What I Learned About Mice After I Graduated From Vet School

Skin, fur and respiratory ailments are only some of the mouse health issues a veterinarian learned about after graduating from vet school.

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The most common cancer in mice is mammary cancer. Via Erik Paterson/Flickr
Dr. Jerry Murray

When I was in the College of Veterinary Medicine at Texas A&M University, I had a short “everything you need to know about mice” lecture. The professor only covered a few topics in his 50-minute presentation. His talk was mainly about lab animal mice and not aimed toward pet mice. Needless to say his presentation did not cover everything I would need to know about pet mice.

Very few articles on pet mice were in the veterinary journals back then. The only textbook at that time was The Biology and Medicine of Rabbits and Rodents, which was a textbook primarily about lab animal mice. It would be six more years before the first edition of the “pink book” (“Ferrets, Rabbits, and Rodents Clinical Medicine and Surgery”) would come out. The pink book was a big step forward for pet mice.

Skin And Fur Problems In Mice

Skin disease in pet mice is quite common, but I do not remember this being covered in vet school. Pet mice frequently have fur mites. These cause a thin haircoat and a somewhat oily appearance to the skin. The mouse is usually itchy and may do a lot of scratching. The excessive scratching may cause damage to the skin.

Three different species of fur mites can cause problems for mice, and sometimes mice can have more than one species of mite on them. It is usually easy to see the mites on the hair with a magnifying glass. Another option is for your veterinarian to pluck a few hairs and look for the mites under the microscope. Fortunately treatment is the same for all three types of fur mites, and there are some safe products to use now. Selamectin can be used topically or ivermectin can be given orally or by injection.

Mice are also prone to hair loss on the face when housed together in a group. The dominant mouse typically chews off the whiskers and hair of the face on the lower ranking mice. This is called barbering, and this behavioral problem is difficult to solve. Removing the dominant mouse from the group only solves the problem for a short time. The remaining mice soon have a new dominant mouse who starts the barbering behavior all over again.

Male mice are also prone to fighting each other. This frequently results in bite wounds and abscesses on the rump, shoulders and tail.

Mouse Respiratory Diseases 

Diseases of the respiratory tract are very common in mice. This topic was briefly covered in vet school, but the treatment options have improved since then. Respiratory infections are usually caused by a virus (Sendai virus) along with the bacterium Mycoplasma pulmonis. Mice will usually have a nasal discharge, sneezing and difficulty breathing. This infection is difficult to eliminate, so typically two antibiotics (enrofloxacin and doxycycline) are used at the same time to treat it. In most cases the mouse improves, but the Mycoplasma is likely to remain in the lungs. Unfortunately the Mycoplasma will continue to cause damage to the lungs and cause a chronic pneumonia. High ammonia levels in the cage from urine can add to the lung damage, so it is important to frequently clean the cage and change the bedding in the cage.

A Common Cancer In Mice

Male and female mice are also prone to mammary cancer. In some strains of mice the rate of breast cancer is high. Most of the mammary tumors are malignant. Surgery to remove them is the main treatment for these tumors, but they may have already metastasized to the lungs or other organs. Chemotherapy or radiation therapy is not a practical option for pet mice.

One Mouse Health Problem You Can’t Ignore

Mouse Digestive Disorders

Mice frequently have pinworms. Pinworms are not seen in dogs and cats, but are common in mice and are occasionally seen in rabbits. Fortunately the pinworms from mice are not the same kind of pinworms that people can get, so you do not have to worry about any person becoming infected from the mouse.

In general pinworms do not cause a serious problem, but they may cause some loose stools, straining to defecate and, in a worst-case scenario, a rectal prolapse. Fortunately it is easy to deworm mice with ivermectin and eliminate the pinworms.

Mice can also have Giardia infections. Mice can be treated with the same antibiotic (metronidazole) that is commonly used in dogs with Giardia.

Dental Problem In Mice

The large incisors at the front of the mouse’s mouth continuously grow. Occasionally these incisors grow too long and prevent the mouse from chewing properly. This same problem is commonly seen in rats and rabbits. Some mice will need to have their teeth trimmed periodically to treat this problem.

It can be a challenge to treat mice due to their small size, but it can be quite rewarding to treat their diseases, especially when caught early. Unfortunately, some of their diseases are still not curable.

Article Categories:
Critters · Mice and Rats