Texas Pet Adoptions on Hold as Screwworm Outbreak Spreads
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.
A Parasite Returns After 60 Years
The New World screwworm is the larval stage of the fly Cochliomyia hominivorax. Despite its name, it is not a worm but a parasite that feeds on the living tissue of warm-blooded animals. Female flies lay eggs in open wounds or natural body openings. Within hours, the eggs hatch and the larvae begin feeding on living tissue — unlike common maggots, which feed on dead or decaying tissue. Without treatment, infestations can be fatal.
The screwworm was largely eradicated from the United States by the early 1970s through the sterile insect technique — breeding and releasing millions of sterile male flies. But the pest, contained in Panama for decades, began moving north in late 2024. As of August 16, the USDA has confirmed 46 infestations, including 45 in Texas and one in New Mexico, according to Texas Public Radio.
The first confirmed case in Texas was in a 3-week-old calf in La Pryor, about 50 miles from the Mexico border, confirmed by the USDA in early June. Since then, detections have grown across southern Texas and southeastern New Mexico, with several infections found in dogs.
Quarantine Restrictions Strain Shelters
Forty-four states have restricted the movement of pets from infested areas, creating a hardship for shelters from Texas that typically send thousands of animals to other states each year. Movement restrictions are in effect in parts of 23 Texas counties, and the Texas Animal Health Commission requires all warm-blooded animals to be inspected and authorized before being moved out of an infested zone.
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.
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.
A Shelter System Already at the Breaking Point
The restrictions hit an animal welfare system that’s long been short of money and other resources, said Delcianna Winders, director of the Animal Law and Policy Institute at the Vermont Law and Graduate School. 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 — and euthanized about 45,000 dogs, more than any other state. Texas also led in cats transferred out of its shelters — nearly 53,000 — and was second to California in those euthanized, with almost 29,000. The state has about 439,000 stray dogs and cats, more than any state other than California.
“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,” Winders said.
The Texas Tribune reported on fears of “mass euthanasias” if animals cannot be moved out of quarantine zones. “There could be thousands of animals dying in shelters because they don’t have the space to continue to cover those animals,” said Rebecca Giamona, a veterinarian with Austin Pets Alive.
Response and Treatment Efforts
Officials are deploying multiple strategies to contain the outbreak. The FDA issued an Emergency Use Authorization on August 13 for Simparica TRIO to treat NWS infestations in dogs and puppies, following earlier approval of Nitenpyram, an over-the-counter medication for dogs, puppies, cats and kittens.
A $750 million sterile fly production facility is under construction in Edinburg, Texas, expected to open by April 2027. The USDA also dedicated $21 million to convert a fruit-fly breeding facility in southern Mexico into one for breeding screwworm flies, and officials deployed 8,000 fly traps along the U.S.-Mexico border.
Gov. Greg Abbott issued a statewide disaster proclamation for all of Texas’ 254 counties in response to the screwworm cases, activating the Texas New World Screwworm Response Team. Texas State Veterinarian Bud Dinges urged residents to cooperate with quarantine measures: “Please help us prevent any further movement of this pest by staying put.”
What’s Next
As officials work to contain the parasite through sterile fly releases, expanded surveillance and treatment options, shelters across Texas remain in a precarious position. The quarantine restrictions, while necessary to prevent the spread of the screwworm, have exposed the fragility of a shelter system that depends on out-of-state transfers to save animals.
Agriculture Secretary Brooke Rollins has expressed confidence that the incursion can be contained, stating there is “no reason to believe this incursion will result in establishment of the pest in our country.” But with the sterile fly facility not expected to be fully operational until April 2027, the coming months will test both the eradication strategy and the resilience of Texas’ animal shelters.
For now, shelters are asking the public to report any suspicious wounds on animals and to consider fostering or adopting locally where possible. As one animal control supervisor in Greenville put it, many pet owners are saying, “I just can’t, I just can’t do it anymore.” The outcome of this outbreak will determine how many more animals — and shelters — reach that breaking point.