Horses travel more frequently ever than before, and it is time to think about infectious diseases more seriously.
What is Equine Herpesvirus and why is it so important?
If you compete with your horse regularly, you probably heard of Equine Herpesvirus infection from your vet, event regulatory body, or perhaps social media.
Equine herpesvirus (EHV) is an infectious virus agent which can cause respiratory disease that is almost indistinguishable from Equine Flu, making horses have fevers, snotty noses, dry coughs, or loss of appetite. However, EHV can cause more serious diseases including abortion in pregnant mares and neurologic disease. Horses affected by the neurologic form of EHV appear weak or wobbly hind legs often accompanied by urinary incontinence. This neurologic form of EHV infection is infrequent but can be deadly and therefore often makes the headline in infectious disease outbreaks in equine competitions.
An interesting point to note is that EHV is very common, and many horses will be exposed to the virus at some point in their life. Once a horse is infected with EHV, the virus is hidden in the horse’s body, and the horse can shed the virus to other horses without showing any outward signs. Virus shedding from infected horses tends to occur when their immune system is weakened, typically moving yards, or competing at a show.
How do I protect my horse?
Fortunately, EHV vaccines are available and are commonly used worldwide. However, vaccination does not completely prevent individual horses from infection, but it reduces the risk of infection and the severity of clinical signs if the horse is infected.
It is true that the EHV vaccination rate is lower in the UK than in other countries like the USA. Having practiced in both the UK and the USA, I believe this is reflected by cultural differences in the equine community, not because the disease is less common in this region. Therefore, EHV vaccination can be recommended to support individual horses’ well-being and to promote herd immunity of the horses in the county.
The vaccine should be given according to your veterinarian surgeon’s guidance
For non-pregnant horses, we recommend a primary course of two injections 4 to 6 weeks apart followed by a booster at 6-month intervals. You might wonder why it is more frequent than Equine Flu jabs. The answer is that both natural EHV infection and vaccination produce short-lasting immunity to the virus. Therefore, it is important to work with your vet and keep your horse up to date for EHV vaccines.
Herd immunity matters
The EHV vaccination is strongly advised in competition yards where horses travel often. Because any horses who have the virus in their body can shed it and spread the virus without any abnormal signs, it is important to understand that vaccinating all horses in the yard is the most strategic program to boost herd immunity in that group to reduce the chance of spread of the virus.
In summary, the benefits of EHV vaccination include.
- Reduced risk of viral infection in an individual horse
- Less severe clinical disease which means less time off from training and lower vet bill
- Reduced viral shedding by infected horses and therefore lower risk of virus circulation in the yard
Contact your vet and learn more about a plan to vaccinate horses in your yard today.
So Young Kwon
DVM, PhD, MRCVS, Dip. ACVIM
American Specialist in Equine Internal Medicine