Health Problems in Rodents

Rodents have several unique problems. Understanding these problems will allow you to better care for your pet and minimize future health care problems.


A common concern among owners of pet rodents is the possibility of contracting rabies if their pet bites them. While any mammal (warm-blooded animal that nurses its young with milk) can contract and transmit rabies, the likelihood of it happening toa pet rodent is almost non-existent, as rodents rarely get rabies - especially those housed inside, away from other animals.

No pet rodent should be left outside, unattended, where contact with rabid animals is more likely (e.g., foxes, racoons, skunk, and bats). Nonetheless, contact your doctor immediately if you are bitten by your pet, as rodent bites can become easily infected.

Cage-Mate Trauma and Barbering

Territorial aggression or male dominance is common amongst all members of the rodent family. Constant chasing or nudging for position often leads to fights. Bite and claw wounds can be serious and, if the wounds get infected, the infection may become life threatening. 

"Separating the animals and providing them with toys for enrichment may help the problem."

Many rodents chew or “barber” their own hair or the hair of a cage mate. Barbered hair appears as an area of thin hair in which each strand has a short, brush-cut appearance or feel to it. Barbering is often caused by stress from overcrowding, fighting, or boredom. Separating the animals and providing them with toys for enrichment may help the problem.

Foot Necrosis

This problem is caused by fine fiber or thread nesting material (bedding), commonly available in pet stores, wrapping around toes or feet and cutting off circulation. As the pets play with the material, the fine thread gets wrapped around a toe, foot, or leg, and within hours the body part swells and begins turning red, then purple, then black. If not caught immediately, the swelling progresses to necrosis or death of the affected toe or limb. In some animals, amputation is curative. 

To prevent this condition, do not use this fine bedding or nesting material. Shredded tissue or paper is much safer and works perfectly as nesting material. Many owners let pet rats crawl around on their shoulders, which can cause human hair to get wrapped around toes or feet. Always examine your pet rat’s feet for evidence of human hair caught around the toes or feet. All cases of hair, bedding, or fibers caught around or between the toes or foot of your pet should be brought to the attention of a veterinarian as soon as possible. If addressed soon enough, the damage should be minimal, with proper care and treatment. In advanced cases where the blood supply has been cut off over several days, your pet may lose its foot.

Vitamin C Deficiency (Scurvy)

Guinea pigs, like all primates (humans, monkeys, and apes), do not make vitamin C in their bodies, so vitamin C is an essential nutrient in their diets. Vitamin C is vital to the normal development and maintenance of skin, joints, and mucosal surfaces like gums. It is also important in the healing of wounds. A lack of vitamin C predisposes your guinea pig to skin problems and makes the body more prone to other diseases. Signs of vitamin C deficiency include a rough hair coat, decreased appetite, diarrhea, reluctance to walk, pain, swollen feet or joints, and hemorrhages or ulcers on gums or skin.

"Be sure that you supplement your guinea pig with vitamin C tablet daily."

Guinea pigs need 50 mg of vitamin C per day. While vitamin C is readily available from fresh fruit and colored vegetables, such as bell peppers, guinea pigs need more vitamin C than fresh vegetables contain. Be sure that you supplement your guinea pig with vitamin C tablet daily. Most high quality guinea pig pellets contain vitamin C, but the vitamin C stability is limited. Because this vitamin breaks down or oxidizes quickly, pellets should be used up or replaced within 90 days of the date of manufacture.

Vitamin C supplements should be given to guinea pigs directly by mouth, rather than in drinking water, because the vitamin breaks down rapidly in water and loses its potency. Several companies make chewable vitamin C tablets.

Hyperthermia (Heat Stroke)

All pet rodents, but especially guinea pigs and chinchillas, are very susceptible to heat stroke from high ambient temperatures. As a rule, the cage should be well ventilated, with an environmental temperature no higher than 80°F (27°C) and a humidity below 70%. Signs of heat stroke include panting, salivating, weakness, convulsions, and refusal to move.

Treatment involves immediately cooling the pet with cool water baths or sprays and seeking immediate veterinary care. Hyperthermia can be life threatening, so veterinary care must be sought as soon as possible.

Antibiotic Toxicity

Pet rodents are extremely sensitive to certain types of antibiotics. Some antibiotics, especially penicillin and similar drugs, upset the normal bacteria that live in rodents’ gastrointestinal tracts and favor toxin-producing bacteria that release substances that can be fatal to rodents. 

The disease caused by using antibiotics that alter the normal bacteria in the intestinal tract is called fatal dysbiosis. This problem can occur whether the antibiotics are given orally, topically (on the skin), or injected. Antibiotics that should not be given to rodents include penicillin and related drugs, bacitracin, erythromycin, lincomycin, tylosin, procaine additives, and streptomycin. There are some excellent oral and injectable antibiotics that are safe to use in rodents, and a rodent-savvy veterinarian will know which ones are safe and which are not. 

Guinea pig owners should never use antibiotics in or on their pets without first consulting a rodent-savvy veterinarian.

Chromodacryorrhea (Red Tears)

Red tears are seen in mice, gerbils, and most often in rats. The rodent will appear to have dried blood around its eyes, nostrils, and even on the inside of its forearms (from wiping its face with its front legs). This is not dried blood, but a red pigment called porphyrin that is made from a specialized tear gland called the Harderian gland, which gives the tears a reddish or rusty red color. This gland increases its secretions in response to stress and illness. The increased tear production may overflow the eyes and stain the surrounding fur. 

"Chromodacryorrhea can occur as a result of disease or as a sign of environmental or social stress."

Tears naturally drain through the tear duct into the nasal passages. In many cases, the drainage comes out the nose, where it may form a dried red discharge. Veterinarians often get calls or emergency visits from pet rodent owners that mistakenly think their pets are bleeding from their eyes and/or noses, where the condition is actually porphyrin staining around the eyes and nostrils. This condition still needs attention, as some problem is causing the excess production of porphyrin.

Chromodacryorrhea can occur as a result of disease or as a sign of environmental or social stress. Often it is hard to tell what is causing the problem. A veterinarian familiar with rodents should examine your pet, treat any specific disease or illness, and try to identify and help you eliminate the stresses in your pet's life.

Diarrhea (Wet Tail)

The most serious intestinal disease of young hamsters is commonly referred to as wet tail. Wet tail simply means diarrhea, and it can have several different causes in rodents, including anything that disturbs the natural bacterial balance of the intestines (e.g., infections with different bacteria, parasites, or viruses). More commonly, 3- to 10-week-old hamsters are affected and show signs of lethargy, abdominal pain, loss of appetite, unkempt hair coat, watery or bloody diarrhea, and a soiled tail and rectum. Lawsonia intracellularis is the most common bacterial organism that causes diarrhea in hamsters, but intestinal protozoa may also be part of the disease process.

As diarrhea can lead to dehydration, weight loss, and weakness, it requires immediate treatment and supportive care, including fluid therapy, antibiotics, and anti-inflammatory medications. If the animal is severely debilitated, hospitalization may be required. Animals may die even with early, aggressive treatment. Any hamster with diarrhea must be seen by a veterinarian as soon as possible.


Leg fractures are very common and usually result from injuries sustained on exercise wheels (typically those with slotted bottoms in which feet can get caught) or from mishandling or falls.

Mild fractures in which the broken bones are still aligned (non-displaced) may heal on their own with cage rest for 2-4 weeks. Severe injuries involving displaced fracture fragments, as seen on X-rays, may require surgical pinning of the fracture, splinting, or amputation of the leg. In very rare cases where the fracture either becomes infected or is not repairable, euthanasia may be recommended. All handling by children should be supervised, and only solid-bottom exercise wheels should be used in your pet’s cage.


A bacterial skin infection, often caused by infection with Staphylococcus bacteria, can occur on the muzzle and nose of gerbils. It is seen as areas of hair loss and moist skin, often due to the simultaneous presence of chromodacryorrhea, as described above. Bacterial infection is often secondary to other causes, including mange (skin mite infection) or skin trauma from constant digging or burrowing. Treatment involves antibiotics to eliminate the secondary bacterial skin infection, and treatment of the primary cause.

All rodents can become infected by either skin mites or hair lice. With mites, there will be noticeable thinning of the hair coat all over and a dry/crusty skin condition or very thickened skin (like mange in dogs).

Hamsters may develop circular raised bumps all over the body due to a skin cancer called Mycosis fungoides. This disease is a specific type of T-cell lymphoma. Treatment may be effective, but recurrence is common.


The gerbil is unique among rodents in that spontaneous, epileptic-type seizures can occur, often after handling the pet. Most gerbils do not require medication for the seizures. Guinea pigs with severe skin mite infections may also experience seizures as a result of the mites burrowing beneath their skin and causing extreme itchiness. Rodents with seizures should be examined by a veterinarian as soon as possible. This article describes these conditions and their signs and treatments.

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