • Trophoblasts: large (> 100 um), abundant amphophilic granular cytoplasm, large nuclei, prominent nucleoli

Question 76

What rodent does not have any reported spontaneous tumors?

What neoplastic like lesion is commonly reported in the teeth or rodents? What rodents commonly get these? What lesions occur as a result?

Answer 76

Neoplasia

• Naked mole rats: extreme longevity and purported cancer resistance, currently no reported spontaneous tumors but subcu tumors (fibromas and fibrosarcomas) may be induced with carcinogenic compounds
• Odontoma (odontogenic dysplasia): several rodent species (prairie dogs, rats, mice, guine pigs, chichillas, degus, chipmunk, squirrel)
  
  • Most not true neoplasia, instead dysplastic changes from chronic inflammation or trauma
  • Increasingly identified as hamartomas or pseudo-odontomas
  • Regionally destructive, almost exclusively incisors
  • Gross: nodular swellings around incisors
  • Histo: disorganized and dysplastic proliferations of odontogenic epithelium, enamel matrix, and mineralized enamel, dentin, pulp, and cementum. Contain fully differentiated tooth elements but do not form tooth-like structures found in other species (horse)
    
    • Rodent: well-differentiated odontogenic epithelium among enamel organ with dental pulp mesenchyme and variably mineralized enamel matrix

Question 77

Describe Naked Mole Rat Medicine & Management

What is the scientific name of the naked mole rat?

What is its social structure like?

What are the husbandry and nutritional needs of these animals?

What is their reproduction like?

How is contraception achieved without causing queen succession?

What diseases have been reported?

What medications have been used?

Answer 77

Chapter 73 – Naked Mole Rat Management and Medicine

• Biology (Heterocephalus glaber)
  
  • Small (~35g), long-lived - average life span >16yrs
  • Native to Ethiopia, Somalia, Kenya
  • Eusocial, only dominant queen reproduces, others assist with pup rearing, defense, maintenance; functions like social insects; 1 of 2 mammal species
  • Underground, tunnel systems (up to 2-3km long) for up to 300 individuals
    
    • Stout cylindrical body, robust skull, reduced eyes/functionally blind, reduced ears, scant pelage, powerful incisors, forelimbs for digging
    • Lack of thermoregulation, high circulating hemoglobin and myoglobin
• Husbandry
  
  • Naturalistic or acrylic chambers connected with pipe system
  • Supplemental heat 84-95 degrees F, humidity 80-85%
  • Very sensitive to vibration – control noise (double paned glass, white noise)
• Nutrition
  
  • Herbivorous, hindgut fermenters, practice coprophagy
  • Water from diet - tuberous vegetables daily
  • Check commercial diet calcium levels, do not supplement vitamin D3
• Reproduction
  
  • Queen is largest female – vertebral lengthening, long lived
  • Workers have minimal sexual dimorphism, breeding individuals more obvious
    
    • Nonbreeding males - more circular anal and urogenital sphincter
    • Nonbreeding female -broader/more flattened urogenital area
  • 5-7 litters/year, 1-27 pups/litter (more pups in captivity)
  • Pups nursed by queen for 4 weeks, other colony members help care for offspring
  • Spontaneous ovulators, accessory corpora lutea - progesterone secretion
  • 1-3 largest males mate with queen
    
    • Other males - low LH/testosterone -> small, intraabdominal testes
  • Nonbreeding females - prepubescent ovaries due to inhibition of GnRH that can become active within 24 hours of loss of queen
    
    • activation of several females leads to aggression, social instability
    • New queen reimposes reproductive suppression -> serious injuries
  • Year-round breeders -> reach carrying capacity in captivity, dispersal in wild
    
    • Rapid population growth in limited space contributes to pup mortality
      
      • Colony collapse if pup mortality is 95-100%
  • Contraception without causing queen succession is difficult
    
    • Surgical sterilization
      
      • Flank approach reduces herniation risk
      • Tubal ligation or hysterectomy, spare ovaries
    • Hormonal manipulation
      
      • Melengestrol acetate (MGA) – blocks ovulation, follicle growth and estrous behavior continue, successful for 2 years
  • Vaccination
    
    • Porcine zona pellucida (PZP) vaccine – 0.2mL(50ug) IP, booster 2 weeks
      
      • Annual booster, no pups >3 yrs
  • Xenophobic – will kill individuals not recognized/those removed for long period
• Restraint/anesthesia
  
  • Manual restraint, wear gloves at all times – foreign odors can lead to aggression
  • Do well with inhalant anesthesia
• Therapeutics
  
  • Oral antibiotics (TMPS 15-30mg/kg PO SID-BID, enrofloxacin 5mg/kg PO/IM SID)
  • NSAIDS (meloxicam 0.1-0.2mg/kg PO SID)
  • Response to analgesics may be minimal. Lack C fibers and substance P and nerve growth factor – reducing or eliminating cutaneous or thermal pain
    
    • Reduces acid accumulation in tissues due to hypoxic environment
• Diseases
  
  • Trauma, Pasteurella from bite wounds
  • Noninfectious disease issues related to husbandry
  • Neonatal death from maternal neglect -> signals impending colony collapse
  • Calcinosis circumscripta and cutus
    
    • Swellings 2mm-2cm, white opaque pasty material, prevent movement
    • Inappropriate vitamin D
• Use in research
  
  • Aging research – slower rate of aging, resilience to oxidative stress and mitochondrial injury, minimal cellular senescence, maintain fertility until death, cytoprotective genes

Question 78

Describe the anesthesia and medicine of free-ranging capybara.

What is the scientific name of the capybara?

What is their social dynamic like?

Capybara are amplifiers of what infectious diseases?

What physical restraint methods are used in wild capys?

What drugs are commonly used for anesthesia?

Answer 78

Fowler 9, Ch. 74 – Immobilization, Health, and Current Status of Knowledge of Free-living Capybaras

• The Capybara (Hydrochoerus hydrocharis and Hydrochoerus isthmius)
  
  • Largest living rodent species in the world; only surviving member of family Hydrochoeridae
  • Found in Panama, Colombia, Venezuela, Ecuador, Peru, Paraguay, Uruguay, Brazil, Bolivia and Northern Argentina
    
    • Historical rapid decline in wild populations in Colombia
  • Semiaquatic behavior adapted to swampy areas, areas subject to flooding, areas of agriculture and cattle ranching, etc.
  • High fecundity; well-regarded as a good source of meat for people
• Habitat
  
  • Many ecosystem changes (petroleum expansion, road building, expansion of monoculture and subsequent agrochemical use, etc.) impede on available habitat and the capybara’s health
    
    • Still listed as a “least concern” animal by IUCN
  • Cannot live in extreme flood zones, as they require dry zones to rest; however, large die-offs during the dry season when floods/bodies of water disappear
• Biology and State of Conservation
  
  • Highly social animals; population dynamics are intensely related to reproductive competition in males and females
  • Infanticide by groups of male individuals killing juvenile competitors can be common
    
    • By killing the young, there is often an induction of estrus in the females
  • Evidence of possible estrual suppression – not necessarily all females in the group reproductively active at one time
  • Considered the most efficient nitrogen recycler of all animals – within hours, their urine makes large quantities of nitrogen soluble, which are re-integrated into pastures
• Capybara as Microorganism Amplifier
  
  • Individuals with Brucella abortus, Leptospira interrogans, Leishmania spp., Trypanosoma spp. multiple enterobacteria and others may infect people in Colombia through direct contact, ingestion of meat, etc.
  • May be a good sentinel for emerging zoonotic diseases
  • Can be infected with Amblyomma ticks and may help transmit rickettsial diseases (specifically Rickettsia rickettsi causing significant cases of Rocky Mountain spotted fever in people); can also be infected with ticks of the genus Dermacentor
    
    • Primary host for Amblyomma cajennense
    • Evidence they may also transmit anaplasmosis as well; no significant evidence of ehrlichiosis yet, however
• Immobilization
  
  • Capture Corrals
    
    • Use conditioning techniques (availability of food such as sugar cane, carrots, corn, etc.) to train capybaras to approach a corral – generally during the 1-3 months of the dry season
    • Generally have a guillotine-style door attached to a string that can be engaged when individuals are far enough in the corral
  • Roping
    
    • Chasing the animals on horseback and using lariats (lassos) for restraint
  • Chemical Immobilization
    
    • Xylazine and other alpha-adrenergic agonists are frequently combined with ketamine for short-term immobilization and surgical anesthesia
      
      • This protocol can produce hypertension, bradycardia, arrhythmias, and respiratory depression, however
    • Ketamine/benzodiazepine has less of the side effects listed above
    • Telazol may cause long inductions and difficult recoveries (even postanesthetic suffocation)
• Diseases
  
  • Malnutrition (in the dry season) and predation are typically highest causes of mortality
  • See microorganism section above, as these bacteria may also cause significant disease

Question 79

Describe the anatomy of the guinea pig.

What is their integument like? What is the caudal gland?

What is their dental formula? What type of teeth do they have?

What is the palatial ostium?

How does their stomach differ from that of rats, mice, and hamsters?

What is gastric emptying time and total GI transit time?

How does the mucus trap strategy for particle separation differ from the wash-back strategy of lagomorphs?

Describe the urine of guinea pigs?

Answer 79

GENERAL

• Males (boars) = 900-1200g; Females (sows) = 700-900 g; obesity common
• Life span: up to 8 years (captive), 4-5 years (wild)
• Hair coat: large guard hairs surrounded by undercoat of fine hairs
  
  • Physiologic alopecia caudal to ears
  • Androgen-dependent sebaceous glands along dorsum, around anus for marking
    
    • Caudal gland (AKA grease/coccygeal gland) = focal accumulation of sebaceous glands 1 cm dorsal to anus at base of spine; more developed in males
      
      • Older males: excessive secretions à thick/matted/greasy fur à predisposes to infection
• 1 pair of inguinal nipples (both sexes)
• 32-36 vertebrae: C7, T13(14), L6, S2(3), Cd4(6)
  
  • 13-14 pairs of ribs (last 1-2 cartilagenous)
  • Small, cylindrical clavicle attaches laterally to coracoid process of scapula, medially to manubrium
• Pelvic symphysis stays fibrocartilaginous (gap palpated during impending parturition)
• Digits: 4 on front feet, 3 on rear feet
• Large tympanic bullae
• Thymus in immature animals, adults may have thymic remnant
  
  • Corticosteroid-resistant species: steroid administration not associated w/ changes in thymic physiology or peripheral lymphocyte counts
• No laryngeal ventricles; small vocal folds
• Lungs: right lung 4 lobes (cranial, middle, caudal, accessory), left lung 3 lobes (cranial, middle, caudal)

GASTROINTESTINAL SYSTEM: herbivorous hindgut fermenters

• Dental formula: 2(I1/1, C0/0,PM1/1,M3/3)=20
  
  • Elodont (grow throughout life), 30* occlusal plane
  • Malocclusion: maxillary growth laterally into buccal mucosa, mandibular growth medially w/ tongue entrapment
  • White incisors
• Large tongues, continuous soft palate w/ base of tongue
  
  • Palatial ostium: hole in soft palate through which the oropharynx communicates w/ remainder of pharynx
• 4 pairs of salivary glands (parotid, mandibular, sublingual, molar): ducts empty into oral cavity near molars
• Alimentary tract measures 2.3 m (7.5 ft) from pharynx to anus
  
  • Stomach lined w/ glandular epithelium (no non-glandular portion unlike rats, mice, hamsters)’
  • SI on right side of abdomen, cecum in central/left abdomen
    
    • Cecum = 65% GI content, large (15-20 cm long), thin-walled sacs w/ many lateral pouches formed by action of 3 taeniae coli
• Liver: 6 lobes (right, medial, left lateral, left medial, caudate, quadrate)
  
  • Gallbladder well-developed
• Gastric emptying time = 2 hours
  
  • Total GI transit time = 20 hours (range 8-30 hours) or 66 hours including coprophagy
  • Gastric pH 2.9, SI pH 6.4-7.4
• Coprophagic: ingest pellets from anus, floor (if obese/pregnant), or from dam (if youg & unweaned)
  
  • Nutritional function unknown (B vitamins? Optimizing protein utilization?)
  • NOT cecotrophic – need dietary source of 7 out of 10 B vitamins
  • If coprophagy is prevent à weight loss, digest less fiber, excrete more minerals in feces
• “Mucus trap” strategy: cecal bacteria trapped in mucus in colon w/ few/no food particles & returned to cecum by antiperistalsis
  
  • (vs. “wash-back” strategy of rabbits/lagomorphs: bacteria, solutes, small food particles returned to cecum by antiperistalsis in stream of water from proximal colon)
  • Mucus-trap less effective than wash-back in extracting bacteria from colonic digesta à gpig colon comparatively heavier/larger than rabbits
• Colonic furrow in ascending colon = 2x concentration of bacteria/nitrogen as in lumen
  
  • Bacteria in proximal colon transported in furro to the cecum as part of separation mechanism
  • Primarily gram-positive aerobic bacterial flora (like rabbits)

UROGENITAL SYSTEM

• Male accessory sex glands: vesicular glands, prostate gland, coagulating glands, bulbourethral glands
  
  • Vesicular glands = long, coild, blind sacs ventral to ureters, extend 10cm into abdomen (mistaken for uterine horns)
  • Testes in open inguinal canals & in poorly developed scrotum
  • Os penis
  • Intromittent sac = pouch caudoventral to urethral opening which everts during erection to project 2 horny styles (DO NOT MISTAKE OPENING FOR URETHRA)
• Females: bicornuate uterus (short uterine body [12mm long], paired uterine horns, single cervix opening into vagina)
  
  • Vaginal closure membrane: opens at estrus, parturition, & at day 26 of gestation (in most)
• Renal pelvis: large, single longitudinal renal papilla
  
  • Female urethra is outside vagina on urinary papilla (cranial to vaginal opening)
  • Urine = opaque yellow amber, pH 8-9, USG 1.005-1.050, predominately amorphous crystals

Question 80

Describe the husbandry of guinea pigs.

What environmental and social needs do guinea pigs have?

Describe the ideal diet of a guinea pig. What are their vitamin c requirements?

Answer 80

HUSBANDRY

HOUSING

• Social, do not house alone (pairs OK)
  
  • For breeding: harem-style housing common (single boar + 1-10 sows)
  • Intensive breeding systems: sow, young left in breeding pen so sow can be rebred @ postpartum estrus
    
    • Remove sow/young to nursery area shortly after parturition to reduce trampling, ear chewing by adult
• Simple housing w/ good ventilation
  
  • Solid-sided cages (open glass aquarium): change bedding frequency to minimize ammonia levels
  • Open-top cage OK (do not jump/climb)
  • Solid flooring better than wire (incr risk of foot/leg injuries)
  • Bedding: recycled paper products preferred over wood chips
    
    • Cedar chips associated w/ respiratory dz
  • Provide shelter/hide box (cardboard box or plastic hide)
• Temperature: 65-79*(18C-26C)
• Humidity: 30-60%

NUTRITION & FEEDING: herbivorous

• Crude protein 18-20% for growth/lactation, minimum crude fiber 10%
• Recommended diet: guinea pig pellets + good-quality grass hay (free choice), supplemented by fresh vegetables
  
  • Commercial pellets: crude protein 18-20%, fiber 10-16%
  • Offer RARE fruits/treats (if at all)
  • All diet changes made gradually
• Dietary vitamin C required (ascorbic acid) – lack L-gulonolactone oxidase (cannot synthesize vitamin C from glucose)
  
  • Nonbreeding adults: 10-25 mg/kg daily
  • Growing/pregnant: 30 mg/kg/day
  • ½ of naturally occurring vitamin C content in foods lost w/in 90 days, vitamin C oxidizes readily when exposed to air/heat/light so commercial foods have stabilized form (L-ascorbyl-2-polyphosphate) which maintain adequate levels for 6+ months when stored in dry conditions at room temperature (70F/21C)
  • Do not use liquid vitamin C supplement – changes water taste
  • Fresh foods high in ascorbic acid = red/green peppers, broccoli, tomatoes, kiwi, oranges
    
    • (Also leafy greens [kale, parsley, beet greens, chicory, spinach] but some have high levels of calcium/oxalates so offer in small amounts)
  • Nipple drinkers preferred over open dishes – behavioral enrichment

BEHAVIOR

• Seek physical contact w/ other guinea pigs but have little mutual grooming
  
  • Hair pulling/nibbling = aggression or in stressful/crowded conditions
• Vocalizations = chutt, chutter, whine, tweet, whistle, purr, drr, scream, squeal, chirp, grunt
• “Pop corning” = jump from excitement

Question 81

Describe the reproduction of guinea pigs.

When does sexual maturity occur?

What type of cycles do they have?

How can copulation be confirmed?

How long is gestation?

Describe the nutrition of the pups.

Answer 81

BREEDING & NEONATAL CARE

• Puberty @ 2 months (females), 3 months (males)
  
  • Males mount @ 1 mo old, ejaculate @ 2 mos old
• Sows polyestrous, breed year-round, peak reproduction @ 3-20 mo, can reproduce until 4-5 yo
  
  • Estrous cycle: 15-17 days (range 13-21 days), spontaneous ovulation
  • Fertile postpartum estrus 2-10 hrs after parturition
  • Distinct signs of proestrus & estrus
    
    • Proestrus: more active, chase cage mates, sway hindquarters, utter distinct guttural sound
    • Estrus (6-11 hours): lordosis (copulatory reflex – arching/straightening of back w/ elevation of rump & dilation of vulva)
      
      • Mature sows: vaginal membrane opens for 2 days during estrus, closes during ovulation
  • Confirm copulation by finding vaginal (copulatory) plug: solid mass of coagulated ejaculate that falls out of vagina several hours after mating
    
    • Typically hard/rubbery/waxy, are exclusive product of male secretions
• Gestation: 65-71 days (average 68 days)
  
  • Impending parturition = separation of the pubic symphysis (15mm palpable gap 2 days before, increases in width up to 25+mm)
    
    • Dystocia if 1^st bred after 7-8mo due to inadequate separation
    • Normal parturition: rapid, only a few min btwn births
    • Litter: 2-4 (varies by strain), range 1-13
    • Birth weight: 45-150g, inverse relationship to litter size
      
      • Young > 100-120g have better growth/survival
  • Newborns (pups/youngs, NOT piglets) are precocious
    
    • Ideally get sows milk for minimum of 5 days, normal lactation period = 3 weeks
    • Do not survive if no sows milk for 1^st 3-4 days
    • Sows not very “motherly,” passively allow nursing
      
      • Lactating sows permit other young to nurse
    • Voluntary micturition does not happen until 2 weeks old à sow licks pup’s anogenital region to stimulate urination/defecation
    • Weaned @ 21 days (range 15-2 days) or BW 180g
  • Orphans should be fostered to a lactating sow, or feed from dropper/pet nurser at beginning at 12-24 hours after birth
    
    • Feed q2h until 5 days old, then q4h
    • Hand-rearing formula should approx gpig milk: 4% fat, 8% protein, 3% lactose
      
      • Can mix 1:1 evaporated milk w/ water
    • Nibble on solid food @ 2 days old, can offer softened guinea pig pellets

Question 82

Describe the clinical techniques used with guinea pigs.

Where are the commonly used venipuncture sites?

Why is ALT not a useful marker in guinea pigs?

What is a Kurloff cell?

What catheterization sites do they have?

What oral antibiotics shoudl be avoided?

Answer 82

BASIC PROCEDURES & PREVENTATIVE MEDICINE

HANDLING & RESTRAINT: docile, support weight, avoid excessive handling

PHYSICAL EXAMINATION:

• Observe in cage, should eat readily when offered food
• Body weight, temp, check fecal impaction (older boars – can lower “rectal” temp), palpate ventral neck (enlarged thyroid), peripheral LN (esp submandibular)
• Overgrown nails common; older animals may have horny growth present from footpads

BLOOD COLLECTION:

• Blood volume = 70 mL/kg BW, safe to collect 7-10% (5-7 mL/kg) if healthy
• Venipuncture sites: lateral saphenous, cephalic veins, jugular, gingival vein (labialis mandibularis vein)
  
  • Cranial vena cava = increased risk of hemorrhage (close to major vessels, heart)

URETHRAL CATHETERIZATION & CYSTOCENTESIS

• Wide urethra 3-4mm diameter
• Ureteroliths often deeply embedded in mucosa à catheterization to force into bladder can be traumatic/nonproductive
• Catherization: 5- to 8Fr red rubber or clear NG tube, do not place in intromittent sac, minimize handling of penis (irritation/trauma à temporarily partial prolapse)
• Cystocentesis – need sedation/anesthesia

CLINICAL LABORATORY FINDINGS

• ALT is low in hepatocytes = insensitive marker of hepatocellular injury
• Hypercholesterolemia common (usu fatty infiltration of many tissues incld liver)
• Kurloff cell = unique leukocyte; mononuclear cell resembling lymphocyte containing round/ovoid inclusions (Kurloff bodies)
  
  • = modified natural killer cell, possible antileukemia activity
• Cell distribution of bone marrow = 26.7% erythroblasts, 63.3% myeloid cells, 4.6% lymphocytes, 5.4% reticulum cells
  
  • Myeloid/erythoid ratio: 1.2 and 1.6:1

DIAGNOSTIC IMAGING: often need sedation

TREATMENT TECHNIQUES:

• INTRAVENOUS & INTRAOSSEOUS CATHETER:
  
  • IV: cephalic, medial saphenous veins – 26G indwelling catheter
  • IO: cranial tibia (need general anesthesia)
• FLUID THERAPY: normal daily water intake = 100 mL/kg, give 25-35 mL per SC site
• ANTIBIOTIC THERAPY: do not use penicillins, cephalosporins, lincosamides, older macrolides
• ADMINISTRATION OF MEDICATIONS: PO/IM/SC, upper back skin may be thick esp. males

Question 83

Describe the GI diseases of guinea pigs.

What is unique about dental disease in guinea pigs?

What are some predisposing factors to GI stasis in guinea pigs? How do these animals present? How are they diagnosed and managed?

How do guinea pigs present with GDV? How are they treated?

Dysbiosis and enterotexemia are due to what? How are they managed?

What are the two most common causes of enteritis in guinea pigs?

What demographics are affected by fecal impaction?

Answer 83

GASTROINTESTINAL & HEPATIC DISEASES

• DENTAL DISEASE:
  
  • Predisposes to malocclusion: diets deficient in fiber/vitamin C, infection, trauma, possibly genetic
  • Complete oral exam requires sedation/anesthesia
  • Cheek teeth sloped angle (30*)
  • Tongue entrapment most common by overgrown mandibular crowns
  • Skull radiographs/CT to evaluate reserve crowns, bones of skull
  • Often have concurrent systemic disease along w/ dental disease
  • Perioperative supportive care for dental treatment: pain, hydration, nutrition (incld vitamin C supplementation), secondary infection
  • Prevention: high-fiber diet w/ vitamin C support
• GASTROINTESTINAL HYPOMOTILITY: (GI STASIS)
  
  • Primary or secondary process
  • Predisposing factors: inadequate dietary fiber, any disease process causing pain/anorexia à GI hypomotility & dehydration of GI contents
    
    • Need thorough Hx incld recent Abx
    • Common: dental disease
  • Hepatic lipidosis secondary to anorexia (esp obese Gpigs)
  • Clinical signs: decreased/absent fecal material, anorexia, bruxism, gas-or-fluid-distended stomach, cecum, bowel loops, abdominal pain, decreased GI sounds
    
    • GI contents dehydrate à exacerbates pain, anorexia
    • Stasis à gas accumulation in GIT (“bloat”) à can be life-threatening
      
      • DDX for GDV: intestinal obstruction d/t intussuception or omental torsion
  • Diagnostics: abdominal imaging (radiographs, ultrasound), bloodwork
  • Medical management: aggressive supportive care w/ replacement fluid therapy, pain management, assisted nutrition
    
    • Pain is visceral, often too severe for NSAIDs alone; good response to buprenorphine, morphine, methaone, oxymorphone, fentanyl
  • Gastric decompression is high-risk, often cannot remove significant volume of gas à ER basis (gastric tympany – pass large-bore red rubber through oral cavity, do not obstruct glottis, need to r/o gastric torsion first)
• GASTRIC DILATION & VOLVULUS: acute, generally fatal, stomach fills w/ gas/fluid & rotates on mesenteric axis
  
  • Cannot vomit due to muscularity of diaphragm, stomach geometry
  • DDX for GD without V: severe dysbiosis, SI intussuception
  • Clinical signs: acute onset depression, reluctance to move, abdominal distension, inappetence, severe depression, painful body posture, tachypnea, gas-filled tympanic cranial abdomen, abdominal pain, hypovolemic shock if advanced
  • Diagnostics: abdominal radiographs – no fold of stomach along incisura angularis like in dogs
  • Px: poor, 25% survival rate after surgery
    
    • Tx: stabilize w/ IV/IO fluids, opioids, oxygen, attempt decompression (OG/NG tube), pursue surgery once stabilized (reduce volvulus +/- gastrectomy, gastropexy)
• DYSBIOSIS & ANTIBIOTIC-ASSOCIATED ENTEROTOXEMIA: Clostridium difficile overgrowth from Abx or abrupt dietary change
  
  • Clostridium enterotoxin à secretory diarrhea, hemorrhagic typhlitis
  • Clinical signs: anorexia, dehydration, tympany, hypothermia, +/- diarrhea
  • Diagnosis: Hx, clinical signs, histopath
    
    • C. difficile difficult to isolate but there are PCR/EIA tests
  • Tx: symptomatic, can try commercial probiotics containing Lactobacillus species; suppress further clostridial growth w/ chloramphenicol, florfenicol, metronidazole
• ENTERITIS & DIARRHEA: uncommon but can have soft stools from excess dietary simple carbs or inadequate fiber (some have intermittent soft stools w/o identifiable cause)
  
  • Tyzzer’s disease (Clostridium piliforme): fecal-oral, usu young/stressed/immunocompromised
    
    • Clinical signs: lethargy, anorexia, diarrhea, unthrifty, acute death
    • Nx: intestinal inflammation, focal hepatic necrosis
    • Tx: unrewarding
    • Prevent w/ good husbandry, reducing stress (esp at weaning)
  • Salmonella typhimurium & Salmonella enteritidis: less frequently reported, high mortality during outbreaks
    
    • Fecal-oral through feed/water
    • Susceptible: weanlings, pregnant, aged, nutritional deficiencies
    • Clinical signs: scruffy hair coat, weight loss, weakness, conjunctivitis, abortion, +/- diarrhea
    • Nx: splenomegaly, hepatomegaly, yellow necrotic foci in viscera
    • Diagnosis: fecal/intestinal culture
    • Tx: not recommended b/c can become asymptomatic & salmonellosis can be zoonotic
    • Prevention: disinfection/sanitization environment, store food in airtight containers, thoroughly washing fruit/veggies
  • Other bacterial causes – Yersinia pseudotuberculosis, Clostridium perfringens, Escherichia coli, Pseudomonas aeruginosa, Citrobacter freundii, Listeria monocytogens
    
    • Usually contaminated food
    • Yersinia – abscesses in intestine, liver, regional LN
    • E. coli – wasting, depression, death in weanlings (intestines have yellow fluid)
  • GI parasites – Eimeria caviae, Balantidium caviae, Paraspidodera uncinate
    
    • E. caviae – diarrhea (juveniles, uncommon in adults)
    • Cryptosporidia (e.g. Cryptosporidium wrairi) – failure to gain weight, weight loss, diarrhea (more commonly weanlings, immunosuppressed – can recover spontaneously)
  • Regardless of underlying cause, diarrhea is serious – hypoglycemia, dehydration, hypothemia à correct electrolyte imbalances quickly
• FECAL IMPACTION: older intact boars
  
  • Soiled bedding combined w/ inguinal sebaceous secretions adhere à inguinal sebaceous gland infections, fecal impaction
  • Clinical signs: straining to defecate, constipation, passing large amounts of foul-smelling soft stool
  • PE: enlarged & flaccid anus impacted w/ normal, soft feces
  • Tx: dietary change to increase fiber, manual evacuation of stools w/ CTA

Question 84

Describe the respiratory and cardiovascular diseases of guinea pigs.

What are the common bacteria isolated from guinea pigs with pneumonia? How do their presentations differ?

How do guinea pigs present with heart disease? How common are murmurs? What types of heart disease are documented? What is the general prognosis?

Answer 84

RESPIRATORY DISEASES: small thorax, sensitive to airborne pollutants/respiratory infections, husbandry important

• PNEUMONIA: bacterial pneumonia common (Bordetella bronchiseptica, Streptococcus pneumoniae, Streptococcus equi subsp. Zooepidemicus, Pseudomonas aeruginosa etc.)
  
  • B. bronchiseptica – gram-negative rod, purulent bronchopneumonia involving consolidated lung lobes & fibrinosuppurative pleuritis, +/- otitis media, encephalitis, metritis, abortions, death
    
    • Clinical signs w/in 4-6 days of exposure
    • Suggest TMS, florfenicol as first line therapy
    • Prevent exposure to rabbits, dogs (asymptomatic carriers)
  • Streptococcus pneumoniae – from asymptomatic carriers of many spp, serotypes III/IV/XIX cause gpig disease
    
    • Predisposition – poor husbandry, young animals
    • Bronchopneumonia, fibrinopurulent pleuritis, pericarditis
  • (Adenovirus pneumonia described in lab gpigs)
  • General progression – tachypnea, dyspnea, incr respiratory sounds, sneezing, coughing, depression, anorexia, weight loss, unthrifty coat
  • Thoracic auscultation – crackles, rales, wheezing, minimal air movement
  • Diagnostics – CT or thoracic radiographs
  • Tx – systemic Abx, supportive care, consider nebulized Abx
• CARDIOVASCULAR DISEASE: 8% gpigs w/ cardiac dz have heart murmur
  
  • Clinical signs: dyspnea, lethargy, anorexia
  • Thoracic radiographs – cardiomegaly +/- tracheal elevation
  • Echocardiogram – pericardial effusion, DCM, pleural effusion, HCM, valvular heart dz
  • Tx – pericardiocentesis, enalapril, pimobendane, furosemide
  • Px – poor (3-6 mos)

Question 85

Describe the urinary diseases of guinea pigs.

What are the most common types of uroliths? Where are they found most commonly? UTIs with what bacteria have been associated with uroliths? How are these treated?

What are the most common bacteira to cause urinary tract infections in guinea pigs?

What is the suspected cause of chronic interstitial nephritis? How do these animals present? What are the histologic lesions?

Answer 85

URINARY DISEASES

• UROLITHIASIS: common, unknown etiopathogenesis, usually >2 yo
  
  • >90% calcium carbonate, most in bladder (sows – urethral orifice) or ureters; also kidneys, seminal vesicles, vagina
    
    • Males – bladder neck at seminal colliculus (narrowing of urethral mound where seminal vesicles & prostate gland open into urethra)
  • Clinical signs: depend on size/location of calculi
    
    • Bladder/uretheral – micturition abnormalities (hematuria, stranguria, dysuria), vague signs (lethargy, reluctance to move, anorexia)
    • Higher in urinary tract – micturition abnormalities or only have vague signs
  • Concurrent UTI involving Corynebacterium renale, etc. may be associated w/ urolithiasis
  • Diagnosis – clinical signs, PE, diagnostic imaging, urinalysis, +/- contrast urethrogram, +/- excretory IV pyelograms or contrast CT
    
    • Calcium carbonate uroliths radioopaque
    • Hematuria is most commonly reported abnormality on urine sediment
  • Tx – medical tx unrewarding, <5 mm diameter uroliths may pass unaided, surgical/cytoscopic removal of larger stones
  • Recurrence is common
  • Prevention – increasing water intake, reducing (but not eliminating) dietary calcium
    
    • Diets – high % grass hay, low % pellets, wide variety of low calcium veggies
    • Potassium citrate – binds intestinal/urinary calcium, decreases urinary calcium excretion, alkalinizes urine à tx efficacy unclear, monitor blood potassium for hyperkalemia
• CYSTITIS & URINARY TRACT INFECTIONS: bacterial cystitis frequently concurrent w/ urolithiasis
  
  • Corynebacterium renale, E. coli, Enterococcus spp, others
  • Clinical signs – mimic urolithiasis, vocalizing/straining during urination, pollakiuria, dysuria, hematuria, anorexia, depression
  • Diagnosis, treatment based on urinalysis, urine culture, diagnostic imaging
  • Anecdotal: intact female predilection for recurring cystitis?
• OTHER UROPATHIES:
  
  • Chronic interstitial nephritis - >3 yo, unclear pathogenesis, suspect water scarcity
    
    • Clinical signs: PU/PD, chronic weight loss, cardiac compromise, other vague signs
    • Diagnosis: incr BUN/creatinine/electrolytes, isosthenuria, nonregenerative anemia, US
    • Histo – interstitial fibrosis, glomerular ectasis, sclerosis, variable mononuclear inflammatory cells
  • Renal cysts – incidental at Nx
  • 1 report of renal failure following ingestion of peace lily

Question 86

Describe the reproductive disorders of guinea pigs.

What is the most common lesion in females? What are the two types of cysts?

What bacteria are commonly isolated from pyometras?

What is teh most common uterine tumor of guinea pigs?

What are some common causes of dystocia in guinea pigs? How are they managed?

What are predisposing factors to pregnancy toxemia? How do these animals present? How is this diagnosed and treated?

Answer 86

FEMALE REPRODUCTIVE DISEASES

• OVARIAN CYSTS: common, no correlation w/ reproductive hx, concurrent problems reported (leiomyomas of uterine structures, granulosa cell tumors, cystic endometrial hyperplasia, endometeritis), 2 types of cysts
  
  • Serous cyss (cystic rete ovarii, nonfunctional) – spontaneously develop throughout estrus cycle, do not respond to surges of luteinizing hormone
    
    • Single or multilocular, usually filled w/ clear fluid
    • 0.5-7 cm diameter, increases in size/prevalence w/ age
    • Usually no clinical signs unless large/compressive on organs
    • Tx- OVH or palliative drainage (may refill in days)
  • Hormone-producing follicular cysts – from preovulatory follicles that fail to ovulate
    
    • Associated w/ bilaterally symmetric nonpruritic flank alopecia, mammary hyperkeratosis
    • May response to short-acting GnRH & hCG
      
      • Deslorelin not effective (can open vaginal opening, predispose to vaginal infection)
• ENDOMETRITIS & PYOMETRA: bacterial infections – B. bronchiseptica, hemolytic Streptococcus species, E. coli, Corynebacterium pyogenes, Staphylococcus spp.
  
  • Clinical signs: bloody/purulent vaginal discharge, depression, anorexia, fever
  • DDX: endometrial hyperplasia, neoplasia
  • Diagnosis: clinical signs, imaging (US, CT), cytology of discharge
  • Tx: supportive care, broad-spectrum Abx, OVH
• UTERINE & OVARIAN NEOPLASIA
  
  • Uterine leiomyomas – most common uterine tumor
    
    • Others – leiomyosarcoma, endometrial adenoma, adenocarcinoma
    • DDX – endometrial hyperplasia (associated w/ ovarian cysts)
  • Ovarian tumors uncommon – rete adenomas, papillary adenomas, teratomas, granulosa cell tumors
  • Clinical signs: mistaken for pregnancy, hemorrhagic vaginal discharge, abdominal distension, palpable abdominal mass, abdominal pain
  • Tx – OVH, consider prevenative OVE in unbred sows
• DYSTOCIA: predisposed due to large pups, narrow pelvic canal, inadequate separation of pubic symphysis at parturition
  
  • Other causes – uterine torsion, uterine inertia, obesity, nutritional deficiencies
  • Most occur in sows 1^st bred after 8-12mo
  • May require C-section (palpate pelvic area for relaxation of symphysis – if 2.5-3 cm then may assist-deliver pup manually w/ lubricant) – 20 min continuous straining or unproductive contractions >2h
  • May have temporary paresis/paralysis or rear legs
  • Uterine intertia w/ relaxed symphasis – calcium gluconate, oxytocin (controversial – may have strong detrimental uterine contractions)
  • Uterine prolapse commonly associated w/ parturition à stabilize then OVH
• TOXEMIA OF PREGNANCY: sows 2 weeks prepartum to 2 weeks postpartum from negative energy balance
  
  • Predisposing factors: obesity, lack of exercise, large fetal loads, change in diet and/or environment, lack of exercise, large fetal loads, change in diet and/or environment, heat stress, primiparity
  • Pregnancy ketosis when gravid uterus compresses own blood supply or to kidneys/GI à tissue ischemia, hypertension, DIC
  • Clinical signs: anorexia, lethargy, depression, uncoordinated movements, dyspnea à muscle spasms, paralysis, death
  • Diagnosis: ketonuria, proteinuria, aciduria, hypoglycemia, acidosis, hyperlipemia, hyperkalemia, frequently hepatic lipidosis
  • Tx: IV/IO fluids, dextrose/glucose, feeding à OFTEN UNSUCCESSFUL
  • Prevention: avoid stress, obesity, changes in diet/environment in late pregnancy, increase carbs w/ critical care diet in last 2 weeks of gestation & early postpartum period

MALE REPRODUCTIVE DISORDERS

• Bacterial infection of scrotal area/prepuce – from bite wounds, solid bedding, smegma – unilateral/bilateral swelling of scrotal area, preputial swelling/discharge, anorexia, weight loss
  
  • Smegma accumulation – enlarged/inflamed prepuce/glans penis à smegma dries/hardens
  • Tx – topical cleaning, Abx, supportive care, analgesics, NSAIDs
• Testicular neoplasia (seminoma, embryonal carcinoma) rare – usually enlarged testicle w/ or w/o contralateral testicular atrophy à neuter

Question 87

Describe the integumentary diseases of guinea pigs.

What are their dermatophytes?

What is the guinea pig fur mite? What is the guinea pig sarcoptic mite - how do affected animals present?

How is pododermatitis managed in these species?

What is the most common tumor of guinea pig skin? How is it managed?

What mammary gland neoplasms are common? What is their behavior?

Answer 87

INTEGUMENTARY DISORDERS: need to know what breed-specific normal are – no hair between nose/lips, around lips, outer pinnae, behind ears; teddy/teddy satin/texel breeds have terrier-like course/kinky coat w/ curly whiskers

• ALOPECIA: usually husbandry or hormonal conditions, or nutritional deficiencies, poor sanitation/bedding material, follicular ovarian cysts, hormonal changes in late pregnancy, lactating sows in poor condition or large litters
  
  • Barbering – hairs not completely epilated, broken hair shafts; self-inflicted out of boredom/poor nutrition (lack of hay/fiber); dominant guinea pigs may need to be separated
    
    • If self-inflicted, head/neck are spared
• DERMATOPHYTOSIS: young to middle-aged, immunosuppressed
  
  • Scaly, patchy lesions to face/feet/dorsum à usually circular areas of alopecia w/ inflamed & sometimes crusty edges, +/- pruritic
  • Trichophyton mentagrophytes, T. benhamiae, Microsporidium canis
  • Diagnosis – clinical signs, cytology, dermatophyte culture
    
    • T. mentagrophytes do not fluoresce w/ Wood’s lamp
    • Definitive diagnosis = fungal culture
  • Tx: oral antifungal medication (itraconazole, terbinafine, antifungal shampoos, topical antifungal sprays)
    
    • Terbinafine more effective than intraconazole in gpigs
  • Potentially zoonotic, may survive in environment & reinfect
• ECTOPARASITES: fur mite Chirodiscoides caviae most common, but most severe clinical signs by sarcoptic mite Trixacarus caviae (ZOONOTIC); lice (Gliricola porcelli, Gyropus ovalis), rarely Demodex caviae
  
  • Infected by direct/indirect contact
  • Fur mite – subclinical or severe (pruritus, alopecia, restlessness)
  • Hallmark of T. caviae – severe pruritus (may resemble seizure à can have severe self-induced trauma & secondary fungal/bacterial infections)
    
    • White-yellow crusty areas w/ inflammation, abrasions from self-induced trauma
  • Louse – less severe dermatitis, requires direct contact for transmission
    
    • Heavy infestation: pruritic alopecia, crusty lesions, unthrifty-looking coat
  • If housed w/ rabbits, other rodents: transient infections w/ other ectoparasites (Sarcoptes muris, Notoedres muris, Myocoptes musculinus)
  • Diagnosis: microscopic examination, direct visualization of mites/eggs
  • Tx – ivermectin x4 tx, selamectin (T. caviae), macrocylic lactones (lice), antihistamines, NSAIDs, treat asymptomatic animals, disinfect environment’
• PODODERMATITIS: common, can affect all feet, may be irritated from improper husbandry
  
  • Clinical signs: variable (mild-severe): erythematous lesions w/ or w/o ulceration to granulomatous, callous-like swellings w/ bacterial invasion into tendons, joints, bone
  • Diagnostics: radiographs to r/o osteomyelitis, degenerative joint disease
  • Tx: chlorhexidine/iodine soak (mild-moderate cases), soft substrates, bandages, systemic Abx, surgical debridement w/ Abx-impregnanted beads, long-term wound management, amputation of digits, analgesia, anti-inflammatories
  • Vitamin C deficiency may predispose so may need to supplement
  • Px: poor in severe cases
  • Prevention essential! Diet, husbandry, cleanliness, preventing obesity
• SKIN NEOPLASIA: benign follicular tumors most common (trichofolliculomas > trichoepitheliomas)
  
  • Trichofolliculomas – benign, predominantly in males, usually on dorsal rump incorporating coccygeal gland, may be large/malodorous/ulcerated/exudative
    
    • Tx – complete excision usually curative
  • Others – sebaceous adenomas, fibrosarcomas, lymphoma, lipomas, liposarcoma, fibropapillomas of ear canal
• MAMMARY GLAND DISORDERS:
  
  • Mastitis uncommon – from husbandry (poor cage hygiene, sharp objects, abrasive bedding, wire cage bottoms, trauma from pups)
    
    • Diagnosis: clinical signs, cytology, bacterial culture of discharge/milk
    • Tx: Abx, anti-inflammatories, hot packing of glands, supportive care
  • Mammary gland neoplasia (fibroadenoma, adenomas, adenocarcinomas) common in box sexes (high prevelance in males, 75% malignant)
    
    • Clinical signs: swelling of one or both glands w/ or w/o serous or bloody discharge
    • Differentiate from mastitis – cytology, biopsy
    • Thoracic imaging important (metastasize to lungs)
    • Tx- surgical excision w/ wide margins + local LN, may need skin flap to close

Question 88

Describe the musculoskeletal disorders of guinea pigs.

How long can guinea pigs go without vitamin c before showing evidence of scurvy? What clinical signs and lesions result? How is this diagnosed and then treated?

Fibrous Osteodistrophy is more common in what type of guinea pig? What are the clinical signs? How is this differentiated from vitamin c deficiency?

Answer 88

MUSCLOSKELETAL DISORDERS

• VITAMIN C DEFICIENCY (SCURVY): young, growing more susceptible à 2 weeks of vitamin C deprivation
  
  • Lack of dietary vitamin C à defective type IV collagen, laminin, elastin à compromised blood vessels/joints à joint/gingival hemorrhages, teeth loosen (malocclusion)
  • Clinical signs: rough hair coat, anorexia, difficulty apprehending food, teeth grinding, vocalizing from pain, delayed wound healing, lameness, paresis, swollen joints (esp stifle), incr susceptibility to bacterial infections
  • Radiographs – long bone epiphysis, costochondral junctions of ribs enlarged, pathologic fx
  • Nx: hemorrhage into joints, skeletal muscle, gingiva, intestine, SC tissues from abnormal collagen
  • Diagnosis: Hx, clinical signs, rads, path lesions, serum ascorbic acid levels
  • Tx: parenteral then oral ascorbic acid
• OSTEOARTHRITIS: spontenaous or secondary to ulcerative pododermatitis
  
  • Risk factors: obesity, inadequate exercise, improper substrate
  • High-dose ascorbic acid supplementation may worsen spontaneous OA
  • Tx: palliative (soft clean bedding, analgesia, physical therapy, prevent obesity)
• FIBROUS OSTEODYSTROPHY: may be more common in satin guinea pigs (30% affected by 1 yo) via 1* or 2* hyperPTH à incr osteoclastic absorption of bone & replacement by fibrous tissue
  
  • Predisposing factors??? Vitamin D deficiency, low dietary calcium/phosphorous raio, calcium malabsorption, other calcium metabolism disturbances??
  • Clinical signs are secondary: weight loss, anorexia/difficulty eating, hypersalivation, palpable enlargement of mandibles, lethargy, difficulty walking, unwillingness to move, pain on bone/joint palpation
  • DIFFERENTIATE FROM HYPOVITAMINOSIS C
  • Diagnosis: Hx, PE, radiographs (extensive changes to all bones- osteopenia, osteosclerosis, pathologic fractures); evaluate ALP/total & ionized Ca/vitamin D/PTH
  • Affected satin gpigs à lower calcium levels, higher ALP
  • Nx: severely thinned trabecular bone, marked osteoclastic activity, resorption of cortical bone, extensive replacement w/ fibrous connective tissue, hyperplastic parathyroid glands
  • Px: guarded-poor
  • Tx: normal dietary Ca/P ratio, supplement oral calcium, analgesia, bisphosphonates, supportive care

Question 89

Describe the neurologic diseases of guinea pigs.

What are the most common isolates from otitis cases? What are the typical clincial signs? How are these managed?

What ectoparasite can induce pruritus severe enough to be mistaken for seizures?

What virus produces meningitis and hind limb paralysis? What are the typical lesions? How is it transmitted?

Answer 89

NEUROLOGIC DISEASE

• OTITIS MEDIA & INTERNA: common, can progress to otitis interna, most cases subclinical
  
  • Bordetella bronchiseptic, Streptoccus zooepidemicus, S. pneumoniae, S. pseudointermedius
  • Most common: ascending infection via eustacian tube
  • May induce facial nerve paralysis w/ secondary exposure keratitis
  • Clinical signs: head tilt, ataxia, circling, torticollis
  • Diagnosis: skull radiographs/CT
  • Tx: Abx, analgesics, anti-inflammatories – improves but does not cure clinical signs
    
    • Surgery: TECA-BO (may induce more complications – facial nerve paralysis, anoexia, head tilt, death – more than rabbits)
    • Endoscopy-assisted myringotomy + systemic Abx, weekly endoscopic-assisted lavage of tympanic bulla has fewer complications than TECA-BO
• INSULINOMA: head tilt, ataxia, twitching, seizures, weakness
• RESPONSE TO MITE INFESTATION: severe T. caviae causing severe pruritus mistaken for seizures (may be in lateral recumbency)
• LYMPHOCYTIC CHORIOMENINGITIS VIRUS (LCMV): arenavirus à meningitis, hind limb paralysis
  
  • Lymphocytic infiltrates in choroid plexus, ependyma, meninges
  • Transmission – inhalation, ingestion, direct contact (urine, saliva, feces), biting insects, transplacental
  • ZOONOTIC – humans have headache, vomiting, fever, rare fatalities

Question 90

Describe the ophthalmic diseases of guines pigs.

What organism is commonly isolated from conjuncitvitis cases? How is this diagnosed? How is it treated?

What is the most common cause of exophthalmos? How shoudl these be worked up and managed?

What is “pea eye” or “fatty eye”?

White lesions at the limbus are typically causes by what process?

Answer 90

OPHTHALMOLOGIC DISEASES

• CORNEAL ULCER: usually trauma from hay, foreign bodies or facial nerve paralysis from otitis media – Dx fluorescein stain, Tx as in other spp
• CONJUNCTIVITIS:
  
  • Chlamydophilia caviae – primary cause for conjunctivitis in young gpigs
    
    • Clinical signs: asymptomatic or mild (bilateral ocular serous discharge, conjunctivitis)
    • Diagnosis: intracytoplasmic inclusions in conjunctival scrapings, PCR
      
      • STUDY: 48/75 symptomatic & 11/48 asymptomatic were PCR positive
    • Unknown route of transmission, has zoonotic potential
    • Often self-limiting (3-4 weeks), consider topical tetracycline
  • Often seen w/ hypovitaminosis C
  • Lymphoma of conjunctival tissues
• EXOPHTHALMOS: usually secondary to retrobulbar process (most: odontogenic retrobulbar abscess associated w/ maxillary cheek teeth)
  
  • DDX: glaucoma, uveitis, trauma
  • Diagnostics: CT to assess retrobulbar space, teeth, bones of maxilla/orbit; US
  • Tx: systemic Abx (if mild), tx underlying dental abscess, enucleation (transpalpebral enucleation technique since no retrobulbar venous plexus)
  • Px: guarded-poor depending on underlying retrobulbar process, type of bacteria involved in abscess
• CONJUNCTIVAL TISSUE PROTRUSION (“PEA EYE,” “FATTY EYE”): adults (esp purebread American shorthairs)
  
  • Hypertrophy of lacrimal or zygomatic glands or incr fat deposits w/in conjunctiva
  • May cause ventral ectropion, lagophthalmos, secondary axial corneal degeneration
  • Nonpainul, usually resolves w/o Tx
• HETEROTROPHIC CALCIFICATION OF THE CILIARY BODY: white lesion @ limbs (osseous metaplasia in ciliary body)
  
  • Unknown cause (suspect aging/genetic)
  • Incidental finding

Question 91

Describe the endocrine disorders of guinea pigs.

Insulinoma typically occurs in guinea pigs of what age? How are these diagnosed and treated? What is the general prognosis?

How is diabetes managed in guinea pigs?

What is the most common endocrine disorder of guinea pigs? What is the typical signalment? What are the typical clinical signs? How is this diagnosed? What treatment is recommended?

What are the linical signs of hyperadrenocorticism? How is this diagnosed and treated?

Answer 91

ENDOCRINE DISORDERS

• INSULINOMA: >5 yo, acute neuro signs consistent w/ hypoglycemia (head tilt, ataxia, twitchin, seizures, weakness) +/- weight loss/lethargy
  
  • Diagnosis: Whipple’s triad (symptoms of hypoglycemia, documented hypoglycemia, response to treatment w/ glucose)
    
    • Usually confirmed postmortem
  • DDX: sepsis, hepatopathy, prolonged anorexia
  • Repeat fasting glucose w/ documented hypoglycemia are suggestive of insulinoma
    
    • High blood insulin levels w/ hypoglycemia à reference intervals not established
  • Px: guarded-poor
  • Tx: diazoxide 5-25 mg/kg PO q12h +/- prednisolone
• DIABETES MELLITUS: reported spontaneously in laboratory gpigs
  
  • Shortened life span (_<_5 years), bladder hypertrophy, voiding dysfunction
  • Reported in a pet gpig w/ cystitits, urination in small/frequent amts à responded to insulin therapy
  • May be transient, insulin therapy generally not necessary
  • Tx/Prevention: low-fat, high-fiber diet
• HYPERTHYROIDISM: most common endocrine disorder, usually >3 yo
  
  • Excessive thyroid hormone (thyroxine, triiodothyronine) from thyroid hyperplasia, adenoma, carcinoma
  • 8% (18/236) gpig neoplasms were thyroid origin
  • Thyroid tumors – functional or nonfunctional
    
    • Excessive circulating thyroid hormones à incr metabolic rate, exacerbates effects on sympathetic nervous system
  • Clinical signs: progressive weight loss, reduced body condition, normal/increased appetite, PU/PD, hyperactivity, nervousness, soft feces/diarrhea
  • PE: poor BCS, palpable SC masses on ventral neck, tachycardia, heart murmur, arrhythmia, hyperesthesia, soft feces/diarrhea
  • Diagnosis: full thyroid panel, imaging (US, scintigraphy, CT, MRI), FNA any palpable thyroid masses
  • Tx: radioactive I-131 (potentially curative), methimazole/carbimazole (not curative), thyroidectomy (potentially curative- perform scintigraphy first to check for ectopic thyroid tissue, do not remove parathyroid glands by accident)
• HYPERADRENOCORTISM: pituitary/adrenal tumors uncommon
  
  • Clinical signs: bilaterally symmetric nonpruritic flank alopecia, thick skin, PU/PD, bilateral exophthalmos, muscle weakness
  • Diagnostics: ACTH stim (saliva to measure cortisol levels), AUS (enlarged adrenal glands)
  • DDX: ovarian follicular cysts, hyperthyroidism
  • Tx:
    
    • Pituitary-dependent: trilostane
    • Adrenalectomy

Question 92

Describe the lymphoreticular disorders of guinea pigs

What is the etiologic agent of cervical lymphadenitis? How do these infections typically start? What are the clinical signs? How are these diagnosed and treated?

Lymphoma can occur spontaneously (and often does), but what virus can induce leukemia in guinea pigs? What are the typical clinical signs? How is this diagnosed and treated? What is the general prognosis?

Answer 92

OTHER COMMON DISEASES

• CERVICAL LYMPHADENITIS: usually Streptococcus equi subsp zooepidemicus (part of normal oropharyngeal/nasal flora of gpigs)
  
  • Oral abrasions (from overgrown teeth, bite wounds, rough feed) à bacteria invades deeper tissues & cervical lymph nodes (which abscess)
  • Clinical signs: variably-sized swellings in the ventral neck region which are purulent & occasionally rupture
  • Rarely spread systemically à pleuropneumonia, metritis, otitis media, septicemia
  • Diagnostics: clinical signs, cytology, bacterial culture
  • Tx: surgical excision, lancing/draining abscessed LN, systemic Abx
• LYMPHOMA: common, typically high-stage malignancy w/ poor Px
  
  • Epitheliotrophic T-cell lymphoma also reported w/ pruritic alopecia & scaling
  • Cavian leukemia caused by type-C retrovirus reported in lab gpigs (leukemic animals had WBC 25k-50k/mL w/ large lymphocytes)
  • Clinical signs: anorexia, lethargy, unkempt coat, peripheral lymphadenopathy
    
    • +/- hepatomegaly, splenomegaly, mediastinal masses
  • Diagnosis: CBC, cytology
  • Px: overall poor, depends on stage of lymphoma, presence of systemic disease
  • Tx: prednisolone (palliative) (also reported: L-asparaginase, cytarabine arabinoside)
    
    • Gpigs produce asparaginase on own so drug may be less effective
    • Anecdotal: longer survival w/ lomustine + prednisolone
    • Radiation tx +/- chemotherapy?

Question 93

Describe the anatomy and behavior of chinchillas.

What is the scientific name of the chinchilla?

When are they most active? What is fur slip? Why does it happen?

What is their dental formula? What types of teeth do they have?

What is unique about the female reproductive anatomy?

What is their ideal husbandry set up?

What is the recommended diet?

Answer 93

Chinchilla lanigera

Biology and Anatomy

• Hystricomorph rodents from South America in cool, semiarid rocky slopes of Andes
• Dust bathe, herbivores, do not hibernate and live in large groups

Behavior

• Active at dusk and night but in managed care can be active during the day too
• When frightened can shed patches of fur – fur slip which take 6-8 weeks to fill in. May bite and spray urine
• Most common color is dark blue gray. Other colors are mutations of the originals standard color

Anatomy and Physiology

• Slender body, short forelimbs, and muscular hindlimbs for leaping
• Greatly expanded tympanic bullae which are thin walled. Long tail acts as balance when animal jumping
  
  • Divided into ventral (larger) and dorsal bulla
  • Used as model for human otologic research
• Third eyelid rudimentary and does not provide protection to the cornea
• Lacrimal duct similar course as other rodents and lagomorphs but cannot be catheterized

GI

• Dental formula – same as guinea pigs 2 (I 1/1, C0/0, PM 1/1, M3/3)
  
  • Elodont (grow continuously), labial surface orange yellow, oral cavity small and narrow
• Compared with guinea pigs have a long jejunum and descending colon.
  
  • Cecum large and coiled, colon highly sacculated
  • Cecum holds less of the contents of the large intestine than in a rabbit or guinea pig
• Eat mainly at night and defecate predominantly at night. Produce nitrogen rich pellets (for coprophagy) and nitrogen poor for fecal pellets.

Urogenital

• Produce concentrated urine. Urethra in females terminates on the urinary papilla externally ventral to the vagina.
• Uterus duplex bicollis vagina simplex – 2 uteri, 2 cervices, and single vagina
  
  • The two external openings of the cervices not discernable macroscopically and the two cervices appear as single cervix
• 3 pairs of mammary glands – one inguinal and two lateral thoracic pairs
• Males do not have true scrotum, instead contained within inguinal canal or abdomen and two small movable sacs are next to the anus into which the caudal epididymis can drop
  
  • S shaped penis with os penis
  • Males possess a penile pouch ventral to the urethra – lined with spurs and everted during copulation
  • Accessory sex glands – paired and include prostate, vesicular glands, bulbourethral glands and forms hard plug that remains in the female after copulation

Breeding

• Seasonally polyestrous (breeding season Nov – May)
• Vaginal closure membrane seals the vagina at all times except during estrus, parturition, or underlying disease
  
  • During estrus, mucoid vaginal discharge develops but no obvious vulvar swelling
• Gestation avg 111 days with 1-4 young born in each litter
• Placentophagic, typically give birth in the mornings
• Precocious young – fully furred with teeth and open eyes
  
  • Damn stands and young nurse while laying on their backs, solid food by 1 week old
  • Another lactating female may be used as a surrogate is mother dies

Question 94

Describe the husbandry and clinical techniques for chinchillas.

What injury can occur commonly due to husbandry issues? What is an ideal social structure for chinchillas? What is the recommended temperature? Why do they need a dust bath?

What is the recommended diet for chinchillas?

What are some common signs of intraoral disease?

How common are heart murmurs?

Are calcium carbonate crystals normal?

Answer 94

Housing

• Active and require lots of space – multilevel cages to climb and jump
• Tibial fracture common if chinchilla catches leg in a cage bar
• Need hide spot, not advised to have singe chinchilla due to social nature
• Thick fur and inability to sweat - sensitive to heat. Recommended temp is 50 to 68F
• Provide dust bath daily – dust bathing reduces fur lipids. Excessive use can lead to conjunctivitis

Nutrition

• Eat mainly at night with small amounts during the day
• Feed hay and pellets – vegetables, greens or fruits not recommended and can lead to GI dysbiosis and inadequate Ca/P ratio
• Prefer water in bowls

Clinical techniques

• Do not grasp fur – ma cause fur slip. Grasp around thorax, keep front half of body higher than the back end to prevent them from trying to jump out
• Measure temp 2cm into anus and shortly after restraint, though body temp reportedly not routinely performed unless systemic disease concerns (Temp ~95-100F)
• Tympanic membrane can always be visualized. Careful palpation of mandibles for apical elongation
• Wet fur on mouth, ventral next and forelimbs usually indicative of hypersalivation and intraoral/dental disease
• Benign heart murmurs common in healthy animals.
• Anogenital distance greater in males than females
• Glans penis should be completely extruded in all males to r/o phimosis and remove fur or smegma accumulation
• Absence of vaginal membrane in females can occur during estrus, after birth, or in cases of uterine disease (endometritis).
• Jugular veins are preferred site of venipuncture. Lateral saphenous and cephalic accessible but small. Cranial vena cava only in anesthetized animals
• In healthy chinchillas, urine can vary from yellow to red-brown and amorphous crystals present in most animals
  
  • Do NOT excrete excess dietary calcium via urine, but instead do so in feces so calcium carbonate crystals are abnormal UA finding
• Minimally invasive access to middle ear through dorsal roof of tympanic bulla (transbullar) is common surgical procedure in chinchillas
• CT is preferred imaging modality to evaluate the head
• IO catheter in cranial tibia or femur
• Frequently require prolonged syringe feedings due to propensity of developing ketoacidosis and hepatic lipidosis
• Penicillins, cephalosporins, clindamycin, erythromycin never give orally
  
  • Metronidazole orally can cause reduced food intake and is dose dependent

Question 95

Describe the GI diseases of chinchillas.

How should hepatic lipidosis and ketosis be maanged?

What dental diseases are common in chinchillas?

What are some causes of dysbiosis and diarrhea? What is a common sequela to that?

Answer 95

Diseases of Chinchillas

Hepatic lipidosis and Ketosis

• Hepatic lipidosis secondary to excessive fat mobilization in anorexic or hyporexic chinchillas is one of the most common findings in chinchillas at necropsy
  
  • Often have hx of anorexia and decreased fecal output
  • In severe cases hyperglycemia can develop. Usually chem is normal
  • Test for urinary ketones and decreased pH
• Correct underlying cause for anorexia, fluid deficit, and nutritional support. Measure urinary ketones and pH to monitor response

Dental Disease

• Periodontal disease, caries and tooth resorption common
• Caries characterized by brown discoloration and loss of tooth substance on occlusal and interproximal tooth surfaces due to bacterial infection leading to demineralization. Nutritional and genetic causes proposed as predisposing factors
• Clinical findings – reduced BCS and weight loss, changes in food preferences, reduced/smaller feces, saliva staining on chin and forelimbs , fur chewing.
• Up to 50% of intraoral lesions can be missed in conscious animal especially periodontal disease, tooth resorption and buccal spurs of maxillary cheek teeth
• Widened interproximal spaces facilitates food impaction and development of periodontal disease
• Repeated intraoral exams and treatments often for the life of the animal are necessary to control complications of dental and periodontal disease

Gastrointestinal Diseases

Dysbacteriosis and Diarrhea

• Any painful of stressful condition can result in gastrointestinal signs
• Constipation, tympany, diarrhea, intussusception and rectal prolapse.
• Sudden dietary changes or inappropriate antibiotic use common. Secondary infectious (giardia, coccidiosis, Pseudomonas, enterobacterial overgrowth)
• Dx: radiographs/CT, fecal parasite screening, cytology and culture (e coli, pseudomonas aeuginosa, Proteus)
• Avoid oral drugs because absorption and effectiveness decreased when GI function abnormal – recommended enrofloxacin for dysbacteriosis
  
  • Intestinal yeast overgrowth (Cyniclomyces guttulatus) lines the stomach and can cause soft feces

Tympany

• Often secondary to gastroenteritis, dysbacteriosis, ileus luminal obstruction of intestinal torsion

Rectal prolapse and Intussusception

• Frequently occur together secondary to dysbacteriosis, enteritis, constipation or diarrhea.
• Intussusception of descending colon and rectum associated with most cases of rectal prolapse
• Affected portion usually cyanotic, congested and in advanced cases, nonviable
  
  • Surgical correction of intussusception necessary, cannot just replace tissue if intussusception present.
• Prognosis poor in most cases and depends on duration of intussusception, viability of tissues and primary cause.

Esophageal disorders

• Cannot vomit – food items or bedding may be ingested and entrapped in oropharynx/upper esophagus.
• Cx – acute anorexia, drooling, retching, dyspnea

Question 96

Epiphora in chinchillas is usually secondary to what disease process?

What are some potential causes of conjunctivitis in chinchillas?

What is a typical cause of nasal discharge?

What cardiac diseases have been reported?

What is the most common urolith?

Answer 96

Ophthalmic diseases

Epiphora

• Epiphora (wet eye) – usually unilateral serous discharge and wetting of periocular fur. Common in dental disease – elongated apical reserve crowns of maxillary cheek teeth and obstruction of nasolacrimal duct
• No effective treatment for apical reserve crown elongation. Cannot flush nasolacrimal duct.

Conjunctivitis

• Irritation from excessive sand bathing, inadequate cage ventilation, or underlying nasolacrimal duct obstruction
• Normal isolates are gram positive species, but alternative study noted that chinchillas with acute onset more likely to have gram negative pathogens (P aeruginosa assoc with animals with concurrent upper respiratory signs)
• Perform aerobic culture and sensitivity, fluorescein,
• Early recognition, systemic antibiotics and supportive care critical for infection with systemic Pseudomonas infection

Corneal diseases

• Corneal damage and keratitis secondary to trauma common assoc with blepharospasm, discharge and conjunctivitis
• Lack of palpebral reflex secondary to facial nerve damage from OM

Misc Ophthalmic Diseases

• Cataracts common – diabetogenic cataracts reported so r/o DM

Respiratory Diseases

• If conjunctivitis diagnosed in addition to nasal discharge, r/o P aeruginosa
• Pneumonia uncommon in pets but common in farmed chinchilla due to husbandry
  
  • Predominantly gram-negative organisms. Presenting animals often have respiratory signs in addition to poor haircoat and decreased BCS
  • First r/o CHF and diaphragmatic hernia

Cardiac Diseases

• Labored breathing, weakness, lethargy and possible heart murmur should be evaluated radiographically and echo.
  
  • MV insufficiently, dynamic right ventricular outflow tract obstruction, TV insufficiency and LV hypertrophy reported. VSD and DCM also reported.
• High prevalence of heart murmurs but heart disease is rare – many are considered benign murmurs but recommend echo in chinchilla with pronounced murmur.

Urinary Tract Diseases

• Urolithiasis most common urinary tract disorder, predominantly in males. Most uroliths composed of calcium carbonate – unlikely that excess dietary calcium plays a role because Ca excreted in the feces and not urine
• Cx: hematuria, pollakiuria and stranguria
• Urethral calculi require urinary catheterization to retropulse stones – can be challenging since stone is embedded in the mucosa. Worse prognosis
  
  • Cystoliths had better prognosis but high recurrence rate (50%)

Question 97

Describe the reproductive diseases of the Chinchilla

Answer 97

Female Reproductive Diseases

• Fetal resorption, mummification, retention and abortion common.
• Incompletely reabsorbed, retained or mummified fetuses can remain in uterus and predispose to sterility and endometritis
  
  • In chinchilla with hemorrhagic vaginal discharge consider abortion or fetal or placental retention if housed with a male
• Uterine neoplasms – leiomyosarcoma, leiomyoma, fibroma, hemangioma. Typically present with bloody vaginal discharge and have palpable mass.

Endometritis and pyometra

• Pyometra characterized by accumulation of purulent discharge within the uterine lumen with cystic endometrial hyperplasia and secondary bacterial infection
  
  • Stump pyometra possible from incomplete ovariectomy
• Cx – acute depression or anorexia, lethargy, open vulva and vaginal discharge (mucoid to mucopurulent to hemorrhagic)
• In estrus – predominant cells are partial to complete cornified superficial epithelial cells. Neutrophils absent in estrus but common in proestrus and metestrus
• Lack of open vulva, cervices and discharge does not r/o disease
• Ovariohysterectomy recommended for treatment of endometritis and pyometra

Dystocia

• Cx – restlessness, frequent crying, attention to genital region and widened vaginal opening. Allantoic fluid or mucohemorrhagic discharge often present
• Usually associated with single oversized fetus or malpresentation
• Uterine inertia can occur. Intervene if > 4 hr without delivery
• Respond well to C -sections

Male Reproductive Diseases

Fur rings

• Accumulation of fur at base of glans penis within the prepuce
• Can cause balanoposthitis and paraphimosis and act as nidus for bacterial infection
• Extrude the glans penis in all exams and remove fur/smegma and clean with dilute chlorhexidine

Balanoposthitis and preputial abscesses

• Balanoposthitis is inflammation of prepuce and glans penis usually secondary to infection. Can be associated with fur ring or systemic/localized P. aeruginosa infection. Chronic cases may result in prepeutial abscesses.

Paraphimosis

• Acute balanoposthitis or fur rings can cause paraphimosis – inability to replace glans back into prepuce
• Anuria may develop due to inflammation and trauma

Phimosis

• Inability to protrude glans penis from prepuce or entrapment of the penis within the prepuce
• Can develop from preputial abscesses or adhesion formation between visceral layer of prepuce and glans
• Often subclinical unless balanoposthitis develops – treat by surgically resecting adhesions. Recurrence is common

Question 98

A recent study described the effect of pneumoperitoneum (insufflation pressure) on Guinea pigs.

What is the scientific name of the Guinea pig?

What insufflation pressure was used in this study?

What behaviors changed in insufflated versus control animals?

Answer 98

AJVR 2022 83(8) online
Effect of pneumoperitoneum on gastrointestinal motility, pain behaviors, and stress biomarkers in guinea pigs (Cavia porcellus)

OBJECTIVE To compare stress markers, gastrointestinal motility, and behavioral indicators of pain between guinea pigs undergoing pneumoperitoneum with carbon dioxide (CO2) and control guinea pigs.
ANIMALS Fourteen 4- to 5-month-old intact female Hartley guinea pigs.
PROCEDURES Guinea pigs were randomized to receive insufflation or serve as controls (anesthesia and abdominal catheter placement without insufflation), with 7 animals/group. Insufflated animals underwent 6 mm Hg of CO2 pneumoperitoneum for 30 minutes. Afterward, results for vital signs, blood glucose, fecal cortisol, appetite, fecal output, and behaviors (via video recording) were compared between the 2 groups.
RESULTS There was no difference between groups and over time for body temperature, heart rate, fecal output in grams, pellets consumed, blood glucose, and fecal cortisol. Guinea pigs that underwent insufflation had significantly more fecal pellets at 36 hours after the procedure. Several behaviors were expressed similarly between groups and over time, such as body turns, incomplete movement, rearing, lying down, drinking, and hiding. Coprophagy occurred less often in the insufflated versus noninsufflated group at 12 h postprocedure but was similar between groups at other time points. At 60 hours after the procedure, insufflated animals spent less time squinting compared to noninsufflated animals. Other behaviors were differentially expressed over time but not between treatments.
CLINICAL RELEVANCE Overall, there were no major differences in appetite, stress markers, and behaviors between insufflated and control guinea pigs. CO2 insufflation did not appear to cause undue pain or stress in guinea pigs and may be a reasonable technique to use during laparoscopy.

Intro
* Purpose: compare stress markers (blood glucose and fecal cortisol), markers of gastrointestinal motility (appetite and fecal production), and behavioral indicators of pain between guinea pigs undergoing abdominal insufflation with CO2 and guinea pigs undergoing abdominal catheter placement without insufflation (control).

M&M
* Anesthetized, insufflated for 30 mins or abdominal catheterization with no insufflation
* Measured markers listed above and compared between groups

Results
* All animals lost weight, only one returned to presurgical weight by day 7 post op
* There was no difference between groups and over time for rectal temperature, HR, fecal output in grams, food pellets consumed, blood glucose, and fecal cortisol
* Guinea pigs that underwent CO2 insufflation had significantly higher fecal output in fecal pellet numbers at 36 hours post op than control guinea pigs
* There were less coprophagy behaviors in the insufflated group than in the noninsufflated groups at 12 h post op, but no difference at other time poiints
* At 60 hours after the procedure, insufflated animals spent less time squinting compared to noninsufflated animals but not at other time points
* All guinea pigs survived anesthesia, the procedures, and the postoperative monitoring period.
* Several of guinea pigs (6 of 7 in insufflation group, 3 of 7 in control group) developed pigmenturia, which grossly appeared consistent with hematuria rather than porphyrinuria, after the procedure.
o All treated with marbo due to hx of corynebacteirium renale cystitis outbreaks in g pigs from the same source

Takeaway: Insufflation of CO2 at 6 mm Hg for 30 minutes in guinea pigs is not associated with significant increases in observable pain or stress or decreases in gastrointestinal motility compared to control.

Question 99

A recent study compared the use of alfaxalone-ketamine-midazolam and alfaxalone-ketamine-dexmedetomidine in Black-tailed prarie dogs.

What is the scientific name of the black-tailed prarie dog?

What is the mechanism of alfaxalone?

How was the induction in these protocols?
- How does this differ with the induction of alfaxalone containing protocols in Chinchillas and mice and rats?

What physiologic effects were seen with these protocols?

How did the depth and duration of anesthesia differ between the two protocols?

What support is recommended with these protocols in this species?

Answer 99

Anesthetic effects of alfaxalone-ketamine-midazolam and alfaxalone-ketamine-dexmedetomidine administered intramuscularly in black-tailed prairie dogs (Cynomys ludovicianus)
Kara Hiebert, DVM1; David Eshar, DVM1; Jasmine Sarvi, DVM1; Hugues Beaufrère, DVM, PhD2
Amer J Vet Res, 83(9), 2022, pp. 1-8

OBJECTIVE: To evaluate and compare the anesthetic effects of alfaxalone-ketamine-midazolam (AKM) and alfaxalone-ketamine-dexmedetomidine (AKD) in black-tailed prairie dogs (Cynomys ludovicianus).
ANIMALS: 9 male black-tailed prairie dogs.
PROCEDURES: Prairie dogs were anesthetized with AKM (6 mg/kg alfaxalone, 30 mg/kg ketamine, and 1.5 mg/kg midazolam) and AKD (6 mg/kg alfaxalone, 30 mg/kg ketamine, and 0.15 mg/kg dexmedetomidine) in a prospective, complete cross-over study. Atipamezole (1.5 mg/kg) after AKD or flumazenil (0.1mg/kg) after AKM was administered 45 minutes after induction of anesthesia. Onset of general anesthesia, physiologic parameters, depth of anesthesia, and time to recovery after reversal administration were evaluated for each treatment.
RESULTS: Both AKM and AKD produced a deep plane of anesthesia in black-tailed prairie dogs that varied in duration. The median induction times for AKM and AKD were 82 and 60 seconds, respectively. The median recovery times for AKM and AKD were 27 and 21 minutes, respectively. There were no significant differences between protocols for induction (P = .37) and recovery (P = .51) times. All measured reflexes were absent in all animals at 5 minutes postinduction, with hindlimb reflexes returning prior to forelimb reflexes. Heart rate was lower but respiratory rate was higher in the AKD treatment. Body temperature decreased significantly for both protocols (P < .001) and was significantly lower with AKM than AKD (P < .001).
CLINICAL RELEVANCE: Both AKM and AKD produced a deep plane of anesthesia in black-tailed prairie dogs. For both protocols, heat support and oxygen support are indicated.

Key Points:
- Black tailed prairie dogs (Cynomys ludovicianus) rodents native to NA
- Previous anesthetic studies 🡪 xylazine-ketamine combination resulted in ~3% mortality rate and a dexmed-ketamine-midaz resulted in unreliable plane of anesthesia.
- Alfaxalone – neutoactive steroid that works as a GABA agonist in the CNS
- Ketamine – NMDA antagonist
- Aim: determine effects of two alfaxalone based protocols – AKM (alfaxalone, ketamine, midazolam) and AKD (alfaxalone, ketamine, dexmedetomidine)
- Both protocols resulted in a deep plane of anesthesia with successful reversal though ~half of animals required a second reversal at 20 mins
- No significant different between induction or recovery times. Overall considered smooth.
– Contrasts that of chinchillas during induction with alfax-butorphanol which had rolling, twitching and tremors during induction, and mice/rats which had twitching/limb jerking
- All animals lost measured reflexes by 5 min post induction
– Hindlimb withdrawal returned before forelimb – assess both when assessing depth
– Attained surgical plane of anesthesia – AKD maintained for 20 mins, AKM for 45 mins
- AKM resulted in significantly higher HR that AKD at all time points
- AKM resulted in significantly higher RR than AKD but both were wnl.
– AKM respiratory rate decreased over time. AKD RR remained stable. No change in SpO2.
- AKM resulted in significantly lower temperature than AKD, but both groups developed hypothermia
– Heat support recommended throughout procedure and recovery. Potentially even before the procedure since multiple animals were lower than normal at initial check

Take Home Message:
- Both protocols (AKM and AKD) produced effective anesthesia with rapid and smooth induction.
- AKD reliably produced a brief surgical plane of anesthesia (~ 20 mins) versus AKM which maintained surgical plane of anesthesia for the duration of the anesthetic procedure in nearly all animals (~45min).
- Heat and oxygen support strongly recommended in both protocols.

Question 100

A recent study investigated the ideal laparoscopic working space in Guinea pigs.

What is the scientific name of the Guinea pig?

What were the three intrabdominal pressures investigated in the study?

What complications were seen at higher IAP?

What pressures are recommended during the beginning and maintenance phases of laparoscopy?

Answer 100

AJVR 2022 83(9)
Assessment of laparoscopic working space in guinea pigs (Cavia porcellus) undergoing carbon dioxide insufflation at different intra-abdominal pressures

OBJECTIVE To evaluate pneumoperitoneal volumes (laparoscopic working space) in guinea pigs (Cavia porcellus) undergoing pneumoperitoneum via carbon dioxide insufflation at different intra-abdominal pressures (IAPs) (4, 6, and 8 mm Hg) and recumbencies (dorsal, right lateral, and left lateral).
ANIMALS Six 3- to 4-month-old sexually intact female Hartley guinea pigs.
PROCEDURES Guinea pigs were anesthetized, intubated, and had an abdominal insufflation catheter placed. A baseline abdominal CT scan was performed. Guinea pigs underwent insufflation, with each IAP given in a random order for 10 to 15 minutes with a washout period of 5 minutes between pressures. Abdominal CT scans were acquired at each IAP and at each recumbency. Pneumoperitoneal volumes were calculated using software.
RESULTS Increases in IAP increased working space significantly (P < .001). The 6- and 8-mm Hg pressures increased working space from 4 mm Hg by 7.3% and 19.8%, respectively. Recumbent positioning (P = .60) and body weight (P = .73) did not affect working space. Order of IAP had a significant (P = .006) effect on working space. One of the guinea pigs experienced oxygen desaturation and bradycardia at 6- and 8-mm Hg IAP.
CLINICAL RELEVANCE Although an increased working space occurred at 6 and 8 mm Hg compared to 4 mm Hg, further research is needed concerning the cardiovascular effects of pneumoperitoneum in guinea pigs to determine whether those higher IAPs are safe in this species. An IAP of 6 mm Hg can be considered for laparoscopic cannula placement, followed by a lower IAP for laparoscopic procedures.

Intro
- The objective of this study was to evaluate the pneumoperitoneal volumes (laparoscopic working space) via CT in guinea pigs undergoing pneumoperitoneum via CO2 insufflation at 3 different IAPs (4, 6, and 8 mm Hg) and in 3 different recumbencies (dorsal, right lateral, left lateral).

M&M
- 6 F g pigs, crossover design
- Baseline CTs in 5 of the 6 (they forgot to do the last one)
- Anesthetized and insufflation at each of the 3 pressures in randomized order
- Pressure held forr 10-15 mins, then abdominal CT performed in each of the three recumbencies

Results
- Mean intra-abdominal working space volume was significantly (P < .001) increased with increases in IAP applied
- Recumbent positioning did not have an influence on working space, nor did the body weight
- One of the guinea pigs experienced oxygen desaturation and bradycardia at 6- and 8-mm Hg IAP

Discussion
- In our study, an increase in pneumoperitoneal volume occurred with increasing IAP in a proportional manner
- Based on complications encountered at greater IAPs in our study there is concern that an IAP of 8 mm Hg is not safe in guinea pigs
- In addition, an IAP of 6 mm Hg increased working space marginally compared to that generated at 4 mm Hg in a statistically significant but likely not surgically significant manner.
- Therefore, a reasonable compromise between working space and anesthetic safety may be to use an IAP of 6 mm Hg during placement of the laparoscopy cannula, and a lower IAP of 4 to 5 mm Hg after cannula placement

Question 101

A recent study described the clinical presentation and management of lymphoma in rats.

What is the scientific name of the brown rat?

How prevlent was lymphoma in this study?

How did these animals present?

What findings were observed on diagnostic imaging?

What demographic is more likely to be affected?

What important differentials should be considered?

Answer 101

JAVMA 2022 260(12) 1533-1540
Clinical presentation and treatment of lymphoma in companion rats (Rattus norvegicus; 2008–2020)

Abstract
OBJECTIVE
To describe the clinical presentation, treatment, and treatment outcomes for companion rats (Rattus norvegicus) diagnosed with lymphoma.
ANIMALS
All rats that presented to the exotics service and underwent postmortem examination during the time period of 2008 through 2020 were evaluated.
PROCEDURES
The medical records of 35 rats were evaluated for an ante- or postmortem diagnosis of lymphoma. Cases with a diagnosis of lymphoma were further reviewed for signalment, presenting complaint, clinical signs observed on physical exam, diagnostic testing performed, and treatments administered. Postmortem gross and histologic findings were reviewed.
RESULTS
7 out of 35 rats were diagnosed with lymphoma, either ante-mortem or postmortem. The most common presenting complaint that was present in all rats with lymphoma was respiratory abnormalities. Five out of 7 rats had radiographs performed, all of which had abnormalities noted in the thoracic cavity including pulmonary nodules, cranial mediastinal widening, or alteration to the cardiac silhouette. Diagnosis via cytologic aspirates was performed in 2 cases and each was diagnostic for lymphoma; however, even with treatment, survival time following initiation of chemotherapy was short (less than or equal to 24 days). The definitive diagnosis in the remainder of the cases was via necropsy.
CLINICAL RELEVANCE
Results suggest that lymphoma is a common neoplastic disease in rats and a thorough diagnostic work-up is indicated in any rat that presents for general malaise or respiratory signs.

Key Points
- Lymphoma is more common in the mouse, but is not as well described in the rat
- Overall prevalence of lymphoma in this pop was 4.7%
- Median age at time of death was 2 years; all sexes and both neutered and non-neutered animals got lymphoma
- All animals with lymphoma (7/35) presented with signs of respiratory compromise, one case had palpable splenomegaly.
- Blood smears performed in 4/7 cases, unremarkable in 3 cases
– 1 case had evidence of leukemic phase of lymphoma
– 1 case had lymphocytosis, evidence of lymphoid leukemia
- Radiographic findings included multifocal pulmonary masses, single pulmonary masses, cranial mediastinal widening, enlarged cardiac silhouette
- CT performed in 2 cases, showed mediastinal mass (1) or right-sided pulmonary consolidation (1)
- 2 cases - AUS performed - findings included hyperechoic hepatopathy (1), hepatic nodules, splenomegaly, and central renal mineralization (1)
- 2 cases had cytology performed from FNA of mediastinal mass, both diagnostic for lymphoma
- 5/7 cases diagnosed on necropsy The 2 cases diagnosed antemortem received chemo, died 12d and 24d after diagnosis
- 3 cases of mediastinal lymphoma w/ mets to other organs, 1 case multicentric lymphoma, 1 case lymphoid leukemia, 2 cases lymphoma of pulmonary origin

Take home message
- Lymphoma should be considered a differential for rats presenting in respiratory distress.
- Common features of the lymphomas seen in the rats in this study were a respiratory component, multicentric presentation, and poor prognosis.
- Diagnosis was usually late in life, median age at death 2 years
- Radiographs were useful for seeing pulmonary changes but not for differentiating location or type of lesion (i.e. neoplastic vs infectious). Cytologies from aspirates and hematology may be helpful.

Question 102

A recent study desribed the risk factors and clinical features of urolithiasis in Guinea pigs.

What is the scientific name of the Guinea pig?

What are the clinical signs of urolithiaisis in guinea pigs?

What are the most common stone types?
- How did stone location vary by sex?

What organisms commonly infect the lower urinary tract?

What are negative prognostic indicators for urolithiasis in Guinea pigs?

Answer 102

Retrospective analysis of risk factors, clinical features, and prognostic indicators for urolithiasis in guinea pigs: 158 cases (2009–2019).
Edell AS, Vella DG, Sheen JC, Carotenuto SE, McKee T, Bergman PJ.
Journal of the American Veterinary Medical Association. 2022;260(S2):S95-S100.

OBJECTIVE To investigate risk factors, clinical features, and prognostic indicators in guinea pigs with urolithiasis.
ANIMALS 158 guinea pigs with urolithiasis.
PROCEDURES Medical records of an exotics animal specialty service were searched, identifying guinea pigs with urolithiasis. Signalment, clinical data, and outcomes were recorded. Variables of interest were analyzed for statistical associations with outcome.
RESULTS Overall, 54.4% (86/158) of animals survived to discharge. Median survival time was 177 days. Females (53.2%; 84/158) were more common than males (46.8%; 74/158). Males were presented younger (mean age, 3.64 years) than females (4.41 years). In 81 of 154 (52.5%) cases, animals were presented with primary urinary concerns, while 73 (47.5%) presented for nonurinary primary concerns. Females more commonly presented with distal urinary tract urolithiasis (63/84; 75%) but fared better overall with a longer median survival time (1,149 days) than males (59 days). Surgical intervention was not a risk factor for nonsurvival; however, increased age (> 4.1 years), male sex, anorexia, weight loss, and lower rectal temperature (< 37.2 °C) on presentation were associated with nonsurvival. Reoccurrence was noted in 13.9% (22/158) of cases, at an average of 284 days.
CLINICAL RELEVANCE Urolithiasis should always be considered a differential diagnosis for any unwell guinea pig. In particular, distal urinary tract urolithiasis should be considered in females. A poorer prognosis was associated with older, male guinea pigs, and those displaying anorexia, weight loss, and hypothermia. The need for surgical intervention should not confer a poorer outcome. Further studies are needed to determine specific risk factors and identify possible preventative measures.

Background
- G pig uroliths primarily calcium carbonate, calcium oxalate also identified
- Evidence that female > 2.5 yo ar predisposed but more recently shown male and female equally affected
- Easily diagnosed on rads because usually radiodense
- CS in lower UT: stranguria, hematuria, dysuria, pain-related vocalizations
– Upper UT: loss of body condition, reduced appetite, reduced activity
- Body temp and survival (in general practice)
– G pigs: each 0.55C decrease in rectal temp from 37.9C increased odds of death 1.6x
– Rabbits: each 1C less than 38C doubled odds of death

Key Points
- Uroliths diagnosed on rads (91%) or by palpation, majority urethra or bladder, 10% in multiple locations
- Stone analysis in 2 pigs: calcium carbonate
- Urine culture in 21 pigs: most no growth, Corynebacterium, Streptococcus, 1 pig with Pasteurella and Staphylococcus
- 54% survived to discharge, MST 6 mo, 14% recurrence avg 9 mo later
- 47.5% of g pigs with uroliths presented for nonurinary CS
- Risk factors: females slightly overrepresented (53 vs 46%) and older at presentation (4.4 vs 3.6 yr), had a longer mean survival time than males (3yr vs 2 mo)
- Males had ureteroliths, cystoliths, females had urethroliths and cystoliths
- Lower survival in older patients and lower temp at presentation (<99F)
- Shorter survival with anorexia and weight loss on presentation
- No association with diet identified, most were fed an appropriate diet
- No association with having a water bowl or bottle or both
- No association of survival with stones in multiple locations, with UTI, or based on treatment choice (sx vs medical)

Conclusions
- Consider urolithiasis in any G pig even if nonspecific CS
- G pig urolith treatment plan should be based on urolith retrievability, sex, age of patient, and concurrent disease
- Anorexia, weight loss, hypothermia, older age, and male are negative prognostic indicators

Question 103

A recent study compared alfaxalone and alfaxalone-midazolam in guinea pigs.

What is the scientific name of the guinea pig?

What is the reported anesthetic and sedation related risk of death in guinea pigs?

What physiologic changes were seen in these animals?

How did the addition of midazolam change the sedation?

Answer 103

Comparison of subcutaneous sedation with alfaxalone or alfaxalone-midazolam in pet guinea pigs (Cavia porcellus) of three different age groups
Elena Ríos Álvarez, LV; Laura Vilalta Solé, LV, DECZM; Alejandra García de Carellán Mateo, LV, DECVAA
JAVMA | JUNE 2022 | VOL 260 | NO. 9

OBJECTIVE
To compare the cardiorespiratory effects, quality and duration of sedation of 2 subcutaneous sedation protocols for noninvasive procedures in guinea pigs (GPs).
ANIMALS
24 pet GPs (15 females, 9 males) of 3 different age groups: infant (n = 8), juvenile (8), and adult (8).
PROCEDURES
The study design was a randomized, crossover, blinded, clinical trial with a washout period of at least 7 days between protocols. Guinea pigs were sedated SC with alfaxalone (5 mg/kg; group A) or alfaxalone (5 mg/kg) and midazolam (0.5 mg/kg; group A + M) to facilitate blood sampling, radiography, or abdominal ultrasonography. Vital parameters, hemoglobin saturation (SpO2), and sedation scores were recorded every 5 minutes.
RESULTS
Mean heart rate was lower in group A than group A + M (P = 0.001), and respiratory rate was significantly (P = 0.001) decreased relative to baseline during sedation in both groups. The SpO2 remained above 95% in both sedation groups. Rectal temperature was significantly (P = 0.001) lower during recovery versus baseline. Onset of sedation was shorter and the duration longer in group A + M than in group A. The duration and depth of the sedation was different between age groups (P = 0.001), being longer and deeper in adults. Bruxism, hectic movements, twitching, and some degree of hyperreactivity were observed during 41 of the 48 sedations.
CLINICAL RELEVANCE
Subcutaneous administration of alfaxalone provided reliable sedation for nonpainful procedures in GPs. When combined with midazolam, alfaxalone provided longer and deeper sedation that was more significant in adults than in younger patients.

Key Points
- Reported anesthetic- and sedation-related risk of death in GPs is 3.80%, the highest mortality rate among the studied small mammals
- Objective – evaluate cardiorespiratory effects and sedation of alfaxalone and alfaxalone + midazolam
- Lower HR in Alfax compared to alfax + midazolam
– Initial tachycardia seen in Alfax group (addition of midaz diminished tachycardia)
- Respiratory rate signf lower in both groups compared to pre-sedation though SpO2 > 95% in all
- Hypothermia seen in ~1/4 of individuals – recommend > 1 active rewarming method in GPs
– Minor reactions – bruxism, hectic movements, twitching, and hyperreactivity to auditory stimulus observed in majority of animals with no difference between groups
– Did not see changes in food intake or postprocedure fecal output
- Shorter onset, longer duration of sedation, and higher total sedation score in alfax + midaz group
– Sedation persisted longer in adults than in juv and infants
– Only mild sedation achieved in infant GPs
- Alfaxalone – neuroactive steroid acts on gamma aminobutyric acid A receptor
- In rodents IM injections can lead to self-mutilation, tissue reaction, myositis, and necrosis, often related to pH, excipients and volume used – Alfax dose exceeds maximum safe IM volume in rodents

Take home
- Alfax and alfax + midaz SC provided reliable, good quality sedation for noninvasive and diagnostics with minimal side effects (not suitable for surgery)
- Sedation more pronounced as age increased and alfax + midaz produced deeper and longer sedation in all ages

Question 104

A recent study described the use of medetomidine-ketamine-buprenorphine anesthesia in Cape Dune and Cape Mole Rats.

How do these mole rat species differ from the more commonly managed species?

How well did these protocols work?

Was surgical anesthesia achieved?

Answer 104

JZWM 2022 53(2):357-362
Medetomidine-Ketamine-Buprenorphine Anesthesia Of The Solitary Subterranean Cape Dune Mole-Rat (Bathyergus suillus) And The Cape Mole-Rat (Georychus capensis)
Gardner BR, Okrouhlik J, Zeiler GE

ABSTRACT: A prospective, descriptive study was conducted to evaluate the safety and efficacy of a field-ready anesthetic drug combination of medetomidine-ketamine-buprenorphine for data logger implantation surgery or recheck in free-ranging Cape dune (Bathyergus suillus: n = 41) and Cape (Georychus capensis: n = 37) mole-rats. All anesthesia data were reported as mean (±standard deviation). Medetomidine-ketamine-buprenorphine doses were 0.1 (±0.03), 10.6 (±2.8), and 0.06 (±0.03) mg/kg, respectively, for Cape dune mole-rats; and 0.2 (±0.03), 19.4 (±4.0), and 0.14 (±0.03) mg/kg, respectively, for Cape mole-rats. Induction was calm and took 2.00 (range: 1.00-6.00) min for the Cape dune and 1.75 (range 1.25 to 8.16) min for Cape mole-rats. A surgical plane of anesthesia was achieved in most Cape dune mole-rats (92%) and Cape mole-rats (90%). The remainder required supplementation with a single intramuscular injection of ketamine (3-9 mg/kg) during surgery. Heart and respiratory rates were 149 (±37) beats and 24 (±8) breaths per minute, respectively, for Cape dune mole-rats and 179 (±40) beats and 25 (±10) and breaths per minute, respectively for Cape mole-rats. Surgical time for mole-rats ranged from 25 to 38 min. Recovery was calm and took 8.50 (range: 2.00-19.00) min for Cape dune mole-rats and 9.75 (range: 2.00-34.00) min for Cape mole-rats to recover. For recovery, atipamezole was administered intramuscularly at 0.5 (±0.15) mg/kg for Cape dune mole-rats and 1 (±0.15) mg/kg for Cape mole-rats. All mole-rats were returned to their original burrows within 48 h of recovery. The medetomidine-ketamine-buprenorphine combination induced a predictable, safe anesthesia in Cape dune and Cape mole-rats suitable for short intraabdominal surgery. This combination is suited to in situ studies where the use of a formal surgery or laboratory is not feasible.

Background:
- African mole-rats are well adapted to an environment that is often hypoxic and hypercapnic
- Unlike eusocial (colony living) mole-rat species, the Cape dune and Cape mole-rats are solitary
– A single individual will occupy a burrow system
– Immediate return to a burrow is important for these species
– Unoccupied burrows can collapse or be occupied by a competing mole-rat
- Above-average tolerance to hypoxia in mole-rats is a significant benefit to field-based anesthesia

Key Points:
- IM anesthesia protocol
– Cape dune: 0.08 mg/kg medetomidine + 10 mg/kg ketamine + 0.05 mg/kg buprenorphine
– Cape: 0.08 mg/kg medetomidine + 20 mg/kg ketamine + 0.05 mg/kg buprenorphine
– Supplemented with 3-9 mg/kg ketamine IM intraoperatively
– ~0.2 mg/kg meloxicam SC perioperatively
– Reversal: atipamezole ~0.5 mg/kg for Cape dune and ~1 mg/kg for Cape mole-rats
- Free-floating intra-abdominal temp data loggers were implanted via ventral midline laparotomy
- Substantial weight differences of 300–600 g between the Cape dune and the Cape mole-rats
– Given small BW and concentrated drugs, recommended to use dilute formulations
- Compared to other mole rats, Cape and cape dune mole rats require larger doses of ketamine
- Protocol not adequate for short-duration invasive abdominal surgery in about 10% of mole-rats
– This might be caused by a lag in the onset of buprenorphine mediated analgesia
– Buprenorphine was included in order to provide postoperative analgesia
- Recommend using pedal withdrawal reflex as an indicator of anesthetic depth
- Drug combination was rapid in onset, provided a quick and calm recovery, and is thus ideally suited to field situations where release post-procedure is a requirement

TLDR: Medetomidine-ketamine-buprenorphine combination induced a predictable, safe anesthesia in Cape dune and Cape mole-rats suitable for short intraabdominal surgery

Question 105

A recent paper described the removal of pseudo-ontomas in Richardson’s ground squirrels.

What is the scientific name of the Richardson’s ground squirrel?

What is a pseudo-ontoma?
- What neoplastic disease can occur from similar trauma?
- What species commonly get them?
- What are the associated clinical signs?

What surgical approaches are used to remove them?

Answer 105

JZWM 2022 53(3):600-604
Removal Of Pseudo-Odontomas Via Lateral Maxillotomy In Three Richardson’s Ground Squirrels (Urocitellus richardsonii)
Takami Y, Une Y

ABSTRACT: Pseudo-odontoma can occur in some species with elodont teeth. Pseudo-odontomas affecting maxillary dentition may result in obstruction of the nasal cavities and lead to dyspnea. Effective treatments for the disease in Richardson’s ground squirrels (Urocitellus richardsonii) have not yet been established. Three Richardson’s ground squirrels exhibiting dyspnea and with maxillary pseudo-odontomas, based on diagnostic imaging, were surgically treated. The animals were placed under general anesthesia, and following excision of skin and subcutaneous tissue at the midpoint of the line connecting the medial canthus and ipsilateral nasal opening, maxillotomy of the incisive bone was performed. The reserve crown of the maxillary incisor tooth was exposed via the maxillotomy site and was sectioned into labial and palatal fragments, and the diseased tooth was completely extracted. In all three cases, dyspnea improved immediately after surgery. In one case, no recurrence was observed 600 d following surgery. These results suggest that the procedure used provides a practical approach for treating maxillary pseudo-odontomas in Richardson’s ground squirrels.

Key Points:
- Species w/ elodont dentition (rodents) may develop:
– Pseudo-odontomas = a dysplastic disease of the apex w/ idiopathic etiology
– Causes upper respiratory obstruction/dyspnea in affected animals
– Elodontomas = a hamartoma or benign neoplasm
- CT is particularly useful for evaluating pseudo-odontomas and surgical planning
- Treatment for pseudo-odontomas: surgical removal vs. palliative (create alternate airway)
– Surgical removal previously reported in prairie dogs and guinea pigs
– Present case series used a lateral approach similar to prairie dogs
- No overgrowth of opposing mandibular incisor after maxillary incisor extraction
- Intermittent sneezing post-op, but no reoccurrence up to 600 days after surgery
- Prairie dogs with bilateral pseudo-odontomas more likely to have post-op complication

TLDR: Recommend CT & surgery for maxillary pseudo-odontomas in Richardson’s ground squirrels

Practice Question: Name one dysplastic condition and one neoplasia that can affect species with elodont dention

Answer: Pseudo-odontoma and elodontoma

Question 106

A recent study described mammary gland adenocarcinoma in Indian crested porcupines.

What is the scientific name of this species?

Answer 106

JZWM 2022 53(4) 855-863
MAMMARY GLAND ADENOCARCINOMA IN FOUR INDIAN CRESTED PORCUPINES (HYSTRIX INDICA)

Abstract: Neoplasia in porcupines is rarely reported in the literature, and the prevalence is unknown. A retrospective review of records from a private zoo diagnostic pathology service found four cases of mammary adenocarcinoma in Indian crested porcupines (Hystrix indica) from four separate zoological institutions. All cases presented in geriatric females (14–19 yr of age) as freely movable subcutaneous masses within the mammary chain. None of the individuals had additional clinical signs, radiographic, or hematologic changes at initial presentation. All cases were managed with surgical excision in the form of either an excisional biopsy or a partial mastectomy. Histologic examination diagnosed all tumors with anaplasia and moderate to high numbers of mitotic figures. Two cases required subsequent surgeries for management of local recurrence in the years following initial diagnosis. One case is 19 months postsurgical removal without evidence of metastasis or local recurrence. Two of the cases were euthanized after diagnosis of inoperable metastases to the lungs and spinal cord, including one previously treated with an oral nonsteroidal antiestrogen medication, tamoxifen. The third case was euthanized due to degenerative mobility changes and renal dysfunction and had no evidence of metastasis. The average survival time from initial surgical excision to euthanasia for the three applicable cases was 33 months. These cases suggest that surgical excision alone may result in temporary management of mammary adenocarcinoma in this species. Metastasis can occur, and routine screening with advanced imaging may aid in early detection of these lesions.

Intro
- Mammary tumors are common in pet rodents but not often described in porcupines

Cases
- 4 geriatric porcupines, all with SQ masses on the mammary chain
- Treated with surgical excision or partial mastetctomy
- 2 recurred and required a second surgery
- One still alive with no recurrence, one euthanized for other reasons with no mets, 2 euthanized due to mets to the lung and spinal cord
- One was treated with tamoxifen, but the mass recurred and metastasized despite treatment

Discussion
- All primary masses were diagnosed as mammary gland adenocarcinomas
- Diagnosed on excision–FNA and incisional biopsies were inconclusive
- All of the porcupines presented in this study were intact females of geriatric status
- Tamoxifen used in one case–Tamoxifen is a nonsteroidal antiestrogen oral medication that is commonly used to treat estrogen receptor (ER)–positive mammary carcinomas in human medicine.
- The individual in this case series treated with tamoxifen tolerated the drug for more than 2 yr without adverse effects but was euthanized due to metastasis to the sublumbar region
- Porcupine mammary glands are triangular, with two teats per gland.
- Excision with standard margins is recommended along with continued monitoring