Veterinary Care


Mice and Rats

Mice and rats make excellent pets if they are cared for properly. They seldom bite when raised as pets and handled with care. They are easy to care for and responsive to handling. These timid and social pets are fun to watch performing their natural behaviors of burrowing, searching for food and playing. Unlike their wild counterparts, who are typically nocturnal, pet mice and rats have periods of activity both day and night. The average life span for mice and rats is 1.5 to 3 years. The following information is designed to help you take the best care of your pet.

Many factors will affect your pet's food intake. These include temperature, humidity, food quality, and the pet's health status. His food and water consumption should be monitored closely. If a rodent's appetite or water intake drastically changes he should be seen by a veterinarian. For more information, see the section in this booklet on Health and Medical Problems.

On average, adult mice eat approximately 1/2 ounce of food and drink about 1 tablespoon of water per 4 ounces of body weight daily. Rats eat approximately 1/2 ounce of food and drink 2 teaspoons of water per 1 ounce body weight. However, because of waste, it is necessary to fill food bowls with more than these quantities daily. Both eat generally at night.

Pellets or blocks - It is recommended to feed your pet rodent ration containing at least 14% protein and 4 - 5% fat. These rations are typically processed as dry pellets or blocks.

Seeds - Rodents prefer sunflower-based diets to pellets, but these seeds are low in calcium and high in fat and cholesterol. It is fine to feed your mice or rats seeds, but only as a supplement to the pellets. Seed diets fed alone can cause obesity and nutritional deficiencies.

Water - Water should always be available and fresh daily. The container should be a water bottle equipped with a sipper tube. Always make sure that the tube is positioned low enough to allow the pet easy access.

Cages - Rodents often chew through wood and thin plastics. For this reason cages should be made of wire with a solid floor. Several types of cages which are suitable for housing small rodents are available. Many of these units come equipped with cage "furniture" such as exercise wheels, tunnels and nesting boxes. Such accessories, as well as sufficient litter depth within which to burrow, are desirable for the pet's psychological and physical well-being.

Adult mice require a minimum floor area of 15 square inches each and a cage height of at least 5 inches. Rats need at least 40 square inches of floor space each and a minimum height of 7 inches.

The cage and accessories need cleaning at least once weekly. Factors that may require an increased frequency of cleaning are the number of animals in the cage, the type of bedding used and the cage size and design. Cages should be sanitized with hot water and nontoxic disinfectant; then thoroughly rinsed. Water bottles and food dishes should be cleaned and disinfected daily.

Bedding - These pets thrive in solid bottom cages with deep bedding and ample nesting material. Bedding must be clean, nontoxic, absorbent, and relatively dust free. Shredded newspaper, tissue paper, bathroom or facial tissue, cotton, pine shavings or processed corncobs are the preferred beddings. All bedding material must be free from mold, mildew or other contamination before using. Provide at least 2 inches of bedding in the cage to allow normal burrowing behavior. Do not use cedar shavings or chlorophyll-scented shavings because they may harm your pet.

Temperature - The optimal temperature range for mice and rats is between 65 - 85 degrees F. with a relative humidity of 40 - 70%. Twelve-hour light cycles are preferred because most rodents are more active during the night.

Multiple rodents - Pet mice and rats are colony oriented by nature and can be housed singly or in groups. However, adult male mice often fight when caged together, especially in the presence of females. For this reason, we recommend that males be kept individually. Females may be caged together if a colony is desired. Rats, on the other hand, usually can be caged in mixed groups of males and females without aggression, but they should be spayed and neutered. Breeding is highly discouraged! Group cages should be provided with multiple food and water sources; otherwise territorial disputes could break out.

Mice and rats become tame and seldom bite when accustomed to being handled, but, rats can be very territorial of their cages and should be coaxed out of them before being handled. Also, it is best not to disturb a sleeping rodent because most are usually quite cranky when awakened. Mice housed individually may become more aggressive and apprehensive than those housed in groups. Regular weekly handling is recommended to properly socialize your pets. A lack of handling could result in aggressive behavior.

Mice and rats can be easily picked up by scooping them into cupped hands and holding them near your body. The tip of the tail must never be pulled because the skin can easily tear and become stripped from the tail. Picking up rodents by the scruff of the neck in not recommended.

Inadequate water consumption leads to dehydration, low body weight and death. Rodents will drink only a fraction of the water bottle volume, but the bottles must be emptied, cleaned and refilled with fresh water daily. When more than one animal is in a cage multiple food and water sources must be provided to be assured that each animal is getting enough food and water.

Chronic Murine Pneumonia - Caused by a very elusive bacteria, this disease is one of the most common infectious problems found in mice and rats. Symptoms include sniffling, sneezing, labored breathing, squinting, red-brown tearing and rough hair coat. You may also see head tilt, neurological signs or genital infection. A veterinarian should be consulted at the first suspicion of infection. The disease runs a chronic course and may result in death if not treated early. It is very important to restrict contact between new mice or rats and your current rodents for 4 - 6 weeks. This will allow time to confirm the health status of the new pets without endangering your current ones.

Tumors - Mice and rats are very susceptible to the development of tumors especially after they reach 2 years of age. Mice develop tumors in a wide variety of tissues, with leukemia (cancer of the white blood cells) being the most common Breast cancer is the most common type found in both male and female rats, and tumors are usually found behind their front legs, along their sides, in their flank area and along the underside of their body. Tumors can be removed surgically, but often recur. If not removed, these masses will continue to enlarge and may ulcerate and become infected.

There are other diseases or problems that can be common with mice or rats. If your pet shows any unusual signs or symptoms, his veterinarian should be contacted immediately.

(Some information within taken with permission from
"Mouse & Rat Care," Midwest Bird and Exotic Animal Hospital, Illinois.)


Low-cost feline spay/neuterHeartworm DiseaseMarch for AnimalsThe New Detroit Animal Care CampusGet 10% off your next purchase at


Powered By Blackbaud

Home  |  Contact us  |  Careers  |  Locations & Hours  |  Tell a Friend  |  Search Site
Terms of Use  |  Privacy Policy  |   Log In

The Michigan Humane Society is registered as a 501(c)(3) non-profit organization. Contributions to The Michigan Humane Society are tax-deductible to the extent permitted by law. MHS's tax identification number is 38-1358206. Somebody Here Needs You.

Special Thanks to Our Partners:
MHS Partners