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June/July 2013
EquineWellnessMagazine.com
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chillout
The pros and cons of common quieting agents used in show horses.
By Kelli Taylor, DVM
We have all experienced the spookier than normal
horse, or the equine that gets too anxious at shows. If you are
the lucky owner of one of these horses, like I am, you have
probably asked yourself: Is there anything more I can do to calm
him down?
This is a pretty common problem as evidenced by the number
of so-called calming agents available. Plenty of them are oral
supplements, but there are also some injectable substances that
have recently come under scrutiny in the news (and rightfully so).
Oral calming supplements
Many products fall into this category. The main ingredients
include minerals (magnesium), vitamins (B vitamins, such as
inositol and thiamine), amino acids (l-tryptophan, taurine,
amino propanoic acid), herbs (valerian root, chamomile, passion
flower, oat pods, skullcap, etc), and flower essences (Five Flower
Formula, Rescue Remedy, etc). I also include essential oils here
as they are sometimes taken internally, but more often they
are used for aromatherapeutic purposes (lavender, chamomile,
bergamont and jasmine, to name a few!).
It has been my experience, as well as that of several equine
nutrition specialists, that supplementation of vitamins and
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minerals only has a calming effect in horses that are deficient in
those nutrients. This is why the first thing I recommend when
a client asks me about using calming agents is to take a good
look at your nutrition program. Horses that are receiving good
quality hay with a vitamin/mineral ration balancer formulated
for your geographical region will not be deficient in magnesium
or B vitamins in the first place.
Vitamins and minerals
Symptoms of magnesium deficiency include hyper-excitability
and muscle cramping, which is why the manufacturers of
calming products include this mineral in their formulations.
Symptoms of vitamin B deficiency are quite varied because
of their role in so many of the body’s systems, but normally
include gastrointestinal signs such as diarrhea (particularly
vitamin B1/thiamine deficiency because of its important role
in carbohydrate metabolism) as well as nervous system effects.
t
But as I stated above, horses eating good quality hay along
with a ration balancer will not be deficient in these vitamins
or minerals. One exception is a horse that has a malfunctioning
hindgut. This is because the bacteria in the hindgut manufacture
almost all the B vitamins the horse needs, but if the hindgut
is not functioning properly, as in horses with colonic ulcers, B
vitamin production may be diminished.
Amino acids
The basis for giving extra “calming” amino acids to horses is
centered upon their known effects in people. But we need to
remember that the horse’s digestive system is different from a
human’s, so horses absorb these amino acids at a different rate
than we do. The horse is able to synthesize many amino acids
from building blocks they receive from proper nutrition, and
those they cannot make themselves they will get through high
quality forage.
L-tryptophan is converted to serotonin (a neurotransmitter) in
the body through complex biochemical reactions. It is thought
that increased serotonin levels in horses will act the same way
they do in people and have an anxiolytic effect. There have been
a few studies looking at the effects of l-tryptophan in horses,
but they all show no change in behavior after consuming levels
of l-tryptophan commonly found in commercial supplements.
Also, doses lower than what is found in these supplements
actually caused the study horses to become mildly excited!
And high doses reduce a horse’s endurance capacity and can
cause acute hemolytic anemia.
Taurine seems to calm the sympathetic nervous system in
people, but again this has not been studied in horses. The
sympathetic nervous system is the part that responds to stress
(fight or flight). Amino propanoic acid, also known as beta–
Alanine, has been shown to have anxiolytic effects in mice, but
I cannot find any research specific to horses.
Herbs, flower essences and essential oils
Herbal preparations work for some horses, but not every herb
works for every horse, and many of these products are now
prohibited by the FEI and USEF as performance-enhancing
substances. If you are interested in trying an herbal supplement
for your horse, I suggest you discuss available options with an
integrative veterinarian so
the correct herbs for your
particular horse in your
particular situation are
chosen. Flower essences,
on the other hand, can be
safely used in all animals
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as they work on an energetic level and will not test positive. I have also found the
aromatherapeutic use of essential oils to be very effective in animals.
Injectable calming agents
Injectable sedatives/tranquilizers include Diazepam (valium), Reserpine (Rakelin),
Xylazine (Rompun), Detomidine (Dormosedan) and Acepromazine; neurotransmitters
(gamma amino butyric acid (GABA), Gabapentin); and various other human anxiolytics
and anti-psychotics.
– Supplementation of vitamins and minerals only has a calming
effect in horses that are deficient in those nutrients. –
Two of the most worrisome calming agents readily available on the lay market are
injectable magnesium sulfate and GABA (the main ingredient of “Carolina Gold”). Both
were added to the FEI and USEF prohibited substances lists earlier this year because of
their potential side effects.
• I njection of magnesium sulfate does have a profound calming effect, but there is a small
margin of safety when it’s administered intravenously, as it has sedating effects on both
muscles and the heart. If too much of this drug is given, or if it’s given too fast, it will
affect the horse’s heart rate and rhythm, causing him to collapse and most likely die.
• G
ABA acts as an inhibitory neurotransmitter when administered intravenously and
therefore has the potential to be anxiolytic, analgesic, anticonvulsant and sedative.
Adverse side effects include dizziness, fatigue and drowsiness. I would not want to ask
a horse that was administered this drug to perform, let alone get on his back! This is a
very risky undertaking by competitors who are more concerned about winning their
next ribbon than their horses’ welfare.
Legalities and ethics
No drug (or herb, for that matter) can be given without the potential for side effects.
If you are considering the use of a calming agent in your horse, I cannot stress enough
that you should get your veterinarian involved. There are many reasons for a horse to be
hyper-excitable, including an excess of caloric intake, lack of exercise and pain, as well as
improper or inadequate training. Your veterinarian will be able to rule out pain, go over
your nutrition plan, and give advice on calming agents that can be used safely and legally.
Above all, the welfare of our horses has to come first.
Injectable sedatives/tranquilizers should only be used under direct veterinary supervision
during medical procedures (such as dentistry or wound repair). They have a fine margin of
safety, and produce effects in the horse that make him unsafe to ride. Certain tranquilizers
may be prescribed by your veterinarian to keep a horse calm on stall rest, and should only be
used for that purpose as directed.
Dr. Kelli Taylor is a 2008 summa cum laude graduate of Washington State University’s College of Veterinary Medicine. Just after veterinary school, she
completed a year-long internship in Equine Medicine & Surgery at Pilchuck Veterinary Hospital in Snohomish, WA and has continued her education in
equine athletic rehabilitation by completing certifications in veterinary chiropractic and acupuncture. Dr. Kelli is currently working toward becoming the
first Certified Equine Rehabilitation Therapist in Washington State. [email protected]
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Reproduced by Equine Wellness Magazine with permission.
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