Sarcocystis sp. in the eastern cottontail (Sylvilagus floridanus)

Sarcocystis sp. was observed in 100 of 185 (54.1%) Eastern cottontails (Sylvilagus floridanus) examined in Pennsylvania over a three year period. Gross and histologic examination commonly revealed cysts in skeletal muscle of the fore and hind legs, flanks and loins. Two rabbits had cysts in esophageal skeletal muscle. Host response to Sarcocystis sp. is described. Adult rabbits had a significantly greater rate of infection (69.3%) than juveniles (20.7%) (P less than 0.01).