Cystoisospora canis

Cystoisospora canis
Scientific classification
Domain:	Eukaryota
(unranked):	SAR
(unranked):	Alveolata
Phylum:	Apicomplexa
Class:	Conoidasida
Subclass:	Coccidiasina
Order:	Eucoccidiorida
Suborder:	Eimeriorina
Family:	Sarcocystidae
Genus:	Cystoisospora
Species:	C. canis
Binomial name
Cystoisospora canis

Cystoisospora canis, previously known as Isospora canis, is a microscopic, coccidian parasite that causes an intestinal tract infection in dogs. The intestinal tract infection is coccidiosis caused by a protozoa (one-celled organisms) called coccidia.

Cystoisospora, previously known Isospora, is a genus that causes coccidiosis in humans, dogs and cats.Coccidiosis is multiple gastrointestinal infections caused by members of the sporozoan parasite coccidium which includes Cystoisospora. Species that can infect dogs are Cystoisospora canis, Cystoisospora ohioensis, Cystoisospora neorivolta, and Cystoisospora burrowsi. C. Canis oocysts are larger in size compared to the other three and the other three are structurally similar to each other but not with C. Canis, making it easy to identify.C. ohioensis, C. burrowsi, and C. neorivolta oocysts are similar in structure so they cannot be distinguished from each other until further diagnosis.

For a dog to become infected, the dog has to have ingested oocysts that can be found in fecal material or another host animal. When a dog is infected, the parasite can be found in the small intestinal epithelium which are the cells that line the cavity of the small intestine. It can also be found in tissues such as spleen, liver, and mesenteric lymph nodes (located in the walls of the intestines). Sporulated oocyst then releases 8 sporozoites. These sporozoites attack the intestinal epithelial cells where they develop into a schizont. Schizonts are part of the asexual stages where there are three generations of schizonts. After the last part of the multiplication process, gametes are formed. Gametes are part of the sexual stages, and they can invade other cells. Male gametes divide and break out to the host cell, then go invade cells containing the female gamete. Once the male gametes and the female gamete are in the same host cell, they will fuse creating a zygote. The zygote develops into an oocyst. The oocyst then breaks out of the host cell and leaves the host through its feces. The oocyst are noninfectious in the feces but will sporulate in 4 days becoming infectious for the next host and for the cycle to begin again. The clinical signs associated with Cystoisospora canis are severe when the oocysts ingested are sporulated instead of being ingested unsporulated.

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