FDA Triggers Emergency Protocol for a 'Flesh-Eating' Parasite-Is Your Pet at Risk?

In the past few weeks, health officials reported cases of a flesh-eating parasite called New World screwworm (NWS) in Mexico, according to ABC News. If you're unfamiliar with this parasite, there's a good reason. It's because large-scale infestations (myiasis) haven't been documented in the United States for a few decades, USA Today notes. But recent findings near the border prompted the Food and Drug Administration (FDA) to issue an emergency use authorization to treat potential infestations in certain animal species.

As the Centers for Disease Control and Prevention (CDC) explains, these screwworms are parasitic flies that feed on warm-blooded animals and humans. Basically, female flies lay hundreds of their eggs in areas where there are open wounds, such as noses, mouths, or ears. These openings can be as tiny as a tick bite. Then, those eggs hatch into maggots (larvae), and as their name implies, they burrow (or screw) into flesh, eating the live tissue of their host. Most often, their feeding will cause animals to develop painful wounds and even cause death in some cases.

Currently, there haven't been any confirmed reports of NWS infestations in the United States, but pet parents should be aware of the situation, especially if your pet is around livestock. The FDA is focused on expanding treatment options for animals, including livestock and zoo mammals. That's one reason the agency issued a statement authorizing the use of Negasunt Powder.

The FDA determined that the powder helps treat and prevent the spread of NWS infestations in animals such as cattle, swine, goats, sheep, horses, and other susceptible animals. This treatment isn't meant for everyday use. The FDA clarifies that it's meant to be handled by licensed veterinarians, as ingredients in the powder can potentially cause neurotoxicity, which can damage the nervous system.

Screwworm Symptoms in Dogs

Livestock like cattle aren't the only animals targeted by these screwworms. Many pets, like dogs, can be affected if they happen to come into contact with these flies. There are a few signs pet parents can look out for, and the American Veterinary Medical Association lists symptoms that include:

• Irritable behavior in dogs, such as excessive head shaking
• Foul odors coming from wounds that smell like decay
• Visible signs of eggs or maggots (larvae) moving around in wounds

If you notice your dog displaying any of these symptoms, contact your veterinarian immediately, as your dog will need treatment and possibly surgery to remove the maggots (larvae).

Related: Watch Out for This Skin Infection That Can Be Caused by Your Dog's Allergies

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Is Screwworm Dangerous to Cats?

Cats can also be harmed by these parasitic flies. So cat parents should keep an eye out, as they can display symptoms in the same way as dogs. For both cats and dogs, the FDA also authorized the emergency use of NexGard and NexGard COMBO, common flea and tick medications, as part of the treatment for infestations.

Remember, these authorizations are just a precaution, as there haven't been any reported cases of New World screwworm myiasis in the country, as of late April 2026. But if any infestations do occur, there are treatments available to help save a number of animal species who may become affected.

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This story was originally published May 1, 2026 at 8:20 AM.