Rodents commonly kept as pets in the US include the domesticated varieties of the rat, the mouse and the guinea pig (or cavy). Rabbits are not rodents but belong to a closely related group called lagomorphs.
Rats and mice are surprisingly intelligent animals, and, if raised with a close association with their owner, they make very good pets. Properly handled, pet rats and mice rarely or never bite.
The common notion that there is something inherently “dirty” about rats and mice is totally incorrect. If kept properly and hygienically, they represent far less a threat to human health than dogs and cats do.
They are best kept in cages with a bedding of fairly coarse sawdust. This should be changed at least once weekly, and the cage itself thoroughly cleaned each time.
They can be fed commercially available rat and mouse cubes, which require no form of supplementation.
Water is best presented in an inverted milk bottle using a stopper incorporating a sipping tube with a ball-bearing nipple.
They will breed readily, of course. The gestation period is 20 to 23 days and the average litter size varies from 6 to 14. The babies can be weaned about three weeks after birth.
The weaners should be sexed at weaning and separated to prevent early breeding.
Guinea pigs or cavies are interesting animals. Long-haired and curly-haired varieties are available.
These animals can be kept in hutches on the grass, being moved to fresh grass daily, or in cages with a bedding of lucerne hay, changed at least once weekly. Any kept outdoors should have plenty of protection against environmental mental extremes and marauding dogs and cats. Preferably, they should be inside during winter nights.
Cavies can be fed commercial rabbit and guinea-pig pellets, supplemented with grass or lucerne, and a daily supply of freshly washed fruit or vegetables.
Guinea pigs and monkeys are the only animals with a strict requirement for a dietary source of vitamin C, normally supplied by the fruit and vegetables. If these are not given, the ascorbic acid powder should be added to their drinking water at the rate of a gram to the liter. If cavies lack vitamin C, scurvy and death will follow.
Watering, again, is best done using inverted bottles and nipples.
Cavies are extremely sensitive to the toxic effects of penicillin and some other widely-used antibiotics. Fortunately, some of the broad-spectrum antibiotics can be safely used.
Reproduction is also interesting. They have an unusually long gestation period for rodents of about nine weeks. The babies, two to four in number, are born at an extremely advanced or precocious stage of development, fully furred and with eyes open, and will start nibbling solid food from birth. It is possible to wean them at birth but they should normally be weaned at three weeks.
Rabbits also can be fed commercial pellets and watered similarly to rodents. They will appreciate access to grass, hay and vegetables.
If rabbits are kept outside, as well as having protection from dogs and cats, it is highly advisable that the hutch is mosquito screened. Myxomatosis, widespread in the feral-rabbit population, spreads readily to domestic rabbits through mosquitos. The disease is always fatal.
The gestation period of rabbits is about 30 to 32 days and the average litter 6 to 8.
Contrary to general opinion, they may be quite difficult to breed in captivity, often as a result of poor mothering on the part of the doe. If a doe fails to rear her first litter successfully, she should be given a second opportunity to prove herself, but if her second litter is also unsuccessful, she should be discarded as a breeder.
Guinea pigs and other rodents may occasionally be infected with fungal ringworm, possibly contagious to anyone handling them. Any indication of hair loss or skin disease in these animals requires checking by a veterinarian.