Sarcocystis canis n. sp. (Apicomplexa: Sarcocystidae), the Etiologic Agent of Generalized Coccidiosis in Dogs

Abstract

Sarcocystis canis n. sp. is proposed for the protozoon associated with encephalitis, hepatitis, and generalized coccidiosis in dogs. Only asexual stages are known in macrophages, neurons, dermal, and other cells of the body. The parasite is located free in the host cell cytoplasm without a parasitophorous vacuole; schizonts divide by endopolygeny. Schizonts are 5-25 x 4-20 microns and contain 6-40 merozoites. Merozoites are approximately 5-7 microns x 1 micron and do not contain rhoptries. The parasite is PAS-negative and reacts with Sarcocystis cruzi antiserum but not with Toxoplasma gondii, Neospora caninum, or Caryospora bigenetica antisera in an immunohistochemical test.

Sarcocystis arctosi sp. nov. (Apicomplexa, Sarcocystidae) from the brown bear (Ursus arctos), and its genetic similarity to schizonts of Sarcocystis canis-like parasite associated with fatal hepatitis in polar bears (Ursus maritimus)

“…Sarcocystis canis was named based on only the schizont stage to draw attention to a disease causing fatal hepatitis in dogs (Dubey and Speer 1991). Subsequently S. canis-associated hepatitis was diagnosed in additional dogs, a sea lion, a chinchilla, a dolphin, a Hawaiian monk seal, a horse, a black bear (reviewed in Dubey et al 2006).…”

An update on Sarcocystis neurona infections in animals and equine protozoal myeloencephalitis (EPM)

“…The first case was a dog from Illinois (Dubey et al, 1991). Protozoa were seen in the skin of this dog.…”

“…Protozoa were seen in the skin of this dog. The dog was misdiagnosed as Sarcocystis canis infection (Dubey and Speer, 1991). Subsequently, it was diagnosed as S. neurona based on immunohistochemistry (Dubey et al, 2006).…”

Acute Hepatic Sarcocystosis in a Chinchilla

“…The parasite was antigenically and structurally identical to the newly named protozoan Sarcocystis canis from dogs. 7 Although Sarcocystis canis schizonts structurally resemble schizonts of Sarcocystis species with known life cycles, there are some differences. Sarcocystis canis schizonts often have a residual body, whereas schizonts of conventional Sarcocystis species lack a residual body, at least at the light microscopic level.…”