A look at the most common contagious diseases that can affect horses, and what you can do to reduce your equine companion’s risk.

Given the COVID-19 pandemic, contagious diseases are on people’s minds more than ever before. With social distancing, frequent hand-washing and disinfecting becoming the new norm, you may be wondering about the likelihood of your horse contracting a contagious disease, and how to prevent spread if there’s an outbreak at your barn.

What are the most common contagious diseases seen in horses?

The most common horse-to-horse outbreaks seen in barns are coronavirus, influenza, and strangles (caused by a bacteria called Streptococcus equi).

Coronavirus

Coronaviruses are RNA viruses that belong to the Coronavirdea family. Corona means “crown” in Latin, and describes the crown-like appearance of the club-shaped viral spike peplomers (proteins) that surround the virion when viewed with an electron microscope. There are a number of different coronaviruses that can cause GI and respiratory disease in horses. At the time of this writing, there is no evidence that COVID-19 (the strain causing the current pandemic in humans) can be passed to horses. The most common signs of coronavirus infection in horses are lack of appetite, fever and lethargy, with loose stool and colic being less common symptoms.

To prevent your horse from coming down with coronavirus if there’s an outbreak at your barn, it is important to isolate infected horses. These types of viruses can be killed using disinfectants such as rubbing alcohol, povidone iodine and hydrogen peroxide. Sterilizing the stall, tack and equipment that was exposed to an infected horse can aid in stopping the spread. Workers can also decrease the spread of the virus by disinfecting their hands and clothing after handling an infected horse.

Influenza

This is the most common cause of respiratory disease in horses around the world. The equine influenza virus has a short incubation period of 48 hours. The majority of horses who are infected (60% to 90%) will show symptoms such as nasal discharge, coughing, fever, and sometimes weight loss. The mortality rate is normally low, at less than 1%. Infected horses will most often self-resolve in one to two weeks. Similar to coronavirus prevention, you should isolate infected horses and sterilize the area and equipment. Unlike coronavirus, there is a vaccine for equine influenza.

Strangles

This disease is caused by a gram-positive bacteria called Streptococcus equi, and is easily recognized by purulent nasal discharge and swollen lymph nodes (which may rupture). Strangles is highly contagious and spread by horse-to-horse contact, or by contact with feeders, stalls and objects exposed to the discharge. Infected and exposed horses should be isolated for three weeks, and strict sanitization protocols employed for any equipment used on infected horses. Caretakers must use extreme caution to prevent spread to non-infected horses. A vaccine is available for equine strangles.

Supporting your horse’s immune system

Be sure to consult your veterinarian to determine the best ways to prevent infectious disease in your own horse.

• One of the best methods of preventing contagious diseases in your horse is to boost her immune system by introducing beneficial supplements and foods into her diet. Supplements such as vitamins A, E and C, Omega-3 fatty acids, garlic and turmeric can help optimize the horse’s ability to fight off disease. Vitamin and mineral deficiencies can have a negative impact on her immune function, so it is important to give your horse a balanced diet.
• Providing your horse with bodywork sessions (e.g. massage, chiropractic, acupuncture and acupressure) is a fantastic way to increase her immune function while also relieving pain. Both chiropractic and massage have been shown in peer-reviewed studies to increase white blood cell production (cells that fight off pathogens) and decrease cortisol levels (stress hormone that suppresses the immune system).
• Take to your veterinarian about titer testing to determine if vaccines are warranted. This helps decrease the risk of over-vaccination, which can cause unnecessary stress on your horse’s immune system.

A healthy immune system is the best defense against disease!