Parasitic infections are common in ferrets, especially young ferrets. And although parasitic infections can occur on the skin and in other parts of the body, they are often found in the digestive tract (i.e., the stomach and intestines). One such infection, coccidiosis, is most problematic within the United States and is generally caused by two types of protozoal parasites: eimeria and isospora coccidian. A ferret infected with either parasite will primarily display diarrhea and lethargy. These parasites may also be contagious for humans and dogs.
There are many different stages in the life of a protozoan parasite, and this life cycle affects the types of signs and symptoms a ferret experiences. However, most ferrets will show signs of diarrhea, lethargy, weight loss, an upset stomach and sometimes rectal prolapse. This is where the ferret's rectum protrudes out of its anus, which may lead to secondary infections, ulcers, rectal damage and may even prevent the ferret from properly defecating.
As previously stated, coccidiosis is caused by an intestinal infection with protozoal parasites. Ferrets may contract these parasites through contact with infected fecal matter or through other airborne particles and contaminants.
After ruling out other causes for diarrhea such as metabolic diseases or other intestinal disorders, the veterinarian will examine the ferret's stool sample for parasites. Another indication of coccidiosis is increased liver enzymes in the animal.