Caryospora-associated dermatitis in dogs

Numerous developmental stages of Caryospora sp. were seen in skin and lymph node of a 2-mo-old-dog with severe pyogranulomatous dermatitis. Schizonts were up to 20 µm long and contained up to 25 merozoites. Gamonts, unsporulated oocysts, sporulated oocysts, and caryocysts were seen in macrophages, connective tissue cells, and in unidentifiable host cells. Caryocysts were up to 18 µm long, and had thin walls, and contained a host cell nucleus and 1-3 sporozoites. All developmental stages of the coccidium reacted positively with anti-Caryospora bigenetica serum when examined in an immunoperoxidase test.