Basic HTML Version
EQUINE REVIEW
SPRING 2010
8
T
his system involves the laying down
of fat deposits during the spring and
summer when food is plentiful. This fat,
particularly fat in the abdomen of the horse or
pony does not just serve as an energy store
but is also metabolically active and produces
hormones called adipokines. Increased levels
of these hormones result in increased levels of
a steroid hormone called cortisol, which
inhibits the effects of insulin. Insulin is involved
in the uptake of glucose from the bloodstream
and its storage in cells. If insulin is stopped
from doing its job, the body reacts to this by
producing more insulin. This phenomenon
is called insulin resistance. This process is
essentially a normal physiological and health
sustaining survival trait. Problems such as
laminitis occur when this mechanism fails
to operate correctly with the normal
seasonal changes.
Domestication of the horse has resulted in
horses being fed more than adequately during
the summer and winter months on improved
pastures, good hay, haylage and high quality
concentrate feeds. The result of this is that
there is no real requirement for the valuable
winter fuel saving insulin resistance system. This
system remains permanently turned on resulting
in many undesirable effects such as continually
high circulating insulin and glucose levels. A
very similar situation is seen in type 2 diabetes
in humans. High circulating glucose levels are
toxic to the cells lining all of the blood vessels.
In man we see this resulting in cardiovascular
disease. In the horse, this results in blood
vessel problems in the feet and subsequently
causing laminitis.
EMS is often referred to by other names. You
may hear it referred to as peripheral Cushing's
disease, pre-Cushing's disease, obesity-related-
laminitis or even, more sinisterly, as equine
syndrome X. All these names are relating to
the same disease process. There is no real
specific test for Equine Metabolic Syndrome
so your vet will use a combination of medical
history, clinical signs and supportive blood
tests to diagnose the problem.
It is very important that your vet makes the
final diagnosis of EMS as they may need
to rule out Cushing's disease and thyroid
dysfunctions. These are different metabolic
glandular diseases which can appear very
similar to EMS.
Treatment of EMS is very similar to the
treatment of obesity in people and is based
on diet and exercise. As in people this takes
a lot of discipline. The diet should consist of
good quality hay, small amounts of high fibre
concentrates, and a vitamin and mineral
supplement. The amount of hay you should
feed should be ideally 1- 1.5% of your horse
or pony’s ideal weight e.g. If your pony
should be 200kg in weight, feed 2-3kg of
dry hay. Do not guess at this weight. You must
weigh the hay as you will be surprised how
little it is. Absolutely no grass, haylage, apples
or carrots should be fed. This sounds harsh but
is essential for the success of treatment.
Exercise is essential as it aids weight reduction
and improves glucose uptake into the muscles.
If your horse or pony has laminitis, you must
wait until this has been treated successfully
before you start any exercise programme.
Drug therapy using Metformin is proving to
be very successful in the treatment of EMS.
Metformin is also used in treatment of human
diabetes and is given orally to improve insulin
sensitivity. Levothyroxine is used extensively in
the United States for treating EMS as it is
thought to accelerate weight loss and improve
insulin sensitivity. It is unfortunately prohibitively
expensive to use this drug in the UK.
The best treatment is of course prevention.
Ensuring your horse or pony is not overweight
is a great start. If you need help or advice on
EMS, obesity, weight reduction or exercise
programmes, please call your local equine vet.
HORSES AND PONIES
, particularly native breeds
have developed a
METABOLIC SYSTEM
which
enables them to survive the harsh outdoor winters
with little food.
ARTICLE BY
GRAHAM HUNTER
, ARDENE HOUSE VETERINARY PRACTICE, ABERDEEN
CLINICAL SIGNS OF
EMS
INCLUDE;
l
Obesity (although occasionally seen
in lean horses)
l
Abnormal body fat distribution
l
Unexplained and recurrent bouts
of laminitis
l
Altered reproductive function, (abnormal
cycling in mares and infertility)
l
Lethargy
l
More frequent urination
‘Treatment of Equine Metabolic Syndrome is very
similar to the treatment of obesity in people and is
based on diet and exercise...’
EQUINE
METABOLIC SYNDROME
Graham Hunter