Neosporosis - Cattle

Description

Caused by the protozoan parasite Neospora caninum and is the commonest cause of abortion in dairy cattle. Neospora caninum is similar to Toxoplasma gondii and although the complete life cycle of the protozoa is unknown, the dog has been found to be the definitive host.

Stillborn calves can be born from infected dams and congenitally infected calves may be born with encephalomyelitis. Abortion usually occurs between 5-7 months of gestation but can occur as early as 3 months.

Signalment

Neospora has been documented to infect cattle, sheep, goats and the dog.

Diagnosis

The histological appearance of lesions on an aborted fetus can be enough to confirm a diagnosis. Tissue cysts may be evident and can be identified.

Clinical Signs

Often infected cattle present with no clinical signs other than abortion. Calves can be born with encephalomyelitis causing various neurological signs such as paresis. Repeat abortions are often reported in affected animals due to a persistent infection.

Pathology

Non-suppurative encephalitis is most commonly seen in aborted faeces. non suppurative myocarditis myositis widespread non suppurative infiltrates in other organs

Treatment

Do not allow dogs access to calving cows, placental membranes and aborted or dead calves

Do not allow dogs to defecate in cattle feeding areas

Identify and cull seropositive cattle, or do not breed from them or their progeny

Select seronegative cattle for breeding

Vaccinate is possible but only in the USA. It is a killed protozoal vaccine for healthy, pregnant cows and is given in the first 3 weeks of pregnancy and then every 3-4 weeks during gestation. Revaccination with 2 doses should be undertaken during each subsequent pregnancy.