Vets are facing pressure to put down healthy but unwanted pets and the emotional impact is taking its toll.
The Veterinary Council warns euthanasing animals is causing vets to become "stressed and burnt out," and the SPCA is urging owners to take animal ownership seriously.
Veterinary Council spokesperson Mr Ricketts says if vets refuse to put animals down, they may suffer cruel deaths as owners attempt to kill their pets themselves.
"The owner is likely to go another veterinarian or may attempt to kill the animal themselves," Mr Ricketts told Newshub.
"Veterinarians would generally want to ensure that animals are killed humanely so most/many will do it albeit reluctantly."
He says while there's no law against euthanasing a healthy pet, many vets try to save them.
"Many will often ask owners if they can try to rehome the animal. Some will ask if the SPCA could take them."
SPCA CEO Andrea Midgen told Newshub her organisation doesn't put down unwanted healthy animals, and every animal who can be rehomed is put up for adoption. However, it's "not unusual" for animals to wait months to find a home, and some animals have been with the SPCA over a year.
"We understand that sometimes circumstances can change and pet owners might find them in a position when they can no longer care for their pet," she says
"There are options - advertise your pet as widely as possible: on social media, on websites such as Pets on the Net or TradeMe, ask friends, family and colleagues. If you need more help, contact your local SPCA for advice."
But in a best-case scenario, Ms Midgen says owners should think more carefully about their situation before adopting.
"Pets bring such joy to our lives, but we want to remind people that pets are a life-long commitment," she says.
"Before getting a pet you need to understand the financial, emotional and physical commitment that is required of you for that pet's entire life.
"You need to consider housing (both where you live and where your pet will be kept), vet care and pet insurance, exercise and enrichment needs and if you are in the position to meet these needs for a decade or more.
"Adopting a pet needs to be a considered decision that takes into account your lifestyle, and if you can give a pet everything it needs to be physically and mentally healthy."