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S K I N D I S E A S E
SPRING 2011 ISSUE
EQUINE MATTERS
14
ALLERGIC TO MEDICATION
Some horses can be allergic to certain
drugs; when given medications which
would not affect normal individuals, they
react in an adverse way potentially
causing some serious reactions. The
following case developed large areas
of irregular bumps in the skin following
the administration of a routine wormer,
the reaction went down after a while
but the owner was careful to avoid any
similar wormers again.
Another allergic reaction to an insect bite is
Hives or Uritcaria in which a sting from a bee
or wasp causes large swellings to appear all
over the body. In the case opposite the head
had swollen up and the nose band of the
head collar had left an impression where it
had become tight and prevented further
swelling. This resolved after being given
intravenous medication but caused the horse
considerable distress at the time.
Allergies to environmental agents can be
either from direct contact or by a systemic
reaction once the allergen has been inhaled.
Some animals develop an allergic reaction
to something their skin comes into contact
with such as certain types of bedding.
The horse below came out in large skin
reactions when its bedding was changed
from wheat to barley straw. The lumps went
down with treatment and changing the
bedding, but relapsed once exposed to
Barley Straw again.
The predisposition to allergic symptoms
following repeated exposure to inhalant
allergens is called Atopic Dermatitis and
Arabians and Thoroughbreds appear to be
predisposed to the condition. Common
allergens include: pollens, moulds, and Dust
Mites, and the reaction causes intense itching.
The horse bites at itself and rubs itself on
fences and stable walls causing self
inflicted damage with hair loss and ulcerated
skin lesions. The disease can be investigated
by allergy testing where extracts of common
environmental agents are injected into the skin
and the reaction measured. The following
horse was identified as being allergic to
Dust Mites and once kept out at grass and
the exposure to stable dust reduced its
condition improved.
Reducing the exposure of an animal to the
allergens by regular shampooing with a
mild soothing shampoo can also be beneficial
and corticosteroids in the short term to
suppress the sensitivity of the skin to the
allergenic agents is helpful, but long term use
can be harmful with side effects including
Laminitis and liver damage.
ENVIRONMENTAL AGENTS
CONCLUSION
So there are a wide variety of allergic
reactions horses can develop producing
a range of clinical signs. Painstaking
investigation to get to the bottom of the
cause can be very helpful in managing
the problems and allowing the horse to
continue a comfortable life.
Horse with Uritcaria (Hives)
Reaction to a bedding change
from wheat to barley straw
Horse allergic to dust mites
Allergy testing