Neospora caninum infection in the dog: Typical and atypical cases

Nine cases of Neospora caninum infection in dogs are reported. Five cases are examples of the typical protozoal polyradiculoneuritis-myositis syndrome in young puppies. In these dogs, the condition was manifested clinically as a progressive paraparesis, associated with hindlimb extensor rigidity. The other four cases are examples of atypical clinical presentations of N. caninum infection. They were due to neuromyopathy in two and encephalomyelitis in one older puppy, and to encephalitis in an adult dog. In the puppies with neuromyopathy the condition manifested clinically as lameness and hyperesthesia; in the puppy with encephalomyelitis, as multifocal central nervous system disease; in the adult dog as abnormal behaviour and partial, central blindness. Diagnosis was confirmed by demonstration of serum antibodies to N. caninum, but not to Toxoplasma gondii, demonstration of N. caninum organisms by immunohistochemistry (in muscle sections in cases with polyradiculoneuritis-myositis, and in CNS tissue in cases with encephalomyelitis), and by response to treatment with clindamycin in the puppies with neuromyopathy.