DISEASE screening is important prior to breeding activity, as such activity increases the opportunities for infectious disease to be spread. Disease can be passed by sexual contact from stallion to mare and mare to stallion via natural breeding, but also from stallion to mare via semen. Infectious disease can also be spread via contact and the respiratory route (aerosol and nose to nose), when horses are brought into close proximity at a breeding centre or stud. The “core” breeding diseases are contagious equine metritis (CEM), equine viral arteritis (EVA) and equine infectious anaemia (EIA).
Horses showing clinical signs of disease can be isolated and the disease dealt with, but a big concern is horses that are subclinically infected with a disease - that is those not showing clinical signs of illness. In
