Veternarians in North America have commended Australian quarantine authorities for enforcing stringent quarantine measures to protect the country from an outbreak of equine influenza after a quarantined horse at Eastern Creek near Sydney showed clinical signs consistent with the disease.
All 52 horses at the Eastern Creek facility will remain quarantined for 30 days before they can be proven free of the virus. It is unknown whether any North American stallions that recently shipped to Australia are among them.
"Many of the horsemen (in North America) feel (Australia) does a great job, and I think as this has shown, they caught it in their quarantining facilities, and that's what you're supposed to do," said Dr. Robert Holland, a Kentucky veterinarian with a private practice and senior technical service veterinarian with Pfizer Animal Health. "If a horse gets sick, it's better to be in the quarantine facility. This has shown that their quarantine methods work."
Holland said the standard method for sending horses to Australia was to keep them in quarantine for two weeks before shuttling, and then another two weeks after the horses arrive in the country. Following that period, the horses are typically checked by a veterinarian and released.
"An additional 30 days (in quarantine) makes total sense (in this case)," said Holland. "(Australia) is a little bit more stringent because of the fact they have flu-free status."
Holland explained that equine influenza is highly contagious and spreads rapidly among susceptible horses. Two influenza viruses have been found in horse populations worldwide, except in Australia and New Zealand.
"(Australia) tends to hold onto a longer quarantine because they're being careful, and I think it's worked very well," said Holland. He said the flu incubation period is one to three days, with an infected horse typically shedding the virus for about eight days. "So you can see why they (quarantine) for 14 days; it's because they're splintering it out over the one to three days, and then obviously (infected horses) showed fevers by 14 days."
Holland said a horse usually recovers as quickly from the flu as a human would. There is concern, however, when stallions register extremely high fevers, as their sperm counts can be lowered for 30 to 60 days.
"I'm sure these stallions (in Australia) have been vaccinated," said Holland. "The vaccines are probably helping to protect them."
However, he said, equine influenza can sometimes change course, causing what is called an antigenic drift.
"If the flu has changed, then it’s a little bit more troublesome, and the immunity might not work as much," said Holland. "Right now, I'm not hearing anything about that in this outbreak."