Botflies in Cats: Causes, Signs, & Care


A botfly larva doesn’t intend to find its way onto your cat, but it could cause a problem if it does. Once there, it will burrow and make your cat its host for the next month. Skin lesions often look much more severe than they are but require consistent care to heal over time.

However, if an egg or larvae finds its way into your pet’s eye or nose or burrows deep into its skin, it may cause more severe complications. Pet owners with cats who spend time outdoors should know the signs of Cuterebriasis to treat it as soon as possible.1 Keep reading to learn more about botflies in cats.

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What Are Botflies in Cats?

Botflies are a family of 40 or more species of flies that appear bee-like and are quite large. Those that are most dangerous to cats and other small mammals like dogs and rodents are the Ceterebra. These botflies reproduce with parasitic larvae that typically grow inside the flesh of wild rodents.

However, they are not against infecting a cat who happens to pick up eggs as they pass by. Female botflies lay their eggs along rodent burrows on low-lying vegetation or nearby rocks where they are most likely to find a host. Outdoor cats that hunt rodents are especially vulnerable.

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What Are the Signs of Botflies in Cats?

Adult botflies typically lay eggs in the late summer and early fall, which is when pet owners should be most vigilant about looking for signs of warbles. This is especially true for cats that spend time outdoors and live in tropical climates, although botflies are found throughout most of North America.

General Signs

  • Fever
  • Fatigue
  • Lack of appetite
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Subcutaneous Warbles

Most cases of botflies in cats are warbles, which are located in the skin and usually around the head and neck. A large “lump” in the skin with a well-defined pore in the center may have a clear, serum-like discharge. The size of the lump and pore depends on the lifecycle of the larvae at the time it’s discovered. You may see the larvae moving beneath the skin, but warbles rarely cause distress or infection until after the botfly larvae leaves the warble and there is an open wound.

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Other Locations & Signs

Not all Ceterebra larvae stay in the skin to form a warble. While rare, some may migrate through the skin to damage structures or organs underneath, such as the spine or spinal cord. When a larva burrows into the eye, signs may be immediately apparent, but not so if it were to burrow into the nose. In that case, a botfly can develop near or inside the brain, causing permanent neurological symptoms like dementia, circling, and blindness.

Poor old sick cat with hematoma on ear and inflammated eyes
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What Are the Causes of Botflies in Cats?

Botflies are commonly found in tropical climates, like the southern US, but can be anywhere from southern Canada to northern Mexico. Because they are native to such a large area, all cats may be at risk of botflies, even if they are relatively rare.

Because cats are not the intended target of Ceterebra botfly larvae, they are considered an opportunistic host. Once attached, the host’s body heat triggers the egg to hatch. Then, it will burrow into the body, whether the skin, an open wound, or an orifice like the nose or mouth. Once buried in the skin, the larvae are more commonly called warbles. The location and how the larvae develop depend primarily on their species.

After approximately 30 days, the larvae will have completed their lifecycle within the host and will exit the skin to enter their next phase of growth. The exact time needed will depend on the species, time of year, and other factors. The treatment required will also vary depending on when the botfly is discovered and how many are present. Because botflies lay up to 15 eggs at one location, it’s not uncommon for a cat to experience several of them.

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How Do I Care for a Cat With Botflies

If you’ve spotted a botfly in your cat, your vet must care for them, as your vet is more experienced in removing the botfly and caring for the warble to prevent infection. If possible, the larvae should be removed gently and in one piece. Squeezing the warble will only cause it to retreat further and may cause it to rupture, which may cause anaphylaxis, a severe and sometimes deadly allergic reaction. In serious cases with respiratory or neurological signs, a CT scan or other diagnostic tests could help determine the extent of the infestation.

If the larvae are in the skin, the vet will surgically remove them and provide home-care instructions for keeping the wound clean and preventing secondary infection. This will likely include oral antibiotics and wound coverings that may need to be changed daily.

In minor cases where the infestation was caught early, long-acting antibiotic injections may be effective. The Companion Animal Parasite Council suggests using Ivermectin, an anti-parasitic medication, and corticosteroids in some cases where neurological signs aren’t present. Your veterinarian will determine the best treatment for your cat and discuss these with you.

Warbles tend to heal slowly, so treatment could take some time, but the prognosis is usually good. Your cat will depend on you for daily care for quite some time to prevent infection and must stay indoors as they recover.

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Image Credit: Elpisterra, Shutterstock

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Frequently Asked Questions

Can you prevent botflies in cats?

Outdoor cats will likely hunt small rodents, either for fun or food. Rodents’ habitats are the most likely locations for botfly eggs, so preventing botflies may be impossible for those cats who enjoy hunting. If your cat must go outside, pet parents should know the physical signs of warbles and check for them often. While rare, you should also be aware of the neurological signs so treatment can begin as soon as possible should there be a more severe Ceterebra infestation.

Can botflies infect humans too?

Because humans rarely burrow around rodent nests or dens, it is incredibly rare for a botfly to infect a human. It’s also much easier to spot a developing warble on a human. A botfly will not infect a human or another animal after it’s left or been removed from a cat. Humans typically do not have to worry about botflies.

Can you remove a botfly yourself?

No! You should never attempt to remove a botfly at home for several reasons. First, your cat should have a numbing cream or injection to make them more comfortable, and your vet will have the proper medication for that.

The larvae should also be removed in one piece. If you don’t have the right tools or experience, you may damage or rupture the larvae, inadvertently causing an allergic reaction or blood infection with the chemicals released into your cat’s body. Never squeeze a warble to force a larva out of the pore. It will cause it to retreat further.

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Botflies in cats are more common than you think, and most cases can be treated relatively easily at your vet’s office. If your cat has swelling or a skin lesion, it’s time to take them to the vet for evaluation. Remember, botflies should be surgically extracted and treated with antibiotics. Never try to remove one yourself. A pet should always see their vet for respiratory or neurological symptoms since they can be signs of a number of illnesses.

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Featured Image Credit: Peddalanka Ramesh Babu, Shutterstock

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