Dealing with “Equine Metabolic Syndrome”
by Kevin H. Kline, PhD Professor of Animal Sciences University of Illinois
Metabolic Syndrome is basically a "prosperity disease" of horses that are
genetically thrifty. In other words, some types of equines including certain
pony breeds, Morgans, Pasos (Paso Fino, Peruvian Paso), domesticated Spanish
Mustangs and occasionally warm blood breeds of horses are genetically
well-adapted to surviving under harsh conditions, including relatively low feed
intakes. When too much "prosperity" or plenty of rich feed is available, these
"EMS" horses may suffer from obesity, uneven
fat deposition along the crest of the neck and tail head, insulin resistance
and laminitis. The peculiar fat deposition patterns in some EMS horses may also
include fat bulges above the eyes, behind the shoulders, and in the sheath of
male horses, even when these horses are relatively thin overall, and have not
received a great deal of excess dietary energy.
past years, many of these horses would have been labeled as "hypothyroid
horses", because some do in fact have low thyroid hormone concentrations.
However, more recent research suggests that hypothyroidism may be more of a
consequence of the condition, rather than a cause; and that not all EMS horses have low thyroxin concentrations. Equine
Metabolic Syndrome is most likely to be diagnosed in horses between 8 and 18
years of age. When younger EMS horses are in
heavy training for various competitive or intense recreational events, and are
consuming just enough energy to cover the demands for growth and exercise, the
condition may not be readily apparent. As an EMS
horse becomes less active, but may still be receiving similar amounts of hay,
grain and pasture, symptoms worsen.
most debilitating part of Equine Metabolic Syndrome is the associated laminitis
or "founder", which can permanently cripple a horse if enough sensitive laminae
in the hoof are damaged. It is thought that insulin resistance is the component
of EMS that predisposes horses to laminitis.
Insulin resistance basically means that normal concentrations of insulin that
should induce expected changes in target tissues (ie: facilitating uptake of
glucose from the blood by muscle, liver, fat and other tissues) fail to cause
those expected changes. The horse's pancreas then compensates by secreting
higher and higher levels of insulin to cause the required responses in body
tissues. This excess insulin causes numerous negative health consequences that
equine researchers are actively studying, in hopes of finding more effective
treatments for horses that suffer from this condition.
currently recommended management-related treatments for EMS
horses that are prone to obesity and laminitis include reducing the overall
caloric intake, decreasing the starch and sugar content of the diet (no
grain!!), increasing exercise, and limiting access to pasture. Some varieties
of pasture grass contain more sugar and starch than others, so contact your
Horse Specialist for advice on pasture management for EMS
horses. Some severely affected horses may need to be kept off pasture
altogether to avoid recurring problems with laminitis.
medical therapies are available for treatment of EMS
horses as well. These include treatment with Levothyroxine sodium, which recent
research has found to accelerate weight loss and increase insulin sensitivity.
However, medical intervention is expensive, and should be considered to be
short-term assistance to speed weight loss and improve insulin sensitivity
while management practices are being implemented in order to reduce the
likelihood of laminitis. There is no miracle cure available for horses with
Equine Metabolic Syndrome, but proper management, especially avoiding grain and
increasing riding time in affected horses, can greatly improve the quality of
life for EMS horses.
from the AAEP Annual Convention, here's an update on what we know about these
two disorders and how to manage them:
metabolic syndrome typically affects horses aged 8 to 18-years-old. Pony
breeds, domesticated Spanish Mustangs, Peruvian Pasos, Paso Finos, and some
Warmblood breeds appear especially prone. A preliminary diagnosis is based on
obesity, insulin resistance and insidious onset of laminitis. EMS
horses typically have fat deposits in the crest of the neck, over the tail
head, above the eyes, behind the shoulders, and in the sheath of male horses.
Diagnosis is confirmed by measuring insulin and glucose levels in the blood.
Unfortunately, there are no medications to treat EMS.
At this time, experts recommend a low sugar/starch diet, exercise, and
antioxidants such as Vitamin E to help manage the oxidative stress that comes
with the syndrome.
Signs of equine
Cushing's syndrome typically first appear in horses aged 18 to 23-years-old and
include: hirsutism (long curly hair), weight loss and muscle atrophy,
depression and poor performance, normal to increased appetite, laminitis, and
fat deposits as described above. The best tests for Cushing's are the dexamethasone
suppression test and the ACTH stimulation test. And while the disease cannot be
cured, pergolide seems to help manage the disease better than cyproheptadine.
Because some horses with Cushing's develop insulin resistance, they should also
be fed a low sugar/starch diet, although some might need additional calories
from fat. Antioxidants might be useful in this syndrome as well.
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