Systemic neosporosis in a white rhinoceros.

Neosporosis was diagnosed in a 16-year-old female white rhinoceros (Ceratotherium simum) that died suddenly without clinical signs. Histopathology revealed disseminated protozoan tachyzoites in liver, adrenal cortex, kidney, and intestine, with morphology compatible with either Toxoplasma or Neospora. The organism was identified as Neospora caninum with the use of primary rabbit anti-N. caninum antibody immunohistochemistry and polymerase chain reaction. The exact source of infection remains unknown, but it is suspected that N. caninum oocysts were ingested from the soil.