Abstract
Neospora caninum is a recently recognized cyst-forming coccidian parasite associated with severe encephalomyelitis and myositis in dogs of different breeds and ages (Bjerkås et al 1984, Bjerkås & Presthus 1988, Dubey et al. 1988), but has for many years been misdiagnosed as Toxoplasma gondii. In some dogs, the main clinical sign has been attributed to polyradiculoneuritis (Dubey et al. 1988, Cuddon et al. 1992). Furthermore, ulcerative dermatitis (Dubey et al. 1988) and megaoesophagus have been reported (Wolf et al. 1991). The life cycle of the parasite and mode of infection have not been clarified, but transplacental infection seems so far to be the natural route of transmission between intermediate hosts (Dubey & Lindsay 1989). It has been speculated that the disease in young and adult dogs might be due to reactivation of a persistent infection because corticosteroid therapy can activate a latent N. caninum infection (Dubey & Lindsay 1993).