West Nile virus has struck down a horse in the Westman area. In this fast-moving case, the animal had to be euthanized within 12 hours of the first signs of illness.
Dr. Everett More, senior equine veterinarian with the Virden Animal Hospital was on the case.
He said, in an interview, the horse’s owner had observed the four-year-old animal at close quarters in the evening, and the animal appeared normal. But just 12 hours later, symptoms appeared.
At noon on July 23, the animal was examined by Dr. More, samples were taken for laboratory analysis and the animal was treated. At that time, although it was lying down, it was quiet and eating a little, the veterinarian explained.
However, later in the day the horse began to thrash violently and the decision was made to euthanize him.
With a weekend on the horizon, blood samples and swabs were sent to a lab and came back within a week.
More was considering a possibility of four different diagnoses. WNV was not at the top of More’s list, because there had not been a lot of mosquitoes. “We haven’t heard a peep about West Nile,” he said, stating it was his “number two concern.”
What should horse owners look for?
Apparently the range of symptoms is extreme, from slightly depressed to the vast majority who become uncoordinated. “Back when we saw 100 cases, before there was a vaccine, horses appeared simply a little bit dull, and others were like this one.”
The vet, has seen more than his share of horses over the years. But this case was a bit unusual. “That’s the other thing; it’s not the norm that they go down this quickly.”
Yearlings to two-year-olds and aged horses are the most likely to succumb to the virus. This four-year-old horse was unvaccinated this year.
Dr. More recalls an outbreak of WNV some years ago, (about 10 years ago). Out of 100 horses the animal hospital diagnosed, 50 percent lived. He says there is no anti-viral to treat the animals, but nursing care and administration of anti inflammatory drugs, can support the animal in its fight against the disease. It is important to have sick animals diagnosed by a veterinarian. “The number one concern with uncoordination, or depression, is rabies. You need to have that investigated because of the disease being untreatable for humans.” In this case, the disease progressed so rapidly, the vet did not suspect rabies.
The similar disease, Equine Encephalitis, known as sleeping sickness broke out in western Manitoba among horses some 35 years ago.
Now, many horses are receiving a combination vaccine to protect against tetanus, sleeping sickness and WNV. There are also separate vaccines for these illnesses. WNV component adds significantly to the cost. “You take a look at the incidence (of WNV), and weigh the cost,” says the veterinarian. More has seen the deadly WNV in a family horse. “He came through the disease, but he was never as athletic. We knew him before and after. A barrel horse became a safe, trail riding mount.”
Humans and other animals can contract West Nile. However, the horse does not pass the virus on. It is an end host, and only vaccination protects the horse explains the Virden veterinarian.
It is not a reportable disease and at this time Manitoba Health does not seem to be recording dead corvid (birds from the crow family) counts.
West Nile virus (WNV) is a relatively new disease in Manitoba, found here in 2002. The virus is transmitted by the Culex mosquito, an uncommon variety. According to Manitoba Health information, most people who are bitten by an infected mosquito do not become ill and for those who do, the symptoms are usually mild. The number of serious WNV cases in Manitoba has ranged from one to 72 per year since 2003 with the number of WNV-related deaths per year has ranged from zero to four (www.gov.mb.ca/health/wnv/stats.html).