Have you ever heard of a Cuterebra? If the answer is no, you are not alone. They are uncommon, but when you find one, you won't forget it. At Prosper Trail Animal Hospital we typically treat 3-5 pets with Cuterebriasis a year, but this year we have seen an increased number of cases with 4 pets in just the last week. Knowing what a Cuterebra is and what it looks like can reduce the shock factor if you see something like this on your pet.
What is a Cuterebra?
The Cuterebra is an opportunistic parasite found under the skin of small mammals. This parasite is the larval stage of the Cuterebra fly. The parasite infests small mammals that spend time outdoors, such as dogs, cats, rabbits, ferrets, squirrels, and rodents. The Cuterebra fly species are also known as botflies. The adult flies are large and do not feed on or bite animals. Instead, their eggs are laid on soil, stones or plants, often near the entrance to dens, or close to burrows. A female fly may deposit 5-15 eggs per site and >2,000 eggs in her lifetime. As an animal brushes against the stones or plants, the eggs stick to the animal's fur. In response to the body heat of the animal the eggs hatch. The hatched larvae either penetrate the skin, are ingested when the animal grooms, or enter the animal's body through a natural opening such as the nose.
In most cases the larvae then migrate to areas just under the skin on the head, neck, or body of the animal. Dogs and cats are not the usual host of this parasite and the larvae may also migrate to the brain, eye, eyelids, or throat although this is rare.
Cuterebriasis is the condition in which the larvae of the Cuterebra fly develops under the skin. As the larva matures under the skin, it becomes very large (up to a half inch in length) and produces a nodule or swelling. A small opening develops in the skin, through which it breathes. Roughly 30 days later, the parasite exits the skin, pupates on the ground, and becomes an adult fly.
How is Cuterebriasis diagnosed?
The swelling is commonly observed by you, the owner, as a small growth. These swellings usually appear in the late summer and fall. When we examine your pet, the area over the swelling is clipped, and the telltale opening, the breathing hole, can be seen. In some cases, the larva can be seen through the hole. Younger larvae are gray in color and have short rows of spines. Mature larvae are dark in color and covered with spines.
What should I do if I suspect a Cuterebra?
If during your cuddle time with Fluffy you find a swelling with a breathing hole, don't freak out. Although it can be disturbing and disgusting, it is not an emergency. Most of the time this little parasite has actually been squirming around inside your pet for weeks. It is also important to realize this is NOT a do it yourself moment and it is very important not to squeeze the skin in hopes of getting the larva out. Trying to remove the larva yourself can cause the larva to break apart and cause Fluffy to have a chronic infection or an anaphylactic reaction. If you suspect your pet has a Cuterebra, please contact us and we will schedule an appointment for the proper removal and treatment of any secondary infections.
How will you treat my pet?
Extreme care is used to remove the larvae. With the animal under sedation, an incision is made through the skin, and the larva is carefully removed. If the larva is cut or crushed, the animal may develop an anaphylactic reaction or severe skin irritation at the site. The pocket that was formed around the larva is cleaned and flushed, and a topical or oral antibiotis may be prescribed. The thickening of the skin takes considerable time to resolve. If the larva is not surgically removed, it will continue to enlarge and ultimately break though the skin, fall to the ground where is continues its life cycle by developing into a pupae, and then an adult. Without proper removal it can cause irritation and discomfort to your pet and may lead to secondary infections.
If you have concerns about your pet, please give us a call at 972-347-6100.