Botfly infestations in cats require veterinary removal of the larva, followed by wound care and antibiotics to prevent infection. The parasite involved is called Cuterebra, a type of botfly whose larvae burrow under the skin and grow inside a pocket called a warble. Cats are actually abnormal hosts for this parasite (rabbits and rodents are the intended targets), which means the larvae sometimes migrate to dangerous places like the brain or nasal passages. Most cases show up between July and September.
How Cats Pick Up Botfly Larvae
Cuterebra flies lay their eggs near the entrances of rodent or rabbit burrows. When a curious cat sniffs around these areas, the tiny larvae hitch a ride, entering through the mouth, nose, or any small wound on the skin. Once inside, the larva migrates under the skin and settles into a pocket of tissue, where it cuts a small breathing hole through the skin and begins to grow.
Over the next few weeks, the larva feeds on tissue fluid and enlarges steadily. Most owners first notice the problem when a visible, firm lump develops under the skin, often on the head, neck, or chest. A small opening in the center of the swelling is the larva’s breathing hole, and you may notice a thin discharge around it. That hole enlarges as the larva matures and prepares to drop out of the host to pupate in the soil.
What a Botfly Infestation Looks Like
The most obvious sign is a round swelling beneath the skin with a tiny central pore. You might see the dark tip of the larva poking through or notice fluid or pus seeping from the hole. The area around the lump is often inflamed, and your cat may groom or scratch at it obsessively.
Some cats run a fever or seem lethargic. If the larva entered through the nose, you may notice sneezing, nasal discharge, or labored breathing before a skin lump ever appears. One key clue vets look for is a sudden episode of violent sneezing weeks to months before other symptoms develop.
Why You Should Not Remove It Yourself
It’s tempting to squeeze the lump or pull the larva out with tweezers, but this is one of the most important things to avoid. If the larva ruptures during removal, its body contents leak into your cat’s tissues. This can trigger a severe allergic reaction or a dangerous inflammatory response. The proteins inside the larva are highly irritating, and a ruptured larva can turn a manageable problem into a medical emergency.
A vet has the tools and technique to extract the larva intact. Trying to remove it at home also risks pushing the larva deeper or leaving mouthparts behind, which leads to persistent infection and abscess formation.
How Vets Remove the Larva
The standard procedure is straightforward and usually quick. Your vet will sedate or locally numb the area, then carefully enlarge the breathing hole just enough to ease the larva out in one piece using forceps. The goal is to avoid crushing or rupturing the larva at all costs. Once it’s out, the vet flushes the cavity thoroughly to clean out debris and any remaining irritants.
Your cat will typically go home with oral antibiotics to prevent or treat secondary bacterial infection, along with instructions for keeping the wound clean. The empty cavity where the larva lived tends to form a deep abscess if left untreated, so antibiotics and wound care are not optional steps.
Wound Care After Removal
After extraction, the site is usually left open to drain rather than stitched shut. This allows any remaining fluid or pus to escape rather than building up under the skin. You’ll likely need to keep the area clean with a gentle antiseptic solution your vet provides, and you may need to flush the wound daily for several days.
Most skin wounds heal well within two to three weeks if you keep up with aftercare and your cat finishes the full course of antibiotics. An e-collar (cone) is often necessary to stop your cat from licking or scratching at the healing site. Watch for increasing redness, swelling, foul-smelling discharge, or fever, all of which signal the wound isn’t healing cleanly.
Neurological Complications
This is the more frightening side of botfly infestations in cats. Because cats are not the intended host, the larva sometimes takes a wrong turn and migrates through the brain, nasal passages, or eye sockets instead of settling quietly under the skin. Neurological complications are reported more often in cats than in dogs.
Signs of brain involvement include seizures, sudden blindness in one or both eyes, head tilting, walking in circles, pressing the head against walls, confusion, and continuous vocalization. These symptoms often appear suddenly and can progress rapidly. A history of violent sneezing or upper respiratory symptoms one to two weeks before neurological signs is a strong diagnostic clue.
In some cases, the onset is acute and fatal. Other cats survive the initial crisis but are left with permanent changes like constant pacing, circling, altered behavior, or recurring seizures. Diagnosis typically requires advanced imaging like CT or MRI to locate the larva inside the skull. Treatment for neurological cuterebriasis is far more complex than simple skin removal and carries a much more guarded outlook.
Which Cats Are Most at Risk
Outdoor cats and indoor-outdoor cats in rural or suburban areas face the highest risk, particularly during late summer when Cuterebra flies are most active. Kittens and young cats tend to be diagnosed more often, likely because they’re more curious and more likely to investigate rodent burrows. Cats that actively hunt are especially prone to exposure.
Preventing Botfly Infestations
The most effective prevention is keeping your cat indoors, especially during peak botfly season from July through September. If your cat goes outside, limiting access to wooded areas, brush piles, and anywhere rodents or rabbits are active reduces exposure significantly. There is no vaccine or specific preventive medication approved for Cuterebra in cats, so environmental control is the primary strategy.
Check your outdoor cat’s skin regularly during summer and early fall. Run your hands over the head, neck, and chest, feeling for any new lumps or swellings. Catching a warble early, before the larva grows large or has a chance to migrate, makes removal simpler and complications far less likely.