The U.S. Food and Drug Administration has granted emergency approval for a new treatment against a devastating parasitic infection that has been spreading among pets in the southern United States. The decision comes as veterinarians report rising cases of screwworm infestations in dogs and cats, a condition that can be fatal if left untreated.
Screwworm disease is caused by the larvae of the Cochliomyia hominivorax fly, which lay eggs in open wounds of warm-blooded animals. The resulting maggots feed on living tissue, causing severe pain, secondary infections, and often death. The newly approved therapy, doramectin, is a veterinary antiparasitic drug shown to kill screwworm larvae rapidly. In clinical field trials, the treatment achieved a 95 percent success rate in clearing infestations within 48 hours when applied directly to affected wounds.
Until now, options for treating screwworm in pets were limited to manual removal of larvae and supportive care, which can be traumatic for both animals and owners. The FDA’s emergency authorization allows veterinarians to use doramectin topically, bypassing the need for lengthy compounding or off-label prescribing. The drug works by disrupting the nervous system of the larvae, causing paralysis and death without harming the host animal when used as directed. The approval covers dogs and cats of all ages, though the agency advises caution in pregnant or nursing animals.
What This Means for Pet Owners and Communities
The infestation has been particularly problematic in states like Texas, Florida, and parts of the Gulf Coast, where warm climates allow the screwworm fly to thrive year-round. Stray and shelter animals are at highest risk, but owned pets with even minor cuts or surgical wounds can become targets. The FDA’s move is expected to reduce euthanasia rates in shelters, where infected animals were often put down due to lack of effective treatment options.
Veterinary public health officials emphasize that prevention remains critical. Pet owners are urged to keep wounds clean and covered, use approved fly repellents, and report any signs of maggots in wounds immediately. The emergency approval is temporary but can be renewed as the FDA continues to evaluate full licensure for doramectin as a screwworm treatment. Manufacturers have already begun scaling up production to meet expected demand from veterinary clinics across the affected regions.
Looking ahead, researchers are optimistic that this approval could pave the way for broader use of doramectin in livestock, where screwworm outbreaks cause millions of dollars in losses annually. For now, the focus is on saving pets and reducing suffering. With the new treatment now available, veterinarians have a powerful tool to stop this deadly parasite in its tracks, offering hope to countless animal owners facing an otherwise grim diagnosis.