Farmers in the Kaikoura region are being asked to check that their bovine tuberculosis testing is up to date - two dairy herds have tested positive to the disease.
The Animal Health Board says this is the first time in a couple of years that a herd in the area has been found to have Tb.
The board's northern South Island coordinator, Danny Templeman, says he suspects a common source infected the two dairy herds, because they are both on the northern side of Kaikoura.
He says the region has a large wild animal population that is known to carry Tb.
Mr Templeman says farmers and hunters need to ensure that all offal is buried or disposed of, so that scavenging animals cannot get it.