Coccidiosis in Kittens and Cats

Coccidiosis usually targets young kittens shortly after weaning, although adult cats can be affected. The disease is highly contagious. Immunity following recovery from infection is short-lived. Cats who recover often become carriers and shed adult oocysts in their feces.

There are several species of coccidia. Only Cystoisospora (formerly known as Isospora) felis is directly transmitted by fecal contamination from cat to cat. Other species use birds and animals as intermediate transport hosts. These species complete their life cycle when the transport host is eaten by the cat. Kittens acquire Cystoisospora felis from mothers who are carriers.

Five to seven days after ingesting the oocysts, infective cysts appear in the feces. Much of the life cycle takes place in the cells lining the small intestines. Diarrhea is the most common sign of infection. The feces are mucuslike and tinged with blood. In severe cases, a bloody diarrhea may develop. These cases are complicated by weakness, dehydration, and anemia.

Coccidia can be found in the stools of kittens without causing problems, until some stress factor, such as overcrowding, malnutrition, weaning problems, an outbreak of ascarids, or shipping reduces their resistance. Normal fecal flotations will pick up these parasites.

Treatment: Offer a bland diet and encourage fluid intake. A severely dehydrated or anemic cat may need to be hospitalized for fluid replacement or blood transfusion. Kittens are more likely to require intensive care than adult cats.

Supportive treatment is important, since in most cases the acute phase of the illness lasts about ten days and the cat then recovers. Sulfonamides and nitrofurazone are the antibiotics of choice.

Known carriers should be isolated and treated. Cat quarters and runs should be washed daily with disinfectants and boiling water to destroy infective oocysts.


This disease is caused by a protozoan of the Giardia species. Cats have their own species-specific version of Giardia. Cats acquire the infection by drinking water from streams and other sources that are contaminated with infective cysts.

Most infections in adult cats are subclinical. Young cats and kittens can develop a diarrhea syndrome characterized by the passage of large volumes of foul-smelling, watery stools. The diarrhea maybe acute or chronic, intermittent or persistent, and may be accompanied by weight loss.

Diagnosis is made by finding the protozoan or its characteristics cysts in saline smears of fresh stool. Smears from rectal swabs are satisfactory. A negative smear does not exclude giardia, as cysts are shed only intermittently. Three negative fecal smears collected at least two days apart should be obtained before the diagnosis is excluded. Serology tests (ELISA and IFA) are now available.

Cats do not seem to develop an immunity to giardiasis, so prevention includes cleaning up areas of stagnant water where the protozoa may flourish and/or keeping cats away from those areas. The indoor environment should be thoroughly cleaned as well.

Treatment: Giardiasis responds well to Flagyl (metronidazole). Because Flagyl causes developmental malformations in the fetus, it should not be administered to pregnant queens. Metronidazole also prevents bacterial overgrowth and may influence existing immune disorders in the intestines. Other effective drugs are available, such as febendazole. There is now a vaccine available for giardiasis, but it is rarely recommended because the disease is usually mild and responds well to treatment.

This article is excerpted from “Cat Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc.

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