What is Equine Herpesvirus?

What is Equine Herpesvirus? 

Equine Herpesvirus is a viral infection that affects either the respiratory, reproductive or neurological systems of a horse. It is one of the more common viral infections seen in horses. Although there are nine strains of the virus, only 2 cause significant diseases, EHV1 and EHV4. Most horses are exposed to the virus at some stage, but it remains dormant until triggered. It can cause respiratory disease, abortions in mares and neurological symptoms. 

Symptoms 

Signs may vary depending on what system of the body is being affected by the virus. 

• Respiratory 

• High temperature 

• Nasal discharge 

• Loss of appetite 

• Depression and lethargy 

• Swollen lymph nodes 

• In some cases, limb swelling and a cough 

• Neurological 

• High temperature (usually prior to further symptoms developing) 

• May get a nasal discharge 

• Weakness in back half of the body (ataxia) 

• Stumbling/leaning/dog sitting 

• Loss of feeling around back end and tail 

• Lack of bladder control 

• Lying down, not being able to get up, to complete paralysis 

• Reproductive 

• Unexplained loss of foal at about 7-10 months gestation 

• In most cases no clinical signs are visible 

• Affected mares that do give birth, their foals may only survive a few days 

Diagnosis 

If you suspect your horse may have the virus, it is important to contact your veterinarian immediately. They can make a clinical diagnosis, and confirmation via nasal swabs and blood test results. They will advise you on the care and treatment of your horse and any bio security protocols to help keep the virus from spreading. 

Treatment and Recovery  

Recovery times will vary depending on type and severity of the virus 

• Respiratory – As this is a virus and not bacterial treatment, recovery generally involves rest and good care. Non-Steroidal anti-inflammatories may be issued, whilst staying well hydrated and good nutrition are best practice. In some cases, a secondary bacterial infection can develop which may require antibiotic treatment. Recovery times will depend on severity and the horses immunity response. 

• Reproductive – Generally doesn’t require a lot of treatment, possibly some general reproductive work to ensure the mare has cleaned up properly after birth. Mares will normally recover completely and have no long-term affects. 

• Neurological – Treatment will vary depending on how severe the symptoms are. Mild cases will need daily care and monitoring, more severe cases will need full time nursing. Recovery also depends on how much the horse was affected. Mild cases should recover in a few weeks, however those with more chronic symptoms may never recover.  

The positive thing is the EHV1 and EHV4 virus risk can be reduced with good management. There are vaccinations available to help protect your horse and introducing good biosecurity measures also help minimise the risk. 

•  Contact your veterinarian about a vaccination program for your horse or farm. 

• Isolate new horses to the property on arrival. The incubation period for the virus is generally 2-10 days but can be as long as 14 days.  

• Try to avoid mingling with other horses if out competing or attending lessons. Be extra cautious of symptoms in horses that do have high contact with outside horses. 

• Check temperatures regularly. 

• Clean and disinfect surfaces sick horses may have been in contact with. Virkon S is highly effective and a suitable option for disinfecting.  

• If you have broodmares, keep them well away from young horses, horses that are unvaccinated, or have been off property.