Rabies Detected in an Illinois Horse

Illinois agriculture and health officials announced last week that a LaSalle County horse tested positive for rabies at the Illinois Department of Agriculture (IDA) laboratory in Galesburg on Dec. 10, 2004. Eleven people received preventive rabies treatment following exposure to the horse on the small family farm at which it was stabled.

According to state public health veterinarian Connie Austin, DVM, MPH, the horse, which was less than two years old, began showing clinical signs of illness on Dec. 4 and was euthanized on Dec. 9 after its condition deteriorated. Results from the state laboratory indicated rabies, and brain samples were sent to the U.S. Centers for Disease Control and Prevention, where the virus infecting the horse was identified as a skunk strain of rabies. "It was important to us to find out whether it was the bat strain or the skunk strain, since the skunk strain can result in epidemics in the skunk population which can spill over into other animals." said Austin. Any wild animal, like a raccoon, skunk, fox, coyote, or bat, can have rabies and transmit it to people. Currently, bats are the primary mammal positive for rabies in Illinois.

Mark Ernst, DVM, acting assistant bureau chief for animal health with the IDA, described the range of clinical signs that can be seen in an equine rabies case. "You can have the whole gamut--you can go from aggressive behavior to just an animal that is acting depressed. And certainly any abnormal neurological signs would tip you off too." Additionally, progressive gait abnormalities, incoordination, lameness, colic, hypersensitivity, or fever could be indications of rabies, all of which can complicate diagnosis.

What made this case difficult to diagnose, according to Austin, was that this case "didn't have the typical rabies presentation. I thought (the veterinarian) was very astute to be able to diagnose rabies. The horse didn't want to eat and had severe constipation, which he knew could be signs of rabies. He decided to submit the horse brain for rabies testing because he was concerned that rabies was a possibility.

"The owners did report that there was a skunk walking around in daylight hours which is not normal behavior for a skunk," added Austin, indicating the probable source of the illness was a bite from a skunk.  However, the owners did not notice a bite wound on the horse during the preceding weeks and months.

Exposure is problematic. "Since the horse was not eating, a lot of people had contact with saliva and looked in its mouth," said Austin. "Some of the vet staff, the owner, and family members had to be treated. Usually (a person would get the disease via) a bite, but if you did get saliva into eyes, mouth, or an open wound, there is a potential for transmission."

Acting state veterinarian Colleen O'Keefe, DVM, has reminded owners to consult with their veterinarians about vaccinating their horses, along with their cats and dogs.

The Illinois Department of Public Health has asked asking local animal control agencies and the Illinois Department of Natural Resources to increase skunk surveillance in a three-county area including La Salle, Lee, and DeKalb. This surveillance will be used to determine if the virus is circulating widely in skunks in this area of the state.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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