Botflies, known scientifically as Cuterebra species, are parasites that can infect animals throughout North America and other regions. While cats and small mammals are more common hosts, dogs can be affected as well—particularly active pets that spend time outdoors. Because the condition is unusual and the symptoms can resemble other medical problems, dog owners are often startled when they learn their pet has a botfly larva beneath the skin. With prompt veterinary treatment and good follow-up care, however, most dogs recover without long-term complications. Understanding how botfly infections happen, how to recognize them, and what to expect during treatment can help owners respond quickly and confidently.
How dogs get botfly infections
Botflies lay their eggs near the entrances of rodent and rabbit burrows, along grass blades, or in outdoor areas where potential hosts are active. When a dog brushes past these spots, the body heat stimulates the eggs to hatch. Newly emerged larvae then attach to the dog’s fur and work their way into the skin through an existing opening—such as a tiny scratch, the nose, or even the mouth.
Once underneath the skin, the larva creates a small breathing hole and settles in to develop over several weeks. This results in what is called a “warble,” a raised lump formed around the larva. During this period, the dog’s immune system reacts to the foreign organism, causing irritation, swelling, and sometimes infection. Botflies generally do not spread from dog to dog, but outdoor pets are more likely to encounter them during late summer and early fall when larvae are most active.
Symptoms owners may notice
The most visible sign of botfly infection is a firm lump beneath the dog’s skin, which usually has a small opening at the top. This opening may leak fluid or appear as a dark dot. If the dog has long fur, the lump may go unnoticed at first, especially if the dog shows no discomfort. As the larva grows, additional signs may develop:
- Persistent itching or licking at one location
- Localized swelling or redness
- A small hole that seems to pulse or move
- Hair loss around the lump
- Discharge with an odor
- Sudden sensitivity when touched
Some dogs show only mild irritation, while others may become lethargic, lose appetite, or develop fever if infection sets in. Rarely, larvae can migrate internally to the respiratory system or nervous system, leading to more serious illness. Any unexplained lump should be evaluated promptly, even if it appears minor.
Diagnosis by a veterinarian
Veterinarians typically diagnose botfly infections through physical examination. The breathing hole and the larva’s movement beneath the surface are strong indicators. To confirm the diagnosis, the veterinarian may examine the lump more closely or use imaging tools if it is located in a sensitive area. They will also assess whether secondary infection or tissue damage has occurred and determine the safest method for removal.
Treatment and larva removal
Successful treatment involves removing the larva intact, cleaning the tissue, and managing any infection or inflammation. Removal must be done by a professional. Attempting to squeeze, pull, or cut the lump at home can cause several problems:
- The larva can rupture, increasing the risk of severe inflammation or infection.
- Improper removal can leave behind fragments of tissue.
- The wound may not drain properly, leading to abscess formation.
During vet treatment, the area may be numbed or sedated depending on the dog’s comfort level and the size of the lesion. The veterinarian will enlarge the breathing hole slightly if needed, extract the larva safely, and flush the cavity to minimize bacteria. In some cases, antibiotics or anti-inflammatory medications may be recommended to support healing.
Most dogs experience quick relief once the larva is removed. The wound is usually left open to heal naturally, though follow-up visits may be scheduled to monitor progress.
Recovery expectations
Healing time varies from dog to dog but typically ranges from one to several weeks. Owners may be advised to:
- Prevent the dog from licking or scratching the wound
- Keep outdoor activity limited until healing stabilizes
- Watch for unusual swelling, bleeding, or discharge
Most warble sites heal with only a small scar or none at all. Complications are uncommon when treatment is prompt, but delayed care increases the chances of infection or tissue damage. If an owner suspects another lump forming, they should schedule a veterinary appointment right away.
Prevention strategies
It is not always possible to prevent botfly exposure completely, especially for active outdoor dogs. However, a few habits may lower risk:
- Check the dog’s fur frequently during late summer and fall.
- Keep dogs away from rodent burrows or areas with heavy wildlife activity.
- Trim long fur to make inspection easier.
- Maintain routine wellness exams and parasite prevention.
Although flea and tick medications do not remove botfly larvae, they help keep skin healthier overall and can reduce the chances of other parasitic problems.
When to seek help
Any sudden lump, especially one with an opening in the center, warrants prompt veterinary attention. Even if the cause turns out not to be a botfly, many skin conditions—from abscesses to tumors—look similar in early stages. The sooner a diagnosis is made, the sooner effective treatment can begin.
A botfly infection can be alarming, but with expert care most cases resolve smoothly. Outdoor dogs remain at higher risk, so awareness plays a major role in early detection. By paying attention to skin changes, seeking veterinary help quickly, and following through on recommended care, owners can help ensure their dogs stay healthy, comfortable, and active year-round.
