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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

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Rodents Continued: Rats

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  1. Rodents Continued:Rats Dr. N. Matthew Ellinwood, D.V.M., Ph.D. February 22, 2012 Iowa State University College of Agriculture and Life Sciences

  2. Taxonomy Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Rodentia Superfamily: Muroidea Family: Muridae Subfamily: Murinae Genus: Rattus Species: norvegicus (brown rat)

  3. 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

  4. 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

  5. Origins • Originated in China • Spread to Europe • New world in 1700s • Now world wide

  6. 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

  7. 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

  8. Feeding • Rodent Chow • Coprophagic

  9. Anatomy • Rats lack a gall bladder • Harderian gland • Pigmented tears – Porphyrin staining

  10. 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

  11. Fancy Variants • Rat and Mouse Club of America • American Fancy Rat and Mouse Association • Sendai virus and rat mortality

  12. 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

  13. Variants • Siamese rat

  14. Hooded Rat

  15. American Blue

  16. 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)

  17. Knockouts • Knockout rats exist but are far less common

  18. Diseases • Mammary tumors • Obesity • Ulcers over salivary gland • Malocculusions • Chronic respiratory disease • Multifactorial (m. pulmonis) • Bacterial pneumonia • S pneumoniae • Red eye

  19. GUINEA PIG MANAGEMENT Cavia porcellus

  20. Origin • Cavia porcellus – domesticated • Cavia aperia – wild • wild – Peru, Argentina, Brazil, Uruguay • also known as Cavies • domesticated 16th century – England

  21. Varieties of Guinea Pigs • Traditional • American or English – short hair • Abyssinian – whorls of short rough hair • Peruvian – long hair

  22. 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

  23. Traditional varieties of guinea pigs

  24. American – short hair

  25. Abyssinian – whorls of short hair

  26. Peruvian – long hair

  27. New varieties of guinea pigs

  28. Silky – soft, medium hair

  29. Teddy – short, coarse hair

  30. American crested – contrasting whorl on head

  31. Rex – very short, soft hair

  32. Hairless – (well, almost)

  33. Basic Guinea Pig  • compact stocky body • tailless • diurnal – actually • short naps night and day • sebaceous marking glands - rump • open rooted teeth

  34. 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.

  35. Uses of Guinea Pigs • Pets • Scientific research • Food

  36. 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

  37. Home Sweet Home • Bedding • wood shavings – not cedar, pine • shredded paper • not dusty • timothy hay overlay optional • clean weekly

  38. Home Sweet Home • Humidity 50%; 40 – 70 • Light cycle 12:12 • Air changes 10 – 15 per hour

  39. Digestive System • Strict herbivores • Hind gut fermenters – cecum • Lactobacilli sp. • primary fatty acid – propionic acid

  40. 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

  41. 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

  42. Feeding Management • Messy feeders • Use J-feeders not bowl

  43. 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

  44. 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

  45. REPRODUCTION • age to sexual maturity 68-70 • estrous cycle 15-17 days • gestation 59-72 days

  46. SEXING male: straight slit female: Y-shaped

  47. SEXING male: straight slit

  48. SEXING female: Y-shaped

  49. 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

  50. 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)

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