The NSW Government launched the annual permit system for non-desexed cats and restricted and dangerous dogs to promote responsible pet ownership and improve animal welfare standards.

From July 1, 2020, owners of cats not desexed by four months of age will be required to pay an $80 annual permit in addition to their one-off lifetime pet registration fee.

The permits hope create a stronger incentive to desex cats, improving their well-being as well as deterring irresponsible breeding and unwanted litters.

In doing so, it will ease the burden on pounds and shelters, reduce euthanasia rates, and help to address concerns about feral, stray and roaming cats and their effect on wildlife.

SMART Animal Sanctuary and Rehoming Centre founder Lorene Cross said she was glad to hear of action being taken, but held doubts about the effectiveness.

"Any effort to improve desexing rates is a positive thing, but there will still be a lot of people who just don't do it and won't get caught," she said.

"Typically speaking, those who don't desex their animals are also the ones who don't microchip, so it will be hard to monitor and hold owners accountable."

Ms Cross said her Snowy Valleys shelter was feeling the weight of irresponsible pet ownership as they are inundated with both cats and dogs.

"We are absolutely flat strapped right now, it's been extremely busy through COVID-19 and we have worries of dogs in particular getting separation anxiety as people start going back to work," she said.

Exemptions are in place for cats that are registered by July 1, those kept for breeding purposes by members of recognised breeding bodies, and cats which cannot be desexed for medical reasons.

Owners of dogs of a restricted breed or formally declared to be dangerous will be required to pay a $195 annual permit in addition to their one-off lifetime pet registration fee.

Annual permit fees will go directly to the Companion Animals Fund which pays for companion animal management by local councils including pounds/shelters, ranger services, dog recreation areas, and education and awareness programs.