Slaughterman Kent Sambells' workload was "hectic" last week as Waikato farmers called him in to destroy ailing cattle and take them away for processing into pet food.
He said twice as many farmers as usual were calling.
"I had about 50 and it's normally half that. It's got something to do with the summer.
"A lot have been going lame or have broken hips or a bit of facial eczema."
Much of the North Island - including Northland, South Auckland, Waikato, Bay of Plenty, and Hawkes Bay - has been declared a drought zone. Other areas expected to join them are Tararua, Wairarapa, Manawatu-Rangitikei and Taranaki.
Alan Cleaver, of Te Kauwhata-based Down Cow which supplies meat to pet food processors, said it was too early to say whether the drought was responsible for last week's increase in calls from farmers.
Mr Cleaver said he expected that if the dry spell continued, farmers would cull their herds right down and keep only their best cows, making room for the new season's intake of young milking cows.
"We get all those that won't be accepted by the meat works.
"This is the side to be on - being at the bottom of the cliff is better than farming."
However, a pet food industry source, who asked not to be named, said the industry in the North Island was busier.
"It's because of people's need to get rid of stock in a drought because they have no grass to feed them."
Owners were not persevering with animals which had gone lame as they would when grass was growing normally.
Farmer John McCormick of Waikowhai, 11km west of Huntly, said he asked Mr Sambells to put down two of his 310 dairy cows on Monday.
"Cocopops slipped in the yard and dislocated a rear hip.
"We called out the vet the next day and he said she would not recover and it was better to put her down ... she was in pain."
Cocopops was bred on the farm and was four years old and in-calf.
Before her accident she would have been worth $1800 and $600 more with a heifer calf.
Mr McCormick said the second cow, named "Cow 48" was also put down on veterinary advice because she had a recurrence of facial eczema, and was failing fast.
The cows were sold for $50 each to a pet food company because the veterinarian said the meat works would not accept them for human consumption.
"We are faced with these situations all the time. The drought makes you more aware that you can't have animals suffering."
Mr McCormick said the risk of stock losses due to a facial eczema outbreak was high if rain came and created warm and humid conditions.
The farm had lost four cows all season - two of them died during calving. Fourteen cows not in calf had been sent to a bigger farm and 10 older cows were sold at Christmas.
Stock were being fed maize, palm kernel and silage to make up for lack of grass.
"We will cull out a few more if it doesn't rain in April."
Primary Industries Ministry North Island spokesman Stuart Anderson said the ministry monitors the condition of stock coming to slaughter.
Since the drought was declared there had been no significant change in the condition of stock.
He said the drought came after widespread rain in December so there was pasture growth and feed crops were reasonably successful.
English confident on Budget surplus
Finance Minister Bill English says the Government is on track for a Budget surplus in 2014-2015 despite the drought, but said it would affect the economy for a couple of years.
Treasury was looking carefully at the forecasts for the May 16 Budget, he said.
"I would expect though, that we will still be able to achieve surplus."
Its effect on the economy was yet to be known but its impact would last at least a couple of years. It would take some time for farmers who slaughtered stock to rebuild their herds and to work off tax losses.
He said that recent forecasts, showing better revenue, might have given him more choices over spending, but that would now be removed.
"It probably means that where we were expecting a bit more room to move because things were running a bit better than expected, that that is not now going to be the case. The drought will peg that back but we have yet to see how far."
He did not think it would be a dramatic difference but it would continue to be a tight Budget. Some of the banks had estimated that it would affect GDP from $500 million to $1 billion.
"If it is that big it would affect our tax take," Mr English said. The Budget in May last year forecast a $197m surplus in 2014-15 but by the half-yearly update in December that had been reviewed downward to $66m. In the Crown accounts for the seven months to January 31, expenses were $282m under forecast and revenue was $486m above estimates.