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Common furbearer afflictions


Sarcoptic mange

Sarcoptic mange is commonly seen in wolves, coyotes, red foxes, and occasionally raccoons. It is caused by a mite (Sarcoptes scabiei), which lives and burrows into the layers of the skin. The mites cause an irritation, resulting in the animal scratching and biting the affected area and spreading the mite on its body. Hair loss, thickening and wrinkling of the skin, and scab and crust formation on the skin are the result of the infestation. Feeding behavior may be altered due to the intense irritation resulting in malnutrition. In severe cases, the animals can die due to exposure from losing the insulating layer that the hair provides. The mite can live on humans for a period of time causing severe irritation at the exposure site. Mange-infested animals should only be handled while wearing gloves. Freezing the carcass will kill the mites for safer handling.


North American guinea worm

The North American guinea worm has been identified in raccoons, mink, red fox, river otter, fisher, and American marten in Michigan. The worm is commonly found in the subcutaneous space of the front and rear legs, the thorax, abdomen, and inguinal areas. These are a large nematode and are easily seen by the trapper and hunter when skinning the affected animals.



Heartworm (Dirofilaria immitis) has rarely been reported in wolves, coyotes, and red fox in Michi-gan. The adult nematodes live in the right side of the heart and are only found if the trapper or hunter cuts open the heart.

Liver and spleen


Tularemia is a bacterial infection caused by the bacterium Francisella tularensis. The aquatic form of the disease has been diagnosed in beaver and muskrats. Small white necrotic foci (pimple-like in appearance) are observed in the liver and spleen and a pneumonia is often seen in affected animals. Humans can contract the dis-ease via contaminated blood or by ingesting insufficiently cooked infected meat. Beavers or muskrats with liver and spleen lesions consistent with tularemia should be collected and sub-mitted to the Lab for examination.

Intestinal tract

Tyzzer’s Disease

Tyzzer’s disease, caused by the bacterium Clostridium piliforme, has been diagnosed in muskrats in Michigan. The bacterium causes extensive hemorrhaging in the ceca and small tan necrotic foci in the liver. This disease normally occurs when muskrat populations are abundant.

Raccoon roundworm

The raccoon roundworm (Baylisascaris procyonis), a large nematode, occurs naturally in the intestinal tract of raccoons and often in large numbers. If the tract is cut or torn the nematodes can migrate out of the tract and be found lying free in the abdominal cavity. These nematodes do not cause any harm to the raccoon, but eggs of the roundworm are shed in the raccoon's fecal matter and can be ingested and infect a number of abnormal hosts including humans.