Restrictions have been put in place on a stallion in Staffordshire that has tested positive for the notifiable disease Equine Viral Arteritis — or EVA.

Little has been released about the circumstances, but Defra said in a statement: “An investigation is underway to establish the likely origin of the infection, as well as any mares that may have been affected.”

EVA is a highly contagious viral infection that causes a high rate of abortion among pregnant mares.

The disease causes damage to a horse’s arteries and is transmitted through the respiratory tract — coughing and snorting — or venereally via semen from an infected stallion.

Equine Viral Arteritis has a wide range of signs — including fever, conjunctivitis, swelling of the lower legs — but is most dangerous to in-foal mares. There is no treatment yet available for the disease.

Breeding restrictions have been placed on the stallion in Staffordshire.

How to prevent the spread of disease