Managing Hendra without vaccine

The deaths were minimal compared to our wettest year 2011, when 11 horses succumbed.

Whether horses should be vaccinated or not is a debate that remains polarised, with those in favour regarding the vaccine as effective and affordable. But some in the racing and endurance markets won’t buy into it.

After two years of declining show jumping entries the North Coast National committee at Lismore will this year open their gates to non-vaccinated horses and they expect numbers will swell.

“It’s a big risk for them, of course,” said show society president John Gibson. “If a horse falls sick and the blame comes back to an unvaccinated horse that owner will wear the costs.”

Those costs included stabling all non-vaccinated quarantined horses until blood tests are finalised.

Such risks are something many in the equine community are prepared to take.

Peter and Marissa McDonald, Murwillumbah, breed endurance horses that sell to the United Arab Emirates, Malaysia and the United Kingdom. Their major market, the UAE, prefers to buy horses that have not been vaccinated for Hendra.

There is the risk that a vaccinated horse will test positive for Hendra at the border and be refused entry. There is also hearsay evidence that suggests vaccinated horses may lose measurable peak performance. 

“This is a new vaccine and no vet is able to tell us whether its markers will be passed on to our foals via a vaccinated parent,” said Mr McDonald. “This is why we don’t vaccinate our breeding stock at this time. There have also been reports of fertility problems in vaccinated animals.”  

There are high profile and reputable members of all performance horse disciplines, including endurance, eventing, dressage, show jumping and racing who have chosen not to vaccinate. Even some who embraced it initially, but having noted a decline in performance or other side effects, decided not to continue with a vaccination program.

“We are neither anti nor pro vaccination,” said Mr McDonald. “Our decision not to vaccinate at this time has been made after a lot of thought and research, including advice through the CSIRO and vets. There are two sides to every argument.”

Careful risk management includes the use of electric fences to keep horses away from fruiting or flowering trees. They are not fed or watered under foliage that might harbour bats. 

“We limit public access to our horses, and try to practice hygiene and health bio-security protocols in day-to-day animal management,” said Mr McDonald. 

“Even if you do vaccinate your horses there is a need to remain vigilant.”

Some Endurance events, like the one recently held at New Italy on the Far North Coast during August, allow non-vaccinated horses to compete, or they face extinction as a social past-time. Organisers say they have managed to avoid the problem of potential disease transfer by paying close attention to equine health.

New Italy event manager Angela Ward said strictly documented health checks 10 days prior to the 20, 40 and 80 kilometer races in horses that were already in peak fitness, not sick, helped to allay fears for the four veterinarians working the event.

Other precautions were put in place as well, like making sure standing water available on the course was covered at night

“To date, all hendra infections have been in non-vaccinated horses. Vaccination still remains the single most effective part of a complete hendra risk reduction regimen,” urges Northern Rivers based equine vet Bruno Ros.

“People can certainly help reduce the risk of infection by these means, including not having feed and water points under trees. 

“However, infection has occurred by non-resident flying foxes simply flying over a property. Hendra virus still remains relatively uncommon however there are certainly increased risks in certain areas at certain times of the year, and we never know just when an infection may occur.

“Some horse owners don't believe there is a high enough risk. There has also been a relatively successful campaign from anti-vaccination lobbyists, unfortunately though not based on science nor facts.

Paul Freeman, Senior Veterinary Officer with NSW Primary Industries at Wollongbar via Lismore said: “I am a strong supporter of vaccination given that over 500,000 doses have been administered and the side effects claims are largely unsubstantiated when subjected to serious scrutiny.

“There is nothing new in the arguments presented by the anti vaccinators but it might be worth mentioning that other people who handle their horses such as vets and farriers and even young children and neighbours may not feel as comfortable that the risks outweigh the benefits.”