Staff at Waikato's SPCA are being blackmailed and verbally abused, as an influx of unwanted pets come in.

LISTEN ABOVE: Maureen Wallace from the SPCA joins Larry Williams to discuss

Community Liaison Jan Thomson said it's common for pet owners to come in and say they will kill their healthy pet if the SPCA doesn't take it in, which puts a huge amount of emotional stress on workers.

"We'll have people coming along to us with a box full of kittens, and it's 'you take these kittens, if you don't I'll throw them in the river', and that's really alarmingly frequent," she said.

Ms Thomson said funding restraints mean they can only take in sick or injured animals.

"We do everything we possibly can, but in a perfect world, we wouldn't have this problem.

"As I've said often, we don't have any Government funding, we run purely on our own fundraising to cater to everybody's requirements."

She said tenants often bring in healthy pets, because they're not allowed them at their rented property.