Both rats and mice will wash themselves like cats do and you will see them constantly grooming themselves and each other. They’re also clean in their housekeeping, usually urinating in one corner of the cage. Female mice are preferred by many because they do not have the “musky” odor that is natural for male mice.
When choosing your pet, the most important things to look for are health and personality. Some signs that indicate ill health are sneezing, wheezing, rattling, thin condition, ruffled stand-up coat, hunched posture, listlessness, discharge from the eyes or nose, diarrhea, bloated belly (not from being pregnant), and cuts or open wounds.
A healthy rat or mouse will be curious, active, have a sleek, glossy coat, and be in good body weight. Pick out an animal that is curious and inquisitive when you put your hand in the cage and seems friendly towards you. They should be calm and friendly when you pick them up. Any prospective pet should never bite. Baby rats will nibble on your fingers and this should not be confused with biting.
If you find a rat that “kisses” (licks), you have found yourself a very special friend. Try to buy from a reputable pet shop or breeder that knows their animals, has healthy stock, and plays with the youngsters from birth to socialize them to people.
The best age to obtain your future pet is at the age of 4-6 weeks (females older then 6 weeks may be pregnant if housed in community cages) so they grow up with you.
The average life span of rats is 2-3 years; mice 1-2 years. The average body length of adult rats is 9-11 inches; mice 3-4 inches; with an average tail length of 7-9 inches in rats and 3-4 inches in mice.
The average body weight for rats is 350-450 grams for a female, 450-650 grams for a male; mice 30 grams each sex. There have been a few adult male rats that weighed 2 pounds!
Meeting the basic needs of a pet rat or mouse is neither complicated, time consuming nor expensive.