Botflies (Cuterebriasis) in Dogs

Species of botfly are found throughout North America. They are most active in the spring and summer. Species of botflies may infest any type of mammal. The Cuterebra genus are most commonly hosted by rodents and rabbits, but dogs sometimes come into contact with them in outdoor areas where infested rodents and rabbits live.

Usually, botflies infestation causes nothing more than discomfort for the patient, although severe manifestations are possible, especially if larvae migration affects the nervous tissues or other organs. Dogs are abnormal hosts for botflies so developing the condition is rare, with possible peaks during the summer and fall seasons.

Botfly infestation in dogs is rare. It is more likely to occur in areas and times of year when botflies are most active. There are no particular risk factors for specific dogs, but those with active outdoor lifestyles in rodent habitats are more likely to be exposed to botflies.

When infestation occurs, it usually only affects the skin. Left untreated, or in cases where the parasite load is very high, the larvae may migrate to other tissues, causing more severe symptoms.

Larvae can also migrate through the lungs, causing symptoms such as coughing and difficulty breathing.

Pain in the affected area is variable and is often associated with secondary infections.

The infestation is caused by botfly eggs that penetrate the host’s body through the mouth, nostrils, or open wounds. Botflies do not lay their eggs directly on dogs, rather they choose areas normally frequented by their natural host (rabbits and rodents) or around their nests. Dogs usually come in contact with the parasite by passing through a contaminated area, allowing botfly eggs to transfer onto their skin or face.

The most characteristic sign of cuterebriasis is a soft swelling with distinct borders, which might be mistaken for an abscess. These swellings are most common on the head, neck, or trunk. Other symptoms include matted hair and visible bots (maggots) protruding from the swelling.

In cases of skin manifestation, the diagnostic process is straightforward and involves identifying the bot within a skin lesion.

If the larvae migrated through other organs, bloodwork and diagnostic imaging, such as ultrasound, MRI, and CT scanning, might be necessary for a definitive diagnosis.

Treatment involves removal of the maggots from the skin followed by wound cleaning and supportive care. Other therapies include the prescription of anti-parasitic medications or steroids for infections affecting other organs.

Prognosis varies according to the form of cuterebriasis affecting the patient. The cutaneous form has a good prognosis and the patient generally recovers fully with treatment. The neurological form has a poor prognosis as it may affect sight and might lead to seizures or other serious symptoms.

To avoid contact with parasites it is suggested to prevent dogs from wandering in at-risk areas, such as near dens or burrows, especially during the period of higher presence of botflies. Routine deworming protocols are also highly suggested as they may prevent maggots from developing or kill them before they enter the dog.

Botfly infestation in dogs is rare.

• Removal of maggots from the skin
• Medications such as anti-parasiticsand/or steroids