Clinical report of a paralytic syndrome affecting stallions, mares and foals on a thoroughbred studfarm.

An outbreak of ataxia and paralysis on a Thoroughbred studfarm is reported. The cause of the disease was attributed to equid herpesvirus (EHV1) infection which stemmed from a single 10-month abortion on the studfarm. Stallions, mares and foals were all affected but the most serious clinical signs occurred in the mares. there were 35 out of 39 mares, 2 out of 4 stallions and 5 out of 39 foals which exhibited signs of ataxia. Nine mares became recumbent and died or were euthanased. Treatment with betamethasone and antibiotics was given. The outbreak was contained to one area of the stud apart from secondary spread to 2 in-contact mares on different premises.