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S K I N D I S E A S E
13
EQUINE MATTERS
Binscarth Farms
T
here are many agents which cause
allergic skin disease in animals but they
could be broadly categorised into insect
bite reactions, food allergies, contact allergies
and allergies to environmental agents such as
pollens, dust mites or mould spores.
In most individuals an insect will bite an
animal to suck its blood, at the same time it
will leave a small amount of its saliva which
is normally absorbed by the body in a short
period of time. However some individual
animals have an immune reaction which
causes an excessive reaction to the insect
saliva, causing the skin to become very itchy.
The animal then rubs and scratches itself
making large sore patches. A good example
of this in horses is Sweet Itch in which ponies
that are allergic to the bites of midges or
Black Flies (Culicoides), rub themselves raw
on the tail and mane and under the belly.
This has a hereditary component and is seen
particularly in certain breeds such as Shires,
Icelandic and Welsh ponies. The midges
are particularly prevalent near areas of free
standing water and when there are low
winds in the early morning or late evening in
summer and autumn. Management therefore
involves preventing the midge from biting
so having horses stabled between 4pm
and 8am and covering the animal in a
shroud/hood can help (e.g. The Boet
Blanket). A fine mesh screen over stable
windows, having fans in the stable to create
a breeze, and using fly repellents can help.
Anti-inflammatory medication includes
glucocorticoids; oral preparations can
precipitate laminitis, but topical preparations
can be beneficial. Desensitisation using an
allergy vaccine has been investigated and
the results are still being analysed so no
commercial preparation is available yet.
Allergic Skin Disease
in Horses...
An
allergic reaction
is an inappropriate reaction of an individual
animal's immune system to a harmless agent that it is exposed to
which, the majority of animals would not react to.
Veterinary Surgeon
Richard Morris
XLVets Practice
Fenwold Veterinary
Practice, Lincolnshire
Richard Morris BSc, BVetMed, CertVD, MRCVS
Horse with Sweet Itch