Botfly Infection in Dogs: Symptoms, Treatment, and Prevention
If you’ve ever found a strange lump on your dog that seemed to have a small hole or even movement inside it, you might have encountered something alarming — a botfly (Cuterebra) infection. Botflies are parasitic insects that can infect dogs, cats, and wild animals, especially during warmer months.
What Is a Botfly (Cuterebra)?
Botflies are large, hairy flies that look similar to bumblebees. Adult botflies don’t directly harm animals — they lay eggs on grass, leaves, or near burrows where rodents and rabbits live. When a curious dog sniffs or lies down near these areas, botfly eggs or larvae can attach to the dog’s fur and enter through the nose, mouth, or small skin openings.
Once inside, the larva (maggot) burrows into the tissue and creates a warble — a lump with a breathing hole. It stays there for several weeks, feeding on tissue fluids until it matures, then exits the host to pupate in the soil.
How Dogs Get Infected
Dogs usually pick up botfly larvae while exploring areas where wild rodents or rabbits live. Common infection sites include:
- Around the head, neck, and shoulders (from sniffing burrows)
- Near the mouth, eyes, or nostrils
- Occasionally, larvae can migrate internally, reaching the brain or respiratory tract, though this is rare but serious
Outdoor dogs or those that frequently explore tall grass and wooded areas are most at risk.
Symptoms of Botfly Infection in Dogs
A botfly infection is often visible as a lump under the skin, but other symptoms can depend on where the larva is located. Signs include:
- A firm, raised swelling (often 1–2 cm wide)
- A small central hole in the lump (the larva’s breathing pore)
- Oozing or bloody discharge from the hole
- Movement under the skin (in some cases, you can see the larva move)
- Excessive licking or scratching at the site
- Pain, swelling, or secondary infection
If the larva migrates internally (rare), symptoms may include:
- Sneezing, nasal discharge, or respiratory distress (if in the nose/sinuses)
- Seizures, circling, or behavioral changes (if in the brain)
Diagnosis
A veterinarian can usually diagnose a botfly infection by examining the lump and identifying the breathing hole. In some cases, imaging (like an X-ray or ultrasound) helps confirm if there’s only one larva or if it has migrated deeper.
It’s essential not to squeeze or puncture the lump yourself — this can rupture the larva, causing a severe allergic or inflammatory reaction.
Treatment
Treatment involves safe removal of the botfly larva and care for the wound:
- Veterinary removal: The vet will gently enlarge the breathing hole and extract the larva intact using sterile instruments.
- Wound cleaning: The area is flushed with antiseptic to remove debris and prevent infection.
- Antibiotics or anti-inflammatory medication: To reduce swelling and prevent bacterial infection.
- Follow-up care: The wound is monitored until fully healed.
In cases where the larva has migrated internally, more intensive medical management — including imaging, medication, and sometimes surgery — may be required.
Recovery and Prognosis
Most dogs recover quickly once the larva is removed and the wound treated. Mild swelling or scarring may remain for a short time. Complications are rare but can include abscess formation or secondary bacterial infection if the larva dies inside the tissue.
If botfly larvae reach the brain or internal organs, the prognosis depends on how early the infection is detected and treated.
Preventing Botfly Infections
While you can’t completely eliminate the risk, you can significantly reduce it by taking these precautions:
- Avoid letting dogs roam near rodent or rabbit burrows during summer and early fall (botfly season).
- Inspect your dog’s skin regularly, especially around the face and neck.
- Use parasite prevention products recommended by your vet (though not all target botflies specifically, they help prevent other parasites).
- Keep your yard tidy — mow grass, and discourage rodents or rabbits from nesting nearby.
- See a vet promptly if you notice any suspicious lumps or holes in the skin.
Key Takeaways
- Botfly infections in dogs are caused by Cuterebra larvae entering through the skin or natural openings.
- Typical signs include a lump with a small breathing hole and possible discharge.
- Never attempt removal at home — always seek veterinary care.
- Early removal and wound care lead to an excellent recovery.
Botfly infections can be unnerving to see, but with prompt veterinary attention, your dog can recover quickly and safely. The best defense is vigilance — regular skin checks, avoiding wildlife burrows, and quick action if something looks off.
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