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
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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
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Originated in China
Spread to Europe
New world in 1700s
Now world wide
Natural History
• Life span: up to 3 years (extreme cases to 25 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
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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
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Cavia porcellus – domesticated
Cavia aperia – wild
wild – Peru, Argentina, Brazil, Uruguay
also known as Cavies
• domesticated 16th century – England
Varieties of Guinea Pigs
• Traditional
American or English – short hair
Abyssinian – whorls of short rough hair
Peruvian – long hair
Varieties of Guinea Pigs
• New varieties
Silky – medium length soft hair
Teddy – short, coarse hair
American Crested – short hair with
contrasting whorl on forehead
Rex – very short, soft hair
Hairless
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
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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
• Bedding
wood shavings – not cedar, pine
shredded paper
not dusty
timothy 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 – cecum
Lactobacilli sp.
primary fatty acid – propionic acid
NUTRITION
• require vitamin C
• have higher folic acid requirement
• sensitive to excess Ca, Vit. A, Vit. D
leads to metastatic calcification
mineralization of soft tissues
Feeding
• Additional Requirements
~ 6 gm feed/100 gm body weight
18-20 % protein
10-16 % crude fiber
• Use guinea pig feed!!!
• NOT RABBIT FEED
no 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/or
stop up the opening
check frequently
• Change & Clean water bottle daily
• Automatic waterers
check daily; acidify water at source
reduces pseudomonas
Water Management
• Glass/clear bottles preferred
• Like to play with waterers
will empty water bottle and/or
stop up the opening
check frequently
• Change & Clean water bottle daily
• Automatic waterers
check daily; acidify water at source
reduces 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 months
otherwise pubic symphysis fuses
must relax at parturition
Response to the hormone relaxin
Guinea pig once used in bioassays for relaxin
Care of Young
• precocial – born
furred, eyes open, teeth erupted
walking within 2 hours
• two nipples – inguinal region
can care for four young
litters 3-4 (range 1-6)
Care of Young
• milk
3.9% fat
8.1% protein
3.0% lactose
DISEASES
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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 pigs
lower premolars may be tilted inward
eventually tongue is trapped
INFECTIOUS DISEASES
• Bordetella bronchiseptica - pneumonia
do not house with subclinical carriers
rabbits, cats, dogs
• other infectious diseases are much less
common
OTHER DISEASES
• vitamin C deficiency – scurvy
• metastatic calcification
mineralization of soft tissues
• heat stroke
85º F+, high humidity, lack of ventilation
• barbering
small bald patches
Public Health Risks
• minimal
• diseases guinea pigs may carry
Bordetella, 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