The disease coccidiosis is caused by infection of the intestinal tract with microscopic parasites called coccidia. A type called Isospora is the most common cause of coccidiosis in dogs and cats. Animals are infected by ingesting the parasite from an environment that has been contaminated with feces containing Isospora organisms. Coccidiosis is a common cause of diarrhea, which may contain blood, in young puppies and kittens. Adult animals with well-functioning immune systems only rarely develop diarrhea if they come in contact with Isospora.




Any dog or cat with diarrhea that lasts for more than a day or two should have a fecal exam performed by a veterinarian. Puppies and kittens with diarrhea can quickly become dehydrated and debilitated and so should be seen by a doctor immediately. Fecal testing can reveal the presence of coccidia and many other parasitic and bacterial causes of gastrointestinal disease. A negative result on a single fecal exam does not necessarily mean that pathologic microorganisms are not to blame for an animal's diarrhea. In some cases, testing multiple samples is necessary before parasites are observed. Many different disorders can cause pets to develop diarrhea so a thorough work-up that includes blood work, abdominal x-rays, testing for parvovirus (dogs) and other diagnostic exams may be required in some cases.




Several different medications can be used to help an animal's immune system eliminate coccidia from the body. Supportive care, including hospitalization and fluid therapy, may be required in severe cases. Left untreated, coccidiosis can be fatal, but with timely intervention, most animals recover quickly.


Written by: Jennifer Coates, DVM
Last reviewed: October 2, 2008