Prevent equine diseases

Horse shows are a huge part of the horse industry. Some competitors travel to multiple arenas, grounds, and private facilities each year, some across state lines or even national borders. Those competitions can be festering ground for many equine diseases that a horse owner can unknowingly bring back to their own barn. As such, owners should take steps to prevent equine disease spread during and after competitions.

In a new study from Kelsey Spence, PhD, and her colleagues from the University of Guelph’s Ontario Veterinary College, in Canada, computer simulation models were used to assess the risk of disease spread from horse events and the effectiveness of various control protocols in the face of the outbreak at a home stable.

“A computer simulation model is essentially a virtual representation of a situation we could see in real life,” said Spence. “We end up with a virtual scenario that tries to represent what we see in real life.”

They used equine influenza, a well-researched virus, as the disease model.

Study Organization

Equine influenza is a very well-researched virus. Primarily affecting the respiratory system, influenza spreads through direct (physical) contact with infected horses. Influenza can also infect horses indirectly via fomites (contaminated tack, equipment, stalls, etc). Previous research suggests that it might take up to five days for an infected horse to show clinical signs of influenza. In this simulation the researchers assessed only spread through direct contact.

The investigators designed the computer simulation model to represent a two-day show in Ontario, and tracked horses that attended the event and those that did not attend but were co-housed with attendees returning from the show. The simulation was performed for 1,000 cycles. At the beginning of each simulation, a single random horse was infected with equine influenza. They assessed three groups:

What is a Quarantine?

For those unfamiliar with quarantine, it can be a scary word. But in the face of a disease outbreak, it is important to pursue quarantine, separating the affected horse from the rest of the herd. The following are some basic guidelines to initiate a quarantine to prevent a barn-wide outbreak:

  • Ideally, quarantine horses in a separate barn. If this is not possible, house them alone at one end of the barn.
  • Turnout, if any, should be completely separate from the rest of the herd. Do not use a shared fence line.
  • It would be best if a single person is designated to care for the quarantined horse. If that isn’t possible, the horse should have its own equipment and tack, and caretakers should manage these horses only after handling their healthy herd mates.
  • Horses that attended the show that were quarantined from their herd for five days or more, and the herd was not vaccinated against equine influenza;
  • Horses that attended the show that were quarantined for 2 days, as well as at least 75% of the home barn vaccinated against equine influenza; and
  • No quarantine of the attendee horses or vaccination protocol in the home barn.

Study Results

The researchers found that adopting both prevention and control strategies significantly lowered the spread of influenza in the home barn, as compared to using no control strategies. Results showed that the 5-day quarantine was the most effective strategy, though the shorter quarantine and vaccine coverage combo was also helpful in preventing influenza.

“Models are good to use when clinical trials aren’t feasible,” Spence commented. “We can test [the impact of biosecurity measures] effectiveness without waiting for a real outbreak to occur, which can then provide support for disease prevention strategies before that outbreak happens.”

Despite this study being a computer simulation, the research team concluded that horses returning home from a competition or event should be quarantined for a period of time sufficient to rule out any infection.

The study, “Estimating the potential for disease spread in horses associated with an equestrian show in Ontario, Canada using an agent-based model,” was published in Preventive Veterinary Medicine.