Veterinary researchers say a national rethink on the age cats are desexed could have an impact on the number of kittens being put down in shelters every year, as well as the number of stray cats.

They have conducted an Australian first study that shows cats can be desexed safely within the first three months of their lives.

Traditionally cats are desexed at around six months of age but can fall pregnant from just three months of age.

One female cat can have up to 40 kittens a year leaving little wonder why 100,000 cats are taken to animal shelters around Australian annually.

The outcome for most cats and kittens in pounds and shelters is euthanasia.

Cat Protection Society of New South Wales CEO Kristina Vesk said part of the problem was kittens being born to cats under six months of age that have not yet been desexed.

"It is such a frequent occurrence for us to encounter really good responsible pet owners who have a cat who think their cats may be just putting on a bit of weight and growing," Ms Vesk said.

"They have no idea she's already pregnant, she's five months, she's five-and-a-half months and she has her first litter.

"They're just genuinely not aware that their cat could have got pregnant so young."

Educating vets about benefits of early desexing

In recent years animal shelters and some vets have begun desexing cats at about two months.

But Associate Professor of Feline Medicine at the University of Sydney, Vanessa Barrs, said there were still many veterinarians who routinely desexed cats at six months.

"Traditionally there were risks associated with doing surgery and anaesthesia in young animals but technology and expertise has changed over the years," Associate Professor Barrs said.

No increased risk of complications for cats desexed before 12 weeks has been found by Associate Professor Barrs and her team who reviewed 300 operations.

Armed with this new research, her team is now working with the Cat Protection Society to educate vets across the country about the benefits of early desexing.

Ms Vesk believes it will make a significant dent in the number of stray cats and cats being put down every year.

"It's really important to stop that cycle of breeding right up front," she said.

"That's why early age desexing is so important and I think that responsible pet owners and vets can show the way and lead the way in what this means and we can actually start to tackle the problem because it's a tragedy that all these beautiful healthy cats and kittens are being euthanased."