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You are right that tying-up syndrome doesn't have
any easy answers. Most knowlegeable horse owners and veterinarians would
agree that tying-up syndrome (exertional rhabdomyolysis, in the veterinary
papers) is a complex metabolic disorder which often has a number of
pre-disposing factors. Some of these pre-disposing factors are familiar to
horse owners such as yourself and include:
1. Diets that contain a large percentage of
2. Feeding large amounts of grain during periods of
intense exercise followed by rest days without decreasing the grain intake
(classic Monday morning disease more often seen in draft horses);
3. Exercising young, excitable fillies on a cold
4. Horses involved in endurance events such as
3-Day, Combined Driving and Endurance where exhaustion and environmental factors
such as heat/humidity combine to precipitate an episode;
5. and now researcher Dr. Stephanie Valberg has
indentified a genetic pre-disposing factor to tying-up known as polysaccaride
storage myopathy (PSSM) in certain families of horses.
In order for muscle to funtion "normally" in the
exercising horse, there must be a readily available and properly regulated
supply of energy in the form of adenosine tri-phosphate (ATP) to enable
contraction and equally important RELAXATION of the muscle
fibers. In order for muscles to relax following contraction, calcium must
actively be pumped out of the muscle cells. This process and its
regulation also require ATP as an energy source and may be the phase
which -when disrupted - results in tying-up syndrome.
Glucose entry into muscle cells and its subsequent
conversion to ATP represents an important energy source for muscle function and
regulation. When horses are impacted by athletic training and other
enviromental stressors such as heat, humidity, and even long distance travel,
the body produces molecules called beta-lipo-proteins which inhibit the
conversion of glucose to glucose-6-phosphate in the muscle and other cells in
the body as well. This inhibition of the enzyme, hexokinase, reduces the
energy supply available for proper muscle function and in some individuals may
lead to tying-up syndrome. This may explain why some horses tie-up at
the start of exercise, during a fifteen minute warm-up. If the cell
can't access the energy, doesn't matter how much there is. Like swimming
in the ocean...water, water everywhere and not a drop to drink.
The glycosides (plant sugars) found in our herbal
supplement APF have been shown in vitro to increase the transport of
glucose across the cell membrane and to correct the inhibition of hexokinase,
allowing for adequate energy production within the muscle cell to provide for
proper contractile function (AND RELAXATION, to occur). An added benefit
to the un-inhibited flow of glucose metabolism is that there is energy
available for protein synthesis as well, a very important feature when training
an athlete of any species.
Most of this information has been derived from the
literature of human sports nutrition. However, I have been
working with this particular group of herbs for nearly seven years now in an
effort to improve the safety and efficiency of the adaptive response to athletic
training and competition in the horse. Its application as a
management tool for tying-up is a perfect example of the increased level of
safety these herbs provide. I have had excellent success in using it
for even the most difficult cases of tying-up.
Hope this helps.
Michael Van Noy, DVM
Auburn Laboratories LLC
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