A popular pet neuter program has run out of money for the second year in a row, forcing it to temporarily suspend operations, and underscoring its need.

The Hawaiian Humane Society announced that it will immediately stop the city-funded Neuter Now program that offers dog and cat owners certificates for reduced-rate pet sterilizations.

The city gave the program $250,000 last year but the demand outstripped the funding, said Hawaiian Humane Society president and CEO Pam Burns in a news release Wednesday.

Burns called for an increase in the money given so that it can cover all requests for the service.

With pet ownership on the rise, the city should increase funding to this "critical social service," Burns said. The program had an all-time funding high in 2002 at $559,800 but has steadily declined since then, she said.

"Pet owners want to do the right thing and do their part to control pet overpopulation," Burns said. "The county is letting us all down in a big way."

City spokesman Bill Brennan said the city has increased the budget for the program over the past three years and that the program will receive an additional $50,000 this year for a total of $300,000.

"We recognize the importance of the spay/neuter program to control animal overpopulation," Brennan said.

A Humane Society spokeswoman said the majority of animals neutered through the program are likely pets, and not feral. She said feral animals can be neutered for free in a different program covered by private donations.

As of Wednesday, 3,425 pets had been neutered through the Neuter Now program this year. However, there are still some outstanding certificates worth about $68,000, he said.

"Depending upon the redemption rate of the $68,000 worth of outstanding certificates, resumption of certificate sales may occur," Brennan said. In the meantime, next year's funding will become available July 1 and certificates will be available then, he said.

The 3 1/2-month wait until certificates are available again could translate into thousands of unwanted litters in neighborhoods across O'ahu, Burns said.

One female cat and her offspring can produce more than 120,000 cats in seven years, she said, adding that in a lifetime an unspayed dog and her offspring can produce more than 60,000 dogs.

"The county can no longer ignore the facts," Burns said. "Taxpayers and pet owners want year-round access to these low-cost certificates."

The program was established in 1986. More than 180,000 households have taken advantage of it since then.

Veterinarians charge around $200 for the operation, but the certificates honored by participating veterinarians reduce the price for a female dog to $20 for households on government assistance to $75 for others, Burns said.

The program was recognized nationally for its public-private partnership in which government, nonprofit and for-profit veterinarians joined together to curb pet overpopulation.

Reach Eloise Aguiar at eaguiar@honoluluadvertiser.com.