Despite the onset of fall, the state veterinarian says horses still need to be vaccinated against the West Nile virus.
The Associated Press reports that at least 15 horses in the state have been diagnosed with the virus this season at the Wyoming State Veterinary Laboratory.
The Wyoming Livestock Board veterinary staff recommends that owners vaccinate their horses if they have not done so already. Jim Logan is the state's veterinarian. He says the West Nile season can last until a hard frost.
According to the veterinarians, horses are far more affected by the West Nile virus than other livestock and domestic animals.
Initially, the virus comes on with flu-like symptoms, where the horse becomes lethargic and depressed, then the animals become weak, have seizures and struggle with coordination. Of those that become ill, about 30 percent die or are euthanized.