At this time of year, I am always waiting to see my first case of Cuterebra.  Most people  have never heard of Cuterebra, but this parasite peaks in late summer and early fall in our area, and can be just as alarming to owners as it is to pets.

Eastern Squirrel suffering from Cuterebra

Eastern Squirrel suffering from Cuterebra

Cuterebra are the larval stage of a fly.  The fly lays its’ eggs on grass and rocks, and the eggs stick to the fur of a small mammal that passes through the grass.  For this reason, rabbits (only ones that spend time outside), cats, and small breed dogs account for most cases of Cuterebra infestation in pets.  Once the eggs have attached to the fur, they hatch and migrate through the animal’s grooming practices.  They form a nodule under the skin, and open a pore in the skin for breathing.  It is at this point that owners may notice a new “growth” or “wound”.  They often do not notice the open pore, or think it is from a bite wound.  The larvae is actually breathing out of the pore, and if you look closely, you will see the parasite moving up and down under the skin.

Cuterebra Larvae

Cuterebra Larvae

Removal of a Cuterebra is not something you want to attempt at home.  If you suspect your pet has one or more Cuterebra, please contact your veterinarian for removal.  If the larvae breaks under the skin, it can cause a serious anaphylactic reaction or infection.  Your veterinarian may sedate the animal, and widen the pore with a scalpel to more easily extract the larvae.  They can also determine if the animal has other Cuterebra you may have been unaware of, and determine if any additional treatment is warranted.  New and quick growing masses should always be checked, and this time of year the “mass” may be something you hadn’t thought of.


  1. Mark

    Thank you for the Info

  2. Fred

    Cest deguelasse et très désagréable à vivre

  3. Dan

    savez vous si les humains peuvent le contracter? Et quel est la meilleur façon de faire pour débarrasser soit même de cette bestiole a la maison.

    • Hollis Vet

      Luckily, humans cannot be infect directly from their pets. We would be infected in the same accidental manner as our pets, through contact of the maggots on the grass. The best way to avoid infection is primarily to avoid the risk. Staying indoors is the best choice to avoid cuterebra, also known as botfly. If that isn’t an option, making sure your pet is kept on a leash and you are both staying out of high grass is the next best thing. Thankfully, human infection is very rare in the United States. However, in Central and South America, there is a fly that targets humans, the human botfly, Dermatobia hominis.

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