The Ministry for Primary Industries has confirmed a 13th horse has been infected and another has died from a new strain of equine herpes on a thoroughbred stud farm in Waikato.
The ministry said on Wednesday that seven of the mares affected by the Equine Herpes Virus type 1 have died. The virus attacks the brain.
MPI principal adviser Andre van Halderen says he is confident that strict containment measures in place at the farm will help to prevent the virus spreading.
Mr van Halderen says all horse owners and breeders are being asked to keep an eye on their animals and check for signs of urine incontinence and impaired co-ordination.
There is no movement of horses on or off the property and those working with the horses are required to use disinfectant foot baths and shower and change their clothes immediately after, he says.
The Equine Health Association says a veterinarian has been assigned to work exclusively with the farm.
