We all know how achy, horrible and sick we feel when we have the flu; can you imagine how bad it must be for a horse? Horses, just like people, can come down with influenza that is caused by a virus. There are other viruses besides the influenza virus that causes flu-like symptoms in horses and they include Equine Herpes virus, Adenovirus and Rhinovirus, but the influenza virus typically produces more severe respiratory symptoms that may have more likelihood of causing secondary bacterial problems.
The first symptoms of the equine influenza virus are usually a mild to low grade fever, general depression, lack of appetite and energy and some discharge from the nostrils. Within two to five days these symptoms have usually become more pronounced and often include a very deep, dry, hacking cough as well as thick discharge from the nose, high fever as well as food refusal. Most horses will not want to exercise and should not be stressed or worked during this time.
Since equine influenza is a virus, there are no medications that can cure the condition, the horse must develop antibodies and fight off the viral infection. The good news is that typically most horses will do just that in 2 to 3 weeks, provided they are kept warm and dry, provided with lots of fresh, clean water and kept on high quality feeds and supplements during their recovery. Horses that are left outdoors in cold or wet weather, have poor quality feeds and do not have proper care are far more likely to develop serious secondary bacterial infections in the respiratory tract that are more problematic than the virus itself. Antibiotics may be used to treat the secondary viral infections and should be started as soon as the problem is identified.
Equine influenza is very contagious and is most problematic for horses that have not been exposed to the virus before. Infection is through contact with body fluids from an infected horse either through the air when the horse coughs or through touching waterers or feed that an infected horse has had contact with. If the horse is healthy and well kept it is likely that they may be able to fight off the virus with very few symptoms, but horses in poor condition, foals, pregnant mares and older horses may be at greater risk.
Isolation of infected horses as soon as possible is key in preventing a breakout in the stable or pasture. Burn all bedding and disinfect any tack and feeding buckets. Keep waterers isolated and separate from the rest of the horses. Vaccinations can be very effective in minimizing the effects of the virus although they do not prevent the horse from actually catching the virus, rather they allow the antibodies to already be developed within the horse to fight back. Horses that are in contact with unknown or strange horses in shows and competitions or those that are boarded out should be vaccinated routinely for equine influenza if it is problematic in your area.