Basic Care of Mice and Rats

Environmental, Nutritional, and Husbandry Recommendations for pet mice and rats

Mice and rats are both commonly kept small animals. Each have specific environmental and nutritional needs that must be met for proper care.

Environment

The best cages are made of a material that is easy to clean and deodorize and is indestructible to rodent chewing or digging in the corners. The cage floor can be solid but should be waterproof and easy to clean. Wire mesh floors should be avoided, because rats and mice can trap their feet and especially hind limbs in the openings, resulting in fractures and injuries.

Recommended caging materials are wire, stainless steel, durable plastic and glass. Glass and plastic enclosures restrict ventilation and may lead to temperature and humidity problems. These materials are acceptable when at least one side of the enclosure is open for air circulation. These pets thrive in solid bottom cages with deep bedding and ample nesting material. Bedding must be clean, non-toxic, absorbent and relatively dust free. Shredded paper and processed corn cob are acceptable beddings. Wood shavings and ground corn cob must be free of mold, mildew or other contamination. Cedar chips or chlorophyll scented shavings should be avoided because of association with respiratory and liver disease. At least one inch of bedding should be provided to allow for normal burrowing behavior. Cotton and shredded tissue paper make excellent nesting materials.

Adult mice require a minimum floor area of 15 square inches and a cage height of 5 inches. Rats need at least 40 square inches of floor space and a minimum of 7 inches in height. Optimal temperature range for these pets is between 65 to 80 degrees Fahrenheit, with a relative humidity of 40 to 70%. Twelve-hour light cycles are preferred, with most rodents being more active during the night.

Nutrition

On average, an adult mouse will eat 3 to 5 grams of food and drink 3 to 5 milliliters of water daily. Mice should be fed once a day (at night) and all uneaten food should be removed before fresh food is provided. Obesity in pet rats and mice is common, restricting the number of calories, without compromising the overall nutrition in food, results in increased lifespan of the animals. Rats and mice are not strict herbivores like rabbits, guinea pigs, or chinchillas.  They are omnivores and will eat food of both plant and animal origin.  In the wild, rats and mice will eat a wide variety of seeds, grains and other plant material as well as invertebrates, small vertebrates and carrion.  Their ability to scavenge partly accounts for their successful colonization of diverse geographic regions. 

Mice should be fed a combination of fresh fruits and vegetables and small amounts of good quality mouse/rat pellets or cubes (ensure they have a protein content of at least 16% & fat content of 4-5%). Avoid feeding mice a seed/grain mix as these are too high in fat and sugar. Mice are very prone to becoming obese and malnourished on these mixes. They tend to ‘select’ their favorite bits in the mix and therefore miss out on some important nutrients. Access to fresh clean water at all times. The following should be considered as treats and should only be offered in very small amounts: cereals, grains, seeds, breads, biscuits, sweets, cooked pasta and rice and breakfast cereals.

Please ensure that any changes to the diet are made gradually to avoid gastrointestinal upset.

Enrichment

Environmental enrichment is important for both mice and rats. For example, suspended cloth hammocks are popular with rats, and suspended (plastic or stainless steel) shower hooks fitted into one another can make a swinging chain. Rats will use more enrichment devices than mice, but they usually stop using the devices after 3–4 days. Rotation of enrichment toys and introduction of novel devices excite their curiosity. Food treats are also valuable enrichment items. These can range from simple, inexpensive treats such as a daily piece of a breakfast cereal to formulated nutritious or calorie-free treats. Rats also love chocolate, and it is not toxic when fed in small amounts.

We find that rats and to some extent mice will look forward to their daily treat.  If the owner shakes the bag or container holding the treats, the noise will stimulate the pet rodent to stand up in its cage or look for the treat.  We caution owners not to offer treats by placing them between the wire openings of the cage.  Rats conditioned to accept treats this way, can mistakenly bite fingers that are innocently placed between the wire openings when strangers or guests visit, or when the cage is held or moved.

Cleaning

As a rule of thumb, the cage and accessories should be thoroughly cleaned at least once weekly. An exception to this schedule is when newborn babies are present, then wait until they are at least 10 days old. Other factors that may require increased frequency of cleaning are the number of animals in the cage, the type of bedding material provided, and the cage design and size. Cages are sanitized with hot water and non-toxic disinfectant or detergent, then thoroughly rinsed. Water bottles and food dishes should be cleaned and disinfected daily. Before you start cleaning, take your mouse out of its cage and move it to a safe enclosure. If possible, use a container made of glass, plastic, or metal so your mouse can’t chew through it.

Some products considered dangerous to mice and rats:

          Chlorine/Bleach

           Ammonia

           Glycol Ethers

           Formaldehyde

           Window Cleaners

           Concentrated Carpet Cleaners

Common Problems

Pet rodents accustomed to handling will eat food treats out of the owner’s hand. This daily routine can allow owners to detect subtle changes in the pet’s behavior. Sick rodents effectively hide signs of disease. Sick rats do not show the same interest in their daily treat, and this can alert the owner early to disease when it is still treatable and/or reversible. Recognizing disease in prey species such as rodents is more difficult than recognizing disease in predators like dogs, cats, or ferrets.  Prey species are very good at hiding signs of disease and pain as a survival mechanism.  Any obvious indication of weakness makes that animal an easier target for a predator. Recognizing disease in prey species such as rodents is more difficult than recognizing disease in predators like dogs, cats, or ferrets.  Prey species are very good at hiding signs of disease and pain as a survival mechanism.  Any obvious indication of weakness makes that animal an easier target for a predator. 

Rats and mice in pain may show decreased food and water consumption, weight loss, self-imposed isolation, self-mutilation and gnawing at limbs; rapid breathing, open-mouth breathing and abdominal breathing; increased or decreased movement; unkempt appearance such as a dirty, greasy or dull hair coat; abnormal posture such as a hunched back; dehydration, skin tenting and sunken eyes; twitching and trembling; and familiar signs such as redness or swelling around a wound or lesion. 

Unlike other companion animals, pet rodents are not vaccinated.  Because chronic infectious respiratory disease is prevalent in pet rodents, we should also warn owners not to mix their pet with other rodents at rodent-owner-gatherings or pet shows because of the risk of infectious disease. Most problems in mice and rats are skin diseases, respiratory infections, and cancer/tumors.

Common signs of illness

Anorexia

Lethargy/weakness

Changes in droppings

Changes in normal behavior

Nasal or ocular discharge

Our Small Mammal Services

Annual wellness exams

Blood work

Nail trims

Parasite screening/Deworming

Nutritional guidance

Environmental guidance

Emergencies