Published November, 2010

The University of Kentucky Veterinary Diagnostic Laboratory (VDL), formerly the Livestock Disease Diagnostic Center, recently announced a change in the type of samples required to perform a test for Neorickettsia risticii, the causative organism for Potomac horse fever.

In addition to blood samples, the VDL now requires a feces sample or fecal swab. Charges for the test remain the same at $35 for in-state samples and $52.50 for out-of-state samples.

The change comes in response to unpublished data from the University of California, which might suggest the additional testing could uncover positive results that could go undetected in blood.

VDL director Craig Carter, DVM, PhD, Dipl. ACVPM, said the change in procedure is intended to improve the sensitivity of the Neorickettsia risticii test.

Although the infection is not a widespread problem in Kentucky, Carter said it could occur near water. The rickettsia organism is thought to be transmitted by flukes (parasitic flatworms) and passed on to snails living in creeks or ponds.

"[The organisms] don't usually cause a massive outbreak," Carter said.

Often, he said, the symptoms of Potomac horse fever resemble a mild viral infection and include fever, depression, mild colic, and diarrhea. In severe cases laminitis, abortion, and eventual death can result, but many horses can clear the disease with few symptoms.

"The owner generally wants to know what causes [a horse's symptoms]," Carter said. "[The test] is part of the diagnostic procedure, and it's better if it's caught early."

For more information, visit the Veterinary Diagnostic Laboratory website.

Natalie Voss is a UK equine communications intern and recent graduate in equine science and management.