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Cutaneous myiasis

Myiasis is the infestation of living tissue by fly larvae, commonly called maggots. Flies attracted to a wound, a soiled area or a damp coat lay their eggs there. The larvae hatch within a few hours and feed on the tissues, burrowing into t...

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Definition Signs Causes Transmission Diagnosis Treatment Prevention Complications When to see a vet Prognosis FAQ Sources Affected species

What is it?

Myiasis is the infestation of living tissue by fly larvae, commonly called maggots.

Flies attracted to a wound, a soiled area or a damp coat lay their eggs there. The larvae hatch within a few hours and feed on the tissues, burrowing into the skin and rapidly expanding it.

It's a veterinary emergency. The progression is measured in hours, not days, and the general condition can deteriorate very quickly.

Key point

Myiasis is a veterinary emergency. The larvae constantly burrow into the tissues and the animal's condition can deteriorate within a few hours: do not postpone the consultation until the next day.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

Related signs — each one links to its page:

Scabs and skin lesions Pain Swelling Reduction Fever Loss of appetite

White, mobile larvae visible in a wound, under scabs or in soiled hair.

A foul smell, often the first warning sign.

A wound that is visibly widening, with hollowed and oozing edges.

Significant pain, agitation, frantic licking or on the contrary prostration.

Swollen, red skin around the affected area.

Dejection, fever, refusal to eat when the infestation is extensive.

Common locations: existing wounds, hindquarters soiled by stools or urine, folds of the skin, areas between the fingers, around an ulcerated tumor.

When to consult without delay

This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.

Causes and risk factors

The oviposition of flies on living tissue, favored by heat.

The starting point is almost always an injured or soiled area: untreated wound, oozing dermatitis, burn, hair impregnated with urine or feces, matted and damp coat.

The larvae destroy tissues and release substances that attract other flies: the infestation is self-perpetuating and quickly worsens.

Bacterial superinfections are systematically associated.

Hot and humid season: this is the period when the risk is maximum in Tunisia and throughout the Mediterranean region.

Animals living outside, guard dogs, stray or poorly supervised dogs.

Untreated wounds, even minimal, and oozing dermatitis left in the open air.

Animals that are elderly, weakened, incontinent, or unable to groom themselves.

Animals lying down permanently, with bedsores or soiled hindquarters.

Long, felted or knotted coat, which retains moisture and dirt.

Proximity to garbage, manure or carcasses.

Transmission

Myiasis is not transmitted from one animal to another. Each case results from direct oviposition of flies on the animal.

On the other hand, several animals living in the same environment can be affected at the same time, because they are exposed to the same flies.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

The diagnosis is immediate: the larvae are visible to the naked eye.

The veterinarian mows widely and explores the wound, because the larvae dig galleries under apparently intact skin: the actual lesion is almost always much larger than what is seen.

Sedation or anesthesia is most often necessary, the manipulation being very painful.

The general condition is assessed: dehydration, fever, general impairment linked to toxins and infection.

The veterinarian also looks for what caused the infestation: old wound, tumor, incontinence, underlying disease which prevented the animal from grooming itself.

Treatment

Complete mechanical removal of larvae, carried out by the veterinarian after mowing and exploration of all the galleries. A single forgotten larva restarts the process.

Cleaning and trimming the wound, with removal of destroyed tissue.

Antiparasitics prescribed to eliminate the remaining larvae, antibiotics for secondary infections, systematic painkillers.

Supportive care when the animal is dehydrated or weakened: infusion, warming, refeeding.

Dressings and close checks until complete healing.

Do not attempt to remove the larvae yourself, and do not apply petroleum, gasoline, household products, or agricultural insecticides to the wound: these practices are toxic, aggravate the lesions and delay urgent care.

Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.

Prevention

Monitor and protect any wound, even small: in hot climates, a neglected wound attracts flies within a few hours and can develop into myiasis.

Get any wound, weeping dermatitis or area that oozes treated quickly, rather than waiting.

Keep the coat clean and dry, clip soiled areas in incontinent or long-haired animals.

Inspect the hindquarters, folds, spaces between the fingers and any injured areas every day in the hot season.

Eliminate fly breeding grounds around the animal: garbage, droppings, stagnant water, food remains.

Ensure clean and dry bedding for animals living outside, and increased supervision of elderly or lying animals.

Possible complications

Extensive destruction of the skin and underlying tissues, with loss of substance requiring surgery.

Generalized infection from the wound, which can be life-threatening.

Affects deep structures when the larvae progress, particularly on the face and around natural orifices.

Rapid weakening, dehydration and shock in elderly or already sick animals.

Recurrence if larvae were left in place or the initial cause was not corrected.

When to see a veterinarian

You see white, mobile larvae on your pet: consult immediately, it is an emergency.

A sore gives off a foul odor or expands quickly.

Your pet is down, feverish, refusing to eat, or frantically licking an area.

His hindquarters are soiled and the skin is red or oozing.

A wound does not heal in the hot season: have it examined before it becomes infested.

Prognosis

Good when treatment is immediate and all the larvae are removed: the wound heals in a few weeks.

Reserved in cases of extensive infestation, deep damage or in an elderly and weakened animal.

The prognosis depends above all on the delay: every hour counts, because the larvae destroy the tissues continuously.

Frequently asked questions

Can I remove maggots myself?

No. The larvae dig galleries under the skin and those that are not seen are the most numerous. Incomplete removal restarts the infestation, and manipulation is too painful without sedation.

My dog lives outside, how can I avoid this?

By monitoring his skin every day during the hot season, treating the slightest wound without delay, keeping his coat and bedding clean and dry, and eliminating garbage and droppings that attract flies.

Can a tiny wound really get out of hand?

Yes. In hot weather, it only takes a few hours for a fly to lay eggs on a small wound. This is why no injury should be left unattended and unprotected in summer.

Am I at risk of catching this from contact with my dog?

No, there is no transmission from an animal to a person. Still wear gloves during treatment and wash your hands, as with any infected wound.