Potomac Horse Fever until proven otherwise

With warm summer months comes Potomac Horse Fever.

Photo by Karen Waite

Photo by Karen Waite

Although there is much to enjoy about the warm summer months, in many areas including Michigan, with warm summer months also comes Potomac Horse Fever. This potentially devastating Equine disease is often difficult to prevent, expensive to treat, and unfortunately, sometimes fatal. Michigan State University Extension educators warn you to watch for this disease on your farm.

Potomac Horse Fever is caused by the bacteria N. risticii and may present itself with a wide range of symptoms, and contrary to popular belief, diarrhea is not always one of those symptoms. The variety of symptoms often leads to owners spending valuable time treating for colic, or worse, wondering why their horse is simply depressed or off-feed. In addition, and particularly in hot weather, owners may not actually catch the first associated bi-phasic fever that accompanies the disease.

The causative bacteria of Potomac Horse Fever is associated with the life cycle of may flies, damsel flies, and other aquatic insects, and there are several strains of the disease that often are not addressed by available vaccines. Hence, should you have a horse that is depressed, goes off feed, demonstrates colic symptoms that do not respond well to typical treatment, or that displays explosive diarrhea, you should consult with your veterinarian regarding treatment for Potomac Horse Fever. From approximately May until after the first frost, it is reasonable to assume that a horse with these symptoms has Potomac Horse Fever unless or until proven otherwise.

Often, horses that are promptly treated with oxytetracline and non-steroidal anti –inflammatory drugs such as Banamine will respond well, and make a full recovery. Dehydration is also a concern, as well as in severe cases, laminitis or founder. While there is a vaccine for Potomac Horse Fever, it provides limited protection against the disease.

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