Intestinal Parasite (Coccidia) in Cats

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Coccidiosis in Cats

Coccidiosis is a parasitic type of infection, caused by the Coccidia parasite. It most commonly causes watery, mucus based diarrhea in animals. If it is not treated, over time it can cause damage to the lining of a cat's intestinal tract. With appropriate and prompt treatment, the prognosis is good.

Symptoms and Types

The primary symptom of a coccidial infection is watery, mucous-like diarrhea. Bloody diarrhea and an inability to control defecation will become apparent as the infection progresses, and your cat may become weak and feverish, with related vomiting and weight loss. Dehydration is a serious concern, due to the diarrhea and vomiting, and can quickly lead to serious organ complications. The nervous system may also be affected, with tremors and confusion presenting.

Types of Coccidium that infect cats:

  • Isospora felis; Isospora rivolta
  • Sarcocystis
  • Toxoplasma gondii (note that this coccidial infection has zoonotic properties)
  • Hepatozoon – transmitted by ingestion of the 'brown dog tick'



Being in an environment with other infected animals is the most common cause of this infection. It is typically spread through fecal matter, but some types may also spread through the ingestion of intermediate hosts, such as rats, mice and birds. Still, it is most commonly contracted from a parent cat to her litter due to the proximity of feces and the tendency of kittens to eat unfamilair items and explore. The coccidiosis infection is of particular danger for kittens, since their immune systems are still underdeveloped.


A fecal examination is the most common method of diagnosis for this infection. The coccidium parasite will be readily visible under microscopic examination.

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