Equine Influenza By Brian S. Burks, D.V.M., Dipl. ABVP- Board Certified in Equine Practice Hippocrates first described a disease resembling influenza around 412 B.C. It continues to cause significant morbidity and mortality in both humans and animals. Equine influenza is the most common cause of viral respiratory disease. Outbreaks can occur when horses are housed in close contact at race tracks, sale barns and horse shows. The virus spreads when horses cough or sneeze on other horses. Contaminated buckets, clothing, and grooming supplies may also aid transfer to other horses. Clinical signs of equine influenza include fever, partial or complete anorexia, lethargy, watery nasal discharge (it may thicken if secondary bacterial infection occurs) and coughing. Uncomplicated cases resolve in one to two weeks, though a cough can persist longer. Complications may be severe and include bacterial pneumonia, myositis (muscle inflammation) myocarditis (heart muscle inflammation), and limb edema (swelling). Prevention is through biosecurity and vaccination. Biosecurity includes cleaning tack and grooming utensils, as well as buckets. Clean clothing should be donned after handling a sick animal. Do not share anything with another person at any horse show. It is also a good idea to re-clean the stalls at a show facility (fairgrounds). Clean out any organic material (bedding, cobwebs) and spray the walls and floor with 10% bleach water. Lime stone can be put on the floor to further help eliminate any viruses or bacteria. Vaccination is the second most important way to prevent equine influenza. There are several types of vaccination available; killed virus, modified-live virus, and chimera vaccines. The first type must be used frequently to have any affect- every 2 months. The latter two are much more protective and last for 6 months. The intra-nasal Fluavert has a very quick protective time- as little as three days, where the killed vaccine won’t be protective for 2 weeks, as it stimulates the anamnestic response. Influenza vaccines often undergo antigenic drift, the accumulation of small changes over time. This new virus might not be recognized by the body, accounting for repeat episodes of influenza. The process is much slower for equine influenza compared to human influenza strains. Antigenic drift may account for vaccine failure, but sometimes influenza strains from other species may infect a different species. For example transmission of H5N1 and H7N9 bird flu strains to humans. In the United States, equine H3N8 influenza to dogs has occurred, creating a novel canine respiratory pathogen. The reverse has not been found to occur naturally and only very mild clinical signs have been experimentally induced. Influenza represents a significant infectious disease due to antigenic shifts and its occasional ability to cross species. The virus causes fever, nasal discharge, and lethargy, representing a major source of morbidity and the inability to ride the horse. Vaccination and biosecurity are the best ways to prevent this disease. Dr. Brian S. Burks, Dipl. ABVP- Board-Certified in Equine Practice, is the owner/veterinarian at Fox Run Equine Center, a 24-hour medical-surgical center near Pittsburgh, Pennsylvania. He is Board Certified by the American Board of Veterinary Practitioners (Equine Practice). This certifies him as an expert in all categories of equine practice. He enjoys the diagnostic and treatment challenges of internal medicine, neonatology, surgery, and ophthalmology. Find out more and contact us at: foxrunrequine, [email protected] 724-727-3481 Fox Run Equine Center
Posted on: Fri, 28 Nov 2014 22:00:01 +0000
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