A Primer On Coccidia Infection: Does My Dog Have Coccidiosis?

Coccidiosis is an infection of the intestinal tract in dogs. Coccidia are single-cell parasites—protozoa.  

At least four different “species” of coccidia can infect dogs. In most cases, the infected dogs show no apparent symptoms. However, if your dog gets sick, they most likely contracted Isospora canis.

Coccidia life-cycle

Dogs contract the parasite by contact with contaminated poop containing immature forms of coccidia—oocysts. The oocysts then develop through a process called sporulation and become infectious after they have matured. They produce further oocysts, and Infected dogs pass them in their feces.

A Primer On Coccidia Infection


How is coccidia different from other intestinal parasites?

Intestinal parasites such as worms are complex organisms that live primarily within the open tube of the digestive tract.  Coccidia is single-cell organisms that live and reproduce within the digestive tract walls.

Dogs can contract the infection in two ways:

  • directly by swallowing oocysts that have sporulated and matured
  • or by eating the feces or intestines of infected wildlife such as rodents  

Pet stores, boarding kennels, and other areas with large amounts of fecal contamination are common areas for coccidiosis.

What does it look like

Most dogs infected with coccidia do not show any signs.  

However, puppies, kittens, and older dogs can become sick from infection because of weak immune systems.  Diarrhea is the most common sign.  Vomiting is rare.

Coccidia. Image Utah State University

Diagnosing Coccidiosis

Microscopic examination of a fecal sample helps identify oocysts in the stool sample. However, because the oocyst is extremely tiny, the veterinarian might utilize zinc sulfate flotation solution to detect them more easily. In addition, a blood test can help detect some of the less common coccidial parasites.

Coccidiosis Treatment

The typical coccidiosis treatment involves sulfa-type antibiotic—sulfadimethoxine. The treatment might last anywhere between 5 to 25 days. Further, severe infections might require repeat treatment.

Dogs who suffer from severe diarrhea might need more aggressive treatment such as IV fluids.


Re-infection is common, and disinfection of the environment is essential for control. Because the oocysts are tough, chlorine bleach solution might be the only effective treatment of surfaces and premises.

Related articles:
My Dog’s Poop

Further reading:
Coccidiosis in Dogs

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