Australia’s peak body for veterinarians, the Australian Veterinary Association (AVA), has expressed concern about the health and welfare of horses unvaccinated against Hendra virus at equestrian events held specifically for unvaccinated animals.

Ben Poole, BVSc, MANZCVS, AVA spokesman, said the association provides advice based on best practice horse welfare while meeting work health and safety obligations.

“Equine vets work closely with horse owners and event organizers every day of the year to help make Australian horse sport as safe and successful as possible,” he said. “However, events (including endurance rides) that are held exclusively for unvaccinated horses raises serious health and welfare concerns.

“Obviously for these types of taxing, long-distance events it’s common for horses to need veterinary care, and in some instances, urgently,” Poole said. “This is currently not possible however due to protocols around the treatment of unvaccinated horses.”

Biosecurity Queensland dictates that any unvaccinated horse showing suspected signs of Hendra virus must be quarantined and return a negative result for Hendra before they can receive treatment.

Hendra virus has been known to yield numerous clinical signs in horses including lethargy, respiratory distress, frothy nasal discharge, elevated body temperature (above 40°C, or 104°F), and elevated heart rate; however, authorities caution that hendra infection does not have specific signs.

The virus is transmitted to horses from flying foxes, a type of fruit bat that frequents Australia, but the exact method of transmission remains unclear.

The zoonotic disease is transmissible to humans and has killed four people since it was first discovered, including an equine veterinarian who contracted the virus after treating an affected foal in 2009.

Poole said vaccination is the most effective way to prevent the spread of the disease and has undergone a rigorous approval process by Australian Pesticides and Veterinary Medicines Authority to ensure its efficacy and safety. A Parliamentary Inquiry into the vaccine was also conducted last year and recommended that the vaccine is safe and does not have any significant adverse health effects for horses.

“There’s still so much we don’t know about the Hendra virus—even the early signs of this disease can be extremely vague,” Poole said. “The fact is that endurance events bring together a large number of horses from a wide range of geographical locations, and this instantly raises the risk of Hendra virus infection if horses have not been vaccinated.

“Members (of the AVA) decide for themselves which events they do or don’t attend,” he continued. “However, based on current workplace health and safety guidelines, our advice to members is that they apply best practice to protect horses and people against Hendra virus infection.

“Vaccination is the only way to ensure high standards of horse health and welfare while also adequately protecting veterinarians, horse handlers and owners from contracting this deadly virus,” he concluded.