A highly contagious equine virus is causing neurological problems in an "unusual" number of Minnesota horses, and at least three have been euthanized because of it, animal health officials said Thursday.
Despite the symptoms experienced by those horses, the strain of the equine herpesvirus-1 (EHV-1) is not the more dreaded neuropathogenic strain that can be far more lethal.
"This is not the hot neurological virus that scares people to death," said Dr. Paul Anderson, who oversees the equine program for the Minnesota Board of Animal Health. But even this non-neuropathogenic strain can be devastating, he said.
So far, the state has had three confirmed cases of the virus. Two of those horses were euthanized because they couldn't get up, Anderson said. The other is recovering. Tests are pending on four other horses that showed symptoms of the virus. Three of those horses are recovering; one was euthanized, he said.
"This is a common virus that's in the horse population normally," Anderson said. "What is a little unusual is this number of horses with central nervous system signs."
The virus spreads when the horse breathes, spreading easily among horses that come in close contact, he said. The virus is specific to horses and isn't spread to humans or other animals.
"Most horses that get it don't display any symptoms at all," Anderson said. The virus can cause respiratory problems and abortions. "A small percentage can get this neurological form that involves the brain stem and shows central nervous signs, such as problems with coordination and trouble urinating. Occasionally it gets bad enough where there is death," he said.
The more dreaded neuropathogenic strain has shown up in Minnesota in past years but so far not this year, Anderson said.
The infected Minnesota horses have come from various parts of the state — north of the Twin Cities to the Owatonna-Winona area. Some have been to shows; others haven't, Anderson said. "There's no common thread," he said.
"We don't want to overly alarm people, but we want them to be informed," he said. "My best advice is to check in with your vet and decide whether to travel with your horse."
Some people have voluntarily canceled horse events "until this thing calms down," Anderson said.
"There are enough horses involved that the equine community is concerned," he said.
Symptoms include fever, weakness, incoordination and problems with urination. A vaccine is available but it may not protect horses from all strains of the virus, including the neuropathogenic strain.