Four horses euthanized last month had contracted the rare neurological form of EHV-1, the equine herpes virus, the North Carolina Department of Agriculture and Consumer Services confirmed.
After receiving reports of the deaths, state officials began investigating the virus that made the horses so ill. The affected horses showed symptoms of fever and were extremely uncoordinated, but it was not immediately apparent that the horses had neurological EHV-1.
You cant distinguish it from rabies or triple E (eastern equine encephalitis virus that affects a horses brain), or West Nile virus, said Dr. Tom Ray, director of animal health programs for the states agriculture department.
Officials sent samples to a testing lab in Ames, Iowa, for a verification of the virus. The results returned on Dec. 23, and the agriculture department immediately quarantined J&H Stables, where the cases allegedly appeared.
All 29 horses at the stables were exposed to neurological EHV-1 and are being monitored. The boarding facility will remain under quarantine for 28 days after the last signs of fever disappear from any of the horses.
J&H Stables offers boarding, western riding lessons, summer camps and other family-oriented horsemanship activities on 66 acres in northwest Raleigh. According to their website, the fully-booked facility has been in business since 1967.
Contagious only to horses
In its normal state, EHV-1 affects a horses respiratory tract and sometimes causes miscarriages in pregnant mares. It is extremely contagious among horses, but it is not communicable to humans or animals such as cattle.
Its like the common cold we get as humans, Ray said.
But a rare mutation can turn it into a killer the neurological form that leaves horses weak, uncoordinated and unable to control bladder function. It slowly paralyzes them until they cannot stand.
At that point, it becomes apparent they are not going to recover, and it is just more humane to euthanize them, Ray said.
Fever is the first sign of the neurological EHV-1, and Ray recommends that horse owners check their horses temperatures twice a day if they suspect their stable is carrying the virus. Horses get the virus from other horses through mucous, so he said it is crucial to not share tack, water buckets or food bowls.
Horses do not always die from neurological EHV-1. One horse displayed similar symptoms as the other four which were euthanized, but it responded well to treatment and is now completely normal, Ray said.
When a caretaker discovers the symptoms early on, veterinarians can treat the fever and administer pain relief. Most horses in Wake County that have shown signs of the virus have responded well to that treatment, according to Brian Long, director of public affairs for the states agriculture department.
Theres no magic pill you can give for it, so you have to treat the symptoms, Long said.
Mutation attributed to stress
Experts say that stress causes the virus to mutate. But stress can be hard to define for a horse, which might be stressed out by other horses or unfamiliar routines.
A wave of the neurological form of EHV-1 washed over the country in 2011 after first appearing at a national equestrian championship in Ogden, Utah. The 400 horses and riders that attended from around the country may have experienced high amounts of stress in unfamiliar environments and routines.
The mutation is rare, but it is starting to appear more frequently. In 2013, the American Quarter Horse Association reported cases in many states including California, Tennessee, Illinois, Utah, Florida, New Jersey and Montana.
The first case of the neurological form of EHV-1 in North Carolina appeared in December 2011, when a horse from Virginia contracted the virus in Rockingham County. The owners immediately got treatment for the horse and returned to Virginia with it under quarantine.
It was the family pet, and they werent going to put it to sleep, Ray said.
The horse lived but retained neurological problems.
Aside from the four horses euthanized in December, the outbreak is under control. Horses are responding well to treatment, and the virus has not continued to spread, according to Long.
So far, we have not heard of any other suspected cases, and thats a good sign, he said.