Stories From Our Clinic: The Cat With a Lump
Drs. Foster & Smith Educational Staff

Cat with the moving lump
Cat with the moving lump One September weekend, we got a call from Becky, a client, whose 7-year-old black cat, Gatto, had what she thought was a small tumor on his neck. The growth was bothering Gatto who was constantly scratching at it. We had been seeing Gatto since he was a kitten, and knew that although he was an exclusively inside cat, he had a bad habit of scooting out the door and stalking small wildlife in his huge wooded backyard.
We were concerned that although he was a neutered male cat, he had gotten into a cat fight and that the lump was an infection from a bite wound. We told Becky to bring him in, especially since an abscessed cat bite can be very painful for the cat.

When we saw Becky and Gatto, we showed them into the exam room. The lump was a little larger than the size of a marble. Though we thought it would be an abcess, upon closer examination, we discovered a small, match head-sized hole at the top of it. Given the time of year and the circumstances, we knew we had a case of "Cuterebra," and we had not seen one of those in a long time.

What is Cuterebra?

Cuterebra larva
The Cuterebra larvae are capable of creating a cyst just underneath the skin surface, which can be as large as a marble. They also create a tiny hole at the skin surface in order to breathe.

The Cuterebra is a bee-like species that lays its eggs near the entrances to outdoor animal dens or burrows. The eggs stick to the fur of any animal that brushes against them and they hatch into larvae, which penetrate the skin, enter the body through a natural opening, or are ingested when the animal is grooming. The larva usually migrates to an area just under the skin on the head or neck of the animal. It then matures under the skin for about 3 weeks, and creates a cyst that can be as large as a marble. The larva creates a tiny hole in the skin surface in order to breathe. This telltale opening is certain evidence that the suspicious growth contains the Cuterebra larva.

Although rabbits are the more common animal parasitized by the Cuterebra, cats can also be affected. Larvae in cats are usually encountered in the later summer months in the north, slightly earlier in the south. Although this condition is not life threatening, it can be irritating to the cat and the open hole can become infected. However, in some cases, larvae may also enter the nerve tissue, such as the spinal cord, rather than become encapsulated below the skin. Though rare, this can cause neurological damage.

We shaved the area around the growth, scrubbed it, enlarged the opening, and removed the gray, spined larva with a forceps. We were careful not to crush it, as this can cause further skin irritation and, in some cases, an allergic reaction. We flushed out the hole with antiseptic and prescribed a topical antibiotic ointment for Becky to apply.

Do not attempt to remove a Cuterebra larva yourself.
Since the wound generally takes a long time to heal, Becky had to check it frequently to be sure it stayed clean and dry. We told her to come back in 10 days for a re-check. At the re-check, all was going according to schedule. The area typically can take up to a month to heal and it was well on its way.

How could this have been prevented?

We always recommend that a cat be kept indoors at all times except if he can be in a safe and parasitic-free area, such as in a Kittywalk enclosure. Outside cats live much shorter lives, mostly because they are exposed to wildlife and diseases that they would not encounter inside the house. For more information on Cuterebriasis, click here.

Photo courtesy of the Entomology Department of the University of Nebraska.