Transcript Chapter Seventeen Rats ALAT Presentations Study Tips  If viewing this in PowerPoint, use the icon to run the show (bottom left of screen). 

Chapter Seventeen
Rats
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Rats
 Developed from wild brown Norway rat.
 Model for naturally occurring disease studies
such as diabetes & hypertension.
Wistar albino (WI) - wide head, long ears, tail shorter
than body
Sprague-Dawley (SD) – albino; faster growing than WI;
longer, narrower, head & tail long as body
Long-Evans (LE) - smaller than WI or SD, white fur w/
black patches, head is usually black, &
sometimes known as the hooded rat
F344 & Lewis = inbred rat strain commonly used
Handling and Restraint
 Pick up by base of tail.
 One hand is placed over animal’s back, w/ thumb
& forefinger pressing forelegs toward head.
•For control, tail or hindquarters
may be restrained w/ other hand.
•Must not be grasped so tightly
around thorax that breathing is
restricted.
•Can also be wrapped in towel.
 Commercial plastic restraint devices useful for
some procedures.
 Rats more relaxed the more they are handled.
Physiological Data
 Body temp: 35.9°–37.5°C(96.6°–99.5°F)
 Heart rate: 250 - 600 / min.
 Respiration rate: 66-144 / min.
 Weight: adult male 300–500 grams; adult female
200–400 grams; newborn 5 grams
 Water consumption: 24-60 ml / day or 10-12
ml/100 g body weight daily
 Food consumption: 15-30 g / day or 5-6 g / 100
gm body weight daily
 Feces: firm, dark brown, elongated mass.
 Urine: urine should be clear & yellow.
 Life span: 2.5-3.5 years
(Images) Size and Age of Rats
4 weeks old and
6 months old
2 years old
>500 grams
porphyrin stained hair coat
Sexing and Breeding
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Anogenital distance is about 2x > in male as in female.
In adult rats, testes protrude from beneath tail.
Females are polyestrous & have a postpartum estrus.
Receptive to male within 24 hours of parturition
Born pink-skinned, hairless, & helpless.
Other breeding data:
sexual maturity: 65–110 days
estrous cycle: 4–5 days
gestation: 20–22 days
litter size: 7–11
 Cannibalism: Usually female rat does not cannibalize.
 Weaning: 21 days
(Images) Sexing Rats
Behavior
 Sitting hunched over is an early sign of poor
health.
 Keep groomed & clean if healthy.
 Nocturnal
 Group housed males rarely fight.
 Female rats usually docile in group housing.
 Tears & saliva contain porphyrin.
Seen around eyes & end of nose, noticeable on white
fur.
Older animals, all of fur appear reddish in color due to
licking itself while grooming.
Excessive accumulation of porphyrin around eyes,
nose or on front legs can be a sign of illness.
Husbandry
 Shoebox & suspended wire-bottom
 Single & group housing
 Can knock off unsecured cage lids.
 Change shoebox cages 1 or 2x/wk.
 Sanitize shelving & racks at least 1x / 2 wks.
 Clean drop pans at least 2x / wk.
 Front (incisor) teeth grow continuously.
Gnawing hard pellets keeps teeth to normal size.
Overgrown teeth protrude from mouth.
decreased food intake & weight loss
Clipping w/ scissors or small wire cutters cures
problem temporarily.
Diet
 Fed & watered ad libitum
 Pelleted commercial rodent chow diets
 Automatic watering devices or water bottles can
also be used.
Additional Reading
Anderson, R.S. and A.T.B. Edney. Practical Animal
Handling. Pergamon Press, Oxford, UK. 1991.
Harkness, J.E. and J.E. Wagner. The Biology and Medicine
of Rabbits and Rodents. Williams and Wilkins. 1995.
Hrapkiewicz, Karen, Leticia Medina, and Donald D. Holmes.
Clinical Laboratory Animal Medicine: An Introduction, 2nd
Ed. Iowa State University Press, Ames, IA. 1997.
Laber-Laird, K., M.M. Swindle, P. Flecknell, Handbook of
Rodent and Rabbit Medicine. Pergamon Press, Oxford,
UK. 1996.
Sharp, Patrick, and Marie LaRegina. The Laboratory Rat.
CRC Press, Boca Raton, FL. 1998.