Adoptions are on hold for thousands of dogs and cats in Texas, potentially putting the animals at risk of being euthanized, because of efforts to stop the spread of the New World screwworm, an insect that has crossed the border from Mexico into the United States for the first time in 60 years.

The flesh-eating parasite threatens the nation's $113 billion beef industry, prompting federal officials to close the border to cattle movements. Because the screwworm also can infect pets, most states have restricted the movement of animals from infested areas of Texas, leading to crowded conditions in state shelters that rely on adoptions to other regions of the country.

“It’s thrown a wrench into things, for small rescues as well as the bigger shelters,” said Mia Bendixsen, executive director of the Texas Humane Legislation Network, which promotes animal welfare laws.

The screwworm can lay eggs that hatch into flesh-eating larvae in the wounds or mucous of any mammal, and of the dozens of infections in southern Texas and southeastern New Mexico, several have been in dogs. Forty-four states have restricted the movements of pets from infested areas, creating a hardship for shelters from Texas that typically send thousands of animals to other states each year.

In Corpus Christi, the Gulf Coast Humane Society couldn't get rescued dogs into New York state for weeks, causing the shelter's animal population to climb from around 325 to nearly 450.

The shelter, which sends about 500 dogs a year outside Texas, created more space in outdoor exercise areas until New York again allowed dogs from Texas — if a veterinarian first certified that each one wasn't infected with the screwworm.

She added that if her shelter doesn't have space to take animals from municipal shelters, “then they have to euthanize more animals.”

Surplus of dogs and cats for adoption
Moving dogs and cats from Texas to other states, particularly in the Northeast or Great Lakes region, has become crucial to saving stray and abandoned animals.

In 2025, Texas had more unadopted dogs transferred out of its shelters than any other state — nearly 89,000, according to the American Society to Prevent Cruelty to Animals. Texas also euthanized about 45,000 dogs — more dogs than any other state, according to the data.

And Texas led in the number of cats transferred out of its shelters — nearly 53,000 — and was second to California in those euthanized, with almost 29,000.

Texas has more stray dogs and cats than any state other than California — about 439,000 in 2025 — largely because of its high population and size. Warm weather also allows stray animals to survive longer and breed more, said veterinarians and animal welfare advocates. They added that Texas pet owners seem less willing to spay or neuter their dogs.

“There are people with working ranch and farm dogs, both male and female, who feel like the animal will lose some of its drive," said veterinarian Lori Teller, executive director of the Texas Veterinary Medical Association.

Both shelters and animals are stressed
In Houston, Humane Society shelter Director Aaron Grady said an inability to send animals out of state has left them more stressed.

“If an adopter comes through and they’re going from kennel to kennel and they see one dog who may be sitting calmly and contentedly in one kennel and then in the next kennel, there’s one dog who’s bouncing off of the walls and barking because of how stressed they are, first one may be looking more desirable,” Grady said.

The Houston shelter has worked to keep its animal population — mostly cats and dogs — at about 200 by tapping a network of foster homes for up to 300 more and by helping pet owners keep their animals even a little longer.

Tightened rules for importing animals
Restrictions on animal transports followed efforts by the U.S. Department of Agriculture to keep the New World screwworm fly from crossing the border with Mexico.

Those efforts include construction of a $750 million fly factory in southern Texas that's set to open in April 2027 for breeding billions of sterile males. The U.S. had largely eradicated the fly by the early 1970s by breeding sterile males and releasing them from planes to mate with females, who laid eggs that wouldn't hatch.

Smaller facilities in Texas and southern Mexico have been dispersing sterile flies bred in Panama, and another is planned for Arizona.

Florida — where the screwworm fly can thrive — banned imports of rescued dogs and cats from Texas and New Mexico just a week after the first reported case in Texas this year. Other states required veterinarians to inspect animals and declare them free of the parasite. Many shortened the period that a certification was valid from the typical 30 days to as little as three days.

Shelters worried about space
State restrictions hit an animal welfare system that's long been short of the money and other resources, said Delcianna Winders, director of the Animal Law and Policy Institute at the Vermont Law and Graduate School.

She said shelters need more money and space, but communities also should require animals to be spayed or neutered — and have programs to provide those services if people cannot afford them.

“If we could provide them just with some basic support, they might be able to keep those animals in their homes, and that’s one less animal in a shelter, one less animal being killed,” she said.

COVID-19 stressed the system, too, in part because pandemic restrictions put spaying and neutering on hold. Cost-of-living increases are another reason people turn animals over to shelters.

“A lot of them are just saying, ‘I just can’t, I just can’t do it anymore,’” said Brandon Krodle, animal control supervisor in Greenville, Texas, a fast-growing city northeast of Dallas.

A trip saved her dog's life
Mills, the Corpus Christi shelter director, has a dog who would have died in 2015 but for a nearly 1,000-mile trip from Paris, Texas, to Angola, Indiana, where Mills was working at the time. Zuri, a young female Shepherd-pit bull mix, was on a list of dogs set to be euthanized, and Mills' counterpart in Texas asked Mills to add Zuri to a transport.

Zuri's right ear doesn't fully straighten up, and the puppy had “the cutest face,” Mills said, but she was sold on Zuri because Zuri looked as if she “was actually thinking things through” as Mills spoke to her. Mills broke a personal rule against taking her shelter's animals home.

When Mills moved to Corpus Christi in 2020, Zuri returned to Texas.

“The shelter that I was at in Indiana, we transported from Texas and Southern states every week," Mills said.