Equine Herpes Virus (EHV):
What You Need to Know to Protect Your Horse
SmartPak strongly encourages you to consult your veterinarian regarding specific questions about your horse's health. This information is not intended to diagnose or treat any disease, and is purely educational.
What is EHV?
EHV refers to Equine Herpes Virus and it is a family of viruses named by numbers that commonly infects horses worldwide. In fact, the great majority of horses are exposed to EHV-1 early in life and develop a latent infection, meaning they carry the virus their whole lives without showing signs of illness. The virus seems to be “reactivated” from its dormant status under periods of stress such as travel and competition. Nine different equine herpes viruses have been identified and numbered, but the focus is on EHV-1 and EHV- 4 because those are the two that can result in serious disease in the horse.
Signs & Symptoms
Equine herpesvirus can cause disease in three separate systems: respiratory, neurologic, and reproductive, and therefore the clinical signs can vary. In the case of respiratory disease, a fever in two phases is common. That is, on Day 1 or 2 of the infection and again on Day 6 or 7, rectal temperature may reach 102 – 107 °F. Next, the horse may develop a clear and colorless discharge from the nose as well as the eyes. The horse may or may not cough. Many develop swollen lymph nodes, lose their appetite, and act depressed or lethargic. Swelling of the limbs has also been observed.- Weakness, stumbling, incoordination (“ataxia”)
- Leaning against a fence or wall to maintain balance
- Dog-sitting
- Loss of skin sensation around the tail and hindlimb areas
- Loss of tail tone
- Bladder dysfunction (urine dribbling or inability to urinate)
- Lying down and being unable to rise (“recumbency”)
- Complete paralysis
Diagnosis & Treatment of EHV
Diagnosis of equine herpesvirus is relatively straightforward and is based on clinical signs along with virus identification from either a nasal swab or a blood sample. Alternatively, two blood samples taken 2-3 weeks apart can also be used to diagnose an EHV infection based on a significant increase in antibody titer. Because it is important to know what a horse, herd, or barn is infected with in order to provide appropriate, early treatment as well as to limit an outbreak, it is recommended to contact a veterinarian for physical examination and diagnostic testing upon discovering any FUO (fever of unknown origin), respiratory signs, or neurological signs. The vet can also provide guidance on isolating sick horses and implementing other biosecurity protocols on the farm.
Management & Prevention of EHV
Preventing an outbreak of the respiratory, neurologic, or reproductive forms of equine herpesvirus relies on a two-pronged approach that is developed with the farm veterinarian: 1) appropriate vaccination and 2) common-sense biosecurity.
Vaccination
