Steps To Take When EEE or Rabies Is Suspected in Horses

Oct 1, 2021 | Equine News, News

Dr. Keith Poulsen, Director, Wisconsin Veterinary Diagnostic Laboratory, contributed to this article

Eastern Equine Encephalitis (EEE) and rabies are zoonotic diseases, so when infection occurs, it places both human health and animal health at risk. Following are some commonly asked questions about EEE and rabies testing.

Why are all equine brains required to be tested for EEE prior to rabies?

Climate and arthropod vector population changes have increased the number of EEE cases in Wisconsin over the past four years. Because an EEE vaccine approved for human use is not available, the risk of laboratory-acquired zoonotic EEE infection requires the Wisconsin Veterinary Diagnostic Laboratory (WVDL) to rule out EEE prior to testing for rabies. Positive EEE equine brains are reported to the Select Agent Program at the University of Wisconsin-Madison and Centers for Disease Control and Prevention and are destroyed with no further testing.

Does requiring an EEE test slow down rabies test turnaround time? Horse owners need to know if they need to receive rabies prophylaxis!

There is an established collaborative workflow to test equine brains for EEE and rabies in a timely matter.

“The process involving the Wisconsin State Laboratory of Hygiene (WSLH), the Wisconsin Department of Health Services (DHS) and WVDL has worked extremely well since being implemented in 2017,” says Dr. Keith Poulsen, WVDL Director. “Inevitably, the need for testing arises on a Friday afternoon or the day before a holiday weekend. This is when strong communication from the veterinarian is key to get the head or brain to the WVDL to establish a priority need. While most of the heads received at the WVDL are rule outs and not strong suspects, when there are strong suspects, we need answers quickly.”

For high priority strong suspect cases, the WVDL will perform EEE PCR testing while the remaining brain tissue is couriered to the WSLH. The WVDL communicates with DHS and the Department of Agriculture, Trade and Consumer Protection, who make the call on the need for expedited testing out-of-hours at WSLH.

“There is very little to no delay in rabies testing for these cases – assuming there is clear communication from the submitting veterinarian,” says Dr. Poulsen.

Getting a brain out of a horse head is hard, especially without damaging the tissue. How can I get the intact tissues to the WVDL fast?

The WVDL understands that removing a brain from a horse head with no human exposure is tough to do well. They also understand that shipping a horse head is not simple.

The WVDL offers brain removal for all large animal species and prefers to remove the brain themselves to ensure adequate sample quality and high biosafety for all involved. The WVDL is open six days per week and accepts UPS Saturday Delivery. Backup mechanisms for out-of-hours sample submissions are available on a case-by-case basis.