The country's peak veterinarian body has defended the actions of a north Brisbane vet hospital where four horses were found to have contracted a deadly equine virus.

The Australian Veterinary Association (AVA) said staff at the Redlands Veterinary Clinic had handled the outbreak of the rare Hendra virus in line with all necessary guidelines and were now working closely with biosecurity authorities to pinpoint exactly how the spread had occurred.

So far, only two of the four horses found to be infected with the disease have died.

Tests are now being conducted on 37 other horses, as well as the clinic's 25 staff after it was revealed Hendra could be passed from animals to humans through close contact.

Results are expected this afternoon.

"The clinic has been following all appropriate precautions from the outset and even placed itself into voluntary quarantine after they notified (the Department of Primary Industries and Fisheries) that they suspected an unusual disease outbreak," President of Equine Veterinarians Australia and AVA spokesman Dr James Gilkerson said.

"Four horses have since tested positive to the virus and the clinic has now initiated comprehensive and systematic disinfection procedures to ensure containment."

In the state's most famous case, racing trainer Vic Rail died of a heart attack shortly after showing symptoms of Hendra during the last known outbreak of the disease in 1994.

A second man died the following year.

Sydney vet Dr Nick Kannegeiter, who recently operated on sick horses at the Redlands clinic, yesterday said he was also "very concerned" about human transmission after revealing vet staff had been administering intensive treatment over several days, including hand-feeding at least one of the infected animals.

However, Dr Gilkerson said the risk was low.

"While the disease is of concern because of its ability to be transmitted to humans, it is not highly contagious," he said.