POTOMAC HORSE FEVER (PHF) is a serious equine disease now recognized throughout the United States. Apparently, a diseased horse had ingested the bacteria, Neorickettsia risticii, previously called Ehrlichia risticii. Once ingested, the organism multiplies in the intestinal tract causing inflammation. The clinical signs associated with PHF include fever, depression, poor appetite, and most often diarrhea. Some horses will founder, develop swelling in the lower limbs or body wall. Pregnant mares can abort. An encouraging note is that not all exposed horses develop the disease.

Areas endemic with PHF, or if conditions change in your area that trigger new cases of PHF, the consideration of vaccinating your horse against PHF is warranted. Vaccines contain a single strain of PHF, therefore, the efficiency of the vaccine will be dependent on the type of strain in your area. There have been different strains of PHF isolated from sick horses in different locations. Merial Equine POTOMAVAC has shown to be very effective in protecting horses against mortality and clinical symptoms.

Dr. Richard Porter