Guidelines for dealing with Equine Herpes virus

Equine Herpes virus is a disease endemic to South Africa (and most of the world) causing abortions in mares, respiratory problems in young horses and possibly also neurological disease. The neurological syndrome is seldom seen in the Southern Hemisphere but may occur.

The major problem for the racing industry, apart from abortions on stud farms, is the “down time” and resultant economic loss when young horses in racing yards suffer from respiratory infections. These are not all caused by Herpes virus, but it would probably play a significant role in most cases. This is largely due to the fact that any form of stress will allow Herpes virus to flourish and young horses coming from the farm into racing yards are placed under severe stress.

There is a vaccine available, but the immunity provided by vaccinating appears to be short- lived. Some vets advocate vaccinating every 3 months with 6 months being the maximum interval to provide cover. It is however a disease that can partly be controlled by good management techniques like quarantining young horses when they enter the training yards, keeping stress to a minimum and reducing their exposure to other horses and dust.

Obviously, if these horses were vaccinated on the stud farms it would help to boost their immunity, but vaccinating them as soon as they arrive in the training yard will also get their immunity up. This combined with good management would go a long way to addressing the problem.

The NHA does not feel at this stage that it is necessary to regulate the administration of the vaccine. An investigation in to the prevalence and causes of respiratory problems in young racehorses is going to be undertaken. Should this research give us reason to change our approach, we will revisit the possibility of compulsory vaccination. We feel that the onus is on the Trainer and his vet to implement all the vaccination and management techniques pertinent to their circumstances, to help control this disease. Owners should be aware that vaccination against Equine Herpes virus is a far cheaper “insurance policy” than having to treat their young horses when they get sick. However, there are no guarantees and the immunity provided is short-lived and requires frequent vaccination to maintain.

VETERINARY DEPARTMENT: NHA