The number of properties with the cattle disease Mycoplasma bovis has risen, with 23 farms now infected.
The latest properties are in Southland and the Waitaki District.
First found in South Canterbury in July last year the disease is now spread from Southland to Hawke's Bay.
The Ministry for Primary Industries has 38 farms in lockdown and said it was still aiming to eradicate the disease.
Farmers say the disease is exacerbating an already difficult milking season in southern regions plagued by dry conditions.
Drought was declared in Southland and the neighbouring Queenstown Lakes, Central Otago and Clutha districts late last month.
About six properties in Southland have been identified as having Mycoplasma bovis.
Federated Farmers' Southland president Allan Baird said the combination could be crippling for farmers.
With stock movements restricted, finishing calves was difficult, and cows were being held on properties where grass growth was slow, he said.
The government needed to make decisions soon to alleviate the pressure on farmers, Mr Baird said.