Have you ever noticed a wound on one of your animals that simply did not seem to heal the way you expected? If that happens now, it’s important to be aware that a screwworm infestation could be the cause. Questions about screwworm infestations have become more common as animal owners hear reports about recent New World screwworm activity in North America. Whether you care for cattle, horses, dogs, or cats, recognizing the signs of a potential problem can help you seek veterinary care promptly and protect the animals that depend on you. At Willow Bend Animal Clinic, your Marshall County, MS veterinary clinic, we are here to help!

Understanding what a screwworm infestation looks like starts with recognizing changes in wounds, skin health, and behavior. While most wounds heal without major complications, some deserve closer attention. Learning how infestations may appear in different species helps livestock owners and pet families identify concerns earlier and make informed decisions about their animals’ health.

What Is a Screwworm Infestation?

A screwworm infestation occurs when the larval stage of the fly Cochliomyia hominivorax, commonly known as the New World screwworm, develops in a wound or damaged area of skin.

Unlike many fly larvae that feed on dead tissue, New World screwworm larvae develop within living tissue. This behavior is what makes the parasite a concern for veterinarians, livestock producers, horse owners, and pet owners alike.

Historically, screwworm infestations affected millions of animals throughout the southern United States before a successful eradication program removed the parasite from the country. Recent detections in Mexico and confirmed cases in Texas have renewed awareness among animal health professionals across North America.

Why Are Animal Owners Hearing About Screwworms Again?

Animal health agencies continue to monitor the situation closely because early detection remains one of the best tools for limiting the spread.

The United States Department of Agriculture, state animal health agencies, and veterinary organizations actively track developments and educate animal owners about signs to watch for.

This attention does not mean every wound represents a screwworm infestation. It means that animal owners should remain aware of unusual changes in wounds and seek veterinary guidance when concerns arise.

What Does a Screwworm Infestation Look Like?

One of the most important things to understand is that screwworm infestations often begin with a wound that initially appears ordinary.

Over time, however, the wound may begin behaving differently than expected.

The Wound Does Not Heal Normally

Most cuts, scrapes, and minor injuries gradually improve.

A wound affected by complications may:

• Remain inflamed
• Appear larger over time
• Develop excessive drainage
• Show delayed healing

A wound that seems to worsen rather than improve deserves veterinary evaluation.

Increased Attention to the Wound

Animals frequently communicate discomfort through behavior.

You may notice:

• Excessive licking
• Scratching
• Chewing
• Rubbing against surfaces

This behavior often signals irritation and should not be ignored.

Changes Around the Wound

The surrounding skin may appear:

• Red
• Swollen
• Irritated
• Sensitive

Changes like these can occur with many wound-related problems, which is why veterinary assessment is valuable.

What Does a Screwworm Infestation Look Like in Cattle?

Cattle are often mentioned when screwworms are discussed because of their historical impact on the livestock industry.

Common Areas of Concern

Potentially vulnerable locations include:

• Branding sites
• Ear tag sites
• Castration sites
• Calving-related injuries
• Fence wounds
• Tick bite reactions

Regular inspections help producers identify concerns early.

Behavioral Changes in Cattle

Affected cattle may:

• Separate from the herd
• Show reduced appetite
• Display signs of discomfort
• Become less active

Subtle changes in behavior often provide important clues that something is not right.

What Does a Screwworm Infestation Look Like in Horses?

Horses frequently experience minor cuts and scrapes through everyday activity.

While most heal normally, horse owners should monitor wounds carefully.

Watch for Delayed Healing

A wound that remains irritated or fails to improve deserves attention.

Pay particular attention to:

• Leg wounds
• Saddle-area irritation
• Insect bite reactions
• Surgical sites

Routine observation can help identify problems before they become more significant.

Changes in Behavior

Your horse may become:

• Less willing to move
• More sensitive to touch
• Irritable during grooming
• Less interested in normal activities

These changes warrant closer evaluation.

What Does a Screwworm Infestation Look Like in Dogs?

Dogs often develop wounds through everyday adventures.

Your pup may receive a cut while exploring, hunting, hiking, or simply playing outdoors.

Common Risk Areas

Potential concerns include:

• Hot spots
• Skin infections
• Bite wounds
• Surgical incisions
• Scrapes and cuts

Because dogs frequently lick wounds, behavioral changes may appear before obvious physical changes.

Signs Dog Owners Should Watch For

You may notice:

• Persistent licking
• Increased scratching
• Swelling
• Delayed healing
• Reduced activity

Prompt veterinary care can help determine the cause.

What Does a Screwworm Infestation Look Like in Cats?

Cats often hide signs of discomfort exceptionally well.

Your feline friend may continue acting relatively normal even when dealing with an injury.

Areas to Monitor

Pay close attention to:

• Bite wounds
• Scratches
• Outdoor injuries
• Skin irritation
• Areas hidden beneath thick fur

Regular hands-on examinations can reveal concerns that are easy to miss.

Behavioral Changes in Cats

Possible signs include:

• Hiding
• Reduced appetite
• Less grooming
• Increased sensitivity
• Changes in activity level

Any unexplained change deserves attention.

Are Certain Animals More At Risk?

The New World screwworm depends on access to wounds or damaged skin.

Animals that may face increased risk include:

• Outdoor dogs
• Outdoor cats
• Cattle operations
• Horses with active lifestyles
• Animals recovering from surgery
• Animals with skin conditions

The presence of a wound is often a more important factor than the species itself.

What Types of Wounds Deserve Extra Attention?

Not every wound becomes a serious problem.

However, some situations deserve closer monitoring.

Surgical Incisions

Recovery after surgery requires observation.

Monitor healing carefully and follow veterinary instructions.

Skin Conditions

Hot spots, allergies, and skin infections can create areas of irritation.

Prompt treatment helps support healthy healing.

Livestock Procedures

Routine management procedures sometimes create temporary wounds.

Observation during healing helps identify concerns early.

How Veterinarians Diagnose Potential Cases

Diagnosis begins with a physical examination.

Your veterinarian evaluates:

• Wound appearance
• Healing progress
• Tissue health
• Animal behavior
• Overall condition

Additional evaluation may be recommended depending on the situation.

The goal is to determine the cause of the problem and develop an appropriate treatment plan.

How Can Animal Owners Help Prevent Problems?

Routine observation remains one of the most effective tools available.

Perform Regular Checks

Inspect:

• Skin
• Ears
• Paws
• Surgical sites
• Areas beneath fur
• Livestock processing sites

Small changes are easier to identify when animals are examined regularly.

Address Wounds Promptly

Early treatment often leads to better outcomes.

Do not ignore wounds simply because they appear minor.

Maintain Veterinary Care

Routine wellness visits support overall health and provide opportunities to discuss emerging animal health concerns.

The CDC has a downloadable PDF about symptoms caused by the New World Screwworm. You can also monitor the government’s response on the USDA’s screwworm.gov page. The  University of Minnesota also has a helpful piece on protecting pets from the screwworm.

Frequently Asked Questions

What does a screwworm infestation look like?

A screwworm infestation often begins with a wound that does not heal normally. Signs may include swelling, irritation, delayed healing, excessive attention to the area, and changes in behavior.

Can cattle get screwworm infestations?

Yes. Cattle can be affected when wounds are present. Common areas of concern include branding sites, ear tag locations, castration sites, and injuries.

Can dogs and cats develop screwworm infestations?

Yes. Dogs and cats may be affected if wounds, surgical sites, skin infections, or other areas of damaged skin are present.

When should I call a veterinarian?

Contact your veterinarian if a wound appears unusual, worsens rather than improves, develops excessive swelling, or causes noticeable discomfort.

Are screwworm infestations common in Mississippi?

Widespread infestations are not currently occurring in Mississippi. However, veterinarians and animal health officials continue monitoring developments closely.

Schedule an Appointment at Our Marshall County, MS Veterinary Clinic

Recognizing what a screwworm infestation may look like in cattle, horses, dogs, and cats helps you respond quickly when concerns arise. At Willow Bend Animal Clinic, your Marshall County, MS animal hospital, veterinary care is available for livestock, horses, dogs, cats, and farm animals. If you notice a wound that is not healing properly or have concerns about your animal’s health, schedule an appointment today.

Looking for a trusted vet near me in Marshall County, MS? Willow Bend Animal Clinic provides comprehensive veterinary care for companion animals and livestock. Visit our services page to learn more about wellness care, surgery, diagnostics, preventive medicine, and large-animal veterinary services.

This blog is intended for informational purposes only. Always consult your veterinarian regarding diagnosis, treatment, wound care, and preventive health recommendations for your animals. Follow your veterinarian’s guidance for the care of livestock, horses, pets, and farm animals.

To learn more about our  Marshall County, MS animal clinic, start by visiting our Services page for a great overview of who we are and what we do. We offer a range of services, including Wellness and Vaccinations, Surgery, and more. Please feel free to contact us anytime!