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Laboratory Animal Medicine Blue Book, 3rd Ed. (2015) > Chapter 7. Biology and Diseases of Other Rodents > Flashcards

Chapter 7. Biology and Diseases of Other Rodents Flashcards

1
Q

According to the AWA, what type of field studies are exempt from IACUC review?

A

Field study “that does not harm, or materially alter the behavior of the animal under study”

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2
Q

What species require IACUC oversight if the project i PHS funded?

A

Any vertebrate, including in field studies

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3
Q

Describe how the AWA requirements for USDA reporting apply to field studies.

A

Requirements are retroactive. Many ‘observation only’ or ‘live trapping’ field studies may fall in USDA category C, but if inadvertant injury occurs resulting in pain or need for euthanasia the animal must be reported in the higher pain category

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4
Q

Mycoplasma volis

A

New species of mycoplasma isolated from healthy field-trapped Microtus ochrogaster (prairie vole)

  • Infection of laboratory rats and mice with M. volis resulted in seroconversion & microscopic lung lesions but no clinical signs
  • Wild-caught rodents may carry various Mycoplasma species (M. pulmonis, M. arthritidis)
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5
Q

Limitations of serology testing in wild-caught rodents

A

Relies on cross-reactivity, which can decrease efficiency

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6
Q

Recommendations to prevent disease transmission from wild-caught nontraditional rodents

A

-Case-by-case risk assessment plan that takes into account what is known about the wild-caught rodent to be housed, the infectious agents with the highest likelihood of occurrence, the biology of these agents, the available means for disease transmission control (quarantine and conditioning programs, housing species separately, sentinel program, prevention of airspace or fomite interspecies transmission)

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7
Q

What is the largest order of living Mammalia

A

Order Rodentia - 2277 species placed in 28 families
~42% of worldwide mammalian biodiversity
-Found worldwide except Antarctica and some oceanic islands

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8
Q

Rodent incisors

A
  • Specialized dentition for gnawing (Latin rodens means “gnawing”); single pair of upper and single pair of lower hypertrophied incisors that are actually retained deciduous secondary incisors; diastema between incisors and first cheek teeth; incisors have no roots and grow continuously
  • Enamel deposited on anterior and lateral incisor surfaces, posterior surface is dentin; during gnawing softer dentin wears away leaving a sharp enamel edge
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9
Q

Rodent masseter muscle

A

Forcefully brings the lower jaw forward for gnawing

  • 3 parts: superficial masseter, lateral masseter, medial masseter
  • By moving the skeletal attachment or origin of the masseter muscle rostrally, rodents gain both a mechanical advantage and an additional range of lower jaw movement
  • Traditionally rodents divided into 3 groups based on masseter attachment evolution
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10
Q

Sciuromorphous

A
  • Origin of the lateral masseter moves forward and attaches to the front of the zygomatic arch where it meets the rostrum
  • Origin of superficial masseter also shifted forward
  • Origin of medial masseter not changed much
  • Front of zygomatic arch has developed into large, distinctive zygomatic plate
  • Squirrels, beavers, geomyids, heteromyids
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11
Q

Hystricomorphous

A
  • Infraorbital foramen very large; through it, part of a much-expanded medial masseter passes to originate on the side of the rostrum rostrally to the zygomatic arch
  • Porcupines, guinea pigs, jerboas
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12
Q

Myomorphous

A
  • Probably arouse from the sciuromorphous ancestral state
  • Development of zygomatic plate an rostral shifting of the lateral masseter, as in sciuromorphs
  • Infraorbital foramen is moderately enlarged & a slip of medial masseter passes through it
  • True rats and mice, hamsters, gerbils, voles
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13
Q

Sciurognathous jaw

A

-The angular process, which receives most of the masseter, arises almost in a line with the rest of the jaw - it originates in the same vertical plane that also includes the socket of the incisors

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14
Q

Hystrichognathous jaw

A
  • Origin of the angular process is distinctly lateral to the plane of the jaw & is often flared laterally
  • Coronoid process usually reduced
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15
Q

Number of rodent families recognized in this text.

A

33

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16
Q

Rodent suborders

A

5: Sciuromorpha, Castorimorpha, Myomorpha, Anomaluromorpha, Hystricomorpha
- Sciuromorpha, Myomorpha, and Hystrichomorpha has excellent support as monophyletic taxa; further phylogenetic investigation of Castorimorpha and Anomaluromorpha is needed to determine if they belong within one of the other three a suborders

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17
Q

Ground squirrels

A
  • Spermophila with 8 genera
  • Most common species used in research: Urocitellus richardsonii (Richardson’s ground squirrel), Ictodomys tridecemlineatus (13-lined ground squirrel), Spermophilus lateralis (golden-manteled ground squirrel), Spermophilus beecheyi (California ground squirrel; Beechy ground squirrel; rock squirrel)
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18
Q

Urocitellus richardsonii

A

Richardson’s ground squirrel

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19
Q

Ictodomys tridecemlineatus

A

13-lined ground squirrel

-Series of alternating dark and light longitudinal stripes with a row of light spots on each of the dark strips

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20
Q

Spermophilus lateralis

A

Golden-mantled ground squirrel

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21
Q

Spermophilus beecheyi

A

California ground squirrel; Beechy ground squirrel; rock squirrel

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22
Q

Spermophilus elegans

A

Wyoming ground squirrel

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23
Q

Description of ground squirrels

A
  • Head and body length: 130-406mm
  • Tail length: 38-254mm
  • Weight range: 85-1000g
  • Fur is grizzled brown or yellowish grey, often with fine light spots on the upper parts, and the underparts whitish or yellow
  • Large internal cheek pouches to carry food
  • (Old genus name: Citellus)
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24
Q

Distribution of ground squirrels

A

Great Plains of US and south-central region of Canada

  • U. richardsonii: prairies of central Alberta and western Montana to Minnesota
  • I. armatus: southwestern Montana, southeastern Idaho, western Wyoming, northern Utah
  • I. tridecemlineatus: central Alberta to Ohio and southern Texas
  • S. lateralis: southwestern Canada and from North Dakota to Washington
  • S. beecheyi: southern Washington to northern Baja California
  • Habitat is prairies and steppes, tundra, rocky country, open woodlands, or desert mountain ranges (NOT found in areas with dense forest cover)
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25
Q

Spermophilus armatus (I. armatus)

A

Uinta ground squirrel

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26
Q

Habitat of ground squirrels

A
  • Most construct burrows with length and character varying across species
  • During warm months Richardson’s ground squirrels live in extensive colonies; males have territories of ~0.06 hectares, which cover the burrows of 3-5 females; within a week after mating, females establish their own territories of ~0.016 hectares within the male territories
  • 13-lined ground squirrels live in small, scattered groups; not highly social and lack territorial activity; occupied burrow is defended, but territory around it is not
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27
Q

Use in research of ground squirrels

A
  • Hibernation: despite the virtual arrest of physiologic functions and minimal delivery of glucose and oxygen, homeostatic control is maintained; adaptive hibernation strategies incl hypertrophy of cardiac muscle to maintain cardiac output despite low HR - higher relative proportion of the alpha isoform of the cardiac myosin heavy chain, which preserves contractile strength
  • California ground squirrels have serum metalloproteinase inhibitors with inhibitory activity against rattlesnake venom (regularly confront Pacific rattlesnakes trying to prey on pups)
  • Hepatitis B infections
  • Hepatocellular carcinoma
  • Cholesterol gallstone formation: cholesterol-fed Richardson’s ground squirrel
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28
Q

Biology of ground squirrels

A
  • All ground squirrels are diurna
  • U. richardsonii has 3 daily activity periods: first 2 hr after dawn, 10am-2pm, ~4pm-sunset
  • For about 7 months (Sept or Oct - Apr or May), Richardson’s ground squirrels hibernate in their burrows
  • I. tridecemlineatus doubles its weight by Sept and hibernates from early Oct to Apr
  • Female ground squirrels are monestrous and normally bear one litter per year; mating takes place shortly after emergence from hibernation
  • Gestation: 23-31 days
  • Liter size: 2-15 pups (7.5 in S. richardsonii)
  • Weaning: 4-6 weeks
  • Full size and sexual maturity: by 11 months
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29
Q

Diet in wild for ground squirrels

A

Seeds, nuts, grains, roots, bulbs, mushrooms, green vegetation, insects & other small invertebrates, bird eggs
-May store food in burrow but appear to not use it until awakening in spring

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30
Q

Diet in laboratory-housed ground squirrels

A
  • U of Wisconsin 13-lined ground squirrels: Diet of high protein (≥25%) dog chow, supplemented with black sunflower seeds
  • Carrots, celery, and live mealworms as supplements for breeders and juveniles
  • At same facility at University of Wisconsin, give kitten milk replacer as behavior modifier to facilitate animal observation and medication administration, and in cases of inadequate maternal milk supply
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31
Q

Laboratory housing of ground squirrels

A
  • Room temp 18-22 C
  • Induced to hibernate in an unlighted room at 5-10 C
  • Ground squirrels will lose considerable weight during hibernation and may die if forced to hibernate much beyond the end of natural hibernating season; any emaciated squirrels should be removed from hibernation at any time to reduce mortality
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32
Q

Corynbacterium ulcerans in ground squirrels

A
  • Gangrenous dermatitis has been reported in Richardson’s ground squirrels
  • In report 6 died of toxemia, but 57 responded to topical and parenteral antibiotics
  • Epizootic thought to be assoc w/ bite wounds due to fighting
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33
Q

Staphylococcus aureus in ground squirrels

A

-Purulent cutaneous and visceral lesions observed in a colony of commercially supplied golden-mantled squirrels & were assoc w/ death in 1/3 of animals

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34
Q

Yersinia pestis in ground squirrels

A
  • Infection in wild California ground squirrels occurs frequently in plague endemic areas like southern California and Alaska
  • Transmission of bacillus assoc w/ fleas Hoplopsyllus anomalus and Oropsylla montana
  • Ground squirrels become infected following hibernation and again when reoccupying colonial burrows
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35
Q

Ground squirrel hepatitis virus (GSHV)

A
  • Develop mild, progressive persistent hepatitis
  • Histo: chronic portal lymphoplasmacytic hepatitis with small aggregates of mononuclear inflammatory cells in the parenchyma
  • Serum aspartate and alanine transaminases (AST and ALT) are mildly elevated
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36
Q

Western equine encephalomyelitis virus - experimental infection in ground squirrels

A
  • Adult Richardson’s ground squirrels have been experimentally infected
  • Highest titers recovered from brain
  • Hist: meningitis; CNS vasculitis, perivascular cuffing, gliosis, neuronophagia, neuronal degeneration
  • Virus also found in extraneural tissues
  • Duration and magnitude of viremia were sufficient to provide virus source for arthropods
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37
Q

Rabies in ground squirrels

A
  • Ground squirrels are susceptible to rabies
  • Prolonged incubation period of rabies virus during hibernation
  • In the US antigenic or genetic variants of rabies viruses from rodents and woodchucks correspond to the variants assoc w/ the major terrestrial wildlife reservoir within the geographic region of specimen origin
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38
Q

Sarcocystis campestris in ground squirrels

A
  • Richardson’s ground squirrels have been experimentally infected with sporocysts from badgers (coccidian of badgers)
  • Hepatitis and phlebitis of hepatic veins seen between 4-8 days
  • Meronts found in endothelial cells beginning on day 9 & most numerous in lung
  • 4 of 10 infected squirrels died between days 11-13
  • Foci of inflammation visible in myocardium and brain at 64 days
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39
Q

Most prevalent intestinal parasits in survey of wild Spermophilus elegans (Wyoming ground squirrels)

A
  • Coccidia of genus Eimeria

- Most ground squirrels harbored two or more species

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40
Q

Demodex mites in ground squirrels

A
  • Unidentified species of Demodex found in hair follicles, sebaceous gland ducts in the ear canals, and Meibomian glands of the eyelids in California ground squirrels
  • Microscopic changes were minimal and no associated clinical signs or macroscopic lesions noted
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41
Q

Neobellieria citellivora in ground squirrels

A
  • Sarcophagid fly

- Lethal myiasis of wild Richardson’s ground squirrels reported

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42
Q

Emmonsia crescens in ground squirrels

A
  • Saprophytic fungus
  • Detected in lungs of U. richardsonii, I. tridecemlineatus, and S. franklinii in Saskatchewan
  • Infection was more common in adults than young animals
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43
Q

Spermophilus franklinii

A

Franklin’s ground squirrel

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44
Q

Diabetes mellitus in ground squirrels

A

Spontaneous diabetes mellitus is described in a captive golden-mantled ground squirrel

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45
Q

Hepatocellular carcinoma in ground squirrels

A
  • Has developed in California ground squirrels infected with hepadnavirus GSHV
  • GSHV is related to oncogenic hepadnavirus hepatitis B virus (HBV)
  • Liver carcinoma occurred in 2 of 28 GSHV(+) animal studied and in 1 of 23 with antibodies to the virus
  • In a separate study, hepatocellular carcinoma observed in 6 of 12 Richardson’s ground squirrels that were negative for GSHV on serology but positive on southern blot analysis of liver cell DNA
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46
Q

Other neoplasias in ground squirrels

A

-Single cases reports of: exophthalmos assoc w/ Harderian gland adenocarcinoma & squamous cell skin carcinoma in male California ground squirrels

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47
Q

Supernumerary teeth in ground squirrels

A

-Reported in Richardson’s ground squirrels and hybrid individuals

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48
Q

Description - black-tailed prairie dogs

A
  • Stout, short-tailed, short-legged
  • Head and body length: 280-330 mm
  • Tail length: 30-115 mm
  • Weight: 0.7-1.4 kg
  • Coat is grizzled yellow on top and underparts are lighter
  • Tail of C. ludovicianus has a black tip
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49
Q

How many species of prairie dog are there?

A

5

Cynomys ludovicianus is most commonly used in research

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50
Q

Geographic distribution - black-tailed prairie dogs

A
  • Open planes and plateaus in Great Plains from Montana and southern Saskatchewan to extreme northern Mexico
  • Numbers have declined recently due to habitat encroachment
  • From 2003-2008, joint ruling from FDA and CDC made it illegal to buy, sell, trade, or transport prairie dogs in the US d/t transmission of monkeypox to humans from prairie dogs that had been co-housed with Gambian pouched rats
  • Ban on domestic commerce or transport of prairie dogs lifted in 2008, but ban on import of exotic African rodents for the pet trade remains in place
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51
Q

Habitat - black-trailed prairie dogs

A
  • Nest in 300-450 mm chambers within elaborate tunneled burrows up to 34m long and topped by volcano-shaped cones of soil
  • Found in large colonies, or ‘towns’, that usually cover 100 hectares
  • Towns are divided into ‘wards’, which are made up of several ‘coteries’
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52
Q

What is a coterie?

A
  • A discrete social unit typically consisting of a single adult male, three or four adult females, and several 1-2 yr old juveniles
  • Contains an average of 8.5 individuals
  • All members of a coterie are socially integrated and display territorial defense toward outsiders
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53
Q

Use in research - black-tailed prairie dogs

A
  • Historically used to study biliary physiology and the pathophysiology of gallstone formation
  • Infectious disease research: monkeypox or other orthopoxviruses, Yersinia pestis (plague), Francisella tularensis
  • Model of human pathogen Orthopox variola (smallpox) - when experimentally infected did NOT develop clinical disease nor was viral DNA detectable after nasal or intradermal inoculation, although seroconversion was demonstrated
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54
Q

Biology - black-tailed prairie dogs

A
  • Diurnal
  • Become dormant during severe weather but are not deep hibernators
  • Very social and reinforce their relationship within a coterie by nuzzling, grooming, playing together, and vocal communication
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55
Q

Reproduction - black-tailed prairie dogs

A
  • Female prairie dogs are monestrous; in the wild do not start breeding until 2 years of age
  • Mating takes place from early March to late April and gestation lasts 34-37 days
  • Each coterie is a cooperative breeding unit in which breeding occurs at the same time; each adult female produces one litter per year
  • To offset nepotism and potential inbreeding, lactating females will kill offspring of close kin
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56
Q

Hearing - black-tailed prairie dogs

A
  • Good low-frequency hearing (as low as 4 Hz)
  • More sensitive than any other rodent yet tested at frequencies below 63 Hz
  • Relatively insensitive in midrange and have poor high-frequency hearing
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57
Q

Husbandry - black-tailed prairie dogs

A
  • In the wild, eat herbs and grasses, maintaining a ‘rotating pasture’ that causes fast-growing plants to predominate around colonies
  • Do NOT store food in burros
  • Limited information on captive diets; some feed specially formulated high fiber diet with fruit or beet-based treats, sweet potatoes, timothy hay, monkey biscuit, commericially available prairie dog feed (Oxbow Animal Health) or rabbit diet, veggie or cereal treats
  • Formula described as one part goat’s milk, one part pureed sweet potato, two parts water or Pedialyte for syringe-feeding unweaned juveniles
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58
Q

Monkeypox in black-tailed prairie dogs

A
  • Direct vector for human infection
  • Prairie dogs became infected by housing in proximity to Gambian pouched rats
  • High incidence of clinical disease and mortality
  • Lesions: fibrinonecrotizing bronchopneumonia, enteritis, lymphadenopathy, sometimes pulmonary vasculitis
  • Diagnosis: poxvirus intracytoplasmic eosinophilic inclusion bodies difficult to detect on light microscopy; viral assays evident ultrastructurally; PCR
  • Transmission from prairie dogs to humans believed to be mucocutaneous or respiratory route
  • Disease in humans: fever, lymphadenopathy, maculopapular rash, skin lesions progressing from vesicular to ulcerative and crusting; miniority pneumonitis and encephalitis
  • Last clinical case in US in 2003; prairie dogs should not currently be considered a high zoonotic risk for monkeypox transmission in the US
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59
Q

Francisella tularensis (tularemia) in black-tailed prairie dogs

A
  • Bacteria occurs sporadically in wild or wild-caught animals
  • IHC can demonstrate bacteria in lesions in formalin-fixed tissue
  • Gross lesions: scattered white pinpoint hepatosplenic lesions and massive, purulent bronchopneumonia
  • Diagnosis: direct fluorescent antibody tests; culture of spleen and liver
  • Clin Signs: sudden death, nonspecific signs of systemic illness with hepatic or respiratory involvement
  • Transmission to humans by MMs (GI, conjunctival), biting insects or needlesticks, respiratory transmission; risk of aerosolization = necropsy suspected cases under BSL3
  • Animal housing and handling of diagnostic materials can be done at BSL2
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60
Q

Yersinia pestis (plague) in black-tailed prairie dogs

A
  • Prairie dogs highly susceptible
  • Not reported in captive populations, but consideration when working in the field or with wild-caught prairie dogs
  • Transmission: direct contact, inhalation of aerosolized droplets, flea bites (most common)
  • Prevention of flea bites or parasite extermination should be implemented to field studies or quarantine
  • Dusting with deltametrin (pyrethrin-type insecticide) successfully controlled plague in prairie dogs in a field setting during an epizootic outbreak
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61
Q

Clostridium difficile in black-tailed prairie dogs

A
  • Prairie dogs susceptible to C. difficile typhlocolitis
  • Can be induced by adminsitration of cephalosporin cefoxitin
  • Disease in prairie dogs has more chronic course than in other animals models of C. difficile diarrhea
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62
Q

Eimeria in black-tailed prairie dogs

A
  • 5 species of Eimeria identified in wild-caught black-tailed prairie dogs in Wyoming
  • Eimeria spp. appear cross-reactive between prairie dogs and ground squirrels
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63
Q

Baylisascaris spp. in black-tailed prairie dogs

A
  • CNS migration of larvae can cause ataxia, torticollis, loss of righting reflex
  • In case study infection transmitted from Baylisascaris eggs on the cages, which had previously housed raccoons; infx occurred despite washing cages at 82.2 C (180 F) and storage of cages for 6 months
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64
Q

Hepatic cysticercosis in prairie dogs

A
  • Larval Taenia species infx; has been described in wild-caught black-tailed and white-tailed prairie dogs
  • In the white-tailed dogs, larval T. mustelae identified; speciation of larvae in black-tailed dogs not possible
  • Small, 1-2mm diameter white, fluid-filled cysts containing the larval forms of the cestode
  • Speciation based on morphlogical characteristics of the cyst and larvae
  • Presence of larval cysts typical of INTERMEDIATE HOST, and maturation does not occur in this host; intermediate host typically a prey species of the definitive host - ingests intermediate host
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65
Q

Microsporum gypseum in prairie dogs

A
  • Dermatophytosis due to M. gypseum reported in 3 Mexican (C. mexicanus) prairie dogs
  • Associated with alopecia
  • Can be treated with sponge application of 250ppm amitraz dips for 3-5 min at 4 day intervals for 2 months
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66
Q

What are the two most-reported spontaneous neoplasms in prairie dogs?

A

Hepatocellular carcinoma and elodontoma

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67
Q

Hepatocellula carcinoma in prairie dogs

A
  • Metastasis to lung, spleen, heart reported

- Virus-like inclusio bodies have been reported in case reports, but virus identification has been unsuccessful

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68
Q

Elodontoma in prairie dogs

A
  • Elodontoma (odontoma) = proliferative, expansile masses of the incisors; essentially hamartomas (benign malformations)
  • Consist of abnormal odontogenic epithelium and alveolar bone at the apex of the maxillary incisors
  • Aberrations of growth; NOT true neoplasms
  • Frequently seen in captive prairie dogs and other members of Sciuromorpha
  • Prairie dogs have elodont (continuously growing) incisors that are subject to trauma, insufficient wear, abnormal growth d/t husbandry or nutrition
  • Maxillary elodontomas commonly cause upper respiratory obstruction as they expand into nasal cavity; mandibular elodontaoms reported less frequently put assoc w/ pharyngeal obstruction
  • Palliative tx: antibiotics, decongestants, steroids; surgical extraction on incisors is difficult and often results in fractured incisors - can be extracted through nasal cavity but recurrence and incomplete resoluation still common
  • In one case, elodontoma-associated breathing problems successfully treated with placement of an earlobe retractor (earlobe ‘plug’) as a breathing tube via rhinotomy
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69
Q

Name sporadic neoplasms reported in prairie dogs

A

Thoracic lipoma

Epiglottal fibrosarcoma

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70
Q

Respiratory disease in prairie dogs

A
  • Common independent of or in assoc w/ elodontomas in captive prairie dogs
  • NOT common in wild or zoo prairie dogs so diet or environment may be the underlying cause
  • One author found captive zoo prairie dogs become obese and developed severe dermatitis after 2-3 years in captivity
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71
Q

How many species of Geomys (Eastern pocket gophers)?

A

8
Geomys attwateri - Attwater’s pocket gopher
Geomys pinetus - Southeastern pocket gopher
Geomys breviceps - Baird’s pocket gopher

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72
Q

How many species of Thomomys (Western pocket gophers)?

A

9
Thomomys talpoides - Northern pocket gopher
Thomomys mazama - Western pocket gopher

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73
Q

What is the taxonomic family for pocket gophers?

A

Geomyidae

  • Species boundaries in genera Geomys and Thomomys are poorly defined; hybridization exists
  • Intraspecific genetic diversity appears driven in part by microgeographical habitat restriction
  • Mitochondrial DNA analysis has been used to analyze closely related suspecies
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74
Q

Description of pocket gophers

A
  • Stout, thickset bodies and large skulls adapted for burrowing
  • Tail is short, naked, and very sensitive to touch
  • Ears and eye are small
  • Well developed lacrimal glands supply a thick fluid that cleans the cornea of dirt when burrowing
  • Lip can be closed behind curved incisors - gnaw dirt while burrowing
  • Two long, external fur-lined cheek pouches
  • Short legs, powerful forearms & five strong digging claws
  • Males larger than females
  • Head and body length: 90-300 mm, tail length: 40-140 mm
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75
Q

Geographic distribution of pocket gophers

A
  • Western pocket gophers: deserts, prairies, open forests, meadows; west of Rocky Mountains from SW Canada to southern Baja California and central Mexico
  • Eastern pocket gophers: loose sandy soil in open and sparsely wooded areas; east of Rocky Mountains from southern Manitoba and Wisconsin to northeastern Mexico and across to Florida
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76
Q

Habitat - pocket gophers

A
  • Fossorial: spend most of life underground, surfacing to gather food for storage
  • Dig 2 types of tunnels: Long, winding shallow tunnels to obtain food (roots, tubers from above) & deep tunnels for shelter with chambers for nests, food storage, and fecal deposits
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77
Q

Use in research - pocket gophers

A
  • Aspects of molecular evolution, including influence of geographic isolation on speciation and coevolution of parasite-host relationships
  • Health and environmental impact studies of heavy metals, radionuclide wastes, and other soil contaminants = sentinel species for this purpose (high contact and ingestion of soil contaminants)
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78
Q

Biology - pocket gophers

A
  • Do not hibernate, but may be inactive during winter
  • Solitary & fight when placed together, except during breeding season
  • Adult weight at 5-6 months & sexually mature the following breeding season (exception is G. pinetis -females reason sexual maturity at 4-6 months)
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79
Q

Reproduction - pocket gophers

A
  • Promiscuous mating system with female choice
  • Western pocket gophers: monestrous; produce 1 litter/yr; gestation 18-19 days; litter size 1-10
  • Eastern pocket gophers in NORTHERN regions: 1 litter/yr
  • Eastern pocket gophers in SOUTHERN regions: 2 litters/yr, with smaller average litter sizes
  • Weaned at 4-5 weeks; remain in mother’s burrow for 1-2 months
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80
Q

Husbandry - pocket gophers

A
  • Housing with only soil substrate has resulted in death d/t exhaustion because of continuous digging behavior
  • System of 3 polycarbonate cages interconnected with PVC piping has been described - contain pine wood chips, hay, and topsoil, respectively, to provide varied burrow substrate
  • Partial covering used to provide dark environment
  • Tx for internal and external parasites (topical insecticide powder and ivermectin injectons) during quarantine cited as important for colony success
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81
Q

Diet - pocket gophers

A
  • Diet in the wild: Roots, tubers, stems
  • Diet in captivity: rodent chow, sweet and russet potatoes, carrots, apples, bean sprouts
  • Reportedly do not drink free-standing water in wild = no water provided in captivity (needs met by washed veggies)
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82
Q

Parasitism - pocket gophers

A
  • Heavy ascarid (roundworm) infestation cited as cause of death in a captive pocket gopher
  • ~90% of wild pocket gophers harbor Eimeria spp.
  • Filariid nematodes of genus Litomosoides have been reported in the abdominal and/or thoracic cavities of wild pocket gophers
  • 122 species of biting lice (order Mallophaga) known to infest pocket gophers = model for host-parasite evolutionary cospeciation; lice are highly host-specific
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83
Q

Malocclusion - pocket gophers

A

-Incisor malocclusion leading to malnutrition described in a male pocket gopher & captive management included provision of fruit bark for chewing

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84
Q

Two species of kangaroo rats generally studied

A

Dipodomys spectabilis - Bannertail kangaroo rat

Dipodomys merriami - Merriam’s kangaroo rat

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85
Q

Taxonomy of kangaroo rats

A

Family Heteromyidae - contains 6 genera and 60 species

-Genus Dipodomys recently confirmed as monphyletic division and contains 21 species that primarily live in North America

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86
Q

Description of kangaroo rats

A
  • Highly modified for jumping - long, powerful hind legs, reduced forelimbs
  • Tail longer than head and body and used for balance in locomotion and as a prop when standing
  • Leaping action similar to kangaroos (Macropus spp.)
  • External fur-lined cheek pouches - all Heteromyidae (like Geomyidae)
  • Dipodomys unique among Heteromyidae as cheek teeth grow throughout life
  • Head and body length: 100-0200 mm
  • Tail length: 100-215 mm
  • Weight: 35-180g
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87
Q

Distribution of Dipodomys

A
  • North America, including northern Mexico
  • D. spectabilis found in Arizona, New Mexico, western Texas, northern Mexico
  • D. merriami found in southwestern US, northern Mexico, Baja California
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88
Q

Habitat - kangaroo rats

A
  • Arid and semiarid country with some brush or grass
  • Open ground preferred to view surroundings and for their method of locomotion
  • Construct burrows in well-drained, easily worked soil
  • D. spectabilis build labyrinth tunnels with prominent mound that is gradually built up as soil is excavated
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89
Q

Use in research - kangaroo rats

A
  • Renal physiology and water conservation
  • Behavior
  • Disuse osteoporosis
  • Evolutionary neuroanatomy
  • Decompression sickness
  • Climate change
  • Biosentinels for environmental contamination in mining operations
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90
Q

Biology- kangaroo rats

A
  • Primarily diurnal
  • Seldom drink water; use metabolically derived water from food
  • Conserve moisture by coming out of burrows at night when humidity is highest and concentrating urine with highly efficient kidneys
  • Highly territorial with one adult per burrow; fight when placed together
  • Not vocal, but thump or drum with hind feet - functions as alarm system to warn against predation by snakes, advertise territory, repel intruders
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91
Q

Dorsal gland in kangaroo rats

A
  • Prominent, androgen-dependent, oil-secreting gland

- Present on the back between the shoulders of males and females

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92
Q

Reproduction - kangaroo rats

A
  • Breeding may occur throughout the year
  • Females seasonally polyestrous; estrus correlated with availability of food
  • Gestation ~29-33 days
  • Litter size: 1-6 in the wild, 1-8 for D. spectabilis and average 2.6 in D. merriami
  • Weaning: 21-29 days
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93
Q

Should ad lib water be provided to kangaroo rats?

A

No.
-Providing captive animals with water for restricted periods mimics abundant seasons, BUT providing ad lib water NOT recommended as some kangaroo rats become addicted to drinking and develop a diabetes-insipidus like syndrome

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94
Q

Husbandry - kangaroo rats

A
  • Difficult to breed b/c aggressive towards each other; can be maintained together in extremely large housing area
  • NOT aggressive towards humans
  • Diet in wild: mostly seeds, some fruits, leaves, stems, buds, insects and other invertebrates
  • B/c of potential food shortages due to droughts, will store food in burrows
  • Diet in lab: grains and seeds with lettuce as water source
  • Dust baths necessary for welfare; if denied dust bathing develop sores on body and fur becomes matted from oily secretions on the back
  • Fragile tails that will break off if used for restraint; recommended restraint is scruffing
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95
Q

Infectious diseases - kangaroo rats

A

Parasitic diseases extensively documented in wild-caught kangaroo rats, but appear to be no cases in lab-reared kangaroo rats

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96
Q

Trichobezoars - kangaroo rats

A

-Report of male, wild-caught kangaroo rat that developed anorexia and wasting d/t gastric trichobezoar

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97
Q

Spongiform degeneration of central auditory system - kangaroo rats

A
  • Particularly affects cochlear nucleus and auditory nerve root
  • Lesions similar to that seen in Mongolian gerbil (Meriones unguiculatus)
  • Degeneration is more numerous in animals continually exposed to modest levels of low-frequency noise (<75 dB SPL)
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98
Q

Neoplasia in kangaroo rats

A

-Mammary gland adenocarcinoma diagnosed in a female kangaroo rat from San Diego Zoo

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99
Q

Species of pack rats/wood rats (Neotoma)

A

Neotoma floridana - Allegheny wood rat/Eastern wood rat
Neotoma floridana smalli - Key Largo wood rat
Neotoma albigula - white-throated wood rat
Neotoma mexicana - Mexican wood rat
Neotoma cinerea - bushy-tailed wood rat
Neotoma fuscipes - dusky-footed wood rat

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100
Q

How many species in the genus Neotoma?

A

19.
-Name ‘pack rat’ or ‘trade rat’ comes from habit of dropping the item they are carrying and taking new material they find more attractive during foraging; often also pick up shiny material or silverware from camps

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101
Q

Description - pack rats

A
  • Head and body length: 150-230 mm
  • Tail length: 75-240 mm
  • Weight: 200-450g
  • Fur generally soft and dense; color ranges from pale to dark grey with underparts ranging from pure white to pale grey
  • Ears are large without fur on the tips
  • Some species have sparsely haired tails, but in the bushy-tailed wood rat the tail is well covered
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102
Q

Distribution - pack rats

A
  • Central America (Honduras and Nicaragua) and North America
  • N. floridana: primarily east coast of US
  • N. albigula: southwest US to central Mexico
  • N. mexicana: Colorado to southwest Utah to western Honduras
  • N. cinerea: northwestern Canada to North Dakota and Arizona
  • N. fuscipes: western Oregon to Baja California
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103
Q

Habitat - pack rats

A
  • Variety of habitats from low, hot, dry deserts to humid jungles and rocky slopes above timberline
  • Some species build elaborate dens composed of twigs, stems, foliage, bones, rocks; dens often rest on ground or placed against rocks or bases of trees
  • Species inhabiting areas with spiny cacti build their houses almost entirely over this plant - impossible for predator to approach without encountering thorns
  • Some species do not build large houses but use crevices among rocky outcrops & close opening with sticks, etc.
  • Much variation exists between shelters, even in the same species (e.g., all three types of housing have been reported for N. lepida)
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104
Q

Use in research - pack rats

A
  • Behavioral and neurological studies
  • Reservoirs for zoonotic diseases, including endemic murine typhus, trypanosomiasis, Leishmaniasis
  • Are mammalian hosts of Yersinia pestis in British Columbia and California
  • N. fuscipes (dusky-footed wood rat) is important mammal reservoir of Lyme disease in California and Oregon & human granulocytic ehrlichiosis in some areas of northern California
  • Hantavirus (sin nombre virus) identified in 4 species from Arizona and Utah
  • Other Bunyaviridae (Jamestown Canyon virus and Morro Bay virus) isolated from N. fuscipes in California
  • One or more indigenous arenaviruses assoc w/ Neotoma spp. in North America (some, like Catarina virus, believed to only affect pack rats); Whitewater Arroyo virus has been assoc w/ lethal hemorrhagic fever in human
  • Dietary influences on gut microbiota and cytochrome P450 patterns; microbiota included lots of novel species with cellulolytic and detoxification genes adapted to ingested plant species
  • Experimental feeding of plants with differing endogenous toxin properties influenced cytochrome P450 expression patterns
  • An antihemorrhagic factor in serum of N. micropus against western rattlesnake venom identified & is similar to that in hispid cotton rat (Sigmodon hispidus) and opossum (Didelphis virginiana)
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105
Q

Biology- pack rats

A
  • Nocturnal and active through the year
  • Eastern wood rats have a ventral marking gland that is androgen-dependent
  • Normal hematology and serum chemistry values for dusky-footed wood rat (N. fuscipes) comparable to house rat (Rattus rattus)
  • Stress-related neutrophilia seen in animals sampled immediately following capture
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106
Q

Reproduction - pack rats

A
  • Long or all-year breeding cycles but small litters
  • In southern part of range females can breed all year; in northern areas begin breeding in Dec-Jan and continued producing litters until Aug-Oct
  • Gestation: 30-40 days
  • Weaning: 4 weeks
  • Sexual maturity: 7-8 months
  • Incisors teeth of nursing pups laterally divergent for first 2 weeks of life to fit mother’s nipple in gap & young dragged along while attached
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107
Q

Husbandry - pack rats

A
  • Some researchers find easy to handle but some wear metal mesh gloves
  • Have been successfully bred in captivity
  • Diet in wild: roots, stems, leaves, seeds, some invertebrates
  • Diet in lab: can be maintained on standard lab rat diets, sometimes supplemented with daily fresh veggies and forage
  • Most water in wild obtained from food, but can provide ad lib water in captivity
  • Bedding may be hay, palm fronds, wood shavings, grasses
  • Neotoma are neat, sanitary animals and can make good pets if they overcome extreme timidity
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108
Q

Social organization - pack rats

A
  • Generally solitary
  • In a colony of captive Eastern wood rats, a tyrannical social order developed where one animal killed or wounded all others
  • In some field and lab studies, males reported to fight with harems of 1-3 females
  • Other authors report fighting is uncommon in captivity, even with overcrowding or multigenerational cages & males do not attack pups
  • Caging can be joined via wire mesh tubing and effective behavioral markers of breeding receptivity determined to allow safe pairing for breeding
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109
Q

Research techniques - pack rats

A
  • Blood samples can be obtained via femoral vein in bushy-tailed wood rats (N. cinerea) anesthetized with IM ketamine (dose ranged from 30-110 mg/kg)
  • Can also be anesthetized with isoflurane for handling
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110
Q

Parasitism in pack rats

A
  • Wild-caught wood rats are infected with numerous endo- and ectoparasites including ticks, fleas, and oocysts of host-specific Eimeria spp.
  • Infx with roundworm Baylisascaris procyonis has been assoc w/ decimation of wild populations due to encephalitis from cerebral migration in the aberrant wood rat host
  • Chitin synthase inhibitors (e.g. lufenuron) delivered via a feed cube have been effective to control fleas in wild populations in California, as part of efforts to control Yersinia pests
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111
Q

Trypanosomes in pack rats

A
  • Variety of trypanosomes have been identified in peripheral blood
  • Host specific species: Trypanosoma neotomae & T. kansasensis
  • Zoonotic T. cruzi (Chagas disease) - typically spread by the feces of insect vectors (reduviid bug) which contaminate an insect bite = likelihood of transmission to humans in lab setting low; but direct transmission from blood also possible
112
Q

Arenaviruses in pack rats

A
  • Zoonotic and host-specific arenaviruses have been identified in wood rats
  • Develop encephalitis assoc w/ potentiall zoonotic Whitewater Arroyo virus
  • Transmission of arenaviruses to humans or other animals is by contact with fecal, urinary, pharyngeal secretions, blood
  • Lab colonies should be screened serologically for potential zoonotic agents
113
Q

Brucella neotomae in pack rats

A
  • Reported in desert wood rat N. lepida

- Nonzoonotic

114
Q

Novel Hepatozoon spp. in pack rats

A
  • Identified in 2 species of pack rats; nonzoonotic
  • Hepatozoa: intracellular Apicomplexan parasites of RBCs or other peripheral blood cells
  • Spread by ingestion of ticks (NOT tick bites) or ingestion of intermediate hosts
  • In host species, may be asymptomatic or assoc w/ leukocytosis and/or myositis and proliferative bone lesions (H. americanum in dogs)
  • Patholofic potential in wood rats unknown
115
Q

Dunnifilaria meningica in pack rats

A
  • Described in N. micropus trapped in Mexiceo
  • Small adult worms are found in the subarachnoid spaces along the cerebellum and the medulla oblongata
  • Female worms ~50 mm long, males ~25 mm long
  • Short, sheathed microfilariae found in peripheral blood
116
Q

Echinococcus multilocularis in pack rats

A
  • Encysted larval form found in liver of bushy-tailed wood rat in Wyoming
  • Protoscolices and calcareous corpuscles were absent
  • Besnoitiosis, manifested as SC cysts
  • Concurrent asymptomatic Toxoplasma gondii infx identified in southern plains wood rat from Texas
  • Wood rat is intermediate host for both E. multilocularis and T. gondii = risk of zoonotic transmission in lab setting not high (typical transmission is ingestion of intermediate host)
  • Small change of zoonotic transmission of T. gondii via needlestick if sufficient tachy- or bradyzoites present in blood
117
Q

Rabies in pack rats

A

-Naturally acquired rabies detected in an Eastern woof rat by fluorescent antibody testing and mouse inoculation

118
Q

Chronic glomerulonephropathy - pack rats

A
  • Tubular proteinosis, membranous glomerulonephritis progressing to sclerosis
  • Described as highly prevalent in aged captive Key Largo wood rats (Neotoma floridana smalli)
  • Lesions and progression resemble chronic progressive glomerulopathy in lab rats
  • Dietary influences suspected
119
Q

Uterina adenocarcinoma - pack rats

A

-Described in a 48 month old female Eastern wood rat at National Zoological Park in Washington, DC

120
Q

Grasshopper mice - taxonomy

A
  • Genus Onychomys - contains 3 species of grasshopper mouse
  • Onychomys torridus (Southern grasshopper mouse) & Onychomys leucogaster (Northern grasshopper mouse) used most extensively in research
121
Q

Grasshopper mouse - description

A
  • Head and body length: 90-130 mm
  • Tail length: 30-60 mm
  • Weight: 30-60 g
  • Dorsal coat: O. torridus: gray, O. leucogaster: brown
  • Both species have white ventral fur and distal tail tips
  • Carnivorous and have modifications to jaw-muscle architecture to promote large bite forces for large prey
122
Q

Grasshopper mouse - geographic distribution

A
  • O. torridus: southwestern US & northern Mexico

- O. leucogaster: eastern Washington and southern Manitoba to extreme northern Mexico

123
Q

Grasshopper mouse - habitat

A
  • Short grass prairies and desert scrub
  • Live in any shelter on ground level, although are good climbers; may construct nest in any burrow taken from another rodent
  • Population density low (like most predators) - avg 1.8 per hectare
  • Male-female pairs associate all year
  • Home range is well defined and covers 2-3 hectares
  • Captive individuals of same sex VERY aggressive and will fight to death
124
Q

Grasshopper mouse - use in research

A
  • Aggressive nature: behavior, predator studies; sex diffs in behavior, activity, discrimination learning; drug effects on aggression
  • Lyme disease transmission via urine
  • Effect of photoperiod and melatonin on seasonal gonadal cycles
  • Comparative antibody formation
  • Cancer induction
  • Population dynamics using DNA and mitochondrial analysis
  • Are alternate host for Yersinia pestis - plague can persist in prairie dog colonies for prolonged periods d/t abundance of grasshopper mouse as alternate host; ramifications for plague dynamics in Asia and Africa where usually driven by one main host; abundance thresholds of alternate hosts key to outbreaks in multihost-disease systems
  • Reproduction studies
125
Q

Grasshopper mouse - biology

A
  • Nocturnal, active throughout year & can breed year round but most reproduction in wild from May-Sept
  • 5-7 day estrous cycle
  • Gestation: 26-37 days
  • In wild have several litters per year, in lab reported to have up to 12 litters per year
  • Litter size: 1-6 (avg 3.6 O. leucogaster, 2.6 O. torridus)
  • Weaning: 3 weeks
  • Sexual maturity: 2-5 months in O. leucogaster & 6 weeks in O. torridus
  • Midventral sebaceous gland larger in males than females; castration causes gland involution in both sexes; secretions probably for territorial marking, advertising gonadal status, pup identification
  • Northern grasshopper mice in captivity need dust baths or coat becomes too oily
126
Q

Grasshopper mouse - husbandry

A
  • Main diet: grasshoppers, beetles, small vertebrates incl other rodents, occasional plants
  • O. torridus prey extensively on scorpions and are physiologically resistant to scorpion envenomation following natural stings
  • Venom resistance shows intra- and interspecific variability that covaries with scorpion sympatry and allopatry, patterns consistent with the hypothesis that venom resistance in grasshopper mice is an adaptive response
  • In the lab, can eat mouse carcasses, seeds, and water; commercial mouse diet with grain mixture and canned dog food supplementation
  • Possible to breed year round in captivity with fixed temp and humidity
  • Southern grasshopper mice have been successfully cross-species fostered on white-footed mouse (Peromyscus leucopus)
  • Taste preference studies: strong preference for all concentrations of sugar in water above 0.05-0.1 M and hypotonic saline; similar taste preferences to Mongolian gerbils in this study
  • Don’t hear low frequencies as well as other desert rodents, like kangaroo rats and gerbils
127
Q

Bacterial infections in grasshopper mice

A
  • O. leucogaster populations associated with known epizootic focus of Yersinia pestis were found nearly 2000x more resistant to mortality than another population from an area historically free of plague
  • Carnivorous nature of O. leucogaster appears to promote strong selection for resistance to plague in areas where they are naturally exposed
  • Experimental infx with Lyme disease spirochete, Borrelia burgdorferi: cystitis with lymphoid aggregates, vascular proliferation and hypertrophy, perivascular infiltrates (also in white-footed mice, Peromyscus leucopus)
  • Susceptible to Coxiella burnetti, although spontaneous infx not described in lab conditions
128
Q

Viral infections in grasshopper mice

A
  • Cytomegalovirus (CMV) inclusion bodies found in submandibular & sublingual glands of southern grasshopper mice
  • Serologic evaluation of wild-caught grasshopper mice suggests they can be infected with St. Louis equine encephalitis virus
129
Q

Parasitic infections in grasshopper mice

A
  • One study of O. leucogaster in New Mexico: two species of nematodes (Litomosoides carinii, Mastophorus muris), two species of cestodes (Hymenolepis citelli, one unknown), one species of acanthocephalan (Moniliformis clarki)
  • Eimeria onychomysis: coccidian infecting O. leucogaster
  • New species of Eimeria found infecting O. leucogaster, O. torridus, & O. arenicola with prepatent period 7 days and patent period 7-23 days
  • Monopsyllus exilis (flea)
  • Demodex leucogasteri: in tongue, esophagus, oral cavity of O. leucogaster
130
Q

Fungal infections in grasshopper mice

A

-Susceptible to Coccidioides immitis although spontaneous infx have not been described in laboratory conditions

131
Q

Convulsive seizures in grasshopper mice

A
  • Similar to Mongolian gerbil (Meriones unguiculatus)
  • Observed in southern grasshopper mice in captivity
  • Preweaning parental environment has a significant influence on the prevalence of convulsive seizures
132
Q

Limb defects in grasshopper mice

A

-Observed brachydactyly, syndatyly, hemimelia in a colony of O. torridus

133
Q

Deer mice - taxonomy

A
  • Genus Peromyscus contains seven subgenera and 60 species
  • Two species most commonly used in research: P. maniculatus (prairie deer mouse) & P. leucopus (white-footed mouse)
  • Common name - deer mouse- derives from agility at jumping and running in comparison with house mice
134
Q

Deer mice - geographic distribution

A
  • P. maniculatus: southeastern Alaska through Canada and US to Mexico; NOT regularly in moist environments
  • In New York, Pennsylvania, and Michigan, 2 morphological and behavioral forms of P. maniculatus coexist and occupy different ecologic niches
  • In wild, P. maniculatus builds nests of leaves and lives with a population density of 1-25 individuals per hectare
  • Considered social animal
  • P. leucopus lives in densities of 5-39 animals per hectare with males and females pair bonding and females excluding other females from their home ranges
135
Q

Deer mice - use in research

A
  • Genetic, physiology, aging, cataracts, behavior
  • P. californicus genetically susceptible to heritable hyperlipidemia that is inducible with high fat diet = model of metabolic syndrome
  • Neurologic researcher of epilepsy & refined methods for audiogenic seizures
  • Inbred Peromyscus used to study aging
  • Peromyscus spp. with varying response to lipopolysaccharide challenge were used to elucidate immunological mechanisms of effective bacterial clearance
  • Susceptible to zoonotic diseases: principal vector for North American hantaviruses (incl Sin Nombre virus); P. leucopus host for Ixodes scapularis (black-legged tick) - potential recipient of wildlife oral vaccine control for Lyme disease; ixodid ticks also host Babesia microti and Anaplasma phagocytophilum (human granulocytic ehrlichiosis); trypanosomiasis, toxoplasmosis, tularemia, potential food and water-borne pathogens like Cryptosporidium and Giardia
136
Q

Peromyscus Genetic Stock Center (PGSC)

A
  • University of South Carolina in Columbia, SC
  • Since 1995
  • Houses colonies of WT and mutant Peromyscus spp.
  • Resource for animals and tissues, genetic and husbandry information, assisted reproduction protocols, Peromyscus cell lines and embryonic stem cells
137
Q

Deer mice - biology

A
  • Animals vary in color, but most dark brown to sandy with white or nearly white underparts
  • Adults molt once a year
  • Large, haired ears and a long tail
  • P. maniculatus may live 8 years in lab conditions
  • P. leucopus primarily nocturnal but may be active during day
  • Conserve water through urine volume reduction
  • Reproduction, thermoregulation, molting, and nest building all influence melatonin
  • Molars are rooted
  • Separation of cardiac from pyloric portions of the stomach less distinct than in Old World rodents
138
Q

Deer mice - dental formula

A

I 1/1, C 0/0, PM 2/1, M 3/3

139
Q

Deer mice - reproduction

A
  • Natural breeding season for P. maniculatus: Mar-Oct in northern parts of range
  • P. leucopus also a seasonal breeder in northern range but breeds all year in Mexico
  • Both species breed all year in lab setting
  • P. maniculatus females polyestrous, 3-4 litters per year
  • P. leucopus females have 6 day estrous cycle with spontaneous ovulation and postpartum estrus
  • Litter size: avg 5
  • Gestation: 22-23 days
  • Presence of males does NOT accelerate onset of puberty nor induce estrous cycle synchrony, but is critical for cycle regularity
  • When males and females housed together as preweanlings, show delayed reproduction as adults
140
Q

Deer mice - husbandry

A
  • P. maniculatus & P. leucopus adapt readily to plastic, solid-bottom cages
  • Frequently housed as breeding pairs, with separation of male after parturition only required occasionally
  • High intercolony variation in repro success has been reported
  • P. leucopus self-selected higher room temp (32.4 F) than laboratory mice
  • Cages should have bedding and separate nest-building material
  • 16:8 hr light:dark cycle
  • Move more rapidly than other rodents but easy to handle
  • Wild diet: seeds, nuts, berries, insects, small invertebrates, carrion
  • Lab diet: commercial pelleted rodent food without supplementation
  • Can feed high fat diets to enhance reproduction
141
Q

Deer mice - zoonoses

A
  • Hantaviruses
  • Leptospirosis
  • Hymenolepis spp.
  • Rocky Mountain spotted fever
  • Chlamydiosis
  • Q-fever
  • Western and Venezuelan equine encephalitis
  • Sylvatic plague
  • Coccidioidomycosis
  • Borrelia burgdorferi and Anaplasma phagocytophila - very common in deer mice but usually transmitted by arthropod vector
  • Peromyscus are chronically infected “maintenance host” for B. burgdorferi so small risk from needle stick, but are typically only transiently infected with A. phagocytophila b/c of immune response
142
Q

Parasitism in deer mice

A
  • Both ecto- and endoparasites are common
  • Aspicularis, Syphacia, Capillaria, Nippostrongylus, Nematospiroides, Trichuris, Mastophorus, Ricturlaria coloradensis, Acanthocephala clarki
143
Q

Viral diseases in deer mice

A
  • Shown to seroconvert but not develop clinical disease with mouse hepatitis virus
  • In a screen of wild caught Peromyscus in Michigan: positive for Helicobacter spp., but negative for multiple viruses, M. pulmonis, and CAR bacillus
144
Q

Spontaneous diseases in deer mice

A
  • Adiaspiromycosis (pulmonary fungal infx) - typically incidental
  • Tyzzer’s disease (Clostridium piliforme) - high mortality
  • Ringtail
145
Q

Rice rats - taxonomy

A
  • Genus Oryzomys: 5 subgenera, 50 species
  • O. palustris, O. capito, O. subflavus, etc.
  • Oryzomys palustris most commonly studied species
  • Also called marsh rice rat b/c found in swamps and salt marshes
  • Multiple chromosomal polymorphisms within single, natural populations, more than have previously been reported in a mammal = many aspects of the systematics of this genus undetermined
  • Polymorphic variations seem stable within a population and not the result of hybridization, human disturbance, or nonspecific mutagenic agents
146
Q

Rice rats - physical description

A
  • Head and body length: 100-200mm
  • Tail length: 75-250mm
  • Weight: 40-80g (or 25-150g)
  • Upperparts are grayish brown to yellow brown mixed with black; underparts are white to pale buff
  • Tail varies brownish above and white below to uniformly dusky; tail usually long w/ annulations showing through sparse hair
  • Oryzomys palustris is mouse-like - pelage is coarse but not bristly or spiny
  • May be confused with cotton rats, but cotton rats have longer, grizzled fur and shorter, stouter tail
147
Q

Rice rats - habitat

A
  • Semiaquatic; wetland habitats like swamps and salt marshes

- Eastern and southern US from New Jersey and Kansas south to Florida and northeastern Tamaulipas, Mexico

148
Q

Rice rats - use in research

A
  • Spontaneously develop periodontal disease; placement on a high sucrose diet accelerates periodontitis; effects of drugs, dietary vitamin E, rotational stress on periodontal bone resorption
  • Effect of photoperiod on reproduction and reproductive development - role of pineal gland and its secretion of melatonin on reproduction
  • Metal-pollutant uptake and its relationship to genetic damage
149
Q

Rice rats - biology

A
  • 84 Oryzomys subflavus studied: a Robertsonian chromosome polymorphism, characterized by a varying diploid number of 50, 49, 48, and 46 was found
  • All specimens showed a chromosome arm number of 56
  • G-banding patterns in somatic cells allowed identification of the chromosome pairs (2,3,5,7) involved in centric fusion
150
Q

Rice rats - husbandry

A
  • One author recommended providing a hollow brick as a shelter to reduce stress
  • Several review papers exist discussing husbandry, body growth, breeding in laboratory conditions
151
Q

Rice rats - diseases

A
  • Polyplax spinulosa: sucking louse typically parasitic of domestic rats; sucking lice are normally host-specific so such cross-familial host infestation in note-worthy
  • Predominant reservoir for Bayou virus - a cause of hantavirus pulmonary syndrome
  • Vertebral column deformity reported in a rice rat - kyphosis probably inherited
152
Q

Cane mice - taxonomy

A

-Zygodontomys brevicauda (or Zygodontomys microtinus in some literature)

153
Q

Cane mice - description

A
  • About 100g or less body weight

- Grizzled brown pelage & tail about 3/4 length of head and body

154
Q

Cane mice - distribution

A

-Tropical lowlands of eastern Central America, northern South America, and adjacent continental islands

155
Q

Cane mice - habitat

A
  • Mainland population inhabit savannas or weedy areas around human settlements; sometimes agricultural pest
  • Nocturnal, omnivorous, terrestrial (seldom or never climb trees)
156
Q

Cane mice - use in research

A
  • Comparative studies of mammalian circannual reproductive cycles - one of few tropical species known to lack a reproductive response to photoperiod
  • Model for evolutionary quantitative genetics: short generation time, high diploid chromosome numbers, availability of F1 and F2 hybrids from crosses between geographically isolated populations
  • Yellow fever, nariva virus (a rodent paramyxovirus), Venezuelan equine encephalomyelitis, cocal virus (rhabdovirus)
  • Natural host of Guanarito virus - cause of Venezuelan hemorrhagic fever (VHF); human clin signs: fever, malaise, sore throat; then abdominal pain, diarrhea, variety of hemorrhagic manifestations, convulsions
157
Q

Cane mice- biology

A
  • Rapid sexual maturation: females 21-26 days, males 40-60 days
  • Gestation: 25 days
  • Litters: avg 4-5, range 1-11; larger litters consist of smaller neonates
  • Young open eyes at 6-8 days
  • Weaning: by 16 days
  • Spontaneous ovulator
  • Pairing females with males in cages divided by wire partition permits limited physical contact but NOT copulation
  • Estrous cycling does NOT differ btwn single-housed females and females housed with males in divided cages
  • Have copulatory plugs
158
Q

Cane mice - husbandry

A
  • Urinate and defecate sparingly compared to laboratory mice; can change cages every 1 or 2 weeks
  • Diet in lab: commercial mouse diet supplemented with dry cat food and chopped frozen veggies; lactating females provided double rations
  • Cane mice are strong, agile, and jump quickly - place cages at bottom of deep box before opening
  • Aggressive - wear leather gloves for handling
  • Females become aggressive shortly before parturition = remove males to prevent injuries; pairing younger females with older males reduces female aggression
  • Some other authors reported cane mice as nonaggressive to handlers
159
Q

Cane mice - diseases

A
  • Yersinia pseudotuberculosis isolated from nasal cavity of one cane mouse
  • Natural host of Guanarito virus (family Arenaviridae) - causes VHF - animals have chronic viremic infx characterized by persistent shedding of infectious virus in oropharyngeal secretions and urine
  • Pinworms (Syphacia spp.) and the trichomonad intraduodenal protozoan Hexamita found in a colony
  • 55 species of arthropod parasites known to infest Zygodontomys brevicauda in nature, but only the Tropical Rat Mite (Ornithonyssus bacoti) appears to persist in lab-bred, wild-derived animals
160
Q

Cotton rats - taxonomy

A
  • 8 species of cotton rats
  • Sigmodon hispidus (hispid cotton rat) & Sigmodon fulviventer are most common in laboratories; S. hispidus used far more often than S. fulviventer
  • Rest of cotton rat info from this text refers to S. hispidus unless noted
161
Q

Cotton rats - description

A
  • Robust, stocky rodent
  • Body weight: 80-130g
  • Head to body length: 125-200mm
  • Tail length: 75-166mm
  • Fur is coarse, dark brown to black interspersed with yellow or light tan hairs over the back and sides; underparts usually pale to dark gray
  • Ears are small & 3 central digits of each paw are larger than other two
  • All species of cotton rats are similar in appearance, but wide variation in chromosome number among species
162
Q

Cotton rats - geographic distribution

A
  • S. hispidus: southeren US to northern Venezuela and northwest Peru
  • S. fulviventer: southeastern Arizona and central New Mexico to central Mexicao
163
Q

Cotton rats - habitat

A
  • Prefer grassy and shrubby areas

- The most abundant rodents in the southeastern US, Mexico, and Central America

164
Q

Cotton rats - use in research

A
  • Viral respiratory tract diseases, particularly d/t paramyxoviruses; respiratory syncytial virus (RSV), parainfluenza virus 3, & measles replicate well in cotton rats
  • Particularly useful for RSV vaccine studies, b/c develop “enhanced disease” upon challenge in animals that have previously received certain RSV vaccine formulations (good animal model for known human complication)
  • Avian and swine influenze vaccines
  • Adenovirus pneumonia infection similar to humans; ocular adenovirus infx in cotton rats is only animal model of epidemic keratoconjunctivitis
  • Susceptibility to human adenovirus = studies of adenoviral mediated gene therapy for cystic fibrosis, erythropoiesis stimulation, ocular gene transfer, cervical cancer tx, malignant CNS tumors
  • Biomonitor for impact of environmental pollutants on exposed wildlife
165
Q

Pathogens that can be transmitted to cotton rats for research

A
  • Rickettsia tsutsugamushi (causes scrub typhus)
  • Leishmania donovani
  • Echinococcus multilocularis
  • Naturally infected with filarial nematode Litomosoides carinii - model to screen antifilarial drugs
  • Can be nasally colonized with MRSA to test interventions
  • Investigated as natural reservoir for Lyme disease, hantavirus Black Creek Canal virus, Venezuelan equine encephalitis
166
Q

Cotton rats - biology

A
  • Active day and night in wild; diurnal in lab
  • Relative dominance system: males dominant to females & adults dominant to juveniles
  • Solitary; only prolonged social contact is for reproduction
  • Aggression is common
  • Retroorbital route previously recommended for blood collection
  • Subzygomatic blood collection route has been described that relies on presence of subzygomatic sinus unique to this species
167
Q

Subzygomatic sinus

A
  • Unique to cotton rats

- Can be used for blood collection

168
Q

Cotton rats - reproduction

A
  • Gestation: 27 days
  • Litter size: 1-12; avg 5-7
  • Young weigh 6.5-8g & open eyes at 24 hr
  • Weaning in wild: 5-7 days
  • Sexual maturity: 40-60 days
  • Lifespan in captivity: 14 months (inbred) & 23 months (WT)
169
Q

Cotton rats - husbandry

A
  • Will attempt to bite and escape - leather gloves or handling device to transfer animals during cage change needed
  • Can be kept in standard polycarbonate cages with hardwood-chip or corncob bedding
  • Drink MORE than standard lab rats = change cages twice weekly
  • For breeding in lab: wean at 2-3 weeks into single sex groups & monogamous pair by 6 weeks; performance may be poor when few animals kept in room, but good when fully occupied; don’t separate breeding pairs once established
170
Q

Cotton rats - diet

A
  • Omnivorous - eat veggies, insects, and other small animals; eggs and chicks of bobtail quail; pests of sugarcane and sweet potatoes
  • Commercial standard rodent diets appear suitable for maintenance and reproduction
171
Q

Cotton rats - vendors

A
  • Available from Harlan Labs, Sage Labs, and Charles River-France
  • Sigmovir in Rockville, MD supplies and develops cotton rat as model for infectious disease research
172
Q

Protozoa in cotton rats

A
  • Eimeria spp. and Isospora spp. coccidia
  • Cryptosporidia in large intestine
  • Novel sarcocyst - Sarcocytis sigmodontis - in skeletal muscle (protozoan cysts NOT infectious for dogs and cats
173
Q

Nematodes in cotton rats

A
  • Longistrata adunca, Syphacia sigmodontis, Strongyloides spp., Protospirura muris, & Raillietina spp. helminths found
  • Cotton rats infected with Strongyloides spp. are indistinguishable from noninfected hosts
  • Trichinella spiralis encapsulated larvae found in wild-trapped cotton rats
174
Q

Mites/Lice/Ticks in cotton rats

A
  • One study found 8 species of parasitic arthropods on 28 wild cotton rats
  • Most prevalent were flea Polygenis gwyni. American dog tick Dermacentor variabilis, and tropical rat mite Ornithonyssus bacoti
175
Q

Metabolic/Nutritional diseases in cotton rats

A

-Ringtail reported in a colony in Scandinavia

176
Q

Traumatic injuries in cotton rats

A
  • Main lesions seen in lab colonies result from fighting

- Should NOT be picked up by tail - spin when picked up and tail skin easily degloves

177
Q

Neoplasia in cotton rats

A

-Fundic gastric tubular adenocarcinoma - spontaneously developed adenomatous hyperplasia was described with the lesions

178
Q

Dystrophic calcinosis in cotton rats

A
  • Reported in cotton rats consuming a partially purified diet
  • Lesions in heart, skeletal muscles, liver, adipose tissues, kidnets, urinary bladder
  • Another report found cystic epithelial calcification in wild cotton rats
179
Q

Exophthalmos and heart failure in cotton rats

A
  • Sporadic exophthalmos and heart failure reported in 3-12 mth old inbred cotton rats
  • Exophthalmos secondary to generalized venous stasis d/t right heart failure
  • Histo: multifocal cardiac myocyte necrosis, mineralization, mononuclear inflammatory cell infiltration; cotton rats >5 months also had foci of interstitial fibrosis and myocyte atrophy; right ventricular dilatation and unilateral or bilateral atrial thrombosis
  • Attributed to heritable cardiomyopathy
  • Degenerative cardiomyopathy accompanied by skeletal muscle degeneration, necrosis, mineralization - potential role of Vitamine E or selenium deficiency in spontaneous cardiomyopathy or skeletal muscle degeneration of cotton rats?
180
Q

Age-related disorders in cotton rats

A

-One report found condition similar to chronic progressive nephropathy of lab rats in 1/3 of 18 lab-maintained adult cotton rats

181
Q

White-tailed rat - description

A
  • Only species in genus Mystromys is whitle-tailed rat: Mystomys albicaudatus
  • Subfamily Crecetinae (hamsters): includes Calomyscus, Phodopus, Cricetus, Creicetulus, Mesocricetus
  • Thick-bodied, relatively large (13.6-18.4 cm length) with 5-8 cm long white tail
  • Gray-brown smooth fur and white belly
  • Ungrooved, yellow incisor teeth; sharp-tipped claws; no cheek pouches
  • 2 compartment stomach and a large, ventral sebaceous gland
  • Females have rudimentary prostate gland
  • Ears are erect, eyes dark, animal alert, inquisitive, quick
182
Q

White-tailed rat - ditstribution

A

-Grassy flats and dry, sandy areas of South Africa: Cape Province, Natal, Free State, Swaziland

183
Q

White-tailed rat - habitat

A
  • Live underground, often in burrows made by other animals
  • Nocturnal
  • Eats seeds and vegetable matter
184
Q

White-tailed rat - use in research

A
  • Historically in diabetes mellitus research: spontaneously develop hyperglycemia, polyuria, glycosuria, ketonuria, degeneration of islets of Langerhans; more common in males and NOT assoc w/ obesity
  • Diabetic angiopathy and hepatic mitochondrial function in diabetes
  • American cutaneous leishmaniasis (Leishmania braziliensis) & experimental host for L. donovani and L. mexicani; vaccination studies with L. braziliensis
  • Experimental infection with Crimean-Congo hemorrhagic fever virus, human Streptococcus spp. to investigate caries development
  • Chemically induced carcinogenicity
  • Thermoregulation
  • Digestion
185
Q

White-tailed rat - physiological characteristics

A
  • Although found in a temperate climate, have thermal characteristics of a cold-adapted rodent & thus higher metabolic rate than anticipated
  • Growth and development of the stomach, gastric epithelia, and associated microflora well documented
  • Neonatal mongastric stomach with distinct separations into glandular and cornified regions gives way in the infantile period to fornical papillae that provide microhabitats for colonization by symbiotic anaerobic bacilli - as ingestion of solid food begins, papillae become colonized by baccili that increase in abundance w/out epithelial damage, suggesting the bacilli are autochthonous (indigenous) and symbiotic and aid in digestion
  • Females have 2 pairs of inguinal mammae
  • Males have os penis
186
Q

White-tailed rat - normal values

A
  • Serum chloride and glucose greater and serum sodium lower for females
  • Standard dipstick methods give artificially high urine protein results for white-tailed rats
  • Males over 6 months old have higher RBC counts, PCV, and hemoglobin levels than same age females
  • IP pentobarbital has been recommended for repeat blood sampling
187
Q

White-tailed rat - reproduction

A
  • Sexual maturity in females: 146 days
  • Gestation: 38 days
  • Breeding pairs should be established at a young age to avoid aggressiveness among adults, & males removed at parturition
  • Small litters (avg 3) with high survival to weaning (80%; can be increased to 95% by selecting breeder dams that do not cannibalize their young)
  • Newborns attach to nipples and are dragged around for 3 weeks
  • Lifespan: 6 years
188
Q

White-tailed rat - husbandry

A
  • Wild diet: seeds, veggie matter, insects
  • Lab diet: commercial diet and water ad lib
  • Housed in breeding pairs in solid-bottom rodent cages with corncob bedding with standard temp and humidity & 12:12 light cycle
  • Maintain as monogamous lifetimes mates
  • Pick up by thorax as tail is fragile
  • Can heat dilate tail veins for blood sampling
189
Q

Tyzzer’s disease in white-tailed rats

A
  • Has been induced experimentally in immunosuppressed weanlings by oral inoculation with spores
  • Focal necrosis in tunica muscularis of the intestine, periportal region of the liver, ventricular myocardium, brain stem
190
Q

Ingestion of topically applied TAO (bacitracin, neomycin, polymyxin) in white-tailed rats

A
  • Fatal enteric syndrome with high mortality (59%)
  • Clin signs: anorexia, depression, rough hair coat
  • Necropsy: hemorrhagic typhlitis and colitis
191
Q

Spontaneous diabetes mellitus in white-tailed rats

A
  • More frequent in males
  • Hyperglycemia of >170 mg/dL is a consistent findings
  • Polyuria, polydipsia, glycosuria, ketonuria less common
  • Obestity NOT involved
  • Primary lesion = islets of Langerhans
  • Elevated glycosylated hemoglobin levels CANNOT by used to distinguish diabetic from normal white-tailed rats
  • Glomerulosclerosis associated with diabetes in this species
  • Basement membrane thickness in skeletal muscle capillaries greater in diabetic white-tailed rats
192
Q

Ringtail in white-tailed rats

A

-Reported in suckling (<7 days of age) animals when humidity 12-38% in one case report; when humidity increased to 50% no more cases occurred

193
Q

Neoplasia in white-tailed rats

A

-Spontaneous neoplasms include perianal squamous cell carcinoma, adnexal tumor of the skin, osteosarcoma of the scapula, leiomyosarcoma of the uterus, adenocarcinoma of the liver, hepatoma, pituitary adenoma

194
Q

Partial oculocutaneous albinism in white-tailed rats

A
  • Described as an inherited condition with ophthalmic pathology
  • Appeared similar to Chediak-Higashi syndrome, a phagocyte bactericidal disorder
  • However, no evidence of cytoplasmis granule enlargement found in a follow-up study, so concluded that this inherited partially albinic disease is different from Chediak-Higashi
195
Q

Gerbils - taxonomy

A
  • Generally studied gerbils: Meriones unguiculatus (Mongolian gerbil), Meriones libycus (Libyan jird, red-tailed jird), Meriones crassus (desert gerbil), Meriones hurrianae (Indian desert gerbil), Meriones vinagradovi (grapevine gerbil), Meriones shawi (Shaw’s jird)
  • Common name jird = Arabic for gerbil; often used to describe gerbils from Northern Africa and Central Asia
  • Four subgenera, 14 species
  • All Mongolian gerbils available for research were derived from 20 pairs trapped in eastern Mongolia in 1935 - taken to Kitasato Institute, Japan - later a subcolony established at Central Laboratories for Experimental Animals, Tokyo
  • 11 pairs of Mongolian gerbils imported from Tokyo to US in 1954
  • Rest of gerbil section refers to Meiones unguiculatus unless noted
196
Q

Gerbils - description

A
  • Externally rat-like
  • Head and body length: 95-180mm
  • Tail length: 100-193 mm
  • Weight: 50-55g in lab-raised females, 60g males
  • Short covering of fur on tail near the base and progressively longer toward the slightly bushy tip
  • Upper parts are pale, clear yellowish to sandy or gray
  • Sides of body are generally lighter than the back
197
Q

Gerbils - distribution

A

-M. unguiculatus found in Mongolia, adjacent parts of southern Siberia and northern China, and Manchuria

198
Q

Gerbils - habitat

A
  • Clay and sandy deserts, bush country, arid steppes
  • Terrestrial
  • Construct simple burrows in soft soil where they spend most of their time
  • Tunnels are underground, about 2-3 ft in length and 1.3 inches in diameter
199
Q

Gerbils - use in research

A
  • Highly susceptible to cerebral infarction after unilateral ligation of common carotid artery
  • Epilepsy; spontaneous epileptiform seizures mimic human idiopathic epilepsy; both seizure sensitive and resistant strains have been bred
  • Auditory research - deafened gerbils have been used for ontogenetic cochlear implant research
  • Behavior: territoriality & olfactory communication
  • Parasitic infections: Giardia lamblia, cattle piroplasm Babesia divergens; nematodes Strongyloides stercoralis, Ostertagia circumcincta, Haemonchus contortus, Nematospiroides dubius, Trichostrongylus colubriformis, Heligmosomoides kurilensis, Capillaria philippinensis, Acanthoceiloenema vitae
  • Disease of filarial nematodes: lymphatic filariasis by Wuchereria bancrofti and Brugia malayi; Onchocerca volvulus (cause of blindness), B. pahangi, Loa loa (African eye worm)
  • Hydatid disease: Echinococcus granulosus and E. multilocularis; larval cysts in liver and other organs; zoonotic; investigate larval parasite proliferation and metastasis
  • Cysticercosis and taeniid tapeworm infections: Taenia polyacantha, T. crassiceps, T. solium
  • Digenetic flukes: parasitic trematodes like Schistosoma japonicum, S. haematobium, Paragonimus heterotremus (pulmonary distomiasis), avian schistosome Austrobilharzia variglandis (marine cercarial dermatitis or “swimmer’s itch”)
  • Rift Valley fever: young gerbil model for virus-induced encepalitis without significant extraneural lesions; study enhancement of arbovirus transmission by concurrent host infx with microfilariae
200
Q

Gerbils - sources

A

-Mongolian gerbils available from B&K Universal Ltd. (UK) & Charles River Labs (US)

201
Q

Gerbils - biology

A
  • Large, ventral abdominal marking gland that is androgen-dependent; attains greater size in males and develops at early age
  • Adrenal cortex produces nearly equal amts corticosterone and 19-hydroxycorticosterone; gerbil adrenal gland weight compared to body weight is ~3x the size of rat adrenal glands
202
Q

Gerbils - reproduction

A
  • Sexual maturity: males 70-84 days; females vaginal opening occurs at 40-60 days, 30 days before sexual maturity
  • Tend to pair bond; when older females lose their mate it is often impossible to get them to accept another
  • Gestation period: nonlactating 24-26 days, lactating prolongs to 27 days; if females bred in postpartum period, they delay implantation, and gestation can be as long as 48 days
  • Litter size: avg 3-7
  • Young suckle for about 21 days, being to eat solid foods at 16 days
  • Weaning: around day 25
203
Q

Gerbils - husbandry

A
  • Wild diet: green veggies, roots, bulb seeds, cereals, fruite, insects
  • Lab diet: commercial pelleted rodent diet
  • Because of fat metabolism of gerbils, they develop high blood cholesterol concentrations on diet containing more than 4% fat
  • Excrete little urine; fecal pellets hard and dry; cage requires less cleaning than other lab rodents
  • Generally maintained at 70-72 F
  • Can develop nasal dermatitis at relative humidities above 50% = low humidity advisable
  • Require sand bathing to keep coats from becoming oily
  • Often stand up on hind limbs, so caging should have solid bottom and floor-to-lid height tall enough to allow for standing up
204
Q

Nasal dermatitis in gerbils

A
  • Facial eczema, ‘sore nose’
  • Lesions next to external nares appear erythematous initially, progress to localized aloepcia & then extensive moist dermatitis
  • Etiology: increased Harderian gland secretion of porphyrins similar to chromodacryorrhea in rats, which act as a primary skin irritant
  • Harderian gland-adenectomized gerbils do not develop this condition
  • Various Staphylococcal spp. (S. aureus, S. xylosus0 may act synergistically to produce dermatitis
  • Stress factors may be involved: overcrowding, humidity >50%
  • Bacterial maxillary sinusitis can be detected on MRI
205
Q

Tyzzer’s disease in gerbils

A
  • Naturally occurring enterohepatic Clostridium piliforme is the most frequently described fatal infectious disease of gerbils
  • Clinical signs: sudden death, death after short period of disease, presence of multiple foci of hepatic necrosis, variable diarrhea & necrotic intestinal lesions
  • Experimental infx has confirmed gerbils are extremely susceptible to infx
  • One attempt to eradicate Helicobacter spp. in gerbils with dietary antibiotics was complicated by death of some gerbils from C. difficile
  • Probable route of infx is by mouth w/ exposure to infected bedding
  • Eliminate by fostering offspring to mice
206
Q

Citrobacter rodentium in gerbils

A
  • An epidemic described with acute diarrheal disease in 9 gerbils & 6 dying less than 48 hrs after onset
  • Thickening of colon and rectum with extension into the small intestine; intestinal ulceration and goblet cell hyperplasia
  • Lesions similar to transmissible murine colonic hyperplasia
  • Culture from abdominal masses and kidney grew pure C. rodentium
  • Treatment: 800 mg/L oxytetracycline in drinking water
207
Q

Helicobacter pylori in gerbils

A
  • Severe gastritis, gastric ulceration, intestinal metaplasia
  • Development of gastric adenocarcinoma in subset of infected gerbils
  • Histologic progression of H. pylori in gerbils closely resembles humans, where early intestinal metaplasia and gastric ulceration are repalced by antral gastric adenocarcinoma
208
Q

Cowpox virus in gerbils

A

-Has been isolated from Meriones libycus in the Eastern European republic of Georgia

209
Q

Protozoa in gerbils

A

-Tritrichomonas caviae and a species of entamoeba have been recovered from experimental animals

210
Q

Nematodes in gerbils

A
  • Syphacia obvelata (mouse pinworm) & Dentostomella translucida (oxyurid) have been found in Mongolian gerbisl
  • Research colony and pet store gerbils have been found to have S. obvelata
  • S. obvelata can be transmitted from gerbil to gerbil, gerbil to mouse, and mouse to gerbil
  • No clinical signs of infestation with Dentostomella translucida; prepatent period of infx found to be btwn 25-29 days
211
Q

Cestodes in gerbils

A
  • Hymenolepis diminuta recovered from lab gerbils

- Hymenolepis nana found as a natural infx in gerbils

212
Q

Mites in gerbils

A
  • Liponyssoides sanguineus, the primary vector of Rickettsia akari, has been described in Mongolian gerbils, mice, and lab-reared Egyptian gerbils; no clinical signs of disease seen; only a few mites found on each animal but numerous mites in bedding
  • Tyrophagus castellani (forage mite) found in colony of lab gerbils; pest of stored food products and causes “copra itch” among workers handling copra and dermatitis in people that handle cheese
  • Case report of demodicosis in a male lab gerbil
213
Q

Fungal disease in gerbils

A
  • No reports of naturally occurring dermatophyte infx in Mongolian gerbil & other fungal infections are exceedingly rare
  • Cryptococcus neoformans was reported in a captive M. libycus at a zoo in UK
214
Q

Metabolic/nutritional diseases in gerbils

A
  • Spontaneous, insidious periodontal disease found in research gerbils after 6 months on standard lab diets
  • On same standard lab diets about 10% of animals became obese, some showed decreased glucose tolerance, elevated serum immunoreactive insulin, and diabetic changes to pancreas and other organs
  • Some breeder gerbils have been noted to exhibit hyperactivity of the adrenal cortex assoc w/ hyperglycemia, hyperlipidemia, degenerative vascular disease
215
Q

Tail degloving in gerbils

A
  • Gerbils have thin skin covering their tails - if picked up by tip of tail, skin may slough leaving exposed tail that eventually becomes necrotic and sheds
  • If tail skin is lost, bare tail must be surgically amputate where skin ends
216
Q

Dihydrostreptomycin toxicity in gerbils

A
  • Fatal syndrome of acute toxicity in Mongolian gerbils following injection of penicillin-dihydrostreptomycin-procaine combination
  • 50 mg of dihydrostreptomycin produced 80-100% mortality in 55-65g gerbails
217
Q

Epileptiform seizures in gerbils

A
  • ~20-40% gerbils develop reflex, stereotypic, epileptiform (clonic-tonic) seizures from around 2 months of age
  • Seize in response to sensory stimluation and forced exploratory behavior
  • Incidence and severity of seizures is variable; seizures generally pass within a few minutes with no lasting effects
  • Incidence and severity often DECREASE with age, but some adults can be induced to seize following a prolonged test regimen with progressive severity
  • Susceptibility seen in selectively bred lines - inherited and related to a deficiency in cerebral glutamine synthetase
218
Q

Spongiform lesions in gerbils

A
  • Arise in dendrites and glia in brain stem of domestic Mongolian gerbils & M. libycus
  • Lesions characterized by microcysts and vacuolar neuronal degeneration in absence of astrocytosis
  • Axonal, dendritic, and neuronal perikarya degeneration with phagocytosis
  • Lesions are bilateral, most pronounced within cochlear nucleus; increase in number, size, and extent with age
  • Spongiform lesions cause or are assoc w/ significant neural degeneration
  • Appear to be result of common excitotoxic mechanism of low-frequency noise (in contrast, feral Mongolian gerbils show few spongiform lesions)
219
Q

Cystic ovaries in gerbils

A
  • Occur frequently in gerbils
  • Removal of affected ovaries does not significantly affect reproductive performance; females with one ovary has slightly reduced fertility; general decline in fertility may be noted in older females
  • Early maturing females (vaginal opening before 25 days) more likely to breed successfully on first pairing, and lifetime fecundity of early-maturing females is more than twice that of late-maturing littermates
  • C-section has been reported for dystocia in a gerbil
220
Q

Neoplasia in gerbils

A
  • 24-39% incidence usually occurs after 2-3 years of age
  • Most common: squamous cell carcinoma of the sebaceous ventral scent gland (invade locally and can met to lymph nodes and lung) in males & ovarian granulosa cell tumor in females
  • Next most common: adrenocortical tumors, cutaneous squamous cell carcinoma, malignant melanoma, renal and splenic hemangiomas
  • Others: Duodenal & cecal adenocarcinoma, hepatic lymphangioma, hemangioma & cholangioma, splenic & renale hemangioma, uterine leiomyoma & hemangiopericytoma, ovarian teratoma, testicular teratoma, malignant melanoma
  • Case reports: craniopharyngioma, granulosa cell tumor, lymphoma, histiocytic sarcoma, systemic mastocytosis, sebaceous gland adenocarcinoma, malignant melanoma, astrocytoma
221
Q

Congenital disorders in gerbils

A
  • Ventricular septal heart disease in newborns

- Spontaneous hyperplasia in both seminiferous and epididymal tubules

222
Q

Age-related disorders in gerbils

A
  • High incidence of chronic interstitial nephritis
  • Renal cortical retention cysts
  • Liver disease
  • Calcinosis cutis
  • Aural cholesteatoma - develop spontaneously in aged animals
223
Q

Voles - taxonomy

A
  • Genus Microtus, ~67 species called voles or meadow mice
  • Found in Northern hemisphere primarily in Europe and North America
  • Alternative hypothesis stresses one or two inter continental dispersions and extensive regional cladogenesis - supported by studies of allozymes, chromosomes, mitochondrial DNA, fossils
  • Most commonly used in research: Microtus californicus (California vole), Microtus ochrogaster (prairie vole), Microtus pennsylvanicus (meadow vole), Microtus montanus (montane vole), Microtus oeconomus (tundra vole/root vole), Microtus pinetorum (pine vole), Microtus arvalis (common vole)
  • Microtus longicaudus (long-tailed vole)
  • Myodes glareolus (red-backed bank vole)
224
Q

Voles - description and distribution

A
  • With exception of M. pinetorum, which belongs to subgenus Pitymys, species mentioned on taxonomy card as common in researcb are in subgenus Microtus
  • Subgenus Pitmys: adapted to semifossorial life with reduction in eyes, external ears, and tail with a close, velvety pelage
  • M. arvalis found extensively throughout Europe; all others listed distributed in North America
  • M. oeconomus also distributed throughout northern Europe, Siberia, and north-central China
  • In past two decades, M. oeconomus has become more abundant and widespread throughout Lithuania d/t changes in land use
  • M. pennsylvanicus is found in northern US, Canada, Alaska
225
Q

Voles - use in research

A
  • Nutrition: weanling meadow voles serve as bioassay animals for protein content of feeds, digestibility of forages, presence of toxins
  • Influence of sexually dimorphic spatial learning: M. pennsylvanicus (meadow vole)
  • Experimental infection with Borrelia and Babesia: M. pennsylvanicus
  • Genetic and neurobiological mechanisms governing complex social behavior in vertebrates: M. ochrogaster (prairie vole)
  • Physiology of vomeronasal organ & chemosensory cues in courtship, territorial marking, aggression, reproduction: M. ochrogaster
  • Oxytocin and vasopression role in pair-bonding, paternal care, maternal care, mate-guarding: M. ochrogaster b/c monogamous; M. pennsylvanicus is a polygamous and contrasting species
  • Mu-opioid receptor and neuropeptide Y effect on offspring attachment and social bonding between males: M. pennsylvanicus
  • Anxiety and depression: M. ochrogaster; socially isolating females resulted in elevated corticosteroid conc, prolonged sensitivity to stress-inducing challenges, negative cardiovascular effects
  • Genetics, evolution, molecular mechanisms of social behavior: M. ochrogaster; genome wide, high-resolution linkage map of prairie vole created to facilitate this
  • African trypanosomiasis & plant-dervied 6-methoxybenzoazolinone (alters sex ratio of litters): M. montanus (montane vole)
  • Chemically induced diabetes mellitus & sex chromosome abnormalities: M. arvalis (common vole)
  • Effect of atherogenic diets: M. oeconomus (tundra vole)
226
Q

Voles - sources

A

-List of vole researchers who breed and supply voles at Vole Genomics Initiative website of Emory University

227
Q

Voles - biology

A
  • Rootless molars: allow them to chew large quantities of abrasive grasses as major component of diet
  • Among most prolific mammals; M. pennsylvanicus produce as many as 17 litters in a year
  • M. arvalis (common vole) sexually mature at 2-3 weeks; some females conceive at 13-14 days of age
  • Young grow very fast, reaching 30g by 40 days old
  • Litter size: 4-7 with females capable of having a litter every 3 weeks
  • M. ochrogaster (prairie vole) is monogamous & males assists in caring for offspring; young remain part of family group until establish own relationship; both female and male offspring remain nonproductive into adulthood if maintained in presence of dominant male; presence of fathers within group accelerates pup development
  • M. pennsylvanicus (meadow vole) males are promiscuous and sexes nest separately; presence of fathers hinders pup development
  • Pine voles have cooperative system of breeding in social groups of 2-9 animals in which only one female reproduces but all members care for newborns
  • Pregnancy often terminated in female if urine from an unknown male is introduced
  • Young of M. pinetorum and M. ochrogaster cling to teats and are dragged around if female is frightened; other species display this clinging to varying degrees
228
Q

Voles - nutrition

A
  • High metabolic rate; herbivorous
  • Evolved to subsist on low calorie diet and therefore feed frequently; rely heavily on breakdown of carbs during fasting
  • Carbohydrate catabolism results in profound hypoglycemia after only 6 hr of fasting
  • In voles on high fiber diets, cellulolytic bacteria can be isolated from the esophageal sac where gastric fermentation takes place, leading to higher pH and volatile fatty acids compared to those in fundic or pyloric regions of stomach
  • Sensitive to presence of various solutes in drinking water (complication to oral dosing)
  • Nutritional needs can generally be met by feeding standard mouse or rat breeding chow supplemented with hamster food and/or toasted wheat germ
  • Field voles require 8% or more protein in diet to prevent retardation of growth and sexual development
229
Q

Voles - reproduction

A
  • Breed from early spring through early autumn
  • Polyestrous and have multiple litters each year
  • M. pennsylvanicus (& most Microtus) have 8 mammae and produces 3-10 immature young per litter
  • Weaning: 12 days
  • M. ochrogaster have 6 mammae and procduce 1-7 young per litter
  • M. pinetorum have 4 mammae and produce 1-4 young per litter
  • Neonatal mortality may be high, especially if litter is disturbed during first week
  • M. pennsylvanicus are induced ovulators; ovulation occurs 12-18 hr after copulation
  • Species of voles vary in ability to detect definitive estrous cycle patterns; M. montebelli (Japanese field vole) shows no clear pattern; M. arvalis (common vole) shows 6-18 day cycles
  • Superovulation has been studied in prairie vole and success varied with age and genetic background; females 4-16 wks old produced an average of 14 embryos
230
Q

Voles - husbandry

A
  • All voles can be bred successfully in solid-bottom cages of varying sizes
  • Minimum floor space of 1 ft^2 is recommended for a breeding pair
  • Lab diet: unsupplemented commerical rabbit feed or supplemented (wheat germ and oats) commercial rodent feed
  • Water should be offered ad lib, with special care to provide sufficient water with the diet
  • Temp 23-25 C, humidity 60-70%, 12 hr light cycle for maintenance or 14 hr light cycle for breeding
  • Avoid complete cage changing during first week following parturition b/c commonly results in cannibalism of entire litter
  • Leaving small amount of dirty litter in cleaned cage also helps maintain normal reproductive cycles in females
231
Q

Infectious diseases in voles

A
  • Wild voles have been hosts for hantaviruses, cowprox virus, Leptospira spp., Emmonsia spp., Toxoplasma gondii, Encephalitozoon cuniculi, Neospora caninum, larval stages of Echinococcus multilocularis, mite Echinolaelaps spp., Babesia microti, Haemobartonella microti, Trypanosoma microti
  • Dermatomycoses, rabies-like viruses, and Yersinia pseuotuberculosis have been isolated from voles
  • Acanthocephalan parasites Moniliformis clarki and Cochliomyia hominivorax have been found in meadow voles
  • Bordetella bronchiseptica has been assoc w/ fatal pulmonary infx on Microtus montanus
232
Q

Mycobacterium microti in voles

A
  • Microtus agrestis (field vole) is known maintenance host of Mycobacterium microti
  • Infected animals develop tuberculosis
  • Voles develop systemic disease with most frequent involvement of spleen and liver, followed by skin, lymph nodes, and lungs
  • Bacterial shedding occurs from skin, sputum, and saliva
233
Q

Adenocarcinoma in voles

A
  • Mammary adenocarcinoma infrequently diagnosed in colony-raised M. ochrogaster
  • Lacrimal adenocarcinoma common cause of death in colony reared adult M. montanus
234
Q

Other diseases in voles

A
  • Malocclusion diagnosed in pine, Japanese field, and long-tailed voles
  • Chronic interstitial nephritis not uncommon in older, colony-bred meadow voles; etiology unknown; on histo kidneys have increased interstitial connective tissue with hyaline casts in many tubules
  • Pyelonephritis common in older, wild meadow voles
235
Q

Multimammate rats/mice - taxonomy

A
  • Native to South Africa
  • Usually 8-12 pairs of mammary glands, up to 18 pairs
  • Most commonly used species in research: Mastomys natalensis and Mastomys coucha; these species are morphologically identifical and overlap in native South African habitats; differ in chromosome number, some biochemical traits, sperm morphology
  • Most commonly used species in research is reported as M. natalensis but is actually M. coucha
  • Following genus and species names have been used in the past to identify this animal: Mastromys coucha, Rattus (Praomys) natalensis, Rattus (Praomys) coucha, Rattus (Mastomys) natalensis
236
Q

What biochemical markers differ between Mastomys natalensis and Mastomys coucha?

A
  • Hepatic glucose phosphate isomerase isoenzymes
  • Hemoglobin subunits
  • Certain protein markers in muscle
237
Q

Mastomys - description

A
  • Originally described as South African species, animals with identical chromosomal features have been found in Tanzania and Senegal in West Africa
  • Given confusion in taxonomic status, multimammate rat is one of the most widely distributed and abundant rodents in Africa
238
Q

Mastomys - habitat

A
  • Occur in many types of habitats throghout much of sub-Saharan Africa, chiefly in assoc w/ people
  • Do not occupy large towns probably d/t competition with Rattus
239
Q

Mastomys - use in research

A
  • Host for infectious agents: M. natalensis is natural host for hemorrhagic fever agent Lassa virus; M. coucha is natural host for bubonic plague
  • M. natalensis lymphocytes show greater proliferation to Y. pestis antigens that M. coucha (greater resistance of M. natalensis to plague?)
  • Impact of rodent population density on spread of Mopeia virus: M. natalensis; arenavirus related to Lassa virus but nonpathogenic to humans
  • Zoonotic agents: leptospirosis, leishmania, Crimean-Congo hemorrhagic fever; M. natalensis is a reservoir for numerous non-TB Mycobacterium spp. incl M. intracellulare complex; M. natalensis used as model for infx with water-borne Mycobacterium ulcerans
  • Pathogenesis and treatment of parasites: Plasmodium berghei, Entamoeba histolytica, Trypanosoma brucei rhodesiense; nematodes Nippostrongylus brasiliensis, Dipetalonema viteae, Brugia malayi, B. pahangi, Litomosoides carinii, Acanthocheilnema viteae, Wuchereria bancrofti; trematode Schistosoma mansoni
  • Zollinger Ellison syndrome: M. natalensis spontaneously develops gastric carcinoid; role of hypergastrinemia in tumor production, CCK-A and CCK-B/gastrin receptors on enterochromaffin-like carcinoid cells and relationship to histamine secretion
  • Mucosal anaphylaxis on gastric ulcer formation
  • Autoimmune thymiditis: some individuals spontaneously develop
  • M. natalensis as model of chemical oncogenicity and general toxicology
240
Q

Papillomavirus in Mastomys

A
  • M. natalensis has endogenous papillomavirus (MnPV): has been sequenced and shown to produce cutaneous tumors on activation
  • M/ coucha has related virus (McPV2) that produces anogenital condylomas
  • Serological markers for detection for these agents and monitoring for tumor development have been developed
241
Q

Mastomys - physiology

A
  • Submaxillary salivary glands of M. natalensis are the richest available source of nerve growth factor
  • Both males and females have a prostate gland
  • Like lab rats, do not have a gallbladder
  • Renal physiologic parameters are similar between M. natalensis and M. coucha
242
Q

Mastomys - normal values

A
  • Life span: 3 years
  • Birth weight: 2-3g
  • Eyes open: 13-17 days
  • Weaned: 19-21 days
243
Q

Mastomys - reproduction

A
  • Reproduce well as monogamous pairs and have litters of 6-12 young, although numbers as high as 22 reported
  • Sexual maturity: 55-75 days
  • Breed year-round & have postpartum estrus
  • Estrous cycles average 6-8 days
  • Gestation: 23 days
244
Q

Mastomys - behavior

A
  • Almost appear tame in wild, but very aggressive in lab
  • Keep bodies well groomed and cages cleaned, and will attempt to dispose of waste by pushing it through a hole in the cage
  • In captivity can have stereotypies similar to lab rats: repetitive sniffing, rearing, licking, exhibiting head movements, biting
245
Q

Mastomys -husbandry

A
  • Inbred lines with varying susceptibility to gastric carcinoids have been developed
  • Wild diet: grass and seed, sometimes insects; near humans eat nearly everything humans do
  • Lab diet: commercial lab rat or mouse feed
  • M. natalensis has wider tolerance for protein range in diet than M. coucha, which has depressed reproductive parameters at protein levels both higher and lower than 10-15%
  • Usually housed in standard solid bottom rodent cages with wood-chip bedding and ad lib water
246
Q

Infectious diseases in Mastomys

A
  • Lassa virus and Yersinia pestis have been assoc w/ wild-caught but should not be a problem in lab colonies
  • Mastomys frequently harbor naturally occurring areanavirus - Mopeia virus; nonpathogenic to bumans & pathogenic potential to other rodents unknown
  • MnPV: cutaneous tumors in M. natalensis
  • McPV2: anal condylomata in M. coucha
  • Enteric helicobacter: Helicobacter mastomyrinus - isolated from liver and cecum of asymptomatic M. natalensis and animals with colitis; has been assoc w/ colitis in several strains of genetically engineered mice
247
Q

Neoplasia in Mastomys

A
  • Relatively common: lymphosarcomas, parathyroid adenomas, prostatic tumors, reticulum cell sarcomas, adenomas of glandular stomach, gastric carcinoids
  • Gastric carcinoids particularly common both as spontaneous and inducible tumors and M. natalensis is model organism for this condition
  • Lymphoepithelial thymoma: common in animals over 2 years old; assoc w/ myositis, atrophy of skeletal muscle, myocarditis
  • Less common: granulosa cell tumors of ovaries, testicular tumors, adrenal gland adenomas, pituitary adenomas, hepatomas, nephroblastomas, adenomas of pancreas
248
Q

Aging lesions in Mastomys

A
  • Osteoarthritis in animals over 2 years old
  • Degenerative joint disease of diarthroses and intervertebral discs, with many peripheral joints involved; degenerated discs protrude into vertebral canal
249
Q

Autoimmune thyroiditis in Mastomys

A
  • Occurs spontaneously in many individuals

- As animals age, increasing numbers of autoantibodies found

250
Q

Membranous or membranoproliferative glomerulonephritis in Mastomys

A
  • Frequent lesions
  • In chronic cases, see classic “end-stage” kidney with glomerular changes, tubular nephrosis, tubular atrophy, protein casts and interstitial mononuclear inflammation
  • Thought to have autoimmune pathogenesis
251
Q

Duodenitis and duodenal ulcers in Mastomys

A
  • Relatively high incidence

- Affected rats have been used to study cellular regeneration

252
Q

Degus - description

A
  • Octodon degus
  • Head and body length: 125-195 mm
  • Tail length: 105-165 mm
  • Weight: 170-300g for adults
  • Upper parts are grayish to brown, underparts creamy yellow
  • Black brush at tail tip is prominent; also called “trumpet-tail” rats
253
Q

Degus - distribution

A

-Northern and western Chile, west slope of the Andes up to 1200 m

254
Q

Degus - habitat

A
  • Ope areas near thickets, rocks, or stone walls
  • Construct an elaborate communal burrow system, with the main section under rocks or shrubs; complex network of tunnels and surface paths lead to feeding sites
  • Live in small colonies with strong social organization based on group territoriality; burrow is the center of defended territory
  • Females of same social group often near young in the common burrow
255
Q

Degus - use in research

A
  • Neurobiological developmental patterns: precocious young
  • Neurodegenerative & degenerative conditions of aging: Alzheimer’s, diabetes, cancer
  • Human sleep/wake cycle, circadian behavior, ‘jet lag’: degus are diurnal
  • Effects of altered social structures on behavioral and neurochemical parameters: degus are highly social
  • How herbivores match their foraging and digestion to seasonal changes in availability and quantity of food
  • Drug tolerance, diabetes development and cataract formation
256
Q

Degus- behavior

A
  • First four digits are well developed with sharp claws for burrowing; fifth digit is shorter
  • Four pairs of mammary glands
  • Intra-abdominal testicles
  • Adreal glands are large compared with other rodents on a body weight basis
  • Spleen is unusual, with sinusoids lined by endothelial cells with cuboidal morphology that gives spleen a glandular appearance
  • Hematologic and serum protein values in normal degus were similar for both sexes from 3-49 months of age
257
Q

Degus - husbandry

A
  • Cold Spring Harbor Protocol for use of this species available based on long term University of Michigan colony
  • Social housing much better than individual housing, especially in the juvenile period; animals raised in isolation develop lethargy and behavioral deficits that cannot be remedied by running wheels or other enrichment
  • Short term individual housing (<4 weeks) followed by re-housing with littermates can be used successfully
  • Females are socially tolerant and can be housed together without fighting
  • Males can be pair or group-housed but are less tolerant to re-grouping once they have been individually housed (may tolerate a male littermate)
  • Solid bottom, opaque-sided cagining with non adherent bedding (paper or corn cob)
  • Running wheels are preferred enrichment; do not use PVC tubes or nest boxes
  • Risk of degloving if handle by tail; some colonies use nylon fishnets to handle
  • In the wild, degus use dust baths; in lab, some provide dust bath twice weekly but they have also been successfully maintained without one
258
Q

Degus - reproduction

A
  • Lab colonies breed throughout the year; females may have more than one litter per year
  • Maintain as breeding pairs or one male with multiple females
  • Induced ovulators & require presence of male to induce ovulation
  • Gestation: 90 days
  • Litter size: 1-10, avg 7 pups
  • Young are precocial: born fully furred; eyes open within one day; weigh ~14g at birth; nose to base of tail range in size from 5-6.5 cm
  • Pups nurse for 4-5 weeks & begin eating solid food at 2 weeks
  • In lab, weaned at 5-6 weeks into same sex social groups
  • Sexual maturity variably reported as 45 days to 6 months; with optimal diet is around 3 months
  • Breeding maturity in males can be assessed by presence of penile spines
259
Q

Degus - diet

A
  • Dietary requirements different for juvenile and lactating animals
  • Obesity, diabetes, and insulin resistance can be avoided in adult animals by feeding lower energy, higher fiber diet (like LabDiet 5001), but the same det in lactating or growing animals will result in poor litter size, growth, and survivability
  • Feed a breeder diet to breeders and juveniles & transition to lower energy, higher fiber diet between 10 wks and 6 mths of age
  • Fresh or dried alfalfa provided to breeding females once weekly
  • Water provided ad lib, although degus may not consume much water
  • Acidification of water recommended to about opportunistic Pseudomonas infx
260
Q

Dental condition in degus

A
  • Malocclusion of molars or incisors most common
  • Elodontomas - non-neoplastic proliferative mases of elodont (continuously erupting) teeth (can also occur in prairie dogs)
  • Rigid endoscoprs or laryngoscopes have been successfully used to evaluate degu oral cavity
261
Q

Cataracts in degus

A
  • Common

- May be congenital or acquired as a side effect of diabetes

262
Q

Diabetes mellitus in degus

A
  • Spontaneous; common
  • Has been assoc w/ feeding guinea pig chow, fresh fruit, or other dietary causes of hyperglycemia
  • Diabetic degus will develop cataracts within 4 weeks
  • Has also been assoc w/ islet amyloidosis
263
Q

Polycystic kidney disease in degus

A
  • Similar to congenital condition in humans and mice

- Described in an aged female degu with chronic renal failure

264
Q

Cerebral amyloid deposition in degus

A
  • Similar to the vascular manifestations of Alzheimer’s

- Spontaneous occurrence in degu and proposed as model for Alzheimer’s-related condition

265
Q

Infectious diseases in degus

A
  • Pseudomonas: infection common if acidified water not used
  • Giardia: fatal diarrhea in adults and pups described
  • Klebsiella pneumoniae: acute suppurative bronchopneumonia described in a degu
  • Helminth parasitism including whipworm Trichuris bradleyi
266
Q

Traumatic injuries in degus

A
  • Common

- Tibial fracture in a 3 mth old degu described; repaired by medullary fixation

267
Q

Neoplasia in degus

A
  • Primary bronchioalveolar carcinoma with renal and hepatic mets described in a mature male
  • Reticulum cell sarcoma (histiocytic lymphoma) of a cervical lymph node
  • Hepatocellular carcinoma with mets to lung, kidney, or heart; one reported resembled a mixed hepatocellular and cholangiocarcinoma
  • Splenic hemangioma
  • Mesenteric lipoma
  • Vaginal leiomyosarcoma: one case report
  • Transitional cell carcinoma in renal pelvis: reported in aged female that also has choristoma (normal tissue in abnormal location; in this case made of trabecular bone and adipose tissue) in the contralateral kidney
268
Q

Naked mole rat - description

A
  • Family Bathyergidae: African mole rats
  • Intraspecific polymorphism in size and color patterns and extensive interspecific and intergeneric evolutionary convergence make it difficult to clearly separate genera and species using morphological and morphometric traits
  • Allozyme, nuclear, and mitochondrial DNA markers used to clarify taxonomy and distinguish new genus (Fukomys)
  • At least 30 species in family comprising 6 genera
  • Only species in genus Heterocephalus is Heterocephalus glaber
269
Q

Naked mole rat -distribution

A

-All genera of Bathyergidae found exclusively in hot, arid, and semi-arid regions of sub-Saharan Africa

270
Q

Naked mole rat - habitat

A
  • Subterranean environment and live in colonies
  • Construct extensive foraging tunnels that run at root or tuber level and construct a chamber for nesting deeper underground
  • First collected in Ethiopia in 1842 & have since been found across habitat from northeastern Kenya, throughout Somalia, and into the Southeastern area of Ethiopia
271
Q

Naked mole rat - use in research

A
  • One of only two mammalian species exhibiting eusocial behavior; studied to describe eusocial structure and evolutionary development
  • Longest living rodent known with lifespan up to 30 years: model for aging research & role of oxidative stress (or lack of a role) in aging
  • Rarely develop cancer with age: investigation into underlying factors that confer longevity and cancer resistance
  • Naked mole rat fibroblasts secrete extremely high-molecular-mass hyaluronan, probably to rovide skin elasticity needed for life in underground tunnels - hyaluronan protects cells from perturbation of the signalling pathways that are sufficient for malignant transformation in other species conferring cancer resistance
  • Adapted to living in low O2 and high CO2 with no adverse effects; brain tissue is highly resistant to hypoxia and neurons are able to recover from anoxia lasting 30 min or longer: implictions for clinical prevention of brain damage in face of oxygen deprivation
272
Q

Naked mole rat - biology

A
  • Tube-shaped with loose, wrinkled, pink and gray-tinged skin sparsely covered with thick, tactile vibrissae-like hairs that are prominent on face and tail
  • Mouth closes behind large external incisors to keep mouth and airway clear
  • Tail is ~half the length of body
  • Great variation in body weight within a colony, within each gender, and within litters; at 11 months, captive-bred range from 25.7-43.4g; breeding female can weigh as much as 110g
  • Establish colonies with a single breeding female; nonbreeding animals responsible for food collection and distribution and share in caring for young; when breeding female dies, working females are capable of becoming a breeding female and will compete for the position
273
Q

Naked mole rat - husbandry

A
  • In wild, live in sealed burrows with narrow tunnels running between chambers; minimal noise and airflow; temps between 80-90 F
  • In lab, tunnel system must be transparent, ~4-7 cm in diameter, easily cleaned, and made of durable material; circular or square tunnels made of glass or acrylic have been used; several rodent cages of various sizes are attached to the tunnels to serve as feeding, nesting, and toilet chambers
  • Except for toilet chamber, which may require frequent changing, the system should not be cleaned unless necessary as naked mole rats are easily disturbed and rely on odors to navigate burrows
  • Very sensitive to vibrations and noise - panic response to disturbances; constant low intensity white noise can be used to ameliorate effects of unavoidable noise during routine colony maintenance
  • Ventilation may need to be reduced, and temperature and humidity supplemented with portable units
274
Q

Naked mole rat - diet

A
  • Wild: tubers, roots, and bulbs that extend into their burrows
  • Lab: Veggies provided daily, continual supply of sweet potatoes squash or apples; no source of water as naked mole rats meet water requirement with food supplied
275
Q

Naked mole rat - reproduction

A
  • Breeding female gives birth every 76-84 days
  • More sensitive to colony disturbance when a new litter is present; manipulation of nest chamber during 2 wks following parturition may disturb adults leading to removal or pups from nest chamber & pups may be trampled or killed
276
Q

Naked mole rat - diseases

A
  • Few diseases have been documented despite long lifespan
  • Chronic renal disease, age-associated heart lesions
  • Diet related renal mineralization and hepatic hemosiderosis
  • Behavior-related trauma and extramedullary hematopoiesis - likely related to trauma

Laboratory Animal Medicine Blue Book, 3rd Ed. (2015) (16 decks)

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