Rabbits: Fly Strike

By Gregory Rich, DVM; Rick Axelson, DVM

What is fly strike?

During the summer months, pet rabbits that are allowed to run outdoors might be affected by a fly maggot infestation. This is commonly referred to as "fly strike", Another term used is to say that the rabbit is "fly blown". Generally speaking, healthy well-cared for rabbits are typically not affected by fly strike.

"Fly larvae survive, thrive, spread and may cause a tremendous amount of damage as they eat through the rabbit's tissues."

Three main factors lead to the development of this condition.

1. A fly must be attracted to lay its eggs on the rabbit's skin. Attractive sites from a fly's point of view are skin wounds or areas of soiled and matted fur, especially fur that is soiled by blood, urine, or feces.

2. A rabbit that cannot or does not groom itself around the base of the tail and anus may leave feces or urine-contaminated hair around the rear end, which can become attractive to flies.

3. Damp and soiled bedding is an ideal environment for flies to lay eggs, and for maggot growth and development.

When maggots hatch on the rabbit, and if the rabbit cannot groom or clean itself, these fly larvae survive, thrive, spread, and may cause a tremendous amount of damage as they eat their way through the rabbit's skin and invade deeper tissues.

How can I prevent my rabbit from getting fly strike?

The key factors in preventing fly strike are to ensure that bedding is dry and cleaned daily, that the rabbit does not have any wounds or ulcerated areas of skin, and that there are no problems that prevent him from grooming.

Dental disease can impair a rabbit's ability to groom. An animal that has sharp hooks on its molars or cheek teeth may not be able to groom properly, allowing dirt, dander, or fecal-soiled hair to attract flies. Similarly, overgrown incisor teeth (at the front of the mouth) will prevent grooming. Your rabbit's teeth should be checked regularly by your veterinarian and appropriate treatment given if necessary.

Rabbits with spinal arthritis or joint disease problems may not be able to turn around to groom properly. Any rabbit with diarrhea will be especially prone to fly strike, and will have other problems associated with diarrhea.

Rabbits with cystic calculi (bladder stones), crystals or sludge accumulation in the bladder (hypercalcinuria), and/or a primary or secondary bladder infection (cystitis) are prone to having a wet hind-end and will attract flies.

Any condition affecting the skin, such as fight wounds, skin mites, ear mites, flea bite wounds, or botfly lesions, will be very attractive to flies, potentially tempting eggs to be laid and maggots to hatch.

What is the treatment for fly strike?

The rabbit will need to be sedated or anesthetized so that all the maggots can be removed and the whole area can be cleaned and clipped free of soiled hair. Any and all wounds will need to be thoroughly cleaned and debrided (dead or infected tissue is removed) by a veterinarian. Most cases require sedation and administration of pain medications. The affected area will be disinfected with antiseptic solution and your rabbit will be placed on antibiotics, since there is a high probability of secondary bacterial infection. In severe cases, hospitalization, intravenous fluids, vitamins, and other supportive care may be needed. Such intensive care may cure your rabbit of the maggot infestation but, in severe cases, extensive surgery may be needed to remove all the dead maggot-ridden tissue.

After treatment, it will still be necessary to address the original problem(s) that led to the fly strike. Post-treatment, your rabbit should not be allowed outside for at least a month. If the initiating cause cannot be permanently resolved, it is recommended to keep your rabbit indoors except for supervised playtime outdoors.

Are there other things I should consider?

"Dry, clean, and well-ventilated indoor housing is an ideal, simple, and inexpensive way to minimize the possibility of fly strike."

Ideally, you should take your rabbit to your veterinarian twice a year for a routine health check, to ensure that dental disease, urinary issues, or back problems do not predispose your rabbit to this dangerous condition. Dry, clean, and well-ventilated indoor housing is an ideal, simple, and inexpensive way to minimize the possibility of fly strike.

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