Small Rodents Preventive Medicine

While in many ways less bother than larger species, small mammals actually impose an even greater responsibility on the pet owner, because they are totally dependent. If you forget to put out food for your dog or cat, the animal won’t hesitate to remind you, but a rodent in a cage has very few ways to do so. So, while they are usually thought of as children’s pets, adult supervision is essential to their welfare. It is up to the parent to make sure they regularly receive fresh food and bedding, get the gentle handling they require, and to watch for indications of poor health.


The starling point in caring for your pet is to make sure the animal has a proper environment. Choosing the proper cage will both enhance your enjoyment of the animal and be an important factor in its health. Small rodents do quite well either in aquariums made for fish or in plastic rodent cages, which are available in pet stores. It is essential to have a well-secured and ventilated cover.

While plastic cages seem to have many advantages, bear in mind that they do crack if handled frequently, and some discolor when cleaned over a period of time. Because of its porosity wood cannot be easily disinfected; and if you use a wooden box, remember that all rodents are gnawers. Screening— using mesh hardware cloth — should cover all the inside wooden surface.

Mice should have a minimum floor space of 8 by 10 inches and the cage should be at least 6 inches high. Cages for rats should, of course, be some what larger. The floor space should be about 10 by 12 inches and the height around 10 inches. Commercial cages are available for both mice and rats. Extensive testing has established that rats have an extremely low tolerance for overcrowding. For gerbils, cages should be at least 10 by 14, with a height of 8 inches. Hamsters’ cages should have a floor area of no less than 10 by 12 inches and be at least 10 inches high. Cages for guinea pigs need a floor surface of 3 by 36 inches and a height of 18 inches.

The floor of the cage should be covered with some form of absorbent litter. Substances commonly used include dried rice hulls, wood shavings (preferably not colored), or dried corncob pieces. Because of the strong urine odor problem with mice, you might very well prefer to use some commercially available cat litter. Even so, to prevent odor buildup, this should be changed at least every other day. For the other species, at least once a week should be adequate.

There must be some place in the cage where the animals can hide, completely out of sight. Bedding material should be placed in the cage for their use. Materials include burlap, which the animal will shred, dried grass, hay, and shredded paper. These should be changed every two to ten days, de pending on the animal (see chart above). If the animal eats its bedding or nesting material, switch to another type.

In cleaning the cage, mild disinfectants such as a diluted Clorox or ammonia solution may be used safely. They should be rinsed off well with water as an added precaution.

Regardless of the type of cage, it is a good idea to have an exercise wheel. A dripless watering bottle is absolutely necessary — even for gerbils, despite the fact that they are desert dwellers; many people have the mistaken idea that they will get all the water they need in their diet. Free access to water should be available to all animals.


There are three basic methods you can use to safely and securely handle your pet. For animals accustomed to people and for people accustomed to small rodents, gently using a cupped hand works satisfactorily. But if the animal is unaccustomed to being handled, proceed with caution. With some animals, especially if they are jumpy, you may want to do all your handling on the floor. Most small rodents, if they are frightened, will run off the edge of a table and injure themselves.

When getting the animal out of the cage, it is important to move slowly rather than chasing the pet around and increasing its fear. If possible, when dealing with pets unaccustomed to handling, remove the exercise wheels and close off escape routes first. With animals showing a tendency to bite, such as untrained hamsters, it is wise to use a pair of canvas gardening gloves until they begin to become tame.

If restraint is needed, there are two good techniques for handling:

TOWEL METHOD. This is especially useful for aggressive or frightened pets.

Place a small unfolded towel, thick enough to withstand the animal’s teeth, in the hand you will use to hold it. With the toweled hand, grasp the rodent behind its head gently but securely. The body can be supported either in the palm of the hand holding it or by the other hand. With mice and rats it is easiest to start by using the free hand to gently lift the animal by its tail and place it on top of the cage. Once the rodent is on a surface where it can get traction, it will start walking forward. Keep holding the tail and simultaneously, with the toweled hand, grab the mouse or rat. This should not be attempted with gerbils since tail injury can occur; and it is impractical with short-tailed species.

HAND METHOD. This is essentially the same process, but without the towel. When the rodent has been grasped by the nape of the neck, support the body in the palm of the hand holding it or by the other hand.


It is wise to isolate incoming pets for two to three weeks in a separate room of the house before allowing them to come into contact with your other pet rodents. Always feed, clean, and handle the new animals last, after you have cared for the others. Wash your hands and change your clothes before you come in contact with your original pets.


Because these animals come from different habitats, each has a temperature range which is best for its health. There should be a thermometer mounted on the cage so that it can easily be checked. Optimum temperatures are:

  • Gerbils: 65 - 75°F.
  • Hamsters: 65 - 80°F.
  • Mice and rats: 70 - 80°F.
  • Guinea pigs: 65 - 70°F

If nesting material is adequate, gerbils can stand temperatures as low as 50°F. Guinea pigs, on the other hand, are not usually subjected to temperatures below 65°F, without the risk of pneumonia or other respiratory problems unless they are slowly acclimated to the lower temperature.


For mice, rats, guinea pigs, and hamsters, a relative humidity of around 50 percent is optimal. Gerbils like slightly drier air, but o percent humidity will be fine for them too.

Sensitivity to Sunlight

Burrowing animals, even those active during the day, take shelter when the sun becomes too intense. With the smaller rodents, especially, it is vitally important that their cages not be kept where they will be hit by direct sun light. Their small body size has a larger relative surface area than larger rodents have, so they heat up faster, and the result can be fatal within minutes. It is equally important that cages not be placed where they are exposed to drafts — which might lower temperatures suddenly.

Letting Out of Cage

Mice, because they are harder to tame, should be kept in their cages. The other rodents, however, can be let out for periods of play, so long as care is taken to prevent their getting outdoors and escaping. It is wisest to keep them on the floor, rather than risk a fall off a table or shelf.

Catching Escaped Rodents

If frightened, or sometimes prompted simply by curiosity, your pet might pull a disappearing act. The important thing to remember is that the animal must, in lime, return to find food. The worst mistake would be to start rushing around pursuing it. This will only generate fear and make retrieval more difficult. If the cage is placed on the floor, the pet usually will return to it voluntarily if it sees no signs of danger. If it is under a piece of furniture and cannot be reached, try luring it out with a favorite treat such as a sunflower seed, sifting beside it, and remaining still until it comes within reach. Then pick it up as you ordinarily would, moving slowly and giving it the opportunity to climb onto your hand.


All these species are mainly herbivores, though in the wild state hamsters may be omnivorous. The following diet for each of these species is geared to its nutritional needs:

GERBILS. Commercial mouse or rat chow, with the lowest fat content possible, makes a good basic food; it should be supplemented with seeds (sun flower, pumpkin, watermelon, or birdseed). This diet can be varied with grains such as corn, wheat, rice, oats, rye, or chicken scratch. Fruits and vegetables should be offered, but only in small quantities, and leftovers should be removed daily. A gerbil consumes around ½ ounce (10 to 15 grams) a day.

HAMSTERS. Commercial rat, mouse, or hamster chow supplemented with kale, cabbage (both better sources of nutrients than lettuce), apples (with their peels), and milk (for protein). Mealworms, crickets, and grasshoppers are fine sources of protein. Small pieces of cooked meat and liver will also be accepted, but leftovers must be removed at the end of the day. A hamster will eat less than ½ ounce daily (7 to 12 grams).

MICE AND RATS. Commercial mouse and rat chows will provide the basic needs, but can be supplemented, in small quantities, with fruits such as apples, raw carrots, potatoes, and other vegetables. Grains and wild bird seed will also be eaten. A mouse’s average consumption is less than 1/7 ounce (2.5 to 4 grams) a day. Rats will normally eat around ten times this amount, a little over an ounce daily (20 to 40 grams).

GUINEA PIGS. Commercial guinea pig chow, supplemented with good quality hay, kale, cabbage, fruits, and carrots. The essential thing to remember is that guinea pigs cannot synthesize vitamin C themselves and it must be included in their diet. Commercial guinea pig chow should contain it — be cause the vitamin deteriorates, the pellets should be dated; this date must be checked. Nevertheless, fruits high in vitamin C should be provided. Ascorbic acid (vitamin C) tablets may also be added to the water at a concentration of 50 milligrams to 8 ounces of water. This solution should be made up fresh daily and placed, preferably, in a glass watering bottle. Cod-liver oil can also be added to the food to improve the animal’s coat. In the summer, grasses, dandelions, plantains, and clover will be well received. A guinea pig will consume in excess of an ounce (30 to 35 grams) of food daily. Guinea pigs can also be given salt blocks.

Fresh food and water should always be available — even the gerbil will consume some water each day. Water bottles should be emptied and refilled daily and checked to make sure they’re not leaking. Checking the bedding beneath the spout will give you a clue that leakage is occurring.


All of these species are extremely clean in their habits, grooming themselves and each other as a matter of habit and a major activity. Unless something is spilled on them that is either dangerous or beyond their capacity to handle, bathing should be avoided. Not only is it not necessary — b keeping their cages clean, you assure yourself of (with the exception of the mouse) an odor-free pet— but it could be dangerous to their health. Only the long haired guinea pigs need any human assistance in normal circumstances. For brushing tangles out of their coats, a toothbrush is excellent.


With these small species, the only real training necessary is actually taming, winning their trust by handling them properly and frequently enough for them to become accustomed to the experience. The essential is to convey your own confidence by remaining calm, moving with slow deliberation, and speaking in a low voice. Allow the animal to climb onto your hand, offering it food in your palm. If, when you try to raise the hand when the pet is sitting on it, the pet seems fearful — let it go. In time it will become used to the experience, and to you. So far as tricks are concerned, the pet will pro vide those itself out of its store of instinctive behavior, Give them things they can climb into and out of— such as the paper tubes on which paper towels are rolled — or ladders they can climb up. Their natural curiosity will do the rest. And if you reward them with special treats, they will quickly learn that out-of-the-cage time means playtime.

Next: The Home Clinic and First Aid for Small Rodents

Prev.: Introduction to Small Rodents Pet Health Care

top of page  •  Use & Care of Barnyard Animals  •  Home