A review of Sarcocystis of domestic animals and of other coccidia of cats and dogs.

Abstract

The nomenclature, life cycles, and pathogenicity of Sarcocystis of domestic animals are reviewed. Sarcocystis had a 2-host life cycle, with carnivores as definitive hosts and herbivores as intermediate hosts. The following species are found in domestic animals (with the definitive hosts given in parentheses): 3 species in the ox: S cruzi (dog, wolf, coyote, raccoon, fox), S hirsuta (cat), S hominis (man, monkey); 2 species in the sheep: S ovicanis (dog), S tenella (cat); 3 species in the pig: S miescheriana (dog), S porcifelis n sp (cat), S porcihominis n sp (man); and 1 species in the horse: S bertrami (dog). Sarcocystis cruzi, S ovicanis, and S porcifelis are highly pathogenic to the ox, the sheep, and the pig, respectively. Clinical signs of acute bovine sarcocystosis are: anorexia, pyrexia (42 C, or more), anemia, cachexia, enlarged palpable lymph nodes, excessive salivation, and loss of hair at the tip of the tail. Anemia, anorexia, ataxia, and abortions are the chief clinical signs of acute ovine sarcocystosis. These signs are evident at the time of vascular endothelium is parasitized by schizonts. The schizonts disappear in about 1 month, and cysts are formed in the muscles. The cystic phase of sarcocystosis is virtually nonpathogenic. Carnivores shed sporocysts in their feces after ingesting the intramuscular cysts from the herbivores. Sarcocystis is nonpathogenic to the definitive host. Feline and canine coccidia are also reviewed. The following 11 species are found in cats: Toxoplasma gondii, Hammondia hammondi, Isospora felis, Isosporarivolta, Besnoitia besnoiti, Besnoitia sp, and 5 types of Sarcocystis (S hirsuta from the ox, S tenella from the sheep, S muris from the mouse, S porcifelis from the pig, and Sarcocystis sp from Grant's gazelle). The following 10 species are found in canine feces (Isospora canis, Isospora ohioensis, Isospora wallacei n sp; and 7 types of Sarcocystis (S cruzi from the ox, S ovicanis from the sheep, S bertrami and Sarcocystis sp from the horse, S miescheriana from the pig, S hemionilatrantis from mule deer, and Sarcocystis sp from Grant's gazelle). The history of Isospora begemina in dogs is reviewed; life cycles of feline and canine coccidia are given; oocysts of common feline and canine coccidia are compared and illustrated; and public health significance of Toxoplasma gondii oocysts is discussed, especially in relation to cats in the household of pregnant women.