Canine neosporosis: clinical and pathological findings and first isolation of Neospora caninum in Germany.

Neosporosis was diagnosed in an 11-week-old puppy of the breed Kleiner Münsterländer with progressive hindlimb paresis. Pathohistological and immunohistological examinations revealed a disseminated infection with Neospora caninum. Parasitic stages were demonstrated in the brain, spinal cord, retina, muscles, thymus, heart, liver, kidney, stomach, adrenal gland, and skin. Immunohistochemistry investigations were carried out using polyclonal rabbit antisera developed against N. caninum tachyzoites and the recombinant bradyzoite-specific antigen BAG-5 of Toxoplasma gondii, which is known to cross-react with N. caninum bradyzoites. BAG-5 antibodies recognized tissue cysts within the CNS and some protozoan stages that were not surrounded by a visible cyst wall. All parasite clusters in the retina and some in muscle tissue stained positively with the BAG-5 antiserum. N. caninum was isolated in cell culture and mice inoculated with brain and spinal cord of the puppy. The new isolate is the first reported in Germany and is designated NC-GER1.