Cuterebra is the larva of a botfly that can affect cats, dogs, ferrets, and even humans. It seems like something out of a science fiction movie: a parasitic larva that can live and mature under the skin of a mammal until it's ready to jump out and complete its life cycle. Removing the unwelcome larva is the key to treating this relatively common condition. Here's what you should know about Cuterebra in cats.

What is Cuterebra?

Cuterebra is the scientific name for a type of botfly that causes a parasitic infection called cuterebriasis, which occurs in cats when the larva of the fly enters the cat's body. Cuterebra lesions are sometimes called warbles.

Cats are not ideal hosts for Cuterebra, but they may become infected after coming into contact with botfly eggs. Cuterebra larvae look like short, fat worms that are usually up to an inch long and appear gray or beige.

How Cuterebra Infect Cats

Cuterebra, or warble flies, are large flies that lay their eggs near the nests and burrows of small mammals like rodents and rabbits. When a host animal walks by, the eggs can become attached and hatch in response to the animal's body heat. The newly hatched larvae typically enter the animal's body via the mouth or nose during grooming or through open wounds on the skin. The larvae migrate and incubate in the host's body, getting oxygen through a small, round breathing pore on the skin. After about 30 days, the larvae mature and fall off the host to pupate in the soil until they develop into adult flies.

Symptoms of Cuterebra in Cats

Cuterebra typically appears as a swollen area under the skin with a small hole in the center. These lesions are often seen near the head or neck but they can be found anywhere on the cat's body. They're usually not painful unless they invade sensitive tissues. However, the swelling may bother the cat and cause increased grooming. You may see matted hair over the larva's breathing hole.

Cuterebra lesions are generally not visible until the larva becomes large enough to cause a lump or swelling. In some cases, the larva will mature and leave the cat's body before it is ever seen. A bacterial infection can occur in the remaining skin lesion and lead to an abscess.

Cuterebra Complications

In rare but serious cases, Cuterebra larvae can migrate to the delicate tissues of the nasal cavities, head, brain, eyelids, and pharynx. Cerebrospinal cuterebriasis occurs when a lesion affects the central nervous system, leading to neurological problems like seizures, circling, unusual behavior, and blindness. It is believed that Cuterebra infections can cause a neurological condition called feline ischemic encephalopathy.

Contact your veterinarian if you notice swelling anywhere on your cat's body. Treatment may be needed even if the larva has left the cat.

What Causes Cuterabra in Cats?

Cats are considered "accidental" hosts of Cuterebra. They most often come into contact with botfly eggs while outdoors hunting and exploring the burrows of small wild animals. Therefore, outdoor cats are far more likely to develop cuterebriasis than indoor cats.

Cuterebra is commonly found all over the Americas. In North America, infestations occur most commonly in the summer and fall.

Humans cannot get Cuterebra infections from their cats, but it is possible to develop a lesion after coming into direct contact with botfly eggs.

How to Treat Cuterabra in Cats

Cuterebra lesions are treated by first removing the fly larva from the body, if present. Your veterinarian may recommend sedation for your cat to remove the larva and clean the wound properly.

Larva removal is fairly straightforward, but it can be tricky. The larva should be removed in one piece to avoid contamination. The veterinarian will enlarge the breathing hole, and then grasp the larva with forceps.

After the larva has been completely removed, the remaining wound is cleaned and flushed out. Unhealthy tissue is cut away to promote healing. The affected cat may need treatment with antibiotics. Pain medication and anti-inflammatory drugs may be prescribed to provide comfort if the wound is very irritated.

Prognosis for Cats with Cuterabra

Cats tend to recover well after the removal of a Cuterebra lesion as long as they're unable to groom the affected area during healing. Your cat may need to wear a cone, or e-collar, until the wound has healed completely.

How to Prevent Cuterebra in Cats

The best way to protect cats from Cuterebra infections is to keep them indoors at all times. Outdoor cats often hunt small mammals and may come into contact with Cuterebra larvae. If your cat does go outdoors, check him regularly for signs of swelling. Contact your veterinarians if you notice anything abnormal.

Routine wellness exams are recommended for all cats, generally once or twice per year. These exams can allow your vet to find a Cuterebra lesion and treat it before it even bothers your cat.