neurologic | Horse Racing Free Tips

EHV-1 Outbreak In Europe Improving; Now Found Stateside

Europe has recently experienced one of the worst outbreaks of equine herpes virus (EHV-1) in decades. The neurologic form of the disease has forced the cancellation of international competitions in 10 European countries, including France, Spain, Portugal, Belgium, Italy, Austria, Poland, the Netherlands, Germany and Slovakia. The cancellations remain in place until March 28.

The initial case of EHV-1 was confirmed at the CES Valencia Spring Tour showjumping competition; 83 of the 752 horses at the venue showed clinical signs and are currently being treated for the disease. Six horses have died. An additional 15 horses are being treated at off-site equine clinics.

All horses that had been in Valencia since Feb. 1 are blocked in the Fédération Equestre Internationale (FEI) database. They cannot compete in any FEI-sanctioned event until they complete EHV-1 testing requirements. The FEI is the governing body for international equine competitions. The USDA's Veterinary Services Department has no current international movement restrictions in place.

In the United States, one 8-year-old mare in Ocala, Fla., was confirmed infected with EHV-1 on March 1 and placed in isolation. Florida Animal Health officials have implemented biosecurity protocols and are monitoring the situation. Horse owners and caretakers are reminded to take precautions before introducing new horses to an existing herd.

Monkey See, Monkey Do: Will A Foal Mimic A Mare’s Neurologic Behavior?

Foals often mimic the behavior of their dams, copycatting everything from grazing to running to rolling and more. But what happens when a foal is born to a mare that has neurologic issues? Will it mimic the odd behaviors?

The staff at Mid-Atlantic Equine Medical Center has cared for many foals born to neurologically compromised mares, said Dr. Rodney Belgrave. Often the mares are afflicted with equine protozoal myeloencephalitis (EPM). Belgrave says he has not seen foals mimic the neurological signs their mothers exhibit.

However, foals can be born infected with organisms that cause neurologic disease. One of the organisms that causes EPM can be transmitted to the fetus from the placenta. However, infected foals may not demonstrate neurological signs until they are three months old.

Foals can also be born with equine herpesvirus type-1 (EHV-1) that is contracted from the dam, but many don't show neurologic signs of this disease, either.

The most common cause of neurologic disease in foals is neonatal encephalopathy, which occurs when the fetus is deprived of oxygen. This can be caused by a bacterial infection called placentitis or by a difficult birthing process. Affected foals often don't develop neurologic signs until 18 to 24 hours after birth.

In both cases, the lack of oxygen leads to fluid build up in brain tissue. Though alarming, the prognosis for neonatal encephalopathy is very good if the foals are treated early and appropriately.

Report: 18 Horses Ill As EHV-1 Sweeps Through Canadian Riding Stable

Staff at Venturing Hills Equestrian, a riding stable in Luskville, Quebec, Canada, have been working around the clock to try to save the farm's horses, which have been affected by the neurologic form of the equine herpes virus (EHV).

There are multiple strains of the equine herpes virus, including EHV-1, which can cause respiratory disease, abortion, neonatal death or neurological disease. Some horses exposed to the virus will develop neurologic signs. There is no cure for the neurological symptoms associated with EHV-1.

On Feb. 3, a healthy 5-year-old horse that lived at the farm began stumbling when he walked. His symptoms worsened and he was euthanized later that day. Samples the attending veterinarian had taken were positive for EHV-1. The second horse that died from EHV-1 was a 20-year-old horse on Valentine's Day. Both horses had been vaccinated for EHV.

Currently, 18 horses are sick, two are dead and five remain healthy. To try to keep the remaining horses disease free, staff has completely quarantined the healthy horses from the ill horses by building stalls on the property. They have also instituted biosecurity measures like limiting the people who see the infected horses, wearing hazmat suits and steaming hay nets to kill the virus.

Owner Rae Becke believes a new horse that arrived at the facility on January 15 brought the virus with him from Toronto. She later learned that three horses at the horse's former facility had died from the virus on Jan. 29. Becke was never informed of the situation, so the new horse was turned out with Venturing Hills' equine residents.

Sidewinder Gait: A Poor Prognosis No Matter The Cause

Sidewinder gait in horses looks as odd as its name: An affected horse walks with his body and pelvis drifting out to one side; a severely affected horse may spin or circle with their hind legs moving in one direction and their thoracic limbs moving differently to compensate.

The disease is poorly understood, in part because it's difficult for the horse to stand in one place or symmetrically load his hind limbs. Sidewinder gait can come on gradually or suddenly.

Drs. Monica Aleman, Emily Berryhill, Kevin Woolard, Charlotte Easton‐Jones, Tania Kozikowski‐Nicholas, Sue Dyson and Isabelle Kilcoyne hypothesized that the gait might be caused by neurologic or musculoskeletal issues. They completed a retrospective study of 37 horses that were seen for sidewinder gait at the William R. Pritchard Veterinary Medical Teaching Hospital at the University of California, Davis, and the Centre for Equine Studies at the Animal Health Trust in Newmarket, England, between 2000 and 2019.

Some horses were excluded from the study for a variety of reasons; the scientists used a total 24 horses for the study. They found that the average age of the affected horses was 18.9 years old and that sidewinder gait came on suddenly in 10 of the cases.

In total, 16 cases were caused by neurologic issues, including dynamic thoracolumbar spinal cord compression (five cases), equine protozoal myeloencephalitis (four cases), thoracic myelopathy (four cases), gliosis (two cases) and thrombosis of thoracic spinal cord segments (one case).

Eight cases of sidewinder gait were caused by non-neurologic reasons: osteoarthritis of the hip (four cases), multiple displaced pelvic fractures (two cases), rupture of the ligament at the femoral head (one case) and severe necrotic damage of pelvic muscles (one case).

The scientists reported that though short-term improvement was reported, the sidewinder gait remained unresolved in all horses. The fatality rate was nearly 80 percent (19 of the 24 horses). Of the horses that lived, not one resumed the level of previous activity.

The researchers determined that sidewinder gait is normally seen in older horses of any breed or sex and can have neurologic or musculoskeletal origins. The condition has a poor prognosis for function and life.

Read the study here.