It is about to euthanase abandoned kittens and puppies because it cannot accommodate them and RSPCA team leader customer care Susanne Tobin says things are going to get worse.

Ms Tobin expects more animals to be abandoned throughout the six-week school holiday break and is appealing to anyone who can care for them and give them a good home to come forward.

She said the "unwanted Christmas animal gift" had taken its toll on the already-full Rutherford shelter.

Ms Tobin said cat breeding season had exacerbated the problem, adding that the shelter was more than full, in fact "overflowing".

The shelter had already been trying to cope with 100 surrendered kittens and 40 others already processed and needing homes when six adult cats, three adult dogs, four kittens, eight puppies and four rabbits were dumped there over the Christmas-new year break.

"And we already have an additional 100-plus dogs, 30 available for adoption and the rest waiting to be processed," Ms Tobin said.

Animals available for adoption have already been checked by a vet and vaccinated, desexed and microchipped.

They take priority over those waiting to be processed.

The animals waiting to be processed are the ones most likely to be euthanased.

"Things are generally at a peak this time of year and we are starting to see the unwanted gifts and the animals surrendered by those who have not bothered to have them kennelled while they go away on holidays," Ms Tobin said.

"Sadly, this trend will continue right through to the end of the holidays."