These flies are found in the Americas, where they are
primarily parasites of rodents and rabbits.
The adult files are large and do not feed
on or bite animals. They survive by laying eggs on blades of grass,
or other vegetation, where they wait for a passing host.
The eggs attach to the host and hatch from the body heat
given off by their unsuspecting ride. The small maggots enter
the body through the mouth or nose during grooming
or less commonly, through an open wound.
The larvae then migrate through the body under the skin.
The larvae make a small hole in the skin to breathe.
This is when the parasite is usually discovered; a noticeable lump
in the skin with a small hole. The tip of the larvae will often be
visible deep in the hole. Approx one month later, the parasite exits
the animal host, pupates on the ground, and becomes an adult fly.
In Northern U.S the disease is seasonal, with cases
occurring in late summer and early fall when the adult flies are active.
Southern climates the flies are active for longer periods of the year.
Infection may be detected by lumps on the surface of the skin,
The dog may show signs associated with the larvae migrating through their tissues.
These may include respiratory signs, neurological signs,
Shortness of breath
(caused by the larvae in the eyeball)
Lump in the skin containing the larvae (warble)
Raised opening in the lump on the skin so that the larvae can breathe
If the larvae is at the end of its migratory stage and has
settled into a spot on the body, such as under the skin, eyes, or nose,
your veterinarian will be able to remove it safely.
Signs of lung migration may be controlled by corticosteroids.
Sometimes if the infestation has been on going,
neurological damage can occur.
Very rare cases involve human animals
and these are inconclusive.
A broad-spectrum anti-parasite medication is used
to eliminate larvae in the migrating stage.
A corticosteroid treatment will be given also.
The anti-parasite medication can be administered either
to alleviate the signs caused by larvae in the lungs,
and to kill larvae in other tissues and central nervous system.
Do not squeeze the skin where the larva are located as
this can cause the parasite to break apart there by causing
a chronic infection and or anaphylactic reaction in sensitive animals.
There is not a prevention to infestation at this time
Certain dogs can develop skin lesions several years in a row.
Application of monthly heart worm preventives, flea control products,
and topical flea and tick treatments possibly may prevent the larvae
from developing in the dog. They may also kill the larvae before
they have time to gain access to the host but these have not yet been proven.
John A Sampson I
00 + 1 + 989-662-6230 International
"The Dog Training