Cuterebriasis is a relatively common condition that results from the migration of fly larvae through the bodies of small mammals. A cuterebra is the larval stage of the bot fly, which is found in most regions of North America. Bot flies are large, non-feeding flies and they tend to target small mammals (mostly rodents, including rabbits) as a host for their larvae.
Most cases in North America occur in the late summer/early fall. Bot flies will lay their eggs near the openings to small mammal burrows, so that when contact is made between the animal and the latent eggs, the eggs will hatch into larvae that will penetrate the skin, enter the body through an opening or be ingested. The life cycle of the fly requires migration through the soft tissue (muscle, fat, skin) of the animal, followed by a prolonged period of development to the maggot stage within a “warble” in the skin (a pocket created under the skin with a little air hole by the larva as it develops into a maggot).
Once the maggot stage has been reached within the host, the maggot will “drop off” (i.e. exit the host) and will continue to develop in the ground over winter until it hatches into the mature botfly in the spring. The time period where the larvae matures to the maggot stage within its mammal host usually lasts anywhere from 3 to 7 weeks. Although the intended mammal hosts are wild rodents, rabbits, etc, these ectoparasites are commonly seen in our domestic cats and dogs who sniff areas where the eggs are latent or stick their heads in rodent holes. For this reason, cuterebra are commonly found on the face, neck or even within the nostrils of cats and dogs. Rarely, in cats, cuterebra migration can lead to a condition called feline ischemic encephalopathy, where the parasite can migrate to the brain and cause damage to the brain tissue.
Clinical signs of cuterebras are usually limited to identification of a lump or hole in the skin where the cuterebra is located; however, larvae can migrate elsewhere in the body, including the brain (feline ischemic encephalopathy), pharynx/throat, nostrils and eyes/eyelids. In these cases, clinical signs would depend on the location affected. The most common finding is subcutaneous lesions, which result in a raised, red lump with a central hole that is usually about 0.5 cm in diameter.
Cuterebra after extraction from its warble.
Treatment of subcutaneous cuterebriasis is relatively simple. The most important aspect of treatment is removal of the larva/maggot. In most cases, the central hole must be enlarged to allow the larva/maggot to be removed without being ruptured, as rupturing the maggot can lead to anaphylaxis (a severe and potentially life threatening allergic reaction) in some animals. A secondary skin infection can sometimes occur, in which case antibiotics may be indicated.
Written By: Dr.Amanda Lohin, DVM
This year has already brought severe weather to parts of the globe. Heavy snow and strong winds hit the southern and northeastern United States in early January, while Australia has been experiencing record breaking temperatures leaving melted asphalt and massive bushfires, forcing many to leave their homes. Volcanic activity in Hawaii and earthquakes in Mexico and Papua New Guinea have also left many homeless.
With summer just around the corner, hurricane season has already begun with the first named Atlantic storm hitting the Gulf of Mexico area in late May, and over 300 tornadoes have been confirmed in the US so far this year.
June marks National Pet Preparedness Month – a time to ensure that you are prepared for an emergency – not only for you, but your pets as well. The safety and survival of our pets lies solely on us, as pet owners, so take some time this week to make sure you have all the supplies you need for your pet in case you are faced with an emergency.
The following are items you should have packed in a “pet emergency kit.” Have this kit ready to take with you in case of evacuation:
ALWAYS HAVE A BACK-UP PLAN. Be sure that a friend or neighbor has access to your home to retrieve your pet and emergency kit if you are unable to return home when an evacuation order is issued.
Take a moment this weekend to prepare or update your pet’s emergency kit with all the vital necessities and come up with an emergency plan with your family that includes your pets. With any luck, you will not need the kit this summer, but it is better to be prepared – your pet is depending on you!
LifeLearn Team | Lifelearn News
Canine influenza continues to cause problems in Ontario. The central Ontario (Bracebridge, Gravenhurst, Orillia) clusters continue to be monitored, with new positives that were expected based on known contact with infected dogs. For more information please read the following article by Worms and Germs Blog.