You may have heard about screwworms in the news lately. These are a destructive type of fly that feed on the flesh of warm-blooded animals. This can be scary for dog owners. Although it is more likely to affect livestock, it can show up in dogs. Knowing what to look for and how to prevent an infection is key. Here’s what you need to know about screwworms and dogs:

What Are Screwworms?

A screwworm is a fly that feeds on living animal flesh, specifically warm-blooded animals and humans. Their scientific name is Cochliomyia hominivorax, and that roughly translates to “man-eater”. They get the name screwworm due to the fact that the larva of the fly has a rigid ring of spines. This helps the worm twist and dig deep into wounds, almost like a screw.

The adult flies look similar to a house fly, but they have bodies that look metallic blue or orange, and they have orange-red eyes. They also have three dark stripes on their back. Unlike normal maggots that feed on dead tissue, screwworms burrow into living and healthy flesh. This makes them dangerous to most warm-blooded animals and humans.

Adult female flies tend to lay their eggs near open wounds or moist body openings, like ears, the mouth, nose, and even the genitals. Even the smallest wound, like a tick bite or scratch, can provide an entry point for these larvae to take hold.

How Quickly Does Screwworm Develop?

Once the eggs are laid, they hatch within 24 hours. The larvae burrow into the healthy tissue, which creates a painful wound that enlarges. Without proper treatment, these infestations can become extremely dangerous and even fatal.

Is Screwworm Common in Dogs?

Screwworm is much more common in livestock, especially cattle; however, it can spread to dogs and other animals. Screwworms can infect wildlife, horses, cattle, sheep, goats, birds, cats, and dogs. They can also infect humans, although this is rare.

Recent detections of screwworms have included dogs, which means it’s important to be vigilant, but it’s also not a cause for panic. Screwworm is a much higher risk in dogs that don’t have homes, have been recently rescued or transported, or work regularly around livestock. This is because they might be more likely to have a wound from an injury or a fight and not get the care they need to heal the wound properly.

For most pets in clean and safe environments, the risk remains fairly low. Making sure you check your dog routinely for any wounds and getting care for those wounds is important, especially if something looks unusual or strange. If you notice any weird wound, make an appointment with your veterinarian.

How Can Screwworms Spread to Dogs?

If your dog has an open wound, this is the most likely way they can become infected with screwworms if they come into contact with them. Even the smallest scratch can attract a female fly so they can lay their eggs.

Common entry points include:

• Open wounds
• Skin folds or nasal folds
• Tick bites
• Scratches, even minor ones
• Hot spots
• Cuts
• Surgical incisions
• Mucous membranes, such as eyes, ears, nose, mouth, and genitals

Open wounds are one of the most common ways a dog can be infected with screwworms, which is why it’s important to care for any open wounds, including caring for your dog’s stitches after surgery.

Younger animals are typically more susceptible, and senior dogs might also be at risk if a wound is not noticed and cared for. Because the screwworm looks like a typical house fly, infestations can be hard to spot before they really take hold.

Can Humans Get Screwworms?

Yes, screwworms can infect humans. However, these cases are extremely rare. They only occur in open cuts or sores or in mucous membranes. It’s also important to note that you cannot catch screwworms from another person or animal.

What Are the Signs of Screwworms in Dogs?

Animals infected with screwworms show similar symptoms. These can be some signs of screwworms in dogs:

• There is often a wound that continues to get bigger/worse or refuses to heal.
• Your dog may excessively chew, lick, scratch, or rub the area around a wound.
• There will be inflammation, redness, or swelling around a wound.
• There is often bloody discharge from a wound.
• You will likely notice a foul-smelling odor from the wound.
• Your dog may paw at their face or shake their head a lot.
• There will be sensitivity and pain at the wound area.
• Your dog may be restless or showing clear discomfort.

Signs of an advanced screwworm infection tend to include:

• Visible maggots in the wound or body openings
• Abscesses forming in or around the wound
• Fever
• Lack of appetite
• Weight loss
• Lethargy

If you notice any of these signs, don’t hesitate to give your veterinarian a call. Weight loss, lethargy, and a lack of appetite are some of the signs and symptoms you should never ignore in your dog, so make sure to get your dog seen if you suspect screwworm infection.

This is an overview of what to know about screwworms and dogs. Thankfully, the risk of infection is relatively low, but it’s important to be aware and stay vigilant, especially if your dog has any open wounds or scratches on their skin. If you have any questions or concerns, don’t be afraid to reach out to your veterinarian!