Rodents Continued: Rats
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Transcript of Rodents Continued: Rats
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