British trainers have expressed concerns about new rules set to be introduced by France Galop that will make it mandatory for all runners in France to have been vaccinated against the equine herpes virus.
The BHA has said it has no intention of following France Galop's lead but has warned trainers that if their horses are not vaccinated correctly they will not be able to run in France when the rules come into effect next year.
The French rule change was prompted by an outbreak of the respiratory version of the disease in Chantilly last year that affected a number of stables.
A neurological form of the disease killed two horses at Jean-Claude Rouget's stable this year, while Kevin Ryan had to shut down his yard for a time owing to an outbreak in the summer.
National Trainers Federation chief executive Rupert Arnold said the rule presented problems for his members.
"The first is that there's a serious shortage in the supply of the vaccine that people have in the past been relatively comfortable using," he said.
"The alternative vaccine is one that is imported and that some trainers have had bad experiences using.
"So trainers will be faced with either not having runners in France if they don't want to vaccinate their horses or using a vaccine that some trainers have had a bad experience with."
The BHA's director of equine health and welfare David Sykes believes there should not be any major problems with the new rules.
He said: "What trainers are being asked to do under the new French equine herpes rules is the same vaccination protocol as they're already required to do for equine influenza, so there shouldn't be any major issues for British trainers to adapt to."
However, the BHA believes the costs of following the French example would outweigh the benefits.
Sykes added: "At present, equine herpes cannot be eradicated by vaccination. The majority of horses are exposed to the virus before they're six months old, and the virus is actually latent in most racehorses.
"Vaccination has proved to be effective in some circumstances, for example to protect against abortion in pregnant mares. However, it's effective only for a short period in racehorses, and it doesn't protect against the neurological form of the disease.
“As a result, the benefits of compulsory vaccination are debatable, particularly in light of the significant cost owners would incur."
The principle of the rule change was adopted unanimously by the France Galop administrative council and has been a key demand of both the breeders’ and trainers’ associations.
Subject to the approval of the minister for agriculture, the new rule is due to come into force on January 1.
It will be mandatory for all horses running in France to have had two primary vaccinations, and to allow for this process, with appropriate time between courses, the enforcement of the rule would begin on April 1.
Sykes's French counterpart Dr Paul Marie-Gadot has been in contact with both his opposite numbers in London and Dublin and also spoke at a meeting of the Federation of Thoroughbred Bloodstock Agents in Newmarket late last year on the subject.
"I imagine nearly all veterinarians will be in favour of vaccination," said Gadot. "After that, it's a matter of cost. But when you look at what happened in Chantilly in 2016 – when some yards couldn’t run their horses properly until July or August – the economic impact is a lot more serious.
"It happened to Criquette Head-Maarek [president of the French Trainers' Association] and she was one of the trainers who started saying, 'We have to make it compulsory'.
"We know very well there's a cost implication to the new rule, but the cost of doing nothing is much greater.”
Vaccination against equine herpes for all breeding stock in France has been obligatory for 12 years and auction house Arqana is expected to make it a condition of sale for yearlings, breeze-up two-year-olds and horses in training once the rule is formally adopted by France Galop.
Gadot also believes the adoption of the new rule in France will create a significant boost to the market for the EHV vaccine, which will in turn both lower the unit cost of each dose and ensure a stable production, lessening the threat of stocks running low.