Dawson Creek Veterinary Clinic
238-116 Ave
Dawson Creek, BC V1G 3C8
(250) 782-1080
Dr. Zoë Ross, Dr. Andrew Hodges
Dr. Mike Ross, Dr. Cathy Saker
Dr. Heather Weaver, Dr. Sandy Jameson
Equine Herpes(Rhino)
Herpes viruses are very common in all animal groups. They are usually specific and do not transfer from species to species. Some examples of species specific herpes virus infections are human chicken pox and shingles, bovine IBR (Infectious Bovine Rhiniotracheitis), and canine acidophil hepatitis.
Equidae (horses, donkeys, ponies, mules etc) can be affected by different herpes viruses.- Examples of these are Equine Herpes Virus, of which there are 4 strains:
- EHV 1 causes Rhinopneumonitis and Rhino-myeloencephalitis
- EHV 2 rare, causes Rhinopneumonitis mainly in foals.
- EHV3 causes Coital Exanthema
- EHV4 causes Rhinopneumonitis
(click on thumbnail for larger image) A common name associated with these viruses is “RHINO”
Herpes in horses causes many different types of clinical disease.
- The first and most common is Rhinopneumonitis
This manifests itself as “Common Cold or Flu” type symptoms that are associated with upper respiratory tract disease.- Nasal discharge
- cough
- discharge from the eyes
- depression
- and lowered appetite are all common symptoms of this illness.
- Another disease in horses caused by herpes is Rhino-myeloencephalitis.
This is a debilitating and life threatening syndrome caused by EHV 1.
It causes neurological disease, which symptoms include:- in-coordination
- tremors
- paralysis
- and dribbling of urine
This disease can present after an episode of the respiratory form, Rhinopneumonitis, which was mentioned earlier. Additionally, EHV 1 can cause late term abortion or stillbirths in pregnant mares, which can result from recent exposure to the virus or from re-activation of a virus which was acquired months earlier.
- EHV 3 causes a disease in horses called Coital Exanthema which is a genital infection affecting both mares and stallions. This disease is spread venereally and causes blister like lesions on the genital regions.
Most herpes viruses have a unique ability to become latent (hide out in the body) and appear later. Transmission is accomplished by aerosol (droplet), and by direct or indirect (objects etc) contact. Equine herpes viral infections are significant, not uncommon, and circulate throughout the entire equine population. Therefore due to the latency, ease of transmission, and the ubiquitous nature of the virus (virus is everywhere in the equine population), attention is needed on how to prevent its occurrence.
When attempting to treat EHV one must remember that viruses do not respond to antibiotics. Therefore we usually treat these diseases by helping to lessen the symptoms (anti-inflammatories, fluids etc) or we let it “run its course” in strong, otherwise healthy patients.
Antibiotics are only needed if a secondary bacterial infection is diagnosed.
Prevention is the mainstay of controlling these diseases.
- Vaccination for EHV or RHINO is one measure we can take.
- Unfortunately, immunity from natural infection and also from vaccination is short lived.
- However, there are products on the market which prevent and lessen the symptoms of certain manifestations of herpes viral infections in horses.
- Pregnant mares should be given Rhino inoculations months 5, 7, and 9 of gestation to aid in abortion prevention.
- Other horses, including brood mares can also be given a four-way vaccine including EHV 1, and EHV4.
- Biosecurity and good management practices can also help control the impact of a Rhino outbreak.
We believe vaccination for Rhino or EHV is the most important inoculation we can give our horses. Anecdotally, we have seen far more equine deaths due to EHV in our practice than all the other diseases for which we commonly vaccinate our horses.
Consult our professional staff at the Dawson Creek Veterinary Clinic if you have any questions or want help setting up an equine vaccination strategy to suit you and your horses needs.