A litter of 10 puppies peer out of their cage, Dec. 13, 2005, at the Humane Society of South Mississippi in Gulfport, Miss..

Puppies are popping up everywhere amid the rubble left by Hurricane Katrina - and animal welfare workers on the northern Gulf Coast fear it is only the start of a big boom in dog births.

Officials say more than 6,000 pets were saved after Katrina came ashore Aug. 29, and many of them were relocated to homes elsewhere in the country. An unknown number drowned in the floodwaters or died later of injuries.

But thousands of animals remain, running loose in neighborhoods where fences were flattened and many owners are gone.

"I've never seen so many puppies in my life," said Manny Maciel, an animal control officer from New Bedford, Mass., who made two trips to help trap loose dogs and cats in New Orleans and Mississippi.

Earlier this month, Maciel pulled 10 puppies and their mother from beneath a porch in a hard-hit section of Biloxi. He found seven puppies and seven dogs during another shift.

Maciel took all the dogs to the Humane Society of South Mississippi, where a shelter now holds about 250 dogs and cats, including nearly 50 puppies. The shelter is the largest one on the Mississippi coast.

Workers have yet to see a spike in cat births, but there's no doubt about what dogs have been doing since the hurricane, said Tara High, executive director of the nonprofit group.

"We're beginning to get litters now," High said. "It's a lot of puppies, and it is not the puppy season."

Maciel and partner Janis Moore drive through mostly abandoned neighborhoods checking reports of stray animals and encouraging pet owners to have their animals spayed or neutered.

Some owners are hesitant to part with their pets for fear they'll never see them again.

"A lot of times it's the only thing they've got," said Moore, who has made three trapping trips .

Animals without owners often wind up at the shelter, where workers are overwhelmed despite the trickle of volunteers who help walk dogs and clean up.

About 300 animals had to be euthanized in November at the shelter, High said, but all were too old, sick or aggressive to be adopted. New owners have adopted 378 other dogs and cats.

"It's frustrating," said High, who has worked every day but Thanksgiving since Katrina. "The phone does not stop ringing."