Humane Society animal shelters across the state are joining together this month for their first Feline Fix event, a free spay and neuter program that is part of a national effort to combat cat overpopulation.

Feline Fix services on the Big Island, Maui, Kaua'i and O'ahu will culminate Tuesday in conjunction with national Spay Day USA.

"Sterilization of your pet really is that integral step to making you a responsible pet owner," said Kawehi Yim, director of community relations for O'ahu's Hawaiian Humane Society.

The Hawaiian Humane Society will schedule 200 free sterilization surgeries this week to Monday for healthy socialized cats. Yim estimated that the free spaying and neutering services can save cat owners veterinary fees of $100 to $300.

"Cats don't just have one baby, they have a lot, and people tend to not know what to do with them," said cat lover Katie Bierdz, who was visiting the Humane Society's Cat House in Mo'ili'ili last week. "They just throw them out, and that's how cats end up dead or abused."

The Kaua'i Humane Society is performing 12 free sterilization surgeries daily throughout February and will mobilize its Feline Fix services Tuesday at Ching Young Village Shopping Center in Hanalei.

The Maui Humane Society also is offering free sterilization surgeries in rural areas through its Neuter Scooter program, in which rural veterinarians and property owners will open their facilities for the procedures.

"There are so many good reasons to have your pet spayed or neutered," said Hawaiian Humane Society President Pamela Burns. "It's a fact that surprises many people, but one unspayed cat and her offspring can produce 420,000 kittens in just seven years."

Sterilizing cats improves their health and helps them to live longer, Burns said, and it also tends to make them less aggressive and less likely to roam.