Marlborough Bird & Animal Hospital

21 South Main Street
Marlborough, CT 06447


Pet Rats and Mice

 Pet rats are small rodents that were originally bred for use in research. There are mainly three strains or varieties common to the pet trade—Sprague-Dawley or Wistar-Lewis rats(white rat), Long-Evans rats(hooded rat), and the hairless rat. Rats are tame and very intelligent pets. They rarely bite, unless significantly provoked. White rats have placid temperaments while hooded rats may be more aggressive. Rats are usually nocturnal, but very social rodents. Because they don’t fight, both males and females can be housed in single sex groups. The average life span for rats is 2-3 ½ years with the record being 4 years. Adult males weigh between 270-520 grams, where as the females weigh between 225-325 grams. They become sexually mature between 50-60 days of age. Weaning takes place at 21 days.

Pet mice like rats were originally bred for research. Mice tend to be more timid than rats and can be territorial. They are escape artists and active both day and night. Mouse social systems involve a male hierarchy, meaning males have a tendency to fight when housed together. Females with litters actively defend their nests. Mice may bite when handled roughly or startled. The average life span for mice is 2-3 years. Adult males weigh 20-40 grams with females weighing a little more at 25-63 grams. Mice become sexually mature at 35 days. Weaning like the rat takes place at 21 days.

Caging for pet mice and rats should be escape proof. The cage may consist of a 15-20 gallon aquarium or be made of wire mesh with plastic or metal solid flooring. The minimum size for a single adult rat is 20”X20”X10” high, though larger is better. An aquarium must be cleaned regularly to remove the soiled litter. A dust free absorbent material is best for use as litter—avoid cedar and scented wood shavings. A large exercise wheel, nest or burrow area, and feeding area is needed in the cage. The ideal temperature for rats and mice is between 70-80° F with 40-60% humidity. A light cycle of 12 hrs. on:12 hrs. off is preferred.

Commercial rat/rodent pellets/blocks with a protein level of 20-27% should be offered free choice. Supplementation or treats are not necessary on a good pelleted diet. Common seed based diets are inadequate to meet a pet’s nutritional requirements. As with all pets, fresh clean water should always be available.