Odds On Racing - Harness Racing

EHV-1 Balmoral Outbreak Update
Update for May 1, 2007

All of trainer Nelson Willis’ horses are doing well after being quarantined last week due to an outbreak of Equine Viral Herpes (EVH-1), according to Illinois Racing Board chief Veterinarian David Fitzpatrick, DVM.

“Nelson’s horses are doing very well with no new temperatures since last Thursday (April 26),” Fitzpatrick reported. “The two horses of his that showed signs of neurological problems are responding well to treatment and I look for them to come out of this in fine shape.”

Fitzpatrick stressed that all horses on the Balmoral and Maywood Park backstretches have either been vaccinated, or are in the process of being vaccinated. The Willis’ horses have since been moved to a private quarantine area off of the Balmoral Park grounds.

“Right now we have no other horses who have spiked temperatures or who have showed the clinical signs of the disease,” Fitzpatrick said. “Everyone at Balmoral and Maywood are in the process of either updating their vaccines, or are being vaccinated for the first time.”

As of May 1, 2007 all horses racing in Illinois are required to have the vaccine within the last 60 days, with no exceptions, Fitzpatrick said. Horses without the proper paperwork verifying vaccination will be denied racing privileges at both tracks.

“It’s paramount, to control the spread, to have all horses stabled on the grounds or shipping in, to be vaccinated, with no exceptions,” he said.

EHV-1 is an airborne virus that is easily spread from one horse to another. To date there have been outbreaks in Florida, California and on the East Coast.

“Horsemen who vaccinate might see a elevated temperature in their horses in the first 24 hours following the vaccination, but that’s normal,” Fitzpatrick noted. “It’s also just as common for horses to show no side effects from the vaccine.”

To date, no horses have died or suffered debilitating effects from EHV-1 at Balmoral, Maywood or any other Illinois raceways, including the Willis’ horses, Fitzpatrick said.

Horsemen need to vaccinate their horses against EHV-1 every 60 to 90 days, Fitzpatrick stressed. There is currently no vaccine against the neurological side effects of EHV-1, but vaccinating a horse does decrease nasal shedding, which then helps to contribute to decreased contamination levels.

EHV-1 primarily causes respiratory illness and abortion in pregnant mares, but in some cases can cause neurological effects to occur. The neurological signs can include ataxia, urinary bladder atony and reduced tail tone. In the most extreme cases, horses are unable to stand and have a very poor recovery prognosis.

EHV-1 is a global equine disease to which nearly all horses ages 2 and older have been exposed. Following the initial exposure, EHV-1 has the ability to develop into an inapparent, latent infection. It can therefore reside silently in horses as a persistent infection, providing a reservoir for continual transmission of the virus.

The incubation period of EHV-1 is one to ten days, but signs usually emerge in one to three days. Viral shedding occurs for seven to ten days, but can occur up to 28 days from the original onset of symptoms.

Treatment of EHV-1 is supportive and tailored to each individual. When an outbreak occurs, horses should have their temperatures monitored at least twice daily, and all horsemen should be diligent in not letting their horses co-mingle in all situations.