07. Other Rodents

Per the PHS, use of _____ requires IACUC oversight

any vertebrate animal (includes field studies)

Per the AWA ____ are exempt. A field study that _____ is exempt from IACUC review.

-mus musculus and rattus

-harm or materially alter behavior

Which suborder? squirrels, woodchucks, prairie dogs, beavers, chipmunk, African dormice (Kellen's Dormouse)

Sciuromorpha

Which suborder? pocket gophers, kangaroo rats

Castorimorpha

Which suborder? mice, rats, hamsters, gerbils, voles, jerboas

Myomorpha

Which suborder? chinchillas, guinea pigs, degus, naked mole-rat

Hystricomorpha

How are the suborders of rodents differentiated

attachment points of masseter muscles

All rodent incisors are ____ and ____. ____is deposited on the anterior and lateral incisors surfaces while ____ is deposited on the posterior surface.

-rootless and grow continuously

-enamel

-dentin

Main Gerbil species you need to know

Mongolian gerbil/Jird - Meriones unguiculatus

Other gerbil species you may need to know

Shaw’s gerbil (Meriones shawi)

Libyan or red tailed jird

Meriones libycus

The majority of laboratory gerbils originate from where?

20 pairs trapped in eastern mongolia in 1935

What features in Gerbils prevent them from climbing?

-Bushy tail tip

-large eyes

-hind paw soles covered in fur so cannot climb

-muscular hindquarters so saltatorial (for jumping)

Gerbils are an important model for stroke research due to which anatomical structure?

-incomplete Circle of Willis

-ligation of one carotid artery can induce stroke/cerebral infarction

Gerbils are also Model for human idiopathic epilepsy. Spontaneous, recurrent, epileptiform seizures begin at what age?

6wk

Gerbil seizure resistant strains vs seizure sensitive strains. What makes the strain seizure sensitive?

-Seizure-sensitive - WJL/UC - abnormal GABAnergic synaptic transmission

-Seizure- resistant - STR/UC

Gerbils are also a model for auditory research. What does this entail?

ontogenetic cochlear implant research

Gerbils are definitive animal model for Borna disease. What is Borna disease?

severe, frequently fatal, neurological disease characterized by a progressive, nonpurulent encephalomyelitis in horses and sheep

cause by Borna disease viruses 1 and 2

Gerbils are an animal model for what livestock disease? Induced fatal encephalitis without ____.

-rift valley fever

-etraneural lesions

What are some common research uses of Gerbil?

Stroke, spontaneous epileptic seizures, neuroscience

dental caries and periodontal disease

Cholesteatoma & otitis media

Iron overload - hemochromatosis

Retinogenesis

Hypercholesterolemia

Parasitism

Gerbils are a good model for studying parasites because why?

wide variety of parasitic dz can be transmitted to gerbils (including human ones)

What parasitic diseases have been studied in gerbils?

-filarial nematodes

-giardia lamblia

-babesia divergens

-Hydatid dz (Eichinococcus)

-Cysticercosis

-Schistomiasis

Gerbils are frequently used as an animal model to do what with parasites?

-maintain nematode population

-study antihelmintic drug resistance

What is special about gerbil temperature and humidity?

-live in small burrows

-temp between 70-72F

-low room humidity

What is the recommended housing temperature range for Gerbils per the guide!!!

68-79 F

What extra husbandry care requirement is needed for Gerbils?

-They excrete little urine - less frequent cage cleaning

-They require sand/dust baths- coats become oily if not provided

-need solid bottom caging w/ enough height for them to stand on hind limbs

What Unique features does gerbil have?

-no cheek pouches & no preputial gland

-adrenal glands are larger relative to body size than rats or mice.

-thymus persists in the adult gerbil

-not coprophagic if fed a complete diet

-Gentle nature, docile, live in family groups in the wild

-Food hoarding is common, strong urge to burrow

-ventral abdominal scent gland

Gerbils will develop high cholesterol if fed a diet with ____. Can they be fed the regular rodent diet?

-over 4% fat

-NO

Ventral abdominal marking gland is larger in which sex of Gerbil?

androgen-dependent (larger in males)

What's special about gerbil reproduction?

-they pair-bond

-Accepting another mate can be difficult

-Males participate in nest building and infant care.

What type of ovulators are gerbils?

spontaneous

What is the gestation period of Gerbil? hint - it changes. When can pups be weaned?

-24-26 days if not lactating

-27 days if lactating

-Up to 48 days if postpartum-bred (because of delayed implantation)

-Weaned 21-25 days of age

What is the etiology of Nasal dermatitis "sore nose" in Gerbils?

-irritation from Harderian gland secretions (improper sand bathing)

-Common in young weanling gerbils

-Staphylococcus spp w/ stress (humidity >50%, overcrowding) implicated in development

Treatment: housing on sand, remove Harderian gland

Nasal dermatitis "sore nose" treated in gerbils?

-housing on sand

-remove harderian gland

Gerbils are highly susceptible to which clostridial bacterial infection? Because of this gerbils are good what?

-Tyzzer’s Disease (Clostridium piliforme)

-sentinels - CS is sudden death

Amoxicillin and metronidazole are implicated in development of what bacterial dz in gerbils?

-Clostridium difficile - antibiotic associated enterocolitis

Gerbils can be infected with ____. CS look similar to transmissible murine colonic hyperplasia with blood diarrhea, colon and rectal thickening

Citrobacter rodentium colitis

What helicobacter species causes severe gastritis, gastric ulceration, and intestinal metaplasia in gerbils?

Helicobacter pylori

The gerbil mite Liponyssoides sanguineus is the primary vector of _____. It does not cause dz in gerbils

Rickettsia akari

What endoparasites can infect a gerbil?

-Syphacia obvelata (mouse pinworm)

-Dentostomella translucida (oxyurid)

How many gerbils develop seizures by 2m of age? What triggers it? How is it inherited?

-20-40%

-sensory stimulation

-at least 1 dominant allele, variable penetrance, deficiency in cerebral glutamine synthetase

What cardiac abnormality are gerbils prone to?

ventral septal defect

If Gerbils are fed regular rodent chow, what dental condition tend to develop after 6 months?

Spontaneous periodontal disease

Which antibiotics/ antifungal are toxic to gerbil?

penicillin-dihydrostreptomycin-procaine combo.

Gerbils can develop fatal acute toxicity due to ______ component of the PCN-dihydrostreptomycin-procain combo.

dihydrostreptomycin

Spongiform lesions in dendrites and brain stem glia of domestic gerbils cause/are associated with neural degeneration and are due to what?

low frequency noise

What neoplasia is common in male gerbils? What about females?

-squamous cell carcinoma of sebaceous ventral scent gland in males

-ovarian granulosa cell tumor (80% of tumors in animals >3yr)

Aging diseases of gerbils

-chronic interstitial nephritis

-aural cholesteatoma (inner ear)

-cystic ovaries (50% >400d of age) - removal of affected ovary does not affect reproductive performance

What cause should be taken when picking up a Gerbil?

Tail slip (don't pick up by tip of tail)

What spontaneous neoplasia is common in aged gerbil/guinea pigs, hamster, mouse/rat

Gerbil/G. Pig -ovary

Hamster - Liver

Mouse/rat - Kidney

Richardson’s ground squirrel (Urocitellus richardsonii)

Thirteen lines ground squirrel (Ictodomys tridecemlineatus)

California bechey or rock squirrel (Spermophilus beecheyi)

Golden manteled ground squirrel (Spermophilus lateralis)

Unique features regarding Ground Squirrel

-inuced Hibernators (5 to 10°C w/ no light)

-Large internal cheek pouches

Breeding information of ground squirrels

-seasonal, monoestrus

-1 litter/year

What ground squirrel is resistant to rattlesnake venom?

California; Beechey; rock squirrel (Spermophilus beecheyi)

Because ground squirrels are induced hibernators, what can happen if they are hiberating too long?

extreme weight loss

This ground squirrel lives in small scattered groups and is not highly social

Thirteen-lined ground squirrel (Ictodomys tridecemlineatus)

This ground squirrel hibernates for 7 months of the year (sept/oct to april/may)

Richardson's ground squirrel (Urocitellus richardsonii)

What ground squirrel will develop a gallstone if fed cholesterol?

Richardson's ground squirrel (Urocitellus richardsonii)

What is the research use for Ground Squirrel?

-Hibernation research

-Hepatocellular carcinoma 2° to Hepatitis B virus. (2^nd to woodchuck)

-gallstone formation in cholesterol fed Richardson’s ground squirrel

-snake envenomation

____ ground squirrels are often infected with Yersinia pestis. Plague endemic areas include ___ and ___

-California; Beechey; rock squirrel (Spermophilus beecheyi)

-southern california & alaska

How is Yersinia pestis transmitted?

 fleas (Hoplopsyllus anomalus and Oropsylla montana)

What two ground squirrels can be infected with ground squirrel hepatitis virus? It causes mild, non progressive, but persistant hepatitis

-Richardson's ground squirrel (Urocitellus richardsonii) 

-California; Beechey; rock squirrel (Spermophilus beecheyi)

Ground squirrels are susceptible to rabies. What happens to the rabies incubation period during hibernation?

prolonged incubation

lethal myiasis by sarcophagid fly Neobellieria citellivora is associated with what ground squirrel?

Richardson's ground squirrel (Urocitellus richardsonii)

Spontaneous DM can develop in what ground squirrel

captive bred Golden-mantled ground squirrel (Spermophilus lateralis)

What ground squirrel develops carcinoma secondary to ground squirrel hepatitis virus

California; Beechey; rock squirrel (Spermophilus beecheyi)

What is the common research use of African Spiny mouse?

Skin regeneration research

Naked mole rat (Heterocephalus glaber)

What is the general life style of the Naked mole rat (Heterocephalus glaber)?

-fossorial

-subterranian environment w/ tunnels

-adapted to live in low O2 and high CO2 w/o adverse effects

-high temp and humidity (80-90F)

Since Naked mole rat (Heterocephalus glaber) are so adapted to low O2 environments, what does this mean?

can’t euthanize them via CO2 (brain can recover from 30m of anoxia)

Social structure of Naked mole rat (Heterocephalus glaber)?

-Eusocial - complex colony like social structure

-resemble social insects in behavior w/ 1 breeding female

Unique challenges in husbandry of Naked mole rat (Heterocephalus glaber)?

-do not clean housing unless necessary bc use orders to navigate

-diet - daily veggies, no water needed (in food)

-several chambers made from various sized rodent caging attached via tunnels (need feeding, nesting, and toilet chambers)

Unique features regarding Naked mole rat (Heterocephalus glaber)?

-Longest-living rodent ~ 30 years

-Resistant to both spontaneous cancer and experimentally induced tumorigenesis

What is the reproductive age of queens of Naked Mole Rat? How often does the queen give birth?

-Queens live from 13 to 18 years breeding with 1-4 males

-The queen is extremely hostile to other females behaving like queens, or producing hormones for becoming queens

-every 76-84d

Why can't the skin of Naked mole rat (Heterocephalus glaber) feel pain?

-skin lacks neurotransmitter - substance P - responsible for sending pain signals to the CNS

-normal pain behaviors to mechanical stimuli (no cutaneous pain behavior so no reaction to acid or capsaicin)

Naked mole rat (Heterocephalus glaber) are an animal model for what?

-pain insensitvity

-aging

-anti-cancer

Is water needed for naked mole rat?

Water is supplied in diet via fresh vegetables. No other source is required

What is the recommended housing temperature and humidity for naked mole rat?

Temp 28-30C (82-86F), 50-60% humidity

What is special about the Thermoregulation in naked mole rat?

-The naked mole-rat does not regulate its body temperature

-They are thermoconformers

-adopts the surrounding temperature as its own body temperature, thus avoiding the need for internal thermoregulation

Naked mole rat can have Metastatic calcification if there's high ____ or ____ in their diet

high Ca or vit D diet

1 multiple choice option

When competing to become the next naked mole rat queen females will actually grow _________

grow longer (their vertebrae elongate)

What diseases do Naked mole rat (Heterocephalus glaber) develop?

-none really

-rarely get cancer

-renal mineralization and hepatic hemosiderosis

-trauma

-extramedullary hematopoiesis

Sigmodon hispidus (cotton rat)

Unique features of the Sigmodon hispidus (cotton rat)

-3 central digits are larger than the other 2 sigits

-wide variation in chromosome number

Unique husbandry requirements of Sigmodon hispidus (cotton rat)

-very aggressive with conspecific and humans - normally solitary creatures

-will bite - must wear leather gloves

-change cage 2x/week - drink more than lab rat

-get chronic progressive nephropathy

-do not pick up by tail

-omnivorous

What caution should be taken when restraining Sigmodon hispidus (cotton rat)?

Tail skin easily degloves, do not pick up by tail

Breeding info of Sigmodon hispidus (cotton rat): type of ovulation? Wean?

-spontaneous ovulators

-can wean as early as 5-7d in wild

where can blood be collected in Sigmodon hispidus (cotton rat)

subzygomatic - have unqiue subzygpmatic sinus

Sigmodon hispidus (cotton rat) are natural reservoirs for what diseases?

-Lyme disease

-Black Creek Canal virus (hantavirus)

-VEE

Sigmodon hispidus (cotton rat) is the only animal model for which human ocular disease?

-human epidemic keratoconjunctivitis 2° to ocular adenovirus infection.

-Also adenovirus pneumonia model

Research use regarding Sigmodon hispidus (cotton rat)

-Viral respiratory tract disease model

—paramyxoviruses (respiratory syncytial virus, parainfluenza virus 3, measles), also swine/avian flu and adenovirus

-antifilarial drugs - naturally infected with Litmosoides carinii

-MRSA test intervention

-can get - Rickettsia tsutsugamushi (scrub typhus), Leishmania, and Echinococcus studies

-Adenoviral gene therapy

Sigmodon hispidus (cotton rat) can be used to study adenoviral gene therapy because ____

susceptible to human adenovirus

Neoplasia of Sigmodon hispidus (cotton rat)

fundic gastric tubular adenocarcinoma

Sigmodon hispidus (cotton rat) can get ____ when fed a partially purified diet

dystrophic calcinosis

Merriam’s Kangaroo rat (Dipodomys merriami)

Bannertail kangaroo rat (Dipodomys spectabilis)