The new dog and cat laws introduced last year mean your pooch or kitty must be desexed by six months of age, or within 28 days of when you take possession of the new pet.
Dog and Cat Management Board chair Dr Felicity-ann Lewis said desexing your dog or cat is the socially responsible thing to do.
"It helps control your pets urge to wander, increases the likelihood of your pet enjoying a longer and happier life, and means cheaper council registration for dogs, and prevents unwanted litters," Dr Lewis said.
"The new desexing law is aimed at reducing the number of unwanted dogs and cats that end up in shelters every year.
"When adopting a new dog or cat, owners should be aware of the costs involved, including for health checks, food and desexing.
"Dogs and cats can be desexed as early as six weeks old, but many choose to desex their pets around five to six months of age.
"The procedure usually takes a day, with your pet admitted in the morning and then back home in bed resting by the late afternoon."
RSPCA South Australia Head of Animal Operations Tim Charles said, each year RSPCA shelters take in around 10,000 animals across South Australia, many of which are the result of unplanned litters.
"Desexing your pet is one of the best ways that you can help reduce the number of unwanted dogs and cats ending up in shelters and needing rehoming," Mr Charles said.
The new desexing law does not apply to dogs and cats born before 1 July 2018, and exemptions are available for working dogs and animals belonging to breeders registered with the Dog and Cat Management Board.