State veterinarian alerts horse owners to cases of Potomac horse fever in Tennessee


(July 28, 2022) -The State Veterinarian is advising horse owners to be alert after another confirmed case of Potomac Horse Fever (PHF) in Tennessee. This week’s detection in a horse in Wayne County is in addition to two cases earlier this month in DeKalb and Rutherford Counties.

“We are seeing an uptick in PHF cases in Tennessee compared to previous years,” State Veterinarian Dr. Samantha Beaty said. “This disease typically coincides with hot weather, which is why it’s common in the summer and early fall. Vaccination and minimizing risk can help horse owners protect their animals.”

Aquatic snail larvae and other intermediate hosts including flies are the source of the Neorickettsia risticii bacteria that causes PHF. Horses may be exposed when drinking from creeks, rivers, or ponds and can then suffer from anorexia, diarrhea, colic, fever, and laminitis. If your horse presents symptoms, contact your veterinarian immediately. If left untreated, PHF can be fatal.

There is a vaccine for PHF. Although it may not fully prevent infection in all cases, it does provide protection and minimizes the severity of disease if a horse is infected. Horse owners should consult their veterinarian to establish a vaccination schedule.

Potomac horse fever has not been found to directly transmit from horse to horse nor is it a known threat to human health.

Dr. Beaty suggests these practices to reduce exposure:

  • Provide horses with clean, fresh drinking water at all times.
  • Eliminate or at least minimize horse access to creeks, streams, or ponds
  • Discuss vaccination options with your veterinarian.
  • Eliminate standing water sources where disease-carrying insects may gather and breed.
  • Turn off insect-attracting stable lights at night.

The State Veterinarian’s office seeks to prevent the spread of disease through import and movement requirements, livestock traceability, disaster mitigation, and the services of the C.E. Kord Animal Health Diagnostic Laboratory.


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