A customer came to me recently and was told his cat had a Botfly larvae (maggot). I will tell you, this was not one I was familiar with and the research was unnerving. I feel this is valuable information as Botflies can infest cats, dogs, rodents, rabbits and even humans.

Botflies look similar in appearance to horse flies, but they are black and tan along their winged area. In the Americas, rabbits and rodents are the primary host for the completion of their parasite to adult fly lifecycle. The Botfly will lay eggs along blades of grass or in nest, heavily grassy areas, populated with rabbits and rodents is where they reside. Once the eggs hatch into the larvae stage, the lay in wait for a suitable host to catch a ride. They will crawl into an orifice of the host animal and make its way to the skin of the host, where a small lump (or warble) will be noticeable. This is where the larvae will mature. Cats can become infested with the Botfly larvae while passing through the grass, stimulating the larvae to obtain its host.

The cycle of infestation of the Botflies is seasonal, and in the US, occurring in the late summer or early fall when the flies are active. In warmer areas, such as Texas, the season in longer due to our warmer temperatures in the late summer and fall. Once the maggot has reached maturity, it will drop out of the skin and leave a distinct round wound on the cat.

Symptoms can include respiratory signs, neurological signs, opthalmic (eye) lesions, or the maggots under the skin. Symptoms of a Botfly infestation in your cat are indicated noticeable warble on the skin. You can sometimes even see the larvae moving in the warble under the skin of the cat. The clearest indication of a Blotfly infection is the indicative warble under the skin. Neurological symptoms include dizziness, paralysis, circling and blindness and is difficult to treat due to medications not being able to cross the protective blood/brain barrier.

Once a diagnosis in made of a Botfly infection and the mature larvae removed, an anti-parasitic will be used to irradiated any remaining maggots in the earlier life stages. Prevention is indicated for outdoor cats having access too grassy areas known to have rabbit and rodent populations. Monthly anti-parasitic may be indicated as the cat can develop lesions for years to come from one infestation.

Although I am not a fan of anti-parasitic monthly medications, I would recommend a preventative topical spray for your indoor/outdoor cats in areas that are highly probable of infestation.

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