Farmers are being urged to get their cattle vaccinated earlier than normal to prevent the spread of a potentially fatal disease to farm workers.
The Veterinary Association is urging cattle owners to vaccinate against Leptospirosis at an early age, and to maintain protection with booster shots.
The highly infectious disease can cross over from animals to humans, putting farmers, vets and meat processors at risk.
The president of the NZVA's Society of Dairy Cattle Veterinarians, Dr Jenny Weston, said a recent study suggested vaccinations should be carried out before Christmas.
"It's important that calves that are born in the spring time are fully vaccinated and have had two shots pretty much by this time of year. In the past often vaccinations weren't given against this disease until in the summer or autumn, and there were suggestions from the findings that calves were already infected prior to vaccination.
"If the animal is already infected, it doesn't clear the infection, so it's most important that calves are fully vaccinated before they are likely to be exposed to the disease.
Dr Weston said the disease in people was probably under-reported.
"Because the symptoms are very non-specific, there's probably a lot of people who have Lepto and recover and don't know that they had Lepto."