A horse from Cheyenne, Wyoming, has tested positive for rabies.

Myrna M. Miller, DVM, PhD, associate professor at the University of Wyoming and a veterinary virologist at the Wyoming State Veterinary Laboratory, in Laramie, confirmed that this is the first equine case confirmed in that state this year.

Rabies—a zoonotic disease that can be spread from animals to humans—is caused by a lyssavirus that affects the neurologic system and salivary glands. Horses are exposed most commonly through the bite of another rabid animal.

In horses clinical signs of rabies are variable and can take up to 12 weeks to appear after the initial infection. Although affected horses are sometimes asymptomatic, an infected horse can show behavioral changes such as drowsiness, depression, fear, or aggression. Once clinical signs appear, there are no treatment options