According to  Dr. Michael Radebaugh, the Maryland State Veterinarian & Chief of Animal Health, Potomac Horse Fever has been confirmed in five Maryland horses this summer, as of press time.

The first two horses were confirmed in Frederick County in late July; one of them died. Since then and as of press, there have been three more confirmed cases, one each in Frederick, Montgomery and Washington Counties. All responded well to treatment.

According to Dr. Radebaugh all five horses had been vaccinated for Potomac Horse Fever. Samples have been sent to University of California, Davis, School of Veterinary Medicine to determine which of the 11 strands of PHF these might be, with the hope that useful data will be yielded for the vaccine manufacturers.

In the meantime, until the first frost, all Maryland horse owners (but particularly those whose horses graze near rivers, creeks and streams) should be extra vigilant for early signs of the disease. Clinical signs include mild to severe fever, diarrhea, loss of appetite, laminitis, and mild colic. Potomac Horse Fever is most commonly contracted by horses that ingest infected aquatic insects such as caddisflies and mayflies.

“Potomac Horse Fever surfaces here every few years,” said State Veterinarian Michael Radebaugh. “Because it can be fatal, we urge horse owners to pay special attention to how their horses feel. The vaccine for Potomac Horse Fever is not always effective, so we encourage owners to contact their veterinarian sooner rather than later if they suspect anything, even if the horse has been vaccinated.”

Potomac Horse Fever cannot be transmitted from horse to horse, and people are not at risk. Potomac Horse Fever is a reportable disease. Click here for a complete list of reportable equine diseases.

To Our Readers: Strangles is NOT a reportable disease. The Equiery will only report on cases of strangles when and if the barn owner and/or manager makes the decision that it is better to be pro-active in regards to information management, in order to mitigate rumors.