Chapter 6. Biology and Diseases of Guinea Pigs Flashcards

Question

Guinea pig vocalizations

Answer 1

Use a dozen or more audible calls for various reasons including calls to increase proximity, greeting, proximity-maintaining calls, proximity-regaining calls, distress calls, alarm calls

Answer 2

- Accessory sex glands include larger, transparent, smooth seminal vesicle (up to 10 cm in length), prostate, coagulating glands, bulbourethral glands, and rudimentary preputial glands - Testes remain in inguinal pouches & inguinal canals open for life - Os penis present

Answer 3

- Uterus is bicornate & terminates in single os cervix - Vagina sealed by vaginal closure membrane - epithelial structure that ruptures just before onset of estrus and reforms after ovulation - Sows should be bred first when large enough to bear a litter but before calcification of the fibrocartilaginous pubic symphysis - calcifies and becomes fused between 6-9 months of age - prone to dystocia if first give birth after this fusion - Vendors first breed sows when 350-500g (5-13 weeks) and boars when 500-800g (7-13 weeks) - Spontaneous ovulators and polyestrous; have postpartum estrus - Heavily bred sows may cease hair growth, resulting in patchy alopecia

Answer 4

~16 days (13-21 days) - Proestrus: 1-1.5 days, characterized by vaginal swelling, rupture of vaginal closure membrane, increased activity, nucleated and cornified epithelial cells on vaginal smear - Estrus: 8-11 hours, swollen congested vulva, perforate vaginal membrane, lordosis and rear quarters elevated - Metestrus: 3 days - Diestrus: 11-12 days - Fertile postpartum estrus occurs from 2-10 hour after parturition - Estrus can be synchronized with progesterone administered orally or as a SC implant - Vaginal impedence measureents can be used to assess stage of estrous cycle

Answer 5

- Boar makes one or two intromissions and then ejcaulates - Coital completion indicated by grooming, scooting, and perianal marking by the boar - Copulatory plug may be found in the female or bedding - ~60-85% of matings, including postpartum matings, are fertile

Answer 6

68 days (59-72 days) - Blastocysts implant on day 6 or 7 of gestation - Placentation is labyrinthine hemomonochorionic, similar to humans - good model for reproductive toxicology studies - Fetuses can be palpated at day 15, 5mm diameter firm swelling - Fluid-filled round swellings apparent on U/S at day 16, diagnosis approaches 100% by day 19 - Pubic symphysis separates to 3 cm during last week of gestation - Gestation length generally inversely proportional to litter size - Relaxin produced by placenta beginning around day 30 through about day 63 - responsible for loosening of the fibrocartilaginous pelvic symphysis - Sows do NOT build nests - Pups delivered every 3-7 min; completetion of parturition in 30 min - Large litters (3 or more) assoc w/ higher incidence of stillbirths - Dystocia can occur in sows bred for the first time after fusion of pubic symphysis, obese sows, sows with large fetuses

Answer 7

- Born precocious with hair, teeth, open eyes and ears, fully mobile - Begin to eat and drink within hours of birth; feeder and sipper tube may be lowered to provide access - Average birth weight 45-115g; pups weighing less than 50g at birth generally do not survive - Do not nurse for first 24 hr - Pup mortality of up to 50% can be seen if pups are undersized or do not receive milk from a sow during first 3-4days of life - Voluntary micturition does not occur until 7-14 days of age - Can be weaned at 14 days but generally weaned at 21 days

Answer 8

- Electroejaculation produces 0.4-0.8mL of semen; in some electroejaculated boars the ejaculum coagulates in the urethra - Sperm can be harvested from the vasa deferentia and epididymides - IP insemination has been reported with up to 100% incidence of conception when used in conjunction with estrus synchronization; additional methods include injection of sperm directly into uterine horns following laparotomy, endoscope-guided transcervical insemination - AI has been successful up to 16 hr postestrus

Answer 9

- Superovulation induced by IP human menopausal gonadotropin (hMG) and by active immunization against the inhibin α-subunit - Embryo transfer reported rarely in guinea pigs - a method for rederivation purposes has been described where embryos were harvested from donors at 1.5 and 2.5 days post-coitus and transferred to pseudoprenant females mated to vasectomized males 1.5 to 2.5 days earlier - 59 embryos were transferred & two pups were born at 69 & 71 days gestation

Answer 10

- Naturally occurring Helicobacter spp. in guinea pigs have NOT been reported - Experimental infx with Helicobacter pylori results in severe gastritis that can persist for at least 5 months - model for dz in humans

Answer 11

- Similar pulmonary system to humans - Used to model Legionnaires disease, TB, and other viral and bacterial infx - Extremely sensitive to infection with TB and have been used as sentinels in human hospitals; guinea pig model of TB remains gold standard for testing the potency and standardizing PPD use in humans

Answer 12

Commensal in many species including guinea pigs, rats, rabbits, mice, dogs, swine, cats, turkeys, primates - Short, G(-) rod or coccobacillus, aerobic, motile, non-sporeforming - In vitro growth best at 30 C but slow to poor at 37 C, with minute, circular, pearlescent colonies present at 24 hr and maximum-size colonies at 72 hr; colonies embed in media and surrounded by zone of β-hemolysis - There is serotypic variaton within the species, even within one host species - Variably dissociates in culture (isogenic mutation) - these isolates vary in hemolysin, dermonecrotoxin, proteases, adenylate cyclase, and hemagglutinin production - may affect host specificity, virulence, and disease manifestation

Answer 13

- Subclinical infxs more common - Epizootic respiratory or septicemic disease can progress rapidly (often within 24 hr-72 hr) with high mortality - All ages and both sexes affected - Can see sporadic deaths in enzootically infected colonites - Inappetance, depression, upper respiratory discharge, dyspnea, cyanosis, death - Genital form with a 5-7 day incubation period causes infertility, stillbirth, abortions

Answer 14

Potential for transmission from rabbits to guinea pigs is a primary reason these species are not housed together - Transmission: fine particulate aerosol onto the respiratory mucosa, by contaminated fomites, genital contact - Many guinea pigs carry as a commensal resident - Higher morbidity and mortality occur among young and historically in Strain 2 inbred animals

Answer 15

- Pulmonary consolidation with respiratory exudation, purulent bronchitis, tracheitis, otitis media; consolidated lung areas dark red to red brown to grey - Peribronchiolar and perivascular inflammatory cells contribute to fibrinous or fibrinopurulent bronchopneumonia - Uterine infections may be pyosalpinx and dead embryos/fetuses

Answer 16

Organism attaches to ciliated respiratory epithelium - proliferates rapidly and causes ciliary paralysis, an inflammatory response, antiphagocytic activity, and dermonecrosis - presumably through action of an intracellular heat-labile toxin

Answer 17

Bronchopneumonia: Stretococcus pneumoniae, S. zooepidemicus, Klebsiella pneumoniae, adenovirus - Definitive diagnosis = swabbing of lumen of bronchi or lower trachea and aerobic culture on sheep blood and MacConkey agar or Smith and Baskerville medium - ELISA and IFA more sensitive then culture for detecting, but various Bordetella antigenic variants should be used on serologic testing

Answer 18

- Reduction or elimination of stressors as clinical dz often arises from preexisting subclinical infx - Purchase Bordetella-free stock - Commonly carried by dogs and cats; some research facilities restrict pet ownership - Control by isolating infected animals and those susceptible and treat or remove the clinically ill - Treatment is supportive care and appropriate antibiotics - fluoroquinolones or trimethoprim-sulfonamides

Answer 19

- Lancefield's group C streptococcus; β-hemolytic, G(+), has antiphagocytic capsule (M-like antigen), produces exotoxin including hyaluronidaze, a protease, and a streptokinase - Subspecies zooepidemicus survives longer off host than the obligate pathogen S. equi

Answer 20

- Pyogenic bacterium assoc w/ suppuration and abscess formation - usually at cervical lymph nodes (cervical lymphadenitis or 'lumps') - Torticollis, nasal or ocular discharge, dyspnea, cyanosis, hematuria, hemoglobinuria, cyanotic and swollen mammary glands, abortions, stillbirths, unexpected deaths - Cervical nodes in otherwise health guinea pig is the usual sign - May be inapparent upper respiratory infections

Answer 21

- Zoonotic potential, although transmission from guinea pigs to humans has not been reported - All ages affected, may be more common in females - Organism inhabits mucosal surfaces - Transmission = via aerosol onto respiratory, oropharyngeal, conjunctival, or female genital epithelium - Disease is of low contagion

Answer 22

- Most common = Abscessed and encapsulated cervical lymph nodes (node itself may be destroyed) - abscesses contain a nonodorous, yellow-white to red-grey pus - Pneumonia, generalized lymphadenitis, septicemia, focal hepatitis, otitis media, pleuritis, peri- and myocarditis, nephritis, mastitis, metritis, arthritis with necrosis and hemorrhage

Answer 23

- Cervical lymphadentitis: Streptobacillus moniliformis - carried by wild rats - Upper respiratory lesions & death: S. pneumoniae, B. bronchiseptica, K. pneumoniae, adenovirus - Masses in the neck: lipoma, lymphoma in aged guinea pigs - Diagnosis: clinical and necropsy signs, isolation of β-hemolytic streptococci from abscess margin or heart blood; chains of streptococci can be seen on Gram stain of exudates

Answer 24

- Prevention: obtain disease free stock, nonabrasive feed (assuming crude fiber may abrade pharyngeal mucosa), trim overgrown or broken teeth, use feeders that do not abrade skin of neck - Control: remove affected animals or replace entire colony - Treatment: surgically remove abscess and capsule; antibiotics safe for use in guinea pigs (fluoroquinolones, trimethoprim-sulfonamides, gentamicin, or chloramphenicol) may be effective

Answer 25

- G(+), α-hemolytic, oval to lancet shaped; occurs in culture in paired or chain formation - Two serotypes recovered most often from guinea pigs = 4 and 19F; some of which are assumed to be identical to certain human serovars; one study found guinea pigs may be a reservoir for a serotype 19F that had unique allele combination not found in humans

Answer 26

- Subclinical upper respiratory tract carrier states common in guinea pigs and humans, often over 50% prevalence in some colonies; may then see sporadic epidemics when animals are stressed or malnourished - Clinical signs: high mortality or, in less acute cases, depression, anorexia, nasal and ocular discharge, sneezing and coughing, dyspnea, torticollis, abortions and stillbirths

Answer 27

- Infections rarely reported or detected in research colonies - Transmission: respiratory aerosol, direct contact with infected animals (including humans), vertically during birth

Answer 28

- Primarly pyogenic processes: fibrinopurulent pleuritis, pericarditis, peritonitis, suppurative pneumonia, otitis media, endometritis, arthritis - Pulmonary lesion is an acute fibrinopurulent bronchopneumonia with thrombosis of pulmonary vessels

Answer 29

-Organism becomes established in upper respiratory tract where it is protected by a polysaccharide capsule and can activate an alternative complement pathway which initiates some of the pathologic changes associated with the infection

Answer 30

- S. pneumoniae can usually be observed on Gram-stained impression smears of infected tissue, or can be cultured on blood agar incubated under 5-10% CO2 - ELISA for streptococci available - Definitive dx requires serotyping among the 83 different capsular polysaccharides; serotyping test = Quellung reaction - utilizes a serum pool product or type-specific antisera - bacterial capsule appears opaque and swollen when the antibody reacts with surface antigens - Differentials: Bordetella sp, other streptococci, Salmonella sp., Klebsiella sp., adenovirus

Answer 31

- Seen rarely in research guinea pigs - Caused by several serovars of the G(-) bacillus Salmonella enterica, subspecies enterica - Serovars Typhimurium and Enteritidis are encountered most frequently

Answer 32

- Peracute or acute infections: only signs may be high morbidity and mortality; mortality may be as high as 50-100% of the population - Epizootic outbreaks occur more often in late pregnant, weanling, aged, and malnourished guinea pigs - In longer term survivors or in sporadic clinical cases: rough hair coats, weakness, conjunctivitis, abortion of small litters, light-colored feces or intermittent diarrhea

Answer 33

- Inapparent carriers shed the organisms intermittently - continued threat to other animals and humans - Transmission: fecal-oral, blood-oral, tissue-oral, via conjunctiva - Shed in the feces of wild rodents or other animals, contaminate food (green veggis, hay) intended for guinea pigs - Guinea pigs HIGHLY SUSCEPTIBLE to Salmonella; incubation period is 5-7 days

Answer 34

-Gross lesions may not be present; may see hepatomegaly, splenomegaly, small yellow necrotic foci throughout the viscera

Answer 35

Enter body through GI tract or via conjunctiva & elicit histiocytosis, tissue necrosis, abscess formation

Answer 36

- Diagnosis: recovery of organism from feces, heart, blood, spleen, or other affected organs through enrichment in a broth such as selenite F or tetrathionate, culture on MackConkey's or brilliant green agar, and identification of organism - Serotyping identifies the serovar

Answer 37

- Aging, other diseases, malnutrition, and environmental stress are predisposing factors - Treatment: NOT recommended; antibitoic use may cause infx to become subclinical and antibiotic resistant - Control: euthanize entire colony, sanitize caging and equipment thoroughly, restock with animal known to be free of Salmonella spp.

Answer 38

- G(-), curved rod; obligate intracellular anaerobe with subterminal spores that persist for years in the environment - Causative agent of Tyzzer's disease - dz occurs in several species including rodents, rabbits, cats, dogs, horses, some NHP - Rare in guinea pigs - Clin signs in guinea pigs: emaciation, dehydration, lethargy, diarrhea, death - Necrotizing ileitis, typhlitis, and hepatic necrosis in weanling guinea pigs - Necropsy: multifocal necrosis and inflammation of ileum, cecum, colon - Prevention: avoid stressors and maintain good sanitation - Diagnosis: characteristic filamentous bacteria in a Giemsa or Warthin-Starry stained section of enterocytes; organism has not bee directly cultured in vitro

Answer 39

- Rare in well-managed colonies; prevalence of infection unknown - An epizootic reported in literature involved sporadic, unexpected deaths with pulmonary consolidation, fibrinopurulent serositis, conjunctivitis - Diagnosis: culture and identification of characteristic G(-) coccobacillary rods

Answer 40

- Rare in guinea pigs - Have been associated with pulmonary lesions involving lung consolidation and severe, focal, necrotizing bronchopneumonia; may also cause conjunctivitis and otitis media; one case study found enlarged, inflamed, fibrous prostate gland with local extension of inflammation - Diagnosis: clusters of bacteria surrounded by necrotic debris ('sulphur granules) in suppurative lesions - Pseudomonas is ubiquitous and may be spread in drinking water or in damp bedding or food

Answer 41

- Formerly Chlamydia psittaci - G(-), obligate intracellular bacterium - Causes guinea pig inclusion conjunctivitis

Answer 42

- May be subclinical - Mild reddening of eyelids up to conjunctivitis with serous to purulent exudate, rhinitis, and genital tract infections; abortions and lower respiratory tract infections - Clinical disease is self-limiting with complete recovery in 3-4 weeks

Answer 43

- Demonstration of intracytoplasmic inclusion bodies in Giemsa- or Macciavello-stained conjunctival epithelial cells - PCR - Differentials for bacterial conjunctivitis: streptococci, coliforms, S. aureus, Pasteurella multocida

Answer 44

- Self-limiting and typically does not require treatment; Chlamydiophila sp. sensitive to sulfonamide antimicrobials when indicated - Conjunctival and genital infections have served as models for human disease; ZOONOTIC POTENTIAL - Experimental infx of guinea pig genital tract is good model for human chlamydial genital infx - can be sexually transmitted, similar to children, pups born to infected sows are prone to conjunctivitis

Answer 45

- G(-), nonmotile bacillus; causes rare epizootics in guinea pigs of all ages and both sexes - Predisposing factors: manutrition, magnitude of exposure, unsanitary environments, genetic predisposition - Clinical signs: anorexia, dyspnea, death - Necropsy: seropurulent or serofibrinous lesions in the thoracic and abdominal cavities, mastitis, splenomegaly, thrombosis, coagulative necrosis of the liver, granular degeneration of the renal tubular cells, septicemias; pulmonary lesion is acute bronchopneumonia - Diagnoses: isolate from blood, liver, spleen, peritoneal exudate, cerebrospinal fluid

Answer 46

- Organism of low contagion carried by wild rats and birds; rarely causes disease in research guinea pigs - Lesions: cervical adenitis with abscessation like S. zooepidemicus, and a pyogranulmatous bronchopneumonia

Answer 47

- G(-), nonhemolytic, exotoxin- and enzyme-producing, pleomorphic rod - Optimal incubation temperatures are 20-30 C - Virulent strains may grow within macrophages - Infects both sexes and all ages - Clinical signs: 1) Acute, highly fatal septicemia, 2) chronic emaciation, diarrhea, and death within 3-4 weeks, 3) nonfatal lymphadenitis, 4) subclinical carrier state usually following a clinical phase - ZOONOTIC - Because of persistent carrier state, euthanasia is recommended

Answer 48

- Rare in guinea pigs - G(+) rod; widespread in environment including soil and bedding - Clinical signs: in hairless guinea pigs unilateral or bilateral keratoconjunctivitis and reproductive disorders - Prevention and control involve general precautions - Treatment NOT recommended, instead euthanasia because ZOONOTIC

Answer 49

-Mycoplasma caviae, M. pulmonis, etc. and acholeplasmas may occur as latent infections in the reproductive tract, brain, and nasopharynx of guinea pigs

Answer 50

- Enveloped DNA virus, typical iscosahedral symmetry and 252 capsomers - Genetically distinct from adenoviruses infecting other species; is a separate serotype within the genus Mastadenovirus and has the highest homology with other animal Mastadenoviruses and human subgroups A, C, and F

Answer 51

- Subclinical infections may be common - prevalence unknown - Clinical disease rare - affected animals usually die without prior signs; may develop dyspnea, tachypnea, dry rales, crepitations, lethargy

Answer 52

- Infx occurs worldwide and may have a higher prevalence than reported - Clinical disease has no age predilection, is sporadic in endemically affected colonies, and is characterized by low morbidity and high mortality - Transmission: respiratory route

Answer 53

- Well-demarcated dark red areas of pulmonary consolidation, compensatory emphysema, sometimes catarrhal exudate in air passages - Histology includes necrosis and sloughing of bronchiolar, bronchial, and tracheal epithelial cells - contain large, oval, intranuclear inclusion bodies; surviving epithelium and underlying lamina propria are underlain with a mixed population of inflammatory cells

Answer 54

- Predisposition factors: stress, immunologically compromised, strain and site of replication of the virus, perhaps anesthetic gas irritation of respiratory tract - Virus enters tracheal and bronchial epithelial cells where replication and cell damage occur - followed by epithelial erosion, parenchymal inflammation, exudation in airways

Answer 55

- Diagnosis: exclusion of other causes and by histologic and electron microscope examination of air passageway epithelial tissue; no specific serologic test - use of mouse adenovirus strain FL antigen produces excessive false (+) reactions; active disease can be detected by PCR from feces or freshly frozen lung - Differentials for respiratory disease: B. bronchiseptica, Streptococcus spp., K. pneumoniae, cytomegalovirus, herpesvirus, Sendai, parainfluenza

Answer 56

- Obtain stocks without history of infection, reduce colony stress, observe immune compromised animals - NO treatment

Answer 57

- Adenoviral vectors used for experimental delivery of aural genes in models of hearing loss; natural infx of study animals did not obviously affect the transfection efficiency of human adenoviral vectors expressing GFP - Inapparent pulmonary infections may become clinical problems when animals are stressed

Answer 58

- Species specific pathogen | - Detected sporadically in lab guinea pigs

Answer 59

- Usually subclinical - Strain of host, pregnancy, and immune compromise may predispose to more serious illness - Clinical signs: weight loss, conjunctivitis, lymphadenopathy

Answer 60

- Presence likely partially dependent on housing conditions - Acute infx followed by chronic, persistent infx - Transmission: exposure to saliva carrying the virus, transplacental transmission throughout gestation - preexisting maternal Ab does NOT prevent transmission to fetuses & C-section does NOT interrupt transmission due to transplacental infection

Answer 61

- Experimental infection cases more severe signs - Natural disease: karyomegaly of salivary gland epithelium (submaxillary gland) to severe interstitial pneumonia, splenomegaly, lymphadenopathy, fetal meningitis - Congenital neurological abnormalities and deafness can occur

Answer 62

- Viremia within 2 days of exposure - results in widespread, systemic dissemination - salivary gland, hepatic, and renal cells are primary sites of replication - Many more organs become infected by 10 days - By 12-14 days viremia ceases and virus is more difficult to find in visceral organs - By 3 wks postexposure, inclusion bodies are present in salivary glands - chronic, persistent phase contnues in the salivary gland and thymus in adult and in the salivary gland and spleen of fetuses

Answer 63

- Microscopic identification of large, eosinophilc, usually intranuclear inclusion bodies in the ductal epithelial cells of submaxillary salivary gland - inclusions form at 5 days-3weeks postexposure - Inclusion bodies may also be seen in brain, lung, kidney, spleen, pancreas, thymus, liver - Indirect fluorescent antibody techniques and histopathology are methods of diagnosis

Answer 64

- Prevention and control: select guinea pig stocks known free of GPCMV, screen new arrivals, selective necropsy, serology - NO treatment

Answer 65

-Natural disease may be unapparent (unless detected by serology or necropsy) but could interfere with studies involving tissues harboring virus

Answer 66

RNA virus; family Picornaviridae; some antigenic cross -reaction with the GDVII strain of Theilovirus - Genetic variants among host guinea pigs may affect predisposition to infx and clinical signs - Appears more common in pet store than lab guinea pigs, but still a possible diagnosis in guinea pigs with lameness

Answer 67

- Clinical signs are rare; within colonies clinical disease is sporadic if it exists at all - Clinical signs: depression, lameness in one or more limbs, flaccid paralysis, weight loss, death over 2 weeks

Answer 68

- Transmission route not proven, but fecal-oral common among Picornaviridae - In mice and rats the endemic epizootic cycle of Theilovirus is by fecal-oral transmission

Answer 69

- Findings are histologic and include meningomyeloencephalitis, perineuronal inflammation, neuronal degeneration, necrosis of anterior horn cells of the lumbar spinal cord - In mice the virus replicates presumably in the grey matter of the cortex and progresses into the white matter and upper motor neuron pathways

Answer 70

-ELISA using the Theilovirus strain GDVII mouse virus antigen combined with histo findings of CNS and lumbar spinal cord lesions

Answer 71

- One paper recommended Vitamin C for prevention, control, and treatment, given that Vitamin C contributes to adrenocorticosteroid production and presumably, protection of myelin - Infection may complicated investigations of CNS in guinea pigs

Answer 72

- RNA arenavirus - Causes lymphocytic choriomeningitis in mice, dogs, primates (including humans) and rarely guinea pigs when contracted iatrogenically via inocluation with contaminated biologicals or possibly through inhalation, ingestion, or through the skin following exposure to biting insects or infected wild mice - Clinical signs: CNS dysfunction, hindlimb paralysis - Lesions: lymphcytic infiltration in meninges, choroid plexus, ependyma, liver, lungs - Diagnosis: IFA - liver is best site for detection; ELISA to detect antibodies - ZOONOTIC - Has many systemic effects in guinea pigs that would interfere with research projects

Answer 73

- Rare and usually clinically inapparent - Poxviruses, guinea pig retroviruses, parainflunza viruses, murine pneumonia virus, mammalian orthoreovirus (reovirus 3), simian virus 5, herpesvirus, Sendai virus

Answer 74

Protozoan; phylum Apicomplexa; moderately pathogenic Coccidian with ellipsoidal oocytes without a micropyle -Infx associated with high populations of Balantidium coli may occur in the proximal colon, with B. coli as a secondary agent producing clinical disease -Stress is also significant predisposing factor -Can be commensal without clinical signs

Answer 75

Ingestion of sporulated oocysts - Oocysts in feces require 2-11 days outside the host to develop to an infective stage; factors impacting maturation include heat, humidity, oxygen - Prepatent period = 10 or more days

Answer 76

In severely infected weanlings: lethargy, anorexia, watery to pasty feces lasting 4-7 days - Oocysts may not occur in feces until 10 days post-infx, so may see soiled hair coat, diarrhea, and even death before oocysts detected in feces - In survivors constipation may follow diarrhea

Answer 77

- Edema, hyperemia, hemorrhage, white or yellow plaques in the thickened proximal colon and adjacent cecal wall - Intestinal contents watery and often contain blood - Histo: colonic epithelial cell hyperplasia, intracellular coccidian forms, enterocyte sloughing, edema and congestion of lamina propria - Ingested, sporulated cysts invade the mucosal crypts of Liekberkühn in proximal colon and, during schizogony, damage the epithelium

Answer 78

- Oocysts on fecal float, mucosal scraping, stained tissue sections - Diff Dx: pantothenic acid or Vitamin C deficiency, cryptosporidiosis, bacterial enteropathies, coronavirus

Answer 79

- Good sanitation and husbandry, reduction of stress, provision of fresh, appropriate feed - Sulfonamides with known anti-Eimeria activity and provision of Vitamin C

Answer 80

Coccidium of guinea pigs that has a prolonged phase of endogenous replicaton

Answer 81

- Subclinical infx may be common - Clin signs most often seen in young animals (under 300g or up to 16 wks old); may be exacerbated by concomitant E. coli enterotoxemia - Weight loss (most common sign), anorexia, potbellied appearance, rectal prolapse, uncommonly diarrhea and death

Answer 82

- Transmission: fecal oral; infxs are patent for 2 weeks and cleared by 3-4 wks postingestion in young adults and 1-2 wks in adults - Necropsy: diffuse enteritis from duodenum to cecum; intestinal hyperemia, edema, atrophy or necrosis of villus tips, lymphocyte infiltration, hyperplasia of crypt epithelium

Answer 83

- Cryptosporidial bodies intracellularly in brush border epithelium near villus tips and most numerous in anterior ileum - Bodies are basophilic, round to oval, 1-4 µm diameter - Detect organisms in mucosal scrapings examined on phase contrast microscopy or on stained tissue sections

Answer 84

- Acquired when guinea pigs ingest feces from infected cats - Infx rare and primarily subclinical - Clin signs: vulvar bleeding, abortion; encephalitis - Asexual stages of organism, which may survive up to 5 years, are distributed in most tissues - tachyzoites in virtually every organ, bradyzoites in brain, heart, skeletal muscle where they may be detected histologically - Moderate immune reponses occur in the host & can identify antibodies to T. gondii - Infx of the uterus, placenta, and fetus may be subclinical or cause a blood-filled uterus, fetal deaths, and abortion

Answer 85

- Usually nonpathogenic; ciliated protozoan possessing a micro- and macronucleus - Transmission: fecal oral - Inhabits cecum and colon - Its trophozoites may be an opportunistic pathogen in bacterial enteropathies, following mucosal damage, or with E. caviae present in the intestinal wall - Identified histologically in intestinal wall (postmortem invasion also possible) and in intestinal contents and feces

Answer 86

- Sporocysts ingested with urine and excyst in gut - sporozoites pass via circulation to renal tubule epithelium, glomerular capillaries, spleen, lungs - maturing schizonts contain 8-12 merozoites, which on host cell rupture pass to the proximal tubular epithelium where second generation schizogony occurs - Large schizonts, containing up to 100 merozoites, can cause significant enlargement of infected epithelial cells - Gametogonous and sporogonous forms occur in the epithelium of the loop of Henle, and schizogonous stages occur in the epithelial cells of the proximal convoluted tubules and in the glomeruli - Merozoits in the loop of Henle produce zygotes, which undergo sporogony - Histo: protozoal forms and inflammatory cell infiltrates

Answer 87

Clinical signs and gross necropsy findings are rare except in heavy infestations = renal surface irregular with gray mottling d/t proliferation of interstitial fibroblasts, which may cause some renal impairment -Prevention: good sanitation, removal of susceptible animals from exposure to the urine of infected animals

Answer 88

Endolimax caviae, Entamoeba caviae, Giardia duodenalis (enteritis), Leishmania enrietti (cutaneous nodules and ulcers), Tritrichomonas caviae, Sarcocystis caviae, Trypanosoma cruzi (chronic myocarditis) - Prevention and control are strict sanitation and periodic screening for the organism - Sulfonamides are NOT effective treatment

Answer 89

Cecal worm & only common helminth of guinea pigs - Inhabits but does not penetrate the cecal and colonic mucosa - Considered non-pathogenic; single report that causes bronchoalveolar eosinophilia - Worms mature in 45 days; ellipsoidal egg to egg life cycle is 51-66 days; ova are transmitted in feces and become infective in 3-9 days after shedding - Prevention/control: removing fresh feces and maintaining good sanitation - Adult male worms: 11-22mm long, females 16-28mm long

Answer 90

Guinea pig is a paratenic (substitute intermediate) host -Ingest embryonated ascarid eggs present in raccoon feces - larvae migrate via small intestine, other organs, and the bloodstream throughout the host, often including the CNS (cerebral larval migrans), where they may cause damage and inflammation - Clin signs: torticollis, ataxia, anorexia, opisthotonos, stupor, hyperexcitability - Prevention: exclusion of raccoon feces & removal of ova from environment - ZOONOTIC

Answer 91

- Pentastome 'tongue worm' - Live in nasopharyngeal region of mammals - Nymphs reported in guinea pigs in 1970s

Answer 92

Reported in guinea pigs in South America | -Anoplocephala sp. = tapeworms

Answer 93

- Trematodes; rarely infect guinea pigs - exposed to infectious metacercariae shed from snails - Metacercariae move to a vegatation substrate, lose their tails, and encyst on leafy vegetables that guinea pigs may eat - Adult flukes mature in host liver and shed eggs into the small intestine and feces - Eggs require a snail intermediate host to mature - Consequent biliary and hepatic damage may cause anorexia, debilitation, death; infected guinea pigs may become emaciated, anemic, possibly paretic due to aberrant parasite migration - Primary lesions in LIVER

Answer 94

listrophorid fur mite: Chirodiscoides caviae, Demodex caviae, Mycoptes musculinus, sarcoptids Trixacarus caviae and Sarcoptes scabiei and Notoedres muris -Only Chirodiscoides and Trixacarus reported commonly, and usually in pet guinea pigs

Answer 95

- Usually subclinical, although a dense population of elongated mites moving on hair shafts is apparent - Heaviest infestations on POSTERIOR TRUNK - May cause pruritis, self-trauma, alopecia, and dermatitis - Heavy infestation: self-mutilation, weight loss, lethargy, in response to pruritis run and bump into objects, convulse, die; stress of disease may cause infertility and abortion - Adult males often couple in noncopulatory position with females

Answer 96

- Burrowing, sarcoptidiform mite - Asymptomatic or intensely pruritic generalized dermatitis - presence and severity of lesions related to variations in host strain susceptibility and to self-traumatization - Secondary infx may contribute to severity and distribution of signs - Lesions most common on TRUNK, INNER THIGHS, NECK, SHOULDERS; patchy or generalized; affected skin dry to oily with alopecia and marked hyperkeratosis - Heavy infestation: self-mutilation, weight loss, lethargy, in response to pruritis run and bump into objects, convulse, die; stress of disease may cause infertility and abortion

Answer 97

Confined to the stratum corneum and consist of epidermal hyperplasia (or thinning) and orthokeratotic an parakeratotic hyperkeratosis - Folds in stratum corneum contain mites and eggs; adult mites found in short tunnels - Spongiosis and leukocytic/monocytic infiltration occur in dermis - CBC may show heterophilia, eosinophilia, basophilia

Answer 98

- Reported rarely | - May localize to CONJUNCTIVAE, FOREQUARTERS - alopecia and crust and papule formation

Answer 99

May cause pruritic dermatitis

Answer 100

- Both widely distributed in North America and Europe & probably occur worldwide - Transmission: direct contact, via pelage, cage debris, fomites, bedding - Trixacarus has 10-14 day life cycle - Sows pass mites to weanlings, naive adults; cool carcasses pass mite to warm living guinea pigs

Answer 101

- No abnormal necropsy findings, except mite and ova on hair shafts - Attach to hair shafts and do not burrow in skin

Answer 102

- Severe cutaneous lesions, associated loss of body fat, pale liver, subcutaneous signs of secondary bacterial infx (e.g., staphylococcal pyoderma) - Burrow into stratum corneum; pruritic response apparently due to initial allergic response to mite antigen and consequent inflammation

Answer 103

- Ovoid and elongated with a triangular anterior; paired male and female nymphs also characteristic - Lice, other mites

Answer 104

- Indicated by clinical signs, especially pruritis & mites on skin scraping or biopsy - Shorter than S. scabiei (200-450 µm); skin and hair may have to be dissolved in 10% potassium hydroxide and then filtered to retain the mites - Mites often on lumbar region and lateral aspects of rear legs - Pediculosis, dermatophytosis, barbering, sarcoptic and notoedric mange

Answer 105

- More likely to occur when maintained in unsanitary conditions with inadequate veterinary care - Trixacarus lesions seem to occur in some strains more than others and in stressed animals - Control is by repeated treatment of all animals & thorough cleaning and sanitization of environment; larvae and nymphs in environment may establish new infestations

Answer 106

Application at 2 week interval of a diluted (water and propylene glycol) spray of ivermection, selamectin, or pyrethrin

Answer 107

- Ivermection 0.2-0.5 mg/kg SC or orally 3x at 7-10 day intervals - Treated guinea pigs may be shaved or bathed in medicated shampoo to loosen and remove cutaneous debris - Infestation may persist despite ivermectin tx

Answer 108

- T. caviae can cause transient, pruritic papulovesicular lesions in humans - G pigs with untreated, severe acariasis are not useful in research, especially if study involves cutaneous responses

Answer 109

Suborder Mallophaga (chewing or bitiing lice) - abrade the skin and ingest fluids - Gliricola porcelli = slender louse - Gyropus ovalis = ovoid - Trimenopan hispidum & Trimenopan jenningsi

Answer 110

- 1.0-1.5 mm adult lice attached to hair shafts - Sometimes asymptomatic - Heavy infestations: erythema, scratching, alopecia, scabbing around the ears and nape of neck - Transmisson: direct contact with infected host or via contaminated bedding - Gliricola porcelli seen more often than Gyropus ovalis; infx rare in laboratory guinea pigs - On death of host, lice migrate away from cooling body along hair shafts

Answer 111

- Diagnosis: viewing adult or immature lice with hand lens - Gliricola = narrow head and body (0.3 mm wide) - Gyropus = ovoid and broader (0.5 mm wide) - Prevention: obtaining clean stock, maintaining good sanitation - Control: isolation, treatment with dust, dip, or ivermectin, medicated shampoos and shaving, and cleaning the environment

Answer 112

- Ctenocephalides felis (cats [and dog] flea) & Nosophyllus fasciatus (northern rat flea) reported to be able to infest guinea pigs - Occurrence in laboratory guinea pigs rare - Clin signs: pruritis, skin crusts, anemia - C. felis is intermediate host for cestode Dipylidium caninum, & N. fasciatus for hymenolepid tapeworms - Some tick genera (Dermacentor) could possibly affect guinea pigs

Answer 113

- Primarily caused by Trichophyton mentagrophytes (zoophilic, filamentous dermatophyte; aerobic, ubiquitous, saprophytic, keratinophilic fungus) - Also reported in guinea pigs: Arthroderma benhamiae (teleomorph derived from mating strains of T. mentagrophytes complex), Microsporum spp., Scopulariopsis brevicaulis - Fungi live in soil, on other animals, in straw, wood, food

Answer 114

- Lesions begin on the muzzle and head, hair, nails - Lesions occur most often in young guinea pigs or guinea pigs genetically predisposed, stressed, pregnant, malnourished, diseased, or living in unsanitary conditions - Subclinical infx possible - Lesions in 'hairless' guinea pigs resemble humans lesions more closely - Irregularly shaped areas of alopecia, scaling, crusing, reddening may extend to back and sides but rarely to limbs - May see associated vesicles, pustules, abscesses d/t secondary bacterial infx - Lesions sometimes pruritic, often self-limiting, can last up to 30 or more days - Severely affected young may die

Answer 115

- Dermatophytoses occur in many warm-blooded species, especially younger animals in close contact; primates, dogs, cats, horses, swine, ruminants, rodents, and birds - Transmission: direct contact with spores either on animal itself or fomites like bedding - ZOONOTIC - Incubation period of 9-12 days

Answer 116

- Changes in skin confined to superficial keratin layers and structures of the skin and hair follicles - UV light may cause M. CANIS to fluoresce yellow green, but false positive and false negative possible

Answer 117

-Fungi solubilize keratin with proteases - produces scale accumulation on and around the lesion and loosening and weakening of the hair shafts - dermatophyte penetrates the stratum corneum or invades hair follicles - growth continues down the hair shaft to the keratogenous one until the growth inwards equals the outward growth rate

Answer 118

- Hair loss: protein and caloric deficiency, chewing and barbering, bacterial dermatopathies (Staph and Strep), cystic ovary effects, acariasis, continuous breeding - Diagnosis: observation of irregularly shaped, nonpruritic, flaky-skin lesions on the head; recovery of organism from hair and epithelial debris on Sabourand's dextrose agar or dermatophyte test media; observation of species-characteristic morphologic features and macroconidia in Microsporum or microconidia in Trichophyton - Epithelial cells and debris best obtained by vigourous brushing with a toothbrush - Most reliable diagnostic method: fungal culture; growth usually occurs within 10 days

Answer 119

Selection of nonsusceptible animals, good husbandry including appropriate feed and clean environment, alleviation of stress -Dark, moist environments support survival and replication of dermatophytes

Answer 120

Improved sanitation and husbandry, reduction of stressors, removal of infected animals and environmental control - Infected hairs MUST be removed from environment - Disease is usually self-limiting bu full resolution may take months

Answer 121

- Griseofulvin 25 mg/kg PO Q24hr for 2 weeks past resolution of clinical signs; oral griseofulvin absorbed poorly in the intestine unless given with a high fat meal & is teratogenic - Topical griseofulvin in dimethyl sulfoxide solution for 5-7 days - 1% tolnaftate topically - Butenafine topically for 10 days - Thiabendazole, ketoconazoe (hair clipped), itraconazole, terbinafine hydrochloride

Answer 122

Single-cell, intracellular microsporidian (and true fungus) affecting canids, rabbits, rats, NHPs, guinea pigs, and other species - In guinea pigs no know clinical signs & few if any necropsy findings - True prevalence in guinea pigs unknown due to subclinical infx and infrequent serologic screening

Answer 123

- Infective spores disseminated in urine and then ingested or inhaled; transplacental transmission suspected in several species - Guinea pigs relatively resistant to infx (source of spores may be rabbit urine)

Answer 124

- Microscopic lesions occur primarily in the brain and kidney - Infected brain: may have randomly distributed necrotic foci, microgranulomas, perivascular lymphoplasmacytic cuffs, lymphocytic meningitis - Renal lesions: may or may not occur; multiple, 2-4mm grey to white granulomatous foci seen as indentations or plaques just beneath the renal capsule (could confuse with nephrosis in older guinea pigs) - Interstitial, mononuclear nephritis - Lesions may also occur in liver and lungs

Answer 125

- Ingested organism undergoes merogony and then sporogony in cytoplasm of endothelial cells, peritoneal macrophages, renal tubular epithelium, and oligodendrocytes - Spores are found intracellularly and, after cell rupture, extracellularly

Answer 126

- Characteristic histo lesions, birefringence of organisms under polarized light, staining with periodic acid-Schiff or Goodpasture-carbol fuchsin stain, indirect ELISA, fluorescent immunoassay, Western blot - Serologic screening is preferred method - Diff dx: toxoplasmosis - distinguish by Gram stain

Answer 127

Purchase and breed seronegative animals, house away from seropositive rabbits, regular program of serologic screening and removal of seropositive animals, strict sanitation

Answer 128

No treatment reported for guinea pigs, but fenbendazole and albendazole have been used with variable results in rabbits

Answer 129

- Spontaneous infections have occurred | - Emaciation, lameness, gastroenteritis, lymphadenopathy

Answer 130

-Spontaneous infections have occurred - was associated with occlusive capillary embolism and tissue infarction

Answer 131

- Cryptococcus neoformans, Coccidioides immitis, Blastomyces dermatitidis, Aspergillus fumigatus - A normal stomach inhabitant, Torulopsis pintolopesii, may cause enteritis - Scopulariopsis sp., Aspergillus sp., Penicillium sp. may be part of fungal microbiota of guinea pig haircoat

Answer 132

- Increased susceptibility to infectious dz, esp streptococcal infx and enteropathies - Signs of conjunctivitis or upper respiratory dz should always suggest a marginal Vitamin C deficiency and treatment should include Vitamin C supplementation - In group housing, larger guinea pigs can bully smaller or younger guinea pigs, resulting in nutritional deficiencies

Answer 133

- Also known as scorbutus or scurvy - Occurs in a small number of species - notably humans, some other primates, guinea pigs, bats - that lack the genetic code to produce the hepatic enzyme L-gulonolactone oxidase - this enzyme converts L-gulonolactone into the isomers L-ascorbate (AH) & L-dehydroascorbic acid (DHA) - Probable primary roles of vitamin C are acting as a cofactor in hydroxylation and amidation reactions by transferring elections to enzymes that provide reducing equivalents (i.e., protons) and scavenging both intracellular and extracellular superoxide radicals and singlet oxygen, whose activity results in tissue damage - Lack of vitamin C results in defective cross-linking of collagen fibrils characterized by defective wound healing and fragile capillaries

Answer 134

- May be subclinical, accompanied by overt signs of infectious dz (e.g., diarrhea, upper resp infx), or a primary vitamin C deficiency - Marginal deficiencies particularly impt in laboratory guinea pigs d/t increased susceptbility to infectious disease - Signs of secondary (usually bacterial) infx include unexpected death, diarrhea, weight loss, swollen and reddened orbital margins, dehydration, dyspnea - Most obvious clinical signs of Vit C deficiency = fragility of small blood vessels - rupture causing bruises, reluctance to move, screaming when restrained, swollen joints

Answer 135

- Hemorrhage in the subperiosteum, adrenal cortex, skeletal muscle, joints (especially stifles and costochondral junctions), and intestine; gut may be atonic and hyperemic - Histology: changes related in many cases to absence of hydroxyproline and hydroxylysine elements in connective tissue; epiphyseal growth centers of long bones are deranged w/ greatly reduced osteoid formation, degenerating and deranged chondrocytes, decreased bony trabeculae in the marrow cavity, reduced osteoclastic and increased osteoblastic activity, multiple microfractures; myofilaments fragmented and mitochondria swollen; hemorrhage in many tissues

Answer 136

- With defects in amino acid metabolism (including tyrosine and phenylalanine), fibroblasts and osteoprogenitor cells produce defective intracellular architecture and the products dentin, collagen, and osteoid - Junctional defects and cytoplasmic disruption occur between endothelial cells; in muscle, liver, connective tissue cells; in pericapillary fibrous tissue; and in arterial intimae - Subendothelial cholesterol deposition increases, as does lipid peroxidation of cardiac muscle - Iron absorption in the gut and steroidgenesis in the adrenal gland decrease - may be related to increased macrophage cytotoxicity - Macrophage migration and heterophil phagocytosis are decreased - Cholesterol catabolism slowed, reducing bile acid production and consequently fat-soluble vitamin assimilation, and cholesterol accumulates in the liver

Answer 137

- Weakness, pain, and death in young guinea pigs: infectious disease, osteoarthritis, heat stress, toxemias - History of inappropriate feed, decreased prothrombin time, and serum Vitamin C level below 0.55 mg/dL (normal around 2.01 mg/dL) indicate hypovitaminosis C

Answer 138

- Foods providing at least 6 mg Vitamin C per day are adequate - Vitamin C level of 250-500 mg/L in drinking water also provides adequate levels if the water is replenished daily - Vitamin C 'half-life' in glass bottles is ~24 hr - In food stored at 72 F, vitamin C has only 33% of original activity at 30 days postmilling and 14% at 90 days; most commercial guinea pig chows now use a stabilized vitamin C guaranteeing a shelf life of at least 180 days - Guinea pigs on alcohol consumption studies have an increased need for vitamin C - Lesions develop in 7-10 days with NO vitamin C & in ~3 weeks with marginally deficient diets - Improper compounding and storage, autoclaving, and feeding food formulated for other species are common errors - Pregnant guinea pigs may require up to 30 mg/kg daily. but the levels given commonly (10 mg/kg daily) probably exceed requirements

Answer 139

Parenteral or oral administration of Vitamin C daily at levels up to 30 mg/kg -Recovery occurs rapidly over 1-2 weeks

Answer 140

Research with scorbutic guinea pigs is compromised in several ways due to profound and extensive changes, including decreased disease resistance

Answer 141

1) Preeclampsia, eclamptogenic toxemia, or the circulatory form - Arises from abnormal vascular changes that lead to ischemia of the uteroplacental unit 2) Fasting ketosis, of the metabolic-nutritional form - Progresses from hypoglycemia and hyperlipidemia

Answer 142

- Occurs in late pregnancy (last 2 weeks) and immediately postpartum - Occurs more often in obese, multiparous, stressed sows - Affected animals may die without clinical signs or may be dehydrated, depressed, anorexic, underweight - Proteinuria, acidic urine (pH 5-6; normal pH 8), ketonuria, elevated serum creatinine, increased or decreased plasma triglyceride levels - UNLIKE preeclampsia in humans (who also have labyrinthine hemomonochorionic placentation), guinea pigs exhibit hypertension variably and edema rarely - Guinea pig placentation = hemomonochorial with maternal blood circulating around a single trophoblastic layer over fetal capillaries

Answer 143

- Occurs in last trimester (after 45 days), but most often in the last 1-2 weeks - Weakness, depression, dehydration, may die following a 1 to 3 day fast - Acidic urine, ketonuria, variable plasma glucose levels, hyperlipidemia, elevated alkaline phosphatase and ornithine carbamyl transferase serum levels

Answer 144

Many mammals, including humans, NHPs, rabbits, dogs, ruminants, and guinea pigs, exhibit similar conditions in late pregnancy or early lactation but characteristics vary

Answer 145

- Preeclamptic animals usually exhibit more severe changes - Preeclamptic/circulatory form: uterus, placenta and adrenal cortices show petechial and ecchymotic hemorrhage and focal necrosis; placental attachment sites, which detach easily, are also affected; fetuses are dead and decomposing; enlarged, yellow-tan liver with necrotic foci, subcapsular hemorrhage of kidneys, - Fasting ketosis/metabolic-nutritional form: gastric ulcers; fatty infiltration of liver, kidney, adrenal glands, and vessel walls; uterus and placentae have petechial and ecchymotic hemorrhages but NOT as severe as preeclampsia form; livers develop fewer necrotic areas, if any

Answer 146

- Preeclampsia has been induced experimentally in guinea pigs by constricting the abdominal aorta or severing or ligating arteries supplying the pregnant uterus - Pathogenesis behind uteroplacental ischemia poorly defined; proposed course in guinea pigs involves thrombocytopenia, thromoplastin release, alterations in the renin-angiotensin aldosterone system, vasoconstriction, deposition of fibrin, and disseminated intravascular coagulation - Initial causes of preeclampsia IN HUMANS multifactorial and involve reduced placental perfusion d/t insufficient valvular dilation (uterine vessels in late pregnancy only 40% of normal size) and defective trophoblastic replacement of vascular endothelium accompanied by fibrinoid accumulation in and around vessels - proceeds to generalized endothelial dysfunction through a maternal response to trophoblast antigens or vasoconstriction and activation of a clotting cascade initiated by oxygen-free radicals, lipid peroxides, and proteases; triglyceride levels increase within endothelial cells; apparently a genetic predisposition

Answer 147

- Depression and death in late pregnancy suggest pregnancy ketosis - Acidic urine, absence of acute septicemic disease (e.g., salmoellosis, bordetellosis), and poor response to treatment support this diagnosis

Answer 148

- Pregnant guinea pigs should be fed nutritious and balanced diet continuously without changes - Guinea pig breeding stock with no history of obesity or deaths during pregnancy should be selected and housed in a reduced stress environment

Answer 149

- Rare success with treatment - Administration of electrolyte fluids, glucose, calcium gluconate, coticosteroids, and various combintions of fruits and veggies provide no certain disease reversal

Answer 150

Any research project involving breeding or obese guinea pigs, particularly in a stressful environment, can have many sudden animal deaths

Answer 151

- Specific cause of uroliths unknown, but probably involves genetic factors, diets with calcium, magnesium, and phosphorus imbalances, cystitis, nephritis, or urinary tract environmental factors - Decreased urine flow, elevated urine pH, and the uroliths themselves may predispose to cystitis - Proteinaceous urethral plugs fund occasionally in older male guinea pigs probably originate from seminal vesicle content - Bacteria assoc w/ cystitis in guinea pigs include E. coli, Staphylococcus sp., Streptococcus pyogenes - Cystitis often accompanies urolithiasis, lower urinary tract infection, immunosuppression, estrogenic stimulation, diabetes; may be mild to severe, and acute, subacute ulcerative, or chronic

Answer 152

- Urolithiasis usualy subclinical and occurs in older sows - When urinary blockage or infx occurs, can see weakness, weight loss, pain on palpation, vocalization, straining, anuria or dysuria, anorexia, a small thickened bladder, hematuria - Signs may progress over several weeks; untreated animals may die - Urine sediment may contain crystals, erythrocytes, and epithelial cells

Answer 153

- Occurs most often in aged (over 30 months) females | - Urinary tract blockage by proteinaceous plugs occurs in aged males

Answer 154

- Unilateral or bilateral uroliths in the bladder, kidneys, ureters, urethra, vagina, or passed in the urine; concretions of up to 2 cm in diameter may occur in the bladder or urethra - With concurrent cystitis, bladder may be distended with urine and have thickened, hemorrhagic walls with calculi adherent to the mucosa - Proteinaceous plugs occur in the male urethra or bladder - Hydroureter, hydrourethra, hydronephrosis d/t continued occlusion of urinary output with fluid containing white to brown mineral sediment or solid masses

Answer 155

In order of frequency: calcium carbonate, calcium phosphate, magnesium ammonium phosphate hexohydrate, calcium oxalate -Individual uroliths may contain a mixture of these crystal types

Answer 156

- Progression of ionic saturation, supersaturation, nucleation, crystallization, and crystal growth in urolith formation - In urinary bladder, protein may provide a nucleus for crystal formation

Answer 157

- Diagnosis: based on clinical signs of cystitis, detection of uroliths on radiographs or U/S - Diff dx: infection, neoplasia, trauma to genitalia

Answer 158

- Selection of animals known free of urolithiasis, provision of appropriate food and ample water, immediate clinical care of guinea pigs with cystitis - Alfalfa hay and some of the dark leafy veggies are high in calcium - Grass hay and other sources of Vitamin C are preferable in order to avoid stone formation

Answer 159

-Provision of fluids and appropriate systemic antibiotics based on C&S (fluoroquinolones), proper diet, if indicated cystoscopic or surgical removal of uroliths

Answer 160

- Occur occasionally when feeding is restricted or neglected, or due to malocclusion - Usual consequences are reproductive impairment, both infertility and death of low weight (<50g) neonates, hair loss - Pregnancy and lactation may cause a negative energy balance and subsequent hair loss

Answer 161

Arginine, Methionine, Tryptophan | -Guinea pigs can produce niacin from tryptophan - tryptophan-deficient diets can produce cataract formation

Answer 162

Weight loss, ulcerative dermatitis, hair loss, visceral abnormalities

Answer 163

- Rare in herbivores | - Poor growth, keratitis, squamous metaplasia, crust eyelids and pinnae, loss of organization in tooth forming elements

Answer 164

- Can be caused by giving a multivitamin supplement - -Degeneration of cartilaginous epiphyseal plates in long bones, abnormal bone repair, teratogenic effects during organogenesis at 14-20 days

Answer 165

- Effects of vitamin K in guinea pigs not well defined | - May synthesize sufficient vitamin K (and most B vitamins) to prevent overt abnormalities

Answer 166

- Experimental deficiency produces wider epiphyseal cartilage plates, enamel hypoplasia, weight loss - Rickets is NOT a spontaneous disease in guines pigs - Hypervitaminosis D caused by diet misformulation reported to cause anorexia, weight loss, death

Answer 167

- CNS disorders, including tremors and imbalance | - In B-deficient scorbutic animals, increased muscle weakness occurs

Answer 168

-Corneal vascularization, skin lesions, myocardial hemorrhage, decreased growth and failure to thrive

Answer 169

-In young guinea pigs causes anemia and diarrhea

Answer 170

-In young animals causes depression in phagocytic activity of myeloid cells

Answer 171

-In young animals causes general signs as well as profuse salivations and terminal convulsions

Answer 172

-Anorexia, weight loss, and - if deficient in weeks 9-10 of gestation, causes abortion and sometimes death of dams

Answer 173

-Poor growth and fatty liver

Answer 174

- Major signs: Hindlimb weakness through myasthenia or muscular dystrophy, reduced reproductive performance, paralysis, death - Associated signs: coagulative necrosis of muscle, testicular degeneration, degenerative changes in seminiferous tubules, reduction of spermatozoa and spermatids. elevated creatine phosphokinase - Mucular dystrophy precedes testicular degeneration - Lethargy and conjunctivitis seen in debilitated animals - Iatrogenic deficiency of selenium and Vitamin C reported to cause skeletal muscle cell death

Answer 175

- Excess increases the requirement for magnesium, which contributes to metastatic mineralization - Guinea pigs use cation exchange and phosphate anions for removing excess hydrogen ions rather than removing protons by excretion of ammonium ions - Calcium turnover is rapid in guinea pigs - Phosphate ions are critical component of metastatic mineralization; magnesium supplementation essential to offset hyperphosphatemia; high phosphate levels lower plasma pH - Potassium will counteract adverse effects of excess phosphate by providing an exchange cation to remove excess hydrogen ions

Answer 176

-Reproductive disorders, pancreatic hypoplasia

Answer 177

-Slow growth and myelination failure

Answer 178

-Poor weight gain, hair loss, hindlimb weakness

Answer 179

- May occur in guinea pigs over 1 year of age - Usually subclinical - Occurs on skeletal and cardiac muscle fibers; renal collecting tubules, interstitium, convoluted tubules, Bowman's capsule; in other soft tissue esp around elbows and ribs; in lungs, trachea, aorta, liver, stomach, uterus, sclera - Gross lesions: irregular, grey patches on tissue surfaces that grate when cut with a blade - Histo changes: notable in hindlimb muscles; mononuclear cell infiltration, mineralization, fibrosis - Clinical signs: if present, poor growth, hair loss, muscle stiffness, bone deformities, nephrosis, death - Probable causes: diets with calcium, phosphate, magnesium, and Vitamin D imbalances - Mineral deposits are usually calcium, phosphates, or carbonates combined with other minerals - May have local low tissue pH - Prevention: don't feed diets for other species to guinea pigs

Answer 180

- Uncommon in guinea pigs, except for certain inbred colonies or male Abyssinian-Hartley colonies with a genetic predisposition or a yet unidentified infectious agent - Clinical signs evident at 3-6 months of age, affect both sexes; polyuria, weight loss, infertility, cataract formation, variable glycemia, hyperlipemia, glycosuria, (over 100-2000 mg/dl), rare ketouria - Resembles Type I diabetes mellitus in humans = islet hyperplasia, degranulation of beta cells, thickening of basement membranes of peripheral capillaries, fatty infiltration of exocrine cells, glomerulosclerosis - Spontaneous remissions accelerated by feeding hay and leafy greens occur; injected insulin not needed to maintain animals but insulin or an oral hypoglycemia agent has decreased glucosuria

Answer 181

- Common, especially if feeders or waterers or food (odor, taste, density, texture, form) or water (flavor) has changed - Guinea pigs are neophobic & by 4 days old develop food preferences & then may not recognize as food other diets (powders, veggies, supplements, etc.) - Other factors: postsurgical stress, ketosis, malocclusion, drafts, illness, water deprivation - Treatment: provide preferred or sweetened foods, changing feeder or waterer, treating existing disease, reducing crowding, reducing obesity

Answer 182

- Sensitive to sudden or extreme environmental changes; such changes are predisposing factors for respiratory disease and stress-precipitated illnesses - Guinea pigs' ancestors lived at high, cooler altitudes = heat stressed easily, even when in direct sunlight at temps as low as 70 F. - Clinical signs: shallow, rapid respiration; weakness, hyperthermia, coma, death - Treatment: cool water baths, corticosteroids, parenteral fluids

Answer 183

- Pulling and ingestion (trichotillomania) of cage mates' hair occurs primarily in group-housed females; may be precipitated by stressors or need to displace another guinea pig from food/water source - Chewing of hair (trichophagia) may occur without wounds; self-barbering occurs caudal to the anterior shoulders; dominance-associated or agonistic trichophagia by conspecifics usually on rump, back, and around eyes and ears - Barbering and skin damage most often occur among status seeking adult males with or without a sow present, when parents groom young, or weanlings chew sow's hair - Self-barbering may be ameliorated by feeding hay and dark, leafy greens - Biting may cause alopecia, scratches, lacerations, deep wounds; perineal wounds contaminated with bedding or food can become infected, extend to prepuce, cause urine retention & bleeding, pain during mating, reduced reproductive performance; some boars scoot around cage and push bedding into prepuce causing similar signs - Prevention: reduce environmental stressors, early weaning, separation of boars to single housing or provision of shelters, perhaps hay feeding - Treatment: cleaning of wound and placing in clean cage; few topical antimicrobials are effective and, if ingested, may precipitate enterotoxemia

Answer 184

- Aggressive behavior | - Severe damage can results in infections and partial or complete loss of pinnae

Answer 185

- Limbs caught and injured in wire cage walls or flooring - Bone fractures from improper handling or dropping - Diaphragmatic hernia - Broken or luxated vertebral column - Fracture of liver capsule - Broken teeth

Answer 186

- Guinea pigs injected SC with Freud's complete adjuvant may develop pulmonary granulomas - Lesions are similar to perivascular lymphoid nodules or focal pneumonia caused by other conditions

Answer 187

- Frequently bred sows show hair thinning - d/t high metabolic demands or pregnancy and probable genetic and metabolic factors - Hair loss in breeding groups may be d/t trichophagia - Hair regrows when breeding stops or social dynamic changes - Alopecia may also occur in young animals at weaning, when the hair coat changes character, and when guinea pigs are on low-protein or low-calorie diets

Answer 188

- Common in guinea pigs - May be d/t uterine inertia, pregnancy toxemia, fetuses too large to pass through pelvic canal, os coxae failed to separate - despite relaxin release, to the 2.5-3 cm needed to allow fetuses to pass - Failure or fibrocartilaginous pelvic joint to separate occurs most frequently in sows bred for the first time over 7 months of age b/c symphysis usually fuses and becomes resistant to relaxin - Clinical signs: still narrow symphysis near 73 days gestation, straining, depression, vaginal discharge - Prevention: first breeding before 7 months of age, prevent obesity and fasting while pregnant, remove animals with known family history or dystocia - Young guinea pigs involved in dystocia experience hypoxia, which is often fatal - Treatment: digital removal of fetus; calcium, glucose, 1-3 mg/kg oxytocin (ONLY if pubic symphysis confirmed open); C-section

Answer 189

- Occurs on volar surfaces of one or more feet and presents with enlarged, firm, ulcerated wounds - Chronic, ulcerative lesions may have Staphylococcus involvement - Can be associated with amyloid accumulation in the liver, adrenals, spleen, pancreatic islets - Prevention and treatment: provide smooth wire or solid-bottom flooring with bedding, good sanitation, reduction of obesity; severe cases antibiotic treatment, softening with lotion, surgical debriding - S. aureus can cause pneumonia, mastitis, conjunctivitis, cheilitis, osteoarthritis; has been assoc w/ exfoliative dermatitis with alopecia, erythema, scabs, epidermal cracks - Staph enter skin through abrasions - Histology: parakeratosis with minimal inflammation - Pododermatitis rapidly progresses to osteomyelitis is not treated - Amputation NOT an option due to body weight distribution

Answer 190

- Enteropathies and deaths in guinea pigs occurring w/in 1-5 days of administration of certain antibiotics assumed to result from 1) antibiotic-induced suppression of resident microflora, perhaps Bacteroides; 2) loss of cecal colonization resistance; 3) colonization, proliferation, and toxin production by transiting or resident commensals, usually one or more strains of C. difficile - E. coli is NOT a normal intestinal inhabitant in guinea pigs; may proliferate in antibiotic-caused dysbiosis - Antibiotics most often implicated: AMINOPENICILLINS, CEPHALOSPORINS, CLINDAMYCIN, STREPTOMYCIN, LINCOMYCIN (penicillin dose as low as 2000 U or ampicillin over 6 mg/kg Q8hr for 8 days known to cause death) - Clinical signs: vary with drug dose and strain of opportunisitic pathogen; rapidly progressive lethargy, rough hair coat, diarrhea, death - Necropsy: hemorrhagic typhlitis, cecum distended with bloody liquid feces; severe inflammatory rxn in the lamina propria and microulceration of the mucosa with inflammatory cell infiltration - Treatment: supportive fluids, highly palatable food, heat

Answer 191

- Common, fecal-borne, anaerobic, G(+), commensal whose large subterminal spores persist in the environment - Some strains produce protein exotoxins (cytotoxins) A & B - bind to epithelial cell membrane receptors - Toxin B is more cytotoxic but requires Toxin A (enterotoxin) to access mucosal cells - Toxin A causes fluid secretion, mucosal damage, inflammation - results in cell death - Cause of antibiotic-associated typhlocolitis - Drug prophylaxis NOT recommended: treatment of choice in humans, metronidazole, may exacerbate toxicosis in guinea pigs - Treatment: supportive fluids, highly palatable food, heat

Answer 192

- Use cautiously in immature guinea pigs - Report showed single SC dose of 350 mg/kg quinolone nalidixic acid in 6 week old guinea pigs cause severe degeneration of middle-zone chondrocytes

Answer 193

- Otoconial (inner ear cell) loss in the striola region of both utricle and saccule in adult, mixed-sex guinea pigs following seven IP injections of 250 mg/kg streptomycin - Recovery often occurred in 8-10 weeks

Answer 194

-Interfere with calcium uptake into otoconia (inner ear cells)

Answer 195

- Most common in animals over 3 years of age - Most common type are those of hemolymphopoietic system, followed by respiratory system, integument, reproductive tract, mammary gland, hemopoietic system, cardiovascular system, endocrine glands

Answer 196

- Elodontic and hypsodontic teeth - Maocclusion may occur because of shortness of maxilla, abnormally narrow mandibular separation (anaesognathism), nutritional deficiency, broken or deviated teeth d/t trauma or periodontal infx - Root abscesses may extend into mandible or maxillary sinus & cause exophthalmos - Premolars and molars involved most often, but incisors can also be maloccluded - Clinical Signs: weight loss, inappetance, drooling ('slobbers'), oral laceration and bleeding, gaping mouth, death - Necropsy: periodontal dz and overgrown teeth, often with sharp edges and POINTS ON LABIAL SIDE OF MAXILLARY & LINGUAL SIDE OF ROSTRAL MANDIBULAR MANDIBULAR CHEEK TEETH; elongated coronal surfaces may arch, inhibit tongue movement, and force open the mouth - Diagnosis: clinical signs and oral exam - Differentials: drooling can also be d/t folic acid deficiency, chronic fluorosis, heat stress, hypovitaminosis C, dental abscesses - Treatment: trim overgrown teeth to 2-3 mm above the gingiva & file sharp points (dental bur or rongeurs; only in anesthetized animals); remove infected teeth, drain abscess, antibiotics - Tooth extraction via bucotomy is complicated b/c of difficulty in access and relative paucity of alveolar bone in mandible - INHERITED, esp in 2/N and 13/N inbred strains = don't breed

Answer 197

-Probably secondary to uremia, ketosis, excessive stress, Citrobacter infection

Answer 198

Reported in 6 breeder guinea pigs aged up to 26 months - Found dead or with dyspnea, cyanosis, tachycardia, distended stomachs containing fluid and gas rotated 180 degrees on mesenteric axis; diaphragm displaced anteriorly - Cause of volvulus not apparent

Answer 199

- All ages; Strain 13 more commonly involved - May be due to manipulation, antibiotic use, corticosteroid injection, fasting, torsion, advanced pregnancy - May be no clinical signs except death

Answer 200

Caused by wood shavings, hair, inspissated digesta

Answer 201

Colonic stricture, dilation, cecal torsion, cecal and rectal impactions, rectal prolapse, circumanal sebaceous accumulations

Answer 202

Contusion, focal coagulative necrosis (maybe d/t agonal hypoxia), idiopathic cholangiofibrosis

Answer 203

- Cardiac rhabdomyoma - Pale, pink foci or streaks with indistinct margins in the myocardium, usually the left ventricle - Relatively common in guinea pigs; similar lesions occur in dogs, swine, humans - Streaks = glycogen accumulation in myofibers or Purkinje fibers d/t congenital abnormality of glycogen metabolism - Diagnosis: alcohol-fixed specimens stained with periodic acid-Schiff stain - No apparent cardiac impairment caused by the lesions

Answer 204

- May begin at early age and continue as common occurrence in older animals - Primary cause for nodules unknown; may be antigenic stimulation and are less common in SPF guinea pigs - Perivascular lymphoid nodules, consisting of normal lymphocytes, may be in the adventitia of the pulmonary arteries and veins - In older guinea pigs, aggregations reach 0.5mm diameter & visible grossly as pinpoint-sized subpleural foci

Answer 205

- Rarely reported | - Thickened pulmonary artery musculature, osseous metaplasia in alveolar septa, foreign body pneumonia

Answer 206

- Incidental findings in aged guinea pigs - Characterized by weakness, anemia, dilute urine, increased BUN and creatinine - Autoimmune, infectious, and vascular diseases may contribute - Necropsy: pitted subcapsular renal surface with pale streaks extending into the cortex and even medulla; segmental to diffuse interstitial fibrosis causes kidney to have irregular surface - Histo: most glomeruli remain normal, but immune complex deposition occurs in basement membrane - Chronic renal failure may predispose to cochlear dysfunction, especially in the hair cells

Answer 207

- Normal guinea pig: ovaries lie caudo-lateral to kidneys, 6-8mm long & 4-5mm diameter; rete ovarii are derived from the mesonephric tubules & occur in the hilus of the ovary - Cysts of the rete ovarii are common in sows 1.5-5 yrs of age - Cause of cysts unknown; both androgens and estrogens may be involved in the pathogenesis - Incidence may range from 76-90% in older sows - Clinical signs: anorexia, depression, abdominal distension, bilateral symmetric hair loss over flanks and rump, reproductive failure - Diagnosis: careful clinical exam (avoid rupturing cyst), radiography, U/S imaging using a 6.0 or 10.0 MHz mechanical sector transducer - Cysts are up to 7 cm or more in diameter, singular or multilocular, unilateral or bilateral (R more often than L), may be assoc w/ leiomyomas of the uterine body or horn, cystic endometrial hyperplasia, or endometritis; larger cysts may cause pressure atrophy in adjacent ovarian tissue - Treatment: surgical removal

Answer 208

- Report noted spontaneous, progressive osteoarthritis in stifle and other joints of male Dunkin Hartley guinea pigs - Noted as early as 3 months of age; became severe by 22 months - Changes in cartilage included increased levels of proteoglycans and decreased collagen - Histo: osteophytse, calcification of collateral ligaments of the joint, degeneration of weight-bearing, articular surfaces - Hypovitaminosis C, obesity, joint injury may contribute to joint degeneration - Mechanical load and stiffness are significant pathogenic mechanisms

Answer 209

-Scorbutus lesions, osteodystrophy, nutritional myopathy, consequences of injections and bites

Answer 210

- Paurangiotic retina - retinal blood vessels are minute and restricted to the direct neighbourhood of the optic disc - and NO tapetum - Pupil dilation by using 1% tropicamide drops or, in pigmented animals, one drop each of 1% atropine and 10% phenylephrine 3-4x within 15 min - Exam best accomplished using a 20-diopter (D) or 30-D indirect condensing lens - Fluorescein dye use, exfoliative conjunctival exam, and culture are diagnostic methods

Answer 211

- Blepharitis with epithelial flaking, crusting, alopecia, swelling, reddening of lids = 'dull eyes' - Usually seen in guinea pigs with marginal hypovitaminosis C, with subclinical infx - usually of upper respiratory tract, or with malocclusion or renal disease

Answer 212

-Caused by chlamydophilae, streptococci, staphylococci, Pasteurella spp., physical or chemical irritants

Answer 213

-Upper molar root abscess extending into maxillary sinus and orbit, orbital trauma, foreign bodies, sialocele, lacrimal gland cysts or inflammation, neoplasia (lymphosarcoma)

Answer 214

-May be a portion of a lacrimal gland, or a yellow subconjunctival fat deposit

Answer 215

- May result from feeding a diet low in L-tryptophan (under 0.1%). diabetes - Heritable cataracts have been reported in strain 13/N d/t a single, autosomal, gene deletion of 34 residues that produces a novel zeta-crystallin lens protein; homozygous = lenses completely opaque; heterozygous = lenses have a well-demarcated opaque nucleus with a normal cortex

Answer 216

Dermatophytosis of the lids, common bacterial infections, herpesvirus conjunctivitis, listerial keratoconjunctivitis, ophthalmitis, ocular dermoid, microphthalmia, corneal dryness, optotoxicity from toxin ingestion, ulceration, osseous metaplasia, osseous choristoma of the ciliary body

Answer 217

-Topical or systemic antibiotics; known safe and effective = fluoroquinolones, chloramphenicol, trimethoprim-sulfonamide

Answer 218

Hyperthyroidism, hyperparathyoidism, and hyperadrenocorticism have been reported, but incidence of these is low

Answer 219

- Deposition of amyloid A (AA) in the kidney, liver, spleen, adrenal glands - Associated with aging or chronic inflammatory conditions, such as staphylococcal pododermatitis and osteoarthritis, or with multiple casein injections - Amyloid = extracellular deposition of polymerized serum protein subunits that have a role in inflammation - Condition is slowly progressive, begins in the renal mesangium, and extends into subendothelial portions of capillary basement membranes

Answer 220

- Guinea pigs that eat grasses contamined with hyphal masses (sclerotia) of Claviceps purpura - which produces alkaloids ergotamine and ergometrine - may develop dry gangrene of feet - Toxins damage the capillary epithelium and lead to thrombosis and necrosis

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Chapter 6. Biology and Diseases of Guinea Pigs Flashcards

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