Another case of equine brain disease has been confirmed on the Waikato thoroughbred stud farm which is the centre of an outbreak.
The Ministry for Primary Industries has confirmed the equine herpes virus type 1 has been found on a single stud farm in the region. Thirteen horses have been infected, and seven of those have either died or been put down and six are being treated.
Equine Health Association president Ivan Bridge says the new case is from the quarantined area on the farm.
He says it is now not certain that this outbreak is the first ever case in New Zealand.
Mr Bridge says it's the first time it's been identified in New Zealand, although it has been investigated before the disease was not able to be confirmed because there was not the diagnostic ability at that time.
He says the next step is to decide what happens 21 days after the last diagnosed case and the MPI is responsible for that.
Mr Bridge says the property has been under voluntary isolation and has taken a very responsible attitude.
He says the veterinary practice that is responsible for the animals on that property has dedicated one vet to look after those horses and they are not having any contact with other horses.
Andrew Coleman from the Ministry for Primary Industries says the owners of the infected horses had done everything right, including quarantining the horses at risk.
He says ministry officials were confident the outbreak was contained on the one property. They were checking regularly on the horses during the continued quarantine period.
Sir Patrick Hogan, one of New Zealand's most prominent thoroughbred horse breeders, says he is checking his horses regularly for any signs of illness.
"My purpose now is to just make sure, as they are presently, all stock on my farm are healthy and well, keeping our eyes open for any issues that might arise."
Sir Patrick says if all stud farmers do the same it will make it easier to detect the virus if it spreads.