Feline Cuterebrosis (Warbles)

Kitten with a Warble
Kitten with a warble.

Recently, a cat was brought into our clinic with a cyst-like protrusion on its chest. Examination revealed it to be Feline Cuterebrosis, also called “Warbles”, a condition in which fly larvae live in the flesh of cats.

What is Feline Cuterebrosis?

Feline Cuterebrosis is a condition occurring when a cat has become the host of the larval stage of the Cuterebra Fly, commonly known as the Botfly.

There are twenty-six known species of the Botfly (Cuterebra) in the United States and Canada.

This condition is often called “Warbles” because the larvae create a burrow with a breathing hole just under the skin causing a lump on the surface of the skin. These lumps are called “warbles”, hence the name.

Feline Cuterebrosis (Warbles) - Botfly or Cuterebra Fly
The Cuterebra Fly, commonly known as Botfly.

Warbles are usually found under the skin in areas around the legs and neck. Cuterebrosis is most commonly found in rodents and rabbits, but have also been reported on cats, dogs, hogs, mink, foxes, deer, cattle, and humans.

What Causes Feline Cuterebrosis ?

Cuterebrosis is a condition most commonly found in wild rodents and rabbits. This condition is caused by the larvae of the Cuterebra fly, which also known as the botfly.

Feline Cuterebrosis (Warbles) Botfly Larva
This is the larva that Dr. Smith removed from the cat’s neck.

The female botfly, genus Cuterebura, lays eggs along the runways and burrow entrances of rabbits and small rodents. The eggs hatch and turn into larvae which enter the unsuspecting host through a natural body opening (usually the nose or mouth) or a small abrasion on the skin.

The larvae will often remain in an animal’s the nose or mouth for several days before burrowing under the skin where they develop into “warbles”. (“Warbles” is the name given to the small lumps produced by growing larvae.) The larvae live and grow just under the skin inside the “warbles”, where they breathe and excrete.

Cats most likely contract Cuterebrosis  by coming in contact with the newly hatched and unsettled larvae from rodents caught hunting, or from  activity around rodent burrows and runways.

Most cats are asymptomatic in the early stages of Feline Cuterebrosis, but sometimes migrating larva can sometimes cause eye problems, nervous system symptoms, and respiratory issues as they move through these systems.

Feline Cuterebrosis (Warbles)
This is the hole left in the cat’s neck after Dr. Smith removed the larva.

How is Feline Cuterebrosis (Warbles) Treated?

Feline Cuterebrosis is treated by carefully removing the larvae and thorough cleaning of the area involved.

Often the cat will be given antibiotics or an antibiotic injection to treat any possible or already occurring secondary infection.

This particular procedure was done under anesthesia and the cat was given an antibiotic injection to treat and prevent secondary infection.




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  1. sleepyjean1979 says

    I have encountered this larva in a 6wk old kitten in the sinus cavity with the breathing hole near the inner corner of the eye. I squeezed not knowing this worm like creature would pop out with some force and speed. This kitten could not walk correctly and died within days of the removal. That was in year 2012. Does anyone know how long these warbles have been in the Tennessee area?

  2. ellita says

    So I got stuck with this kitten. 8 weeks old approx. I live in a rural part of cumberland county tn. Folks like to pitch their unwanted kittens around me smh. I removed said bot fly thing out of its neck. Used hydrogen peroxide and neosporin. As this isn’t my pet I do not have money for a vet and we like to kill kittens at the local shelter. Now it’s been a few days. He has come to life. But the breathing hole is closed up and it’s hard under and around the hole. Like a knot. Should I reopen the scab to loom for signs of infection bc years ago when my actual cat got one in his cheek I took him to the vet I don’t recall the sore being hard but can’t remember bc it was a decade ago. I don’t want this thing to die but he’s acting so much better. 1000% difference almost immediately upon removing the worm. Have a pic of the worm and can take one of his neck now. He possibly also has internal worms and im battling fleas as well with his tiny butt