HOUSTON - The effort to help control the pet population in Houston got a huge boost as Big Fix Houston kicked off on Saturday.

The first day of the initiative attracted more than 700 pets owners and another 300 on a waiting list. The program offers free spay or neuter, vaccinations, and microchip.

Flyers were sent to residents in 11 of Houston's neighborhoods with the worst complaints about loose animals.

Valerie Espinoza was thrilled to get the flyer in her neighborhood near Hobby Airport.

"I always keep an eye out on social media because I know they do them so this was very helpful when I got it in the mail yesterday," she said.

According to the BARC shelter, Houston has the largest animal overpopulation issue in the nation.

Gloria Zenteno with Unity For A Solution says this is a different approach to a huge problem.

"A lot of these animals end up in our local shelters that are inundated with so many and we're trying to address the problem at the root in the community." said Zenteno.

Because turnout was so good, there are no more opportunities to get the free service until next year.

On their site, you can find low cost vets to do the same service. The website is also where you go if you'd like to make a donation.

Big Fix Houston is made up of public agencies, civic leaders and smaller nonprofit rescue and advocacy groups.