Rodents Continued:Rats

Dr. N. Matthew Ellinwood, D.V.M., Ph.D.

February 22, 2012

IOWA STATE UNIVERSITY

COLLEGE OF AGRICULTURE AND LIFE SCIENCES

Taxonomy•Kingdom: Animalia

•Phylum: Chordata

•Class: Mammalia

•Order: Rodentia

•Superfamily: Muroidea

•Family: Muridae

•Subfamily: Murinae

•Genus: Rattus

•Species: norvegicus (brown rat)

Non-domestic “Brown Rat”• Rattus desiginates “true” rats or old world rats• Rattus norvegicus (city rat, sewer rat – also

the black rat Rattus rattus): a domesticated opportunist

• Other species of rats may act as opportunists in cities but are usually competitively replaced by the brown or black rat

Rats in Popular Culture

• Important figures in Indian and Chinese mythology• In western culture, almost uniformly a negative image• Perhaps associated with the Black Death

– Yersinia Pestis

– 30-60% of Europe's inhabitance

– 1348-1350

– Mongols catapulting infected corpses

– Caffa, Crimea in 1347

– Genoese traders took the plague to Sicily

Origins

• Originated in China

• Spread to Europe

• New world in 1700s

• Now world wide

Natural History• Life span: up to 3 years (extreme cases to 2-5 yr)

• Sexual maturity: 65-110 days

• Estrous; 4-5 days

• Gestation is 21 days

• Weaning; 3-4 weeks

• Pups; 6-12 per litter

• Tolerate group housing better than mice– Males assist with/tolerate nursing young

Housing• Ease of housing/cleaning critical• Rodent chow, less than 6 months since milling• Slotted cage top feeder• Drip bottle water

– Draining/drowning

• Bedding changes– More frequent than mice

• 30-70% Humidity• 65-85 oF

Feeding

• Rodent Chow

• Coprophagic

Anatomy

• Rats lack a gall bladder

• Harderian gland– Pigmented tears – Porphyrin staining

Communication• Ultrasonic vocalization

– Young• Elicits and directs maternal search behavior• Diminishes after 14 days old, especially around males

– Adult• Response to predators or danger• frequency and duration of vary by sex/repro status• Females during mating

• Chirping: short, high frequency, and ultrasonic– socially induced “laughing” at play, mating, and when tickled

• Bruxing, or teeth-grinding– Triggered by well being and 'self-comforting' during stress– Clicking or 'burring' sound

Fancy Variants

• Rat and Mouse Club of America

• American Fancy Rat and Mouse Association

• Sendai virus and rat mortality

Origin of Rat Fancy and Research

• Rat baiting• Popular in Britain

– Cruelty to Animals Act 1835

– 70 gambling rat pits

• Suppliers began breeding and supplying as pets

• Color variants started• Show placement in 1901

Variants

• Siamese rat

Hooded Rat

American Blue

Laboratory• Common Laboratory Rat Strains

– Wistar rat: Albino white• Wistar Institute, Henry Donaldson, 1906, first rat biomed strain

– Sprague Dawley rat: outcrossed albino, WI, 1925– Long-Evans rat

• Wistar and wild cross – outbred, behavior and obesity

– Zucker rat• Lois M. and Theodore F. Zucker, obesity reseasrchers

• Resecessive pbesity trait (leptin receptor polymorphism)

Knockouts

• Knockout rats exist but are far less common

Diseases• Mammary tumors• Obesity• Ulcers over salivary gland• Malocculusions• Chronic respiratory disease

– Multifactorial (m. pulmonis)

• Bacterial pneumonia– S pneumoniae

• Red eye

GUINEA PIG MANAGEMENT

Cavia porcellus

Origin

• Cavia porcellus – domesticated

• Cavia aperia – wild

• wild – Peru, Argentina, Brazil, Uruguay

• also known as Cavies

• domesticated 16th century – England

Varieties of Guinea Pigs

• TraditionalAmerican or English – short hairAbyssinian – whorls of short rough hairPeruvian – long hair

Varieties of Guinea Pigs

• New varietiesSilky – medium length soft hairTeddy – short, coarse hairAmerican Crested – short hair with

contrasting whorl on foreheadRex – very short, soft hairHairless

Traditional varieties of guinea pigs

American – short hair

Abyssinian – whorls of short hair

Peruvian – long hair

New varieties of guinea pigs

Silky – soft, medium hair

Teddy – short, coarse hair

American crested – contrasting whorl on head

Rex – very short, soft hair

Hairless – (well, almost)

Basic Guinea Pig

• compact stocky body

• tailless• diurnal – actually

short naps night and day

• sebaceous marking glands - rump

• open rooted teeth

Additional characteristics

• vocalize – at least 11 sounds

• good swimmers

• seldom jump

• rarely intentionally bite or scratch

• need frequent handling

• lifespan – 5 yr average, ~8 yr max.

Uses of Guinea Pigs

• Pets

• Scientific research

• Food

Home Sweet Home

• Temperature: 70, 65 – 79

• Space< 350 gm 60 sq. in.> 350 gm 101 sq. in.max size 1.2 x 3.8 cm mesh or solid

Home Sweet Home

• Beddingwood shavings – not cedar, pineshredded paper

not dustytimothy hay overlay optional

clean weekly

Home Sweet Home

• Humidity 50%; 40 – 70

• Light cycle 12:12

• Air changes 10 – 15 per hour

Digestive System

• Strict herbivores

• Hind gut fermenters – cecumLactobacilli sp.primary fatty acid – propionic acid

NUTRITION

• require vitamin C

• have higher folic acid requirement

• sensitive to excess Ca, Vit. A, Vit. Dleads to metastatic calcificationmineralization of soft tissues

Feeding

• Additional Requirements~ 6 gm feed/100 gm body weight18-20 % protein10-16 % crude fiber

• Use guinea pig feed!!!

• NOT RABBIT FEEDno vit. C and high in vit. D

Feeding Management

• Messy feeders

• Use J-feeders not bowl

Water Management

• Glass/clear bottles preferred• Like to play with waterers

will empty water bottle and/orstop up the openingcheck frequently

• Change & Clean water bottle daily• Automatic waterers

check daily; acidify water at sourcereduces pseudomonas

Water Management

• Glass/clear bottles preferred• Like to play with waterers

will empty water bottle and/orstop up the openingcheck frequently

• Change & Clean water bottle daily• Automatic waterers

check daily; acidify water at sourcereduces pseudomonas

REPRODUCTION

• age to sexual maturity 68-70

• estrous cycle 15-17 days

• gestation 59-72 days

SEXING

male: straight slit female: Y-shaped

SEXING male: straight slit

SEXING female: Y-shaped

BREEDING

• females pair at 400gm; 2-3 months

• males pair at 600 gm; 3-4 months

• breed females before 6 monthsotherwise pubic symphysis fusesmust relax at parturition

Response to the hormone relaxinGuinea pig once used in bioassays for relaxin

Care of Young

• precocial – bornfurred, eyes open, teeth eruptedwalking within 2 hours

• two nipples – inguinal regioncan care for four younglitters 3-4 (range 1-6)

Care of Young

• milk3.9% fat8.1% protein3.0% lactose

DISEASES

• genetic

• infectious

• environmental

• nutritional

• others

DISEASES

• malocclusion – over growth of teeth• causes

environmental inadequate opportunity wear down teeth

genetic teeth do not meet properly

• in guinea pigslower premolars may be tilted inwardeventually tongue is trapped

INFECTIOUS DISEASES

• Bordetella bronchiseptica - pneumoniado not house with subclinical carriersrabbits, cats, dogs

• other infectious diseases are much less common

OTHER DISEASES

• vitamin C deficiency – scurvy

• metastatic calcificationmineralization of soft tissues

• heat stroke85º F+, high humidity, lack of ventilation

• barberingsmall bald patches

Public Health Risks

• minimal

• diseases guinea pigs may carryBordetella, Salmonella, Yersinia

pseudotuberculosis, Streptococcus

CHINCHILLA MANAGEMENT

Chinchilla lanigera

Origin

• Two species in the wild– Chinchilla brevicaudata

• Shorter, stockier, and facing extinction

• A previously extant species is already extict

– Chinchilla lanigera

• Chinchilla lanigera – domesticated

• wild – Peru, Argentina, Bolivia, Chile

• Spanish discovered them in 16th century

• Crespuscular– Active – require wheels

• Names after the Chincha people of the Andes: “Little Chincha”

• Hunting in the 19th century– Fur trade led to rarity in the wild

• Rock crevices in the wild

• Can jump up to 6 feet high

• In the wild, groups called herds• Nonseasonally polyestrous• Gestation is 111 days

– Usually two offsping– Precocial

• Prey species defense– Fur release– Urine spraying

• Dust baths– Fine volcanic dust (pumice)

• Diet– Pelleted chinchilla with timothy hay

• Raisin supplement 1-2 per day

• Do not over supplement on fruits and vegetables

Research Importance

• Hearing– Range and anatomy

• Chagas disease– Parasitic diseae causing American

trypanosomiasis

• Gastrointestinal disease

• Listeriosis

Colors of Chinchilla

Standard Grey

Ebony

Homozygous beige

Heterozygous beige

Brown Velvet

Black velvet

Golden mosaic

Sapphire

Silver

Silver white

Albino white

Pure white

Degus

South American rodent Related to Guinea pigs Smaller, social rodents