Cuterebra on Cats and Dogs

Dr. Phil Zeltzman is a traveling, board-certified surgeon in Allentown, PA. His website is He is the co-author of “Walk a Hound, Lose a Pound” (

Kelly Serfas, a Certified Veterinary Technician in Bethlehem, PA, contributed to this article.

All spring and summer long, Michelle likes to take her dog Foxy to run and play at the park. One day in September, as she was petting Foxy’s neck, Michelle suddenly noticed a lump the size of a cherry.

Concerned this could be a tumor, Michelle took Foxy to her family vet right away. A nurse shaved away the fur around the lump. The lump looked like a cyst in the skin, with a small, dark opening in the center. Torn between being reassured and feeling grossed out, the vet immediately recognized the problem.

What is cuterebra?
The vet told Michelle that Foxy had a Cuterebra. A cute-what?  Cuterebra is the larva of a fly, which is embedded in the skin. It’s critical not to try and squeeze it out of the skin. Squeezing can cause the larva to break apart, which can cause an infection or even an allergic reaction. The bug needed to be surgically removed.

Michelle was wondering how her cute little Foxy, who was pampered, bathed and groomed regularly, could get such a nasty thing. The vet explained that this was a freak event because dogs are not a natural host of this insect.

How does a dog or cat get cuterebra?
The Cuterebra, or botfly, is an almost 1 inch-long parasite, which needs a small mammal to complete its life cycle. The usual hosts are rodents or rabbits. However, the eggs or hatched larvae can stick onto a dog or cat if they pass by.

The larva finds a natural opening on the animal, such as, the nose, mouth, eyes or even sometimes a cut and enters the body. From there, they migrate through or between organs, until they reach the skin. There, they make a hole to breathe.

In nature, the fly will stay burrowed in the skin for 30 days, then exit and live a few months to a year. It becomes an adult botfly, and the circle of life begins again.

How do you remove cuterebra?
Michelle was horrified at the thought of having some nasty creepy crawly parasite in her dear little Foxy. She begged her vet to remove it right away. Foxy was admitted to the hospital and had surgery later that day to carefully remove the Cuterebra and the infected skin surrounding it. Surgery was a success and Foxy went home the same day on antibiotics and pain medications. 

Two weeks later, she went back to the hospital for a progress exam and to remove the skin stitches. The area looked very good and Foxy received a clean bill of health. The vet assured Michelle that the benefits of running and playing at the park greatly outweighed the small chance of this incident occurring again.

Reassured, Michelle cannot wait to take Foxy back to the park this spring. 

If you ever suspect your pet has a Cuterebra parasite, please contact your veterinarian as soon as possible for proper removal and treatment. As gross as it sounds, this is a very fixable condition.

If you have any questions or concerns, you should always visit or call your veterinarian -- they are your best resource to ensure the health and well-being of your pets.