[Neospora caninum as a cause of lameness symptoms in young dogs].

At the age of three weeks, two Labrador retriever puppies, out of a litter of nine, suffered from diarrhoea and muscular weakness. One puppy died within two days. The other was killed after a tetraparalysis had developed. Two weeks later a third puppy was killed because of a paretic hind leg. At the age of five months another dog had to be euthanized because of progressive hind limb ataxia. Pathological examination revealed polyradiculoneuritis, multifocal encephalomyelitis and polymyositis. In the lesions, particularly in the nerve roots, free and clustered protozoal tachyzoites were found. In the central nervous system tissue cysts were seen. By use of immunohistochemistry the protozoal organisms were identified as Neospora caninum, a newly recognized protozoan in the dog. Fresh bovine heart, that had been fed to the puppies, is regarded as the possible source of infection.