Neospora caninum: the First Demonstration of the Enteroepithelial Stages in the Intestines of a Naturally Infected Dog

A 1.5-month-old Kangal breed puppy from a dairy cattle farm died after showing severe diarrhoea and incoordination. Necropsy examination revealed multifocal pulmonary consolidation and necrosis and fibrinohaemorrhagic enteritis. Microscopically, there was necrotic and purulent bronchopneumonia, myocarditis and non-purulent encephalitis. In the jejunum and ileum there was villous atrophy and crypt hyperplasia with oocyst-like and schizont-like structures in the epithelia. Immunohistochemically, Neospora caninum antigen was detected in association with the intestinal protozoal structures, degenerative neurons and areas of necrosis in the lungs and heart. Polymerase chain reaction confirmed that the organism was N. caninum and not Toxoplasma gondii. The seroprevalence for N. caninum was 74.2% (49/66 animals) for the cattle and 57.1% (4/7 animals) for dogs on this farm. This report documents fatal systemic neosporosis and enteroepithelial stages of N. caninum in a naturally infected puppy. To the authors' knowledge, this is the first definition of intestinal neosporosis in a naturally infected dog as well as the first evidence of fatal canine neosporosis in Turkey.