Obesity: The tendency to become overweight (often grossly overweight) is more often a problem of pet rats than mice. Overindulgent pet owners and the of diets rich in seeds and nuts are most often responsible for this condition. Owners of pet rats must resist the temptation to feed "junk food," such as French fries, doughnuts, cookies and candy. Commercial diets specifically designed for rats are always preferred and can be supplemented with whole-wheat bread, dry cereal, pasta, fruits, vegetables and non-fat yogurt.
Overgrown Incisors: The incisor (front, gnawing) teeth of all rodents and rabbits grow continuously for the life of the individual. The continual wear between the uppers and lowers usually prevents overgrowth of the teeth. Hereditary abnormalities of the jaw bones and/or teeth, abscessation of the incisor teeth, or injury to he jaw may result in malocclusion (improper meeting of the upper and lower incisors). Malocclusion, in turn, results in overgrowth of one or more of the incisors, with subsequent injury to the mouth. Mice and rats with this problem must have their overgrown incisors trimmed periodically by an experienced veterinarian or veterinary technician.
Tumors: Both mice and rats are very susceptible to formation of tumors. Rats over 2 years of age are reported, have an 87% chance of developing one or more types of tumors! Mice frequently develop tumors representing a wide variety of tissue types. The tumors may be external or internal. Leukemia (cancer involving the white blood cells) is quite common in mice as well. Both male and female rats develop benign mammary (breast) tumors, and females develop benign tumors of the uterine and vaginal linings. These are the most common tumors of pet rats. Because rats have mammary tissue in locations beneath the skin other than along the underside of the belly, it is not uncommon to find lumps and bumps representing mammary tumors over the shoulders, flanks and base of the tail. These tumors are relatively easy to surgically remove under general anesthesia. Owners of pet mice and rats should seek veterinary attention at once after discovering a lump, bump or unusual mass protruding from a body opening, the mass can be surgically removed by the veterinarian and biopsied to determine its exact identity issue type, benign vs malignant, etc) which, in turn, helps to determine the long-term outlook for the patient. Tumors tend to grow continuously larger and may ulcerate and become infected if they reach very large size. For this reason, it is always preferable to remove them when they are small.
Red-Brown Tears of Rats: Rat owners, at some point, notice red-brown tears staining the eyelids, nose and sometimes the front paws of their pet rats. This substance is always mistaken for blood. It is actually a normal secretion from a large gland behind the eyes. red-brown tears are noted most often in response to stressful situations (restraint, fright, illness, etc).
Cannibalism: Female rats (mice much less often) disturbed shortly after giving birth to a litter may destroy the pups and eat them. Male rats also engage the same behavior. For these reasons, it is important not to disturb female rodents for 2-3 days after they have given birth. Male rats must be removed m enclosures just before females deliver their litters.
Skin Disease: There are many causes of skin disease in pet mice and rats. Numerous infectious agents, including bacteria, viruses, fungi and parasites may be involved. Cagemates may be responsible for hair loss and/or wounds to the skin. Allergies are also a suspected cause of skin disease of pet rodents. In these cases, it is wise to replace the bedding being used with plain white, unscented paper toweling. A veterinarian should be consulted when pet mice and rats exhibit signs of skin disease. The doctor will need to conduct diagnostic tests. Appropriate treatment is then based on the results of these tests.