Coccidiosis is an infection of microscopic parasites called coccidia that invade the intestines of dogs and cats. The most common type of coccidia in dogs is Isospora canis, while cats are most frequently affected by Isospora felis. Coccidiosis usually is not a great threat to a healthy dog or cat, but animals that are debilitated or immunocompromised can become very ill from a coccidia infection. Puppies and kittens also are much more susceptible to severe coccidiosis.

Animals that are affected by a coccidia infection may experience intestinal problems such as watery diarrhea that can be severe, vomiting and dehydration. Death may result in severe cases. However, antibiotics have been successful at decreasing the presence of the parasites and restoring the animal's health.

Clinical signs can include watery diarrhea that is severe, weight loss, dehydration, anorexia or a decreased or absent appetite, vomiting, abdominal pain, anemia, mental depression, and death.

Coccidia are microscopic parasites that commonly infect the intestines of dogs and cats. Although most often, Isospora canis and Isospora felis forms of the parasite infect dogs and cats, respectively, Cryptospordium and Toxoplasma forms of coccidia may also infect these and other animals. In addition, these less commonly found parasites are zoonotic, meaning that they can be transmitted to humans.

Coccidiosis rarely affects a healthy dog or cat significantly, but it can lead to gastrointestinal problems and death in debilitated or immunocompromised adult animals. Puppies and kittens also are at risk for serious infection.

To diagnose coccidiosis, the examining veterinarian or veterinary technician will perform a fecal flotation examination in which a stool sample is evaluated under a microscope for the presence of parasites. Coccidia may be difficult to detect because these parasites are much smaller than the eggs passed from worms and thus can be easily overlooked.

The prognosis for an animal that has a healthy, strong immune system is good. For puppies and kittens and older animals that have a weak immune system, the prognosis is poor without treatment and death may result. With treatment, however, the prognosis is good.

Transmission of coccidia begins when the immature coccidia, or oocysts, are passed in the feces from an infected dog or cat into the environment, where they can mature and be ingested by another animal. Transmission also can occur when a dog or cat eats an animal such as a rodent that has been infected with the Isospora parasite.

Commonly, treatment involves the use of drugs called sulfonamides, antibiotics that decrease the numbers of coccidia present. The drug should be given for at least 10 to 14 days. In animals that are dehydrated and sick, intravenous fluid therapy may be needed.

The key to prevention is proper sanitation to ensure that the environment is free of feces. Once the Isospora are passed in the feces, they can quickly develop into the infective stage, so rapid removal of the feces is very important. Mature oocysts of Isospora are resistant to most cleaning products and they can survive for months to years in the environment. However, the use of strong ammonia-containing compounds may be helpful in disinfection, and steam cleaning also helps kill the infectious oocysts. Be sure to allow for adequate ventilation while cleaning the infected areas, as fumes from cleaning products can be harmful to animals and people.

Dogs and cats should not be permitted to ingest rodents, since rodents may be carriers of the parasites. The treatment of infected canine and feline mothers soon after parturition may help prevent the spread of coccidia to the young.