The owner of a large dairy farm with more than 100 infected cows believes the bacterial disease has gone undetected in New Zealand for some time.
The Ministry for Primary Industries is continuing its investigation into the infection of 150 New Zealand cattle with the disease Mycoplasma bovis on a farm in South Canterbury.
The Van Leeuwen Dairy Group’s Morven property is currently under MPI control, restricting the movement of risk goods such as stock and equipment off the farm.
Aad van Leeuwen told 1 NEWS the first indication something was wrong was in March of this year.
"We had some troubles with a few cows. The vets were pulling their hair out. We ended up going to MPI and that's how we found out what was going on," he said.
Mr van Leeuwen said half a dozen cows had shown signs of pneumonia, swollen front legs and later sinus problems and "that’s when the alarm bells really started going".
He said he wanted to have the sick cows put down as soon as possible, but has had to wait for the all-clear from the meat industry with concerns over food safety.
The cows are expected to be killed by the end of the week.
Mr van Leeuwen described finding the cause of the spread like "searching for a needle in a haystack".
The Ministry for Primary Industries has been holding meetings with concerned farmers in the area today.