Page 15 - Equine Matters Spring 2013

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L AM I N I T I S
SPRING 2013 ISSUE
EQUINE MATTERS
14
Equine metabolic
syndrome (EMS)
EMS is a clinical syndrome with a collection
of risk factors that are associated with an
increased susceptibility to laminitis. Usually
ponies with EMS are overweight but not all
obese horses have EMS and not all EMS
horses appear obese. More often they
have regions with increased fat deposits,
generally a cresty neck.
To diagnose EMS a blood sample is taken
after the horse/pony has been starved. In
some cases then given a feed of glucose
prior to further blood sampling, to see how
the body responds to the increased glucose
levels. Ponies with EMS are insulin resistant
i.e. they have high resting insulin levels but
the cells are not responding to the insulin
and therefore not taking up glucose. This
insulin resistance is related to obesity
and laminitis.
Management is weight loss, exercise and
sometimes medical treatment. This syndrome
is related to type 2 diabetes in humans.
Most EMS sufferers are detected after they
have had recurrent bouts of laminitis but it is
most likely to be prevented if detected early.
Blood tests can be used to detect those
horses at risk of EMS and therefore at risk
of laminitis.
Cushing's disease
Another endocrine (hormonal) disease,
like EMS, that is highly linked to laminitis is
Cushing's disease. This is a condition that
generally affects older horses (over 15 years
old) although increased blood testing of
laminitics is showing that it does exist in
younger animals too.
Cushing's disease is caused by a
degeneration of nerves in the hypothalamus
(within the brain) which leads to a reduced
production of dopamine which results in
a hormone imbalance which leads to an
increase in the production of cortisol
(steroid) by the adrenal glands. The
increased cortisol level increases the risk of
laminitis by several mechanisms including
insulin resistance.
Cushing's disease is diagnosed by clinical
signs and confirmed by a blood test.
Pergolide is a tablet used to treat Cushing's
disease by stimulating the production of
Dopamine. This treatment reduces the risk of
laminitis and early detection can prevent it.
Diet and exercise
Equine metabolic syndrome, obesity and
to some extent Cushing's disease are all
related to dietary management and exercise.
Many horses and ponies are overfed for
the amount of exercise they do. Pasture
management and hay/haylage production
have improved, increasing the calories
that they receive. The increased use of
supplements also increases the calorie
intake, both the supplements themselves and
also the feed given to disguise them. Plus
rug technology has improved and horses
don't lose weight over winter.
Feeding little and often and a measured
quantity for a 24 hour period is important in
weight control. A guideline is an exercised,
body condition score 2.5 horse should
receive 2.5% of their bodyweight (BW)
in dry matter i.e. a 400kg horse should
receive 10kg over 24 hours including all
hay, feed and grass. For weight loss 1.5%
BW is a guideline but some studies have
revealed far lesser amounts still do not
result in weight loss.
The use of multiple small holed haynets to
reduce bite size, haynets placed around the
stable/yard to promote grazing behaviour,
haynets hanging from above rather than
against a wall to make the horse work
harder for the feed, and soaking hay are
all possible aids to help reduce the quantities
of calories taken in by the horse. Control of
calorie intake is much harder when the horse
is allowed free access to pasture. Grazing
muzzles and strip grazing systems can help.
Exercise is an important factor and it is
important to feed to the required work
demands. Exercise is not only important
for weight management and fitness but
also aiding the blood flow and health of
the hoof.
Hoof care
Regular trimming and care of the equine
hoof is important to maintain the integrity
and health of this continually evolving and
growing structure. Hoof conformation is
important for the balance of pressure through
the laminae and therefore preventing micro
damage to these vital structures. Most
horses from a foal will require trimming
approximately every six weeks to maintain
optimum hoof health. Allowing the toes
and/or heels to become too long or under
run will predispose to laminitis. There will
also be increased risk of infections within
the hoof; abscesses, seedy toe, thrush etc.
Obesity and endocrine disease are the most
common causes of laminitis but this article
would not be complete if I didn't mention
laminitis caused by toxaemia and systemic
infections such as if a mare should retain the
foetal membranes post foaling and treatment is
not started within a few hours. This can cause
a nasty and often fatal laminitis due to toxin
build up. Laminitis can also be caused by
continued loading of one limb if there is an
injury to the opposite limb.
If you are concerned that your horse
may be at risk from laminitis contact
your XLVets Equine vet who will be
pleased to advise on the best course
of action.
Other causes of
laminitis...
Weight tape