A local council on the south-west fringe of Sydney is lobbying the State Government to limit the number of cats non-breeders can own in New South Wales.

Wollondilly councillor Simon Landow is leading the push to impose the statewide cat cap, which he believes will create "an equal playing field between dogs and cats".

Warning: This story contains graphic images

"At the moment if a cat is walking along the street, if it's in someone's yard, if it's attacking a bird — basically that cat is able to do that because it's actually illegal for council or the RSPCA to pick these cats up," he said.

"We need the legislation changed ... so there's actually a notion of a stray cat, because currently there isn't.

"What my proposal seeks is to restrict the numbers of cats someone can have, and [introduce] compulsory desexing of cats if you're not a registered breeder."

Mr Landow said while the limit would ultimately be determined by the Government, he believed owners should have no more than six felines unless they're registered breeders.

He said by introducing amendments to the Companion Animals Act 2008, cats would be treated more like dogs.

"If your dog is off a leash and roaming by itself, council rangers or the RSPA can actually pick these dogs up, scan the microchip and then fine the owners ... so it's about bringing a quality in line with cats to dogs."

The Office of Local Government said recent amendments to state legislation sought to address the overpopulation of cats, including annual permits for owners of female cats not desexed by four months of age, and a new penalty for pet owners who repeatedly fail to register their cat.

Nevertheless, Mr Landow said more needed to be done.

Wollondilly Council's proposal was motivated to pursue the changes to protect native species, millions of which were killed each year by cats, he said.

"Cats are prowling for a reason; they're a natural predatory animal and that needs to stop.

"I'm about protecting wildlife and this is one measure that we could help solve that."

The stomach contents of a feral cat from far northern South Australia. ( Supplied: Dr John Read )

Mixed feelings from cat enthusiasts

NSW Cat Fanciers Association president Joanne Greentree, who owns six cats and is a registered breeder, said the cap would be unfair on responsible pet owners.

"I think they're penalising a majority for what a minority is doing wrong," Ms Greentree said.

Fellow cat enthusiast Sue Thomas, who is secretary of the Burmese Cat Society of Australasia, said she supported the ban on non-breeders and believed compulsory desexing was essential.

"I think it's absolutely necessary because by having them un-desexed, you have the problem of producing far more unwanted kittens that then go on to either get turned out of the home and go feral or they end up in shelters."