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Summer Sores
With
summer comes a hoard of irritating insects that can have damaging
effects on your horse.
by Toots A. Banner
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All horse-owners have to deal with pesky
summer insects; it is simply a part of life around horses. Some
of these summer pests aren't just a nuisance to you but can
be dangerous to your horse's health as well.
One of those pesky summer insects is the fly, and with flies
come habronema, which is a genus of nematode. Habronemiasis
(the infection caused by habronema) can infect the skin and
other moist areas of the horse especially around the mouth,
eyes, prepuce, or foreskin and is commonly called a summer sore.
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Summer is
the season for flies, and with flies can come habronema, a genus
of nematode worm that can infect the skin, eyes, stomach, and
lungs of the horse. Photo by Carien Schippers. |
Lifecycle
Habronema nematodes (stomach worms) inhabit the stomachs of
horses and donkeys. The adult worms live in the horse's stomach
wall. The female worms produce eggs inside the stomach, and
the larvae hatch further down the gastrointestinal tract in
the intestine. They then leave the intestines via the horse's
feces, and stable flies, face flies and house flies pick up
and ingest them. When the fly matures, the stomach worms also
mature into their infective stage. While the fly feeds, it deposits
the infective larvae around the horse's mouth, the horse swallows
the larvae, and the life cycle is completed.
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| Flies
deposit the infective larvae in skin wounds and moist areas
of the horse. If the larvae migrate to other areas, they will
not mature, but their migration can still cause local irritation.
Some can travel through the nose and into the lungs where they
may be trapped and form cysts. |
Habronema infection (known as habronemiasis) commonly manifests
as "summer sores," ulcerations of moist areas of horse's
skin. Photo by Cookie Originals. |
Diagnosis
and Treatment
Summer sores are easily confused with sarcoids or other skin
cancers such as squamous cell carcinoma, a skin biopsy may be
necessary to correctly diagnose habronemiasis. Summer sores
can be treated with the oral administration of an ivermectin
de-wormer as well as topical and/or oral steroids to reduce
the inflammation and irritation, but they can persist over a
long lime if not treated promptly and effectively. Having the
lesions surgically removed is an answer to eliminating sores
that do not respond to traditional medical therapy. Your veterinarian
may also recommend additional medications to assist in healing.
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Prevention
Thorough examination of your horse daily can aid in detection
of small wounds that should be treated before fly infestation
can occur. Horses of any age can get summer sores, although
some are more susceptible especially if an immunodeficiency
exists. A number of products are commercially available since
the best way to prevent summer sores is fly control, and in
this case: an ounce of prevention is truly worth a pound of
cure. |
The adult
habronema lives in the stomach of the horse.
Photo by Andrzej Polozowski, www.parazytologia.pl
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Dr.
Toots Banner is a practicing veterinarian and equine
dentist, located in Micanopy, FL. Email Dr. Banner and
Riverside Equine Dental Services.
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