Cuterebra in Cats - Causes, Symptoms and Removal

Cuterebra is an external parasite which is typical of certain areas in the Americas, but this will vary according to species. Although it was once thought a family in its own right, it is now considered a subfamily of the family Oestridae. It is an obligate parasite of rodents and rabbits, although it can also accidentally attack cats, dogs and ferrets when they hunt near burrows of these animals. Cases appear in late summer and early fall.

These flies may lay eggs on damaged or eroded surfaces of the animal's skin. From here they will hatch and the larvae will start to develop. They can also deposit eggs on the ground or in vegetation. Once hatched, it will be the larvae that enter through the openings of these animals. This can be an opening created by a bite, wound or even skin follicle, but it can also be through the ears, mouth, nostrils or even eyes.

It is the larvae which will work themselves into these openings where they penetrate deeper into the skin. Once they enter the skin, they will develop and create lumps under the cat's skin. Cuterebra which enter the nasal cavity can often be seen when looking into the nostril of the cat.

Generally, these larvae migrate to regions around the head or neck, although they can also affect other parts of the cat's body. About 30 days after entry, the parasite leaves the inside of the cat to pupate outside and give rise to an adult fly. This botfly will reproduce and lay eggs that will parasitize another susceptible animal.

Cuterebra in cats can cause feline ischemic encephalopathy when the larvae enter the feline's nose and reach the brain. This results in neurological signs derived from the involvement of the middle cerebral artery, as well as degeneration and the production of hemorrhages in other areas of the brain.

Learn about other reasons for growths with our article on why my cat has a lump on their neck.

The symptoms a cat with a Cuterebra infestation will have depends on the area of their body affected. For example, if the larvae infest the skin, the symptoms will be hard lumps which we can see on their exterior. This may be more difficult in longhaired cat breeds. The cat's behavior will also change as they will become irritable and lethargic.

If Cuterebra larvae have made their way into the cat's respiratory tract, the cat will show signs such as labored breathing, runny nose, coughing and sneezing. If the larvae enter the eyes, cats will show symptoms such as uveitis, chemosis, blepharospasm, eye discharge and even blindness.

When the cat's central nervous system is affected, they will develop a head tilt, seizures, circling, epilepsy or cognitive impairments that can lead to the cat's death. The appearance of neurological signs indicates the severity of the infection due to the development of feline ischemic encephalopathy. These usually appear a few weeks after the signs of respiratory distress begin.

A cat can accidentally become parasitized by the Cuterebra larva, since the parasite has a predilection for rodents and lagomorphs. Cats can only be parasitized if they go to outside areas where these parasites live. This means the natural habitat of these small animals. The main cause of parasitization in cats is exploring and trying to hunt a rabbit from their burrow or a rodent from their usual habitat. The larvae or eggs about to hatch penetrate through the small feline's natural openings, such as the nostrils or the mouth, and can reach the eyes and brain in the worst and most advanced cases.

Another possibility of the parasite entering the cat is after hunting a rabbit or rodent recently infested by the larvae. The live larvae enter the mouth or nostrils directly and developing their life cycle within the cat.

We can suspect that our cat is parasitized by the larvae of this botfly when we see a lump on their head or neck. Once the lump is detected, we will be able to observe a small hole in the skin which allows the larvae to breathe. This is more or less in the centre of the lump. If we see a lump on our cat's neck or similar area with a hole like this, we should suspect a botfly and take them to a veterinarian.

When the Cuterebra larvae has been able to migrate into deeper tissues of the cat, they can only be diagnosed by imaging tests. These include MRIs and ultrasounds. They will usually be supported by other diagnostic techniques such as urine or cerebrospinal fluid analysis. The best detection test for this disease is magnetic resonance imaging, which can detect the presence of the larvae and even the loss of brain matter produced by feline ischemic encephalopathy two or three weeks after the onset of clinical signs. Doing so will differentiate between other processes such as tumors, external trauma or infectious diseases.

The treatment of this parasitism will depend on the time of the infestation and whether or not the larvae have entered the cat's internal organs, such as the brain. If the larvae are still visible in lumps on your cat's skin, manual removal by your vet is possible. Never attempt this yourself at home. Anesthesia or sedation may be required to allow removal without the cat incurring acute pain and/or stress.

Removal of the Cuterebra larvae should be removed using sterilized tweezers. It is preferable to do so after administering an antiparasitic to the animal so they are dead and do not move. This provides less risk of the larva breaking, which can cause allergic reactions and serious infections. After extraction, the open cyst remains on the skin, which the professional must clean with an antiseptic such as chlorhexidine and saline. The wound will be left to heal in the air once clean. Only in cases of deeper wounds, must it be sutured or bandaged.

Surgical elimination of the parasite in the brain has not been established. Symptoms can be managed with antiepileptic drugs, antiparasitic drugs and supportive treatment with fluid therapy to keep them well hydrated and nourished.

As you can see, this is a serious parasitism that requires the intervention of a professional. If you find lumps or directly see the larvae in your cat, go to the veterinary clinic as soon as possible. Learn more about different feline infestations with our article on intestinal parasites in cats.

As with many types of parasite, Cuterebra is host-specific. This means only certain types of this subfamily will be able to infest cats and none of these are able to infest humans. There are species of Cuterebra botfly which parasitize humans, but these are not the kind with will have infested the cat. We will still need to be careful when disposing of the larvae as we do not want to facilitate infestation of other animals.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Cuterebra in Cats - Causes, Symptoms and Removal, we recommend you visit our Parasitic diseases category.