Each year, millions of pets are euthanized because there aren't enough homes for them. But if that's not enough to convince you to spay or neuter your pet, consider that it's better for the animal's health.

For people who love their pets, spaying and neutering is one of the best things owners can do for their animals, said Kim Peters, director of education and outreach at the Humane Society of Southeast Missouri, which will have its annual Spay Day on Tuesday.

"The average life span of a neutered pet is 25 to 40 percent longer than an unaltered one," said Dr. Gwenn Freitag, a veterinarian at LaCroix Pet Hospital.

Freitag said unspayed female animals are much more likely to suffer from breast cancer and uterine infections. Unneutered males have an increased chance of developing testicular and prostate cancer and urinary tract infections, she said.

Unaltered pets are also more likely to roam, which puts them at risk for accidents involving automobiles, fights with other animals and contracting contagious diseases, Freitag said.

Unaltered animals also are more likely to have behavior problems.

"Often, neutering can change an animal's temperament for the better," said Freitag.

Freitag said people often give money as the reason they don't have their pet spayed or neutered. But in the long run, she said, it's usually cheaper than the cost of care an animal will need if it develops a health problem.

Freitag said, on average, spaying of a medium-size female dog will cost about $75, spaying of a female cat about $60, neutering of a male dog about $60 and neutering of a male cat about $30.

"If people would put aside $5 to $10 per week from the time they get a puppy, by the time the pet is 4 to 6 months old, they would have saved enough for the surgery," said Freitag, who noted that the procedure is major surgery that requires an operating room and anesthetic.

On the other hand, treating a uterine infection on an emergency basis can easily cost $300 to $400, she said.

To help with the cost of spaying/neutering for low-income families, the Humane Society will hand out vouchers for free spaying/neutering surgeries at Spay Day, which will begin at 8:30 a.m. Tuesday in the ShopKo court at West Park Mall. Local veterinarians have agreed to accept the vouchers to perform the procedure.

Peters said the vouchers will be handed out on a first-come, first served basis. Pet owners are asked not to bring their pets, but they need to know the size, weight and breed of their animals.