The Napier SPCA has been receiving up to four calls a day from people worried about animal welfare this holiday season.
"There has been a real spike in dogs in cars," said regional manager Bruce Wills.
"We had quite a mild spring and then all of a sudden summer hits.
"It is quite time consuming for us because we have to wait with the dog until the owner gets back."
SPCA branches around the North Island said the biggest issues this summer were dogs left in cars and unwanted kittens and puppies.