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Hives are a symptom of an allergy from food, environment, or respiratory contaminants, and the best approach is to keep the horse’s allergic threshold below the trigger point through insect control, minimizing dust, and keeping the diet simple.
VETERINARY VIEWS
CRUSTING OR ULCERATED LESIONS
One example of a crusting lesion is sarcoidosis caused by an abnormal reaction to an infectious or non-infectious protein (antigen). Another skin problem that creates crusting lesions
arises from an autoimmune response known as pemphigus foliaceous.
HEREDITARY SKIN DISEASES
Hereditary skin diseases are another concern, such as HERDA (hereditary equine regional dermal asthenia, formerly called hyperelastosis cutis) in horses with Quarter Horse lineage, and chronic lymphedema in draft horses.
THE BOTTOM LINE
In many cases of skin disease, an accurate diagnosis is best achieved by obtaining a tissue sample through a biopsy of the lesion and sending it to a lab for histopathologic examination,
or through bacterial culture and sensitivity.
A definitive diagnosis lends itself to the most expedient means of treating the condition.
Although non-malignant,
if viral in origin sarcoids can be contagious to other horses from shared grooming and tack equipment.
is useful to identify offending proteins. The presence of hives is a symptom of an allergy and not necessarily a diagnosis.
The best management approach for
hives relies on keeping a horse’s “allergic threshold” below a trigger point. This
is accomplished through control of the environment – modifications of stabling as necessary, implementation of insect control, minimization of dust in bedding and hay, and keeping the diet simple.
Many nodular lesions have multiple causes, ranging from bacterial infections such as sporotrichosis and pigeon fever abscesses, to ulcerated or nodular summer sores from Habronema fly larvae, to neoplasia like melanoma, mast cell tumors, or sarcoids.
Sarcoids are reported in 35-90% of skin neoplasms, and although these are non- malignant, they are a cosmetic nuisance as well as potentially interfering with tack and equipment. If they are of viral origin, they can be contagious to other horses from shared grooming and tack equipment. Sarcoids
are commonly found in thin-skinned areas, especially in locations of previous wounds or continual contact irritation by tack.
Other nodular-type skin lesions include plaques in the ears caused by sarcoids, warts (papilloma virus), or to insect hypersensitivity as described above. Nodular necrobiosis on the back and trunk form lumps usually caused by an allergic response to insect bites or saddle pad materials.
SPEEDHORSE
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