Less Common Research Rodents

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Less Common Research Rodents
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Order Rodentia

• Suborder Sciuromorpha
• Squirrels, woodchuck
• Suborder Myomorpha
• Rat, mouse, hamster, gerbil, vole
• Suborder Hystricomorpha
• Porcupine, guinea pig
• Degu, chinchilla

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General Rodent Biology

• Classifications based on jaw musculature and
  skull structure
• Dentition
• Only 1 pair upper incisors - grow continuously
  (open root)
• Cheek teeth
• open rooted in hystricomorphs (herbivores)
• Closed rooted in myomorphs (omnivores)
• Dental formula never exceeds
• 2(I 1/1, C 0/0, PM 2/1, M 3/3)

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General Rodent Biology

• Stomach divided in myomorphs
• Coprophagy reingest excreted feces
• Very active in herbivores - GP, chinchilla
• Less so in omnivores
• Recycle B12, folic acid
• Reproduce rapidly with large litters
• Short gestations and rapidly wean
• Often can reproduce themselves in same season
• Prey animals, mainly active at low light
• Acute sense of hearing, smell touch

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General Rodent Biology

• Hi metabolic rate hi energy intake
• Hi ratio surface area to body mass
• Easily get dehydrated and hypothermic
• Adapt to cold
• Burrowing, nest building, huddling, shivering
• Non-shivering thermogenesis - brown fat
• Some hibernate
• Adapt to heat
• Burrowing, nocturnal - diurnal
• Conserve H2O by concentrating urine

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Mongolian Gerbil

• Meriones unguiculatus

Gerbil, Jird, Desert Rat, Sand Rat
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Mongolian GerbilGeneral Information

• Native to Mongolia and northern China
• Burrower, hoard food - seeds, grains, grass
• Not hibernate or estivate
• Diurnal - alternate intense activity rest
• First imported to N.A. in 1954
• Research

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General Information

• Hair coat - agouti color
• Brown w/ black tips, lighter ventrum
• Adult body weight 55-100 grams
• Live 3-5 years
• Quiet
• Foot stamping with excitement aggression

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Mongolian GerbilAnatomy/Physiology

• Ventral sebaceous marking gland
• 2x larger, orange in males
• Wide thermal neutral zone
• Large adrenal glands - 4x rat
• Skin can fall off of tail
• Spleen - very small, supernumerary common

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Anatomy/Physiology

• Dentition 1/1, 0/0, 0/0, 3/3
• Open rooted incisors
• Coprophagy - not from anus, vitamin B
• Long, fully haired tail
• Rear limbs longer than forelimbs
• Urine - small volume, concentrated
• Feces - firm, dry

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Anatomy
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Anatomy
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Reproduction/Breeding

• Puberty at 9-12 weeks
• Polyestrous 4-6 day cycle
• 22-24 day gestation
• Monogamous pairing pair before maturity
• If separate, lt 2 weeks
• Male helps care for young
• Weaning age 20-26 days

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Mongolian GerbilHusbandry

• Solid-bottom cages
• 6 inch cage height
• Bedding may cause problems
• Fighting may occur if animals are grouped as
  adults (lt 8 weeks)
• Feed low fat diets
• Cup to pick up

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Mongolian GerbilResearch Uses

• Epilepsy
• Hyperadrenocorticism
• Diabetes
• Obesity
• Periodontal disease

• Cholesterol metabolism
• Lead toxicity
• Cerebral infarction
• Protozoal parasitology

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Mongolian GerbilTyzzers Disease

• Clostridium piliforme
• High morbidity and mortality
• Diarrhea, sick rodent signs
• Multifocal necrosis in liver, heart, intestines
• Silver stain required to visualize organism
• Tx antibiotics, supportive care?

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Mongolian GerbilTyzzers Disease
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Mongolian GerbilSalmonellosis

• Salmonella enteritidis
• Diarrhea, dehydration, weight loss, death
• Enteritis, multifocal hepatic necrosis
• Differential for Tyzzers disease

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Mongolian GerbilSalmonellosis
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Mongolian GerbilSore Nose

• Nasal dermatitis
• Common clinical problem, weanlings
• Lesions begin on face and progress toward legs
• Erythema, then alopecia, and moist dermatitis

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Mongolian GerbilSore Nose

• Multifactorial, several etiologies suggested
• Poor grooming
• Hypersecretion of Harderian glands
• Demodex and Staph aureus
• Tx Antibiotics, Ivermectin

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Mongolian GerbilSore Nose
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Mongolian GerbilParasites

• Dentostomella translucida (an oxyurid)
• Syphacia obvelata (a pinworm)
• Hymenolepis nana (a cestode)
• Demodex

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Mongolian GerbilEpilepsy

• 40-80 incidence in some colonies
• Inherited trait
• Occurs with appropriate stimulation
• Handling
• Environmental changes
• Exposure to novel devices
• Confinement to small areas

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Mongolian GerbilEpilepsy

• Develop around 2 months of age
• Death is rare
• May outgrow the problem
• Treatment is not necessary

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Mongolian GerbilMiscellaneous Conditions

• Cystic ovaries
• Common in aged females
• Neoplasms
• Common in aged gerbils
• Skin, ventral gland, ovaries, testes, kidney,
  adrenal glands, liver, and pancreas

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Chinchilla

• Chinchilla laniger
• C. brevicaudata

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ChinchillaBasic Information

• Native to Andes mountains
• Used for fur production
• Blue-gray coat common
• Good jumpers
• Can be housebroken
• Live average of 10 years

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ChinchillaHusbandry

• Standard rabbit cages work well
• Females should be housed separately
• Provide a nest box
• Tolerate cold susceptible to heat
• Provide daily dust bath
• Feed guinea pig or chinchilla feed
• Extra fiber may be beneficial

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ChinchillaHusbandry
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ChinchillaHandling

• Fur slip
• Predator avoidance mechanism
• Releases hair, leaving smooth skin
• Regrows in several months
• Avoid startling
• Handle gently

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ChinchillaAnatomy/Physiology

• Large tympanic bullae
• Vagina opens separately between urethra and anus
• Hindgut fermenters
• Gestation 105 to 114 days
• Young are precocious
• Wean at 3 to 6 weeks

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ChinchillaResearch Uses

• Experimental Chagass disease
• Auditory research
• Large, accessible tympanic bullae
• Freedom from otitis

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ChinchillaGastrointestinal Disease

• Most common clinical problem
• Mutifactorial etiology
• Diarrhea, anorexia, painful abdomen, death
• Hemorrhagic, necrotizing enteritis
• Impactions, intessusception, rectal prolapse
• Supportive care

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ChinchillaPneumonia Listeriosis

• Bronchopneumonia fairly common
• Several agents involved
• Typical respiratory signs
• Treat with antibiotics
• Listeria monoctyogenes
• Sudden death, anorexia, depression, CNS signs
• Multifocal hepatic necrosis
• Treat with antibiotics

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ChinchillaYersinia/Pseudomonas

• Yersinia psuedotuberculosis
• Acute septicemia
• Chronic anorexia, depression, diarrhea, palpable
  mesenteric lymph nodes
• Lymphocytic hepatitis hepatic necrosis
• Pseudomonas aeruginosa
• Cause of conjunctivitis, otitis, pneumonia,
  enteritis, metritis, septicemia

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ChinchillaParasites

• Hymenolepis spp.
• Bayliscaris procyonis
• Multiceps serialis
• Coccidia

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ChinchillaMiscellaneous Disease

• Abscesses
• Paraphimosis (penile hair ring)
• Trichobezoars
• Malocclusion
• Choke
• Bloat
• Dermatophyte infections

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Woodchuck

• Marmota monax

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WoodchuckBasic Information

• Ground hog whistle pig chuck
• Eastern and midwestern US and Canada
• Solitary, nocturnal, burrowing
• Can live 10 years in captivity

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WoodchuckHusbandry

• Males housed individually
• Females may be grouped
• Housed in modified dog, cat, or rabbit cages
• Provide PVC piping or pails
• Also outdoor chain-link enclosures
• Feed cubed rabbit feed

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WoodchuckAnatomy/Physiology

• True hibernators
• Large seasonal weight fluctuation
• 2-3kg in Spring 4.5-7kg in Fall
• Scent glands inside anus

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WoodchuckReproduction

• Moderate breeding success in captivity
• Breed for short time in Spring
• Take male to females cage and leave for 2-3
  weeks after hibernation
• Gestation 31-32 days Wean at 35 days
• Wild caught females usually raise young - females
  born in lab do not

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WoodchuckResearch Uses

• Obesity
• Cardiovascular and cerebrovascular disease
• Arteriosclerosis
• Chronic Active Hepatitis/Heptaocellular carcinoma

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WoodchuckHepatitis

• Common cause of death
• Woodchuck Hepatitis Virus
• Similar to Hepatitis B in humans
• Chronic active hepatitis, hepatic carcinoma
• Immune complex disease

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WoodchuckVascular Disease

• Arteriosclerosis
• Aortic rupture
• Cerebrovascular and cardiovascular disease
• Dietary-related and spontaneous

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WoodchuckParasites

• Filarid infection of lymphatics of liver and gall
  bladder (Ackertia marmotae)
• Round worms and pinworms infect woodchuck
• Mites result in pruritus, weight loss, seborrhea

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Degu

• Octodon degus

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General Biology

• Native to the western foothills of the Andes
  mountains
• Imported from Chile to Europe N.A.
• Now import restricted to U.S.
• Dig elaborate burrows in the wild
• Not heat tolerant
• Life span - 5 years
• Brown hair coat with lighter abdomen
• Dark brush on tail tip
• Dirunal
• Do not hibernate

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Husbandry

• Social animals
• At least pair house
• Aggressive and/or self-mutilate if without social
  interaction
• Cage
• Shelves, nest boxes
• Climbing branches
• Dust baths

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Anatomy

• Dentition 1/1, 0/0, 1/1, 3/3
• Normal yellow to orange
• Normal urine - yellow and thick
• Adrenal glands relatively large
• Long whiskers, large rounded ears, short legs

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Reproduction

• Intra-abdominal testicles, no scrotum
• Breed at 4-9 months lt 250 g
• Induced ovulator, penial spicules
• Mating 10 seconds
• Gestation - 87-93 days
• Neonates
• Sparse hair coat
• Eyes open 3 days
• Males help rear young

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