The Sheep Dog Trial Association is asking triallists to vaccinate their dogs before they gather for upcoming events.
This follows an increase in the rate of infections of a highly contagious disease called kennel cough.
Although not usually life-threatening, the disease causes a dry hacking cough that the association says may affect the dogs' performance during competitions.
Association president Merv King says hundreds of dogs are expected at the South Island final at Geraldine next month, and the disease could easily be passed on.
He says kennel cough has spread nearly everywhere in the South Island since last year's national dog trials in Blenheim. Up to then, says the Veterinary Association's companion animal spokesperson, Pieter Verhoek, it was not a big problem for triallists.