Rat (Rattus norvegicus)
The Norwegian or brown rat (Rattus norvegicus) is originally from Asia where it lived in burrows on the plains of northern China and Mongolia. The rat arrived in Europe in the early 18th century and had reached America by the late 18th century. The brown rat was the first species to be domesticated for scientific purposes.
Suborder: Myomorpha – gerbils, hamsters, mice
Family: Muridae – The largest and most diverse family of mammals including Old World rats and mice, gerbils
A variety of breeds, colors, and markings are recognized.
Rats are omnivores. The bulk of the diet should consist of a rodent block or pellet containing a minimum 16% crude protein and 4-5% fat.
Seed-based diets promote obesity and should be avoided. Longevity is increased by feeding a low fat, vegetable protein-based diet.
Rats are social creatures, although females are more likely to fight.
Rats are also primarily nocturnal, but they will have cycles of activity during the day and night. Avoid bright lighting in albino rats.
Adult brown rats tolerate cold well when allowed to acclimate.
Provide rats with items and materials for burrowing, climbing, and chewing.
Normal physiologic values
|Body weight||Adult male||267-500 g|
|Adult female||225-325 g|
|Mean life span||2.5-3.5y||Female rats typically live longer.|
|Sexual maturity||37-75 days||Puberty occurs earlier in female rats.|
|Birth weight||5-6 g|
|Litter size||6 to 13|
|Weaning age||21 days|
|Target environmental temperature||50-68°F||18-26°C|
|Target environmental humidity||40-70%|
|Water intake||22-33 ml/day|
Anatomy / physiology
Rats are generally docile and are easy to handle. For manual restraint, grasp the rat over the back and place a thumb in the axilla pushing a foreleg up towards the chin.
Collect blood samples from the lateral tail vein, ventral tail artery, femoral vein, jugular vein, or lateral saphenous vein. Warm the tail first to promote vasodilation.
Annual physical examination
Weight control may reduce the risk of mammary gland tumor development.
Studies also suggest that ovariectomy before 5-7 months of age can inhibit the development of spontaneous mammary tumors.
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References and further reading
Banks RE, Sharp JM, Doss SD, Vanderford DA. Exotic Small Mammal Care and Husbandry. Durham, NC: Wiley-Blackwell; 2010.
Dyer SM, Cervasio EL. An overview of restraint and blood collection techniques in exotic pet practice. Vet Clin Exot Anim 11:423-443, 2008.
Mitchell MA, Tully TN. Manual of Exotic Pet Practice. St. Louis, MO: Saunders Elsevier; 2009.
Quesenberry KE, Carpenter JW (eds). Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery, 2nd ed. Philadelphia, WB Saunders, 2003.
O’Malley B (ed). Clinical Anatomy and Physiology of Exotic Species. Saunders Elsevier. 2005. Pp. 209-225.
Sirois M. Laboratory Animal Medicine: Principles and Procedures. Mosby; 2004.
Pollock C. Basic information sheet: Rat. Feb 14, 2010. LafeberVet Web site. https://lafeber.com/vet/basic-information-for-rats/