Hawke's Bay SPCA is hopeful cat lovers will adopt dozens of remaining furballs left over from "kitten season".
Central Hawke's Bay SPCA volunteer Jenny Read said the centre currently had 29 kittens and 22 cats in its care - a standard number for the end of "kitten season".
Ms Read said she hoped all the animals would find new feline-friendly homes.
"What doesn't go stays here, of course. We don't put them down unless they're sick or un-homeable."
Cats with behavioural issues were sometimes deemed un-homeable, Ms Read said.
Royal New Zealand SPCA national president Bob Kerridge said it was "kitten season" nationwide.
Depending on the weather, the kitten season extended from December through to March.
"This year's a bit longer because of the weather."
The kitten overload appeared to be a nationwide event, with many SPCAs' holding facilities filled "to capacity".
Foster homes were an ideal solution to the furball explosion, as kittens could be cared for until they were old enough to be adopted out.
"That means that they don't have to be held at the centre."
Fostering could be hugely satisfying, Mr Kerridge said. "Many lives are saved because of foster homes."
However, adoption was the only permanent solution.
"We urge people if they're thinking of a kitten to come to us."
Cats were held for as long as it took for them to be adopted, Mr Kerridge said. There was no set timeframe, although cats tended to take longer than kittens to be re-homed.
"Sometimes we do get elderly cats in that may have come from a deceased estate, and [they] are a little bit more difficult to adopt."
Economist and philanthropist Gareth Morgan's Cats To Go website drew wide-spread outrage from feline fans earlier this year when he suggested cat owners not replace their pets when they die.
He said local governments should require registration and micro-chipping of cats and to facilitate the eradication of unregistered felines to protect native birds.
The argument reached fever pitch when Morgan offered to donate $5 to the SPCA for every homeless cat they put down.
Mr Kerridge replied: "But out of our lives, and don't deprive us of the beautiful relationship that a cat can provide, individually, and in our families."