Posted by: "ladywife" firstname.lastname@example.org vickiladywife
Feb 10, 2007
For years I have carefully avoided using the term "insulin resistance"
any of my posts to the lists because I didn't want anyone to panic that
their donkeys have a dreaded, incurable disease called insulin
but now that it has been mentioned, we should talk about it.
Okay, first thing: Insulin resistance is NOT A DISEASE. So everyone take
deep breath and relax.
Insulin resistance is the metabolic survival mechanism our donkeys
from generations and generations of their ancestors adapting so they
survive and thrive in harsh environments where there was sparse forage.
Insulin resistance is not a disease, it is their genetic inheritance and
reason donkeys can not tolerate rich grains, feeds, and forage. Those
items are formulated and fortified with packed nutrition for a horse's
much-less efficient digestive system. Now finally after 30+ years
researchers have noticed horses descended from ancestors from the same
of harsh environments as our donkey's ancestors, can't tolerate that
fortified nutrition feed formulas either, such as Arabs, Morgans, and
Icelandic horses to name a few.
That new awareness is a bonus to donkey owners because now research is
directed toward creating a more suitable feed for those types of horses
it will benefit our donkeys too. I can't think of the name of it at the
moment (one of those increasingly frequent memory holes) but there is
vitamin and mineral fortified low carb alternative equine packaged feed
being produced that is based on beet pulp and whole oats, very similar
the donkey diet I have talked about many times on the lists.
Globs of fat deposits on the top line of a donkey; developing a fat
and pones of blubber on the top of the back, draping over the ribs, and
those poofy fat butts are all indications the donkey's inherited
mode is storing fat preparing for times of famine. That is a natural and
normal thing for a donkey to do, it is their body's survival instinct.
is also unhealthy for them and means our husbandry method has not been
adapted to his dietary needs.
I am going to copy/paste a Fact Sheet by Dr. Jenifer Nadeau, Equine
Extension Specialist, University of Connecticut
Insulin resistance is a newly recognized problem in horses that may have
been around a long time. You may be wondering what it is all about and
your horse may/may not be affected. It is probably not as common a
as it may seem. This article will discuss insulin resistance including
causes, effects, diagnosis, treatment and prevention.
What is Insulin Resistance?
Glucose (sugar) normally functions to fuel many metabolic
processes in the body and is the primary energy currency of the body.
Insulin is normally produced in response to elevated blood glucose and
key to the regulation of blood glucose concentrations and glucose
utilization. Insulin promotes glucose uptake by cells and promotes
formation of glycogen or fat. Insulin resistance is defined as a reduced
sensitivity of the body's cells to insulin's facilitation of glucose
Basically what happens in insulin resistance is that the cells
become resistant to the glucose uptake action of insulin. Initially,
just means that more insulin is needed (hyperinsulinemia) to keep blood
glucose concentrations within normal limits after a starchy or high
meal. If it is severe enough even super high insulin concentrations are
ineffective and blood glucose may also be abnormally high. The problem
that not only does this limit energy availability to the cells but
also has other effects on the body that may be detrimental when it is
than normal for prolonged periods of time. Unlike humans, horses rarely
into the second stage, where the pancreas becomes "exhausted" and no
can secrete adequate insulin.
The exact cause of insulin resistance is still unknown.
However, several possible causes include:
* Diet - In a recent study, horses had increased insulin resistance
when fed high sugar/starch feeds compared to high fiber and fat rations,
especially when they were not obese.
* Obesity - Overweight horses tend to be insulin resistant, as are
"easy keepers" even if they are not obese.
* Age - Old horses (>20 years) seem to be more prone to insulin
resistance, probably secondary to pituitary dysfunction (Cushing's
which is extremely common, especially in mares.
* Breed - Ponies were found to have higher degrees of insulin
resistance than Dutch Warmbloods or Standardbreds. Breeds that are prone
developing cresty necks and obesity, such as Morgans and some lines of
Arabians, Quarterhorses, and Thoroughbreds may be more likely to develop
problem, although a study conducted at the University of Connecticut
comparing exercising Morgans and exercising Thoroughbreds did not find a
difference between breeds in insulin resistance.
* Laminitis - Horses with a family history of laminitis and horses
that develop laminitis without an obvious cause (grain overload, sudden
access to lush, green grass) may be insulin resistant.
Effects of Insulin Resistance
Insulin resistance may result in:
* Loss of weight
* Loss of muscle
* Lack of stamina
* A condition similar to human Type II diabetes
Your veterinarian will be able to diagnose insulin resistance.
A single blood sample drawn within 60 to 90 minutes of eating a meal of
grain is a quick screening test for hyperinsulinemia. If the results are
abnormal the veterinarian should perform a more reliable test by
administering a glucose challenge orally or intravenously and measuring
glucose/insulin response over the course of two or three hours. This is
usually practical in the field and the horse may need to be referred to
clinic to get such tests done.
Treatment may consist of the following:
* Weight loss through diet and exercise if the animal is obese
* Addition of a minimum of 30 min of exercise
* Limiting carbohydrate intake through elimination of grain and high
* Soaking hay if it is know to contain high amounts of sugars (> 10
to 12% soluble sugars)
* Feeding warm season grasses, such as Bermuda grass, or feeding beet
pulp that does not have added molasses
* Cutting down on free choice intake of grass if the horse has a
history of founder and is obese
Preventative measures to reduce insulin resistance are:
* Feed primarily grass or legume mix hay or pasture. If the horse
tends toward obesity, limit access to the forages and feed no grain at
* If concentrates are needed to maintain body condition, feed
products formulated to have a low glycemic index. For example, oats are
commonly used as the standard with an index of 100. Plain beet pulp has
lowest index in most studies and barley has the lowest index of the
* Test pastures and dry forages for amounts of sugars present.
* Soak high sugar hay in hot water for 30 min or cold water for 60
* Restrict grazing time but only if the horse has a pre-existing case
of laminitis and grass is lush
* Add fat and fiber to the diet at 6-10% for fat and at least 12% for
Insulin resistance can be a serious problem, but actual
statistics on insulin resistance are currently unavailable. An accurate
medical diagnosis by a veterinarian is extremely important. As with most
equine health concerns, prevention is better than treatment. By paying
careful attention to diet and condition of your horse, you may be able
prevent insulin resistance from becoming a problem in your horse.
1. A.J. Forhed and H. Dobson. 1997. Plasma glucose and cortisol
to exogenous insulin in fasted donkeys. Research in Veterinary Science
2. R.H. Hoffman, R.C. Boston, D. Stefanovski, D.S. Kronfeld, and P.A.
Harris. 2003. Obesity and diet affect glucose dynamics and insulin
sensitivity in Thoroughbred geldings. Journal of Animal Science 81:
3. J. Meszoly. April 2004. Danger in the grass: how you can protect your
horse. The Horse p. 61-71.
4. S. Ralston. October 2004. Equine metabolic syndrome. The Horse p.30.
5. A. Rodiek. June 2003. Sugar levels in horse diets. Horse Journal p.
6. L. Sellnow. April 2004. Obesity and Cushing's disease. The Horse
7. S. Wenholz. April 2005. A closer look at insulin. The Horse p. 91-98.
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