Obesity. The Real Cause. The Real Fix.

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Obesity is an epidemic problem with domesticated horses. Although we most easily attribute the problem to overfeeding concentrates combined with too little exercise, the underlying cause is much less apparent. It has to do with the horse’s brain and his response to stress — a chronic low-grade, inflammatory stress.

Stress tells the horse that he is not safe

Discomfort, from any source, induces a biochemical response in the brain that triggers the horse to do whatever he can to survive. Research with a variety of species has repeatedly shown[i] that stress tells the body to hold on to fat; the chemical changes that occur are similar to those produced during a famine. This is based on a primitive need to feel safe. Therefore, stress “tricks” the horse’s body into gaining weight just to survive.

Stress can come from many sources – stall confinement, isolation from buddies, sleep deprivation, change in environment, travel to strange locations, excessive training and performing, pain and illness, exposure to toxins, and the most stressful of all – not being allowed to graze on forage at all times. Forage restriction is incredibly stressful.[ii]  Putting the horse on a “diet” by limiting the amount of hay he can have will create a chain of chemical reactions that prevent the very outcome the “diet” was meant to ensure. Let’s look at more specifics…

Stress, cortisol, insulin, and leptin

Stress causes the adrenal gland to release the hormone cortisol. Cortisol tells the tissues to ignore insulin’s attempts to get glucose into the cells.[iii] So insulin increases to try to overcome this, but not very successfully. When insulin is elevated, the cells hold on to body fat. And when body fat increases, it releases a hormone called leptin. Normally, leptin is a good thing, but not in this case.

The brain can become resistant to leptin. Under normal circumstances, leptin (secreted from fat tissue), goes to the satiety center in the hypothalamus portion of the brain to tell it that the horse has had enough to eat and is satisfied.[iv] This is the body’s way of maintaining normal weight: fat increases, leptin rises, the brain says the body has had enough to eat, and weight comes down.

The excess body fat of obese horses promotes inflammation through its secretion of substances known as cytokines.[v] Cytokines can damage the areas within the hypothalamus that recognize leptin.[vi] Leptin is high, but the brain is not responding to it. The result? The appetite does not decrease; instead the horse keeps on eating, getting more obese, producing more cytokines, increasing inflammatory damage to the hypothalamus, resulting in greater leptin resistance.

Perhaps you’ve had your horse’s cortisol level checked and it is normal. You assume that stress is therefore not an issue. But this can lead to a false assumption. Cortisol can actually be elevated inside the cell and not in the bloodstream, due to the overexpression of an enzyme called 11-beta-hydroxysteroid-dehydrogenase-1, present in fat, liver and brain cells that produces active cortisol. This has been shown in several species, including horses,[vii] and leads to the vicious cycle resulting in hypothalamic damage.

The over-use of thyroid medication

Elevated cortisol can reduce T4 levels leading one to believe that thyroid medication is necessary. But reduced T4 under this circumstance is not an indication that the thyroid gland is underactive, nor is it an indication that more thyroid medication is needed to help the horse lose weight. Furthermore, adding T4 to the diet will not do any good if the horse is stressed, simply because excess cortisol interferes with the conversion of T4 to T3, the active hormonal form.

Horses with a history of long-term forage restriction

Some horses have suffered from forage restriction for so many years that their metabolic rate has become severely impaired. For these, modest, short-term weight gain can be a consequence of free-choice feeding. Be patient. The transition can take several months. Allow your horse time to become accustomed—both physically and psychologically—to this new way of eating. Healthy weight loss takes time. When fed following the steps outlined below, the large majority of horses, even those grossly overweight, will adjust, lose weight and in time, arrive at a healthy body condition.

Is your horse leptin resistant?

The leptin resistant horse will, first and foremost, have excess body fat. His appetite will seem insatiable and he will rarely lift his head from eating. His metabolic rate is sluggish, causing him to pack on the pounds very easily. He is reluctant to move and his energy level is low.

The fix

Reduce inflammation! Three factors to consider:

1) Stress reduction will calm down the cascade of hormonal events that tell the body to hoard fat.

2) Less body fat will create fewer inflammatory substances. Insulin (an inflammatory hormone) will also decline.

3) Less inflammation will help the hypothalamus return to a normal leptin response.

Important to understand: Once the horse loses body fat, the brain will initially remain leptin resistant, making the horse very hungry so he could gain back all the weight. Therefore, the approach must be to heal the inflammatory signaling in the hypothalamus.

To do this:

  • Never let your horse run out of forage, not even for a few minutes. Not only is free-choice forage feeding critical to your horse’s overall health[viii] , it also increases the metabolic rate.[ix] Feed appropriate hay and/or pasture that is low in calories, sugar, and starch.[x]
  • Add a comprehensive vitamin/mineral supplement to hay-based diets. It fills in nutritional gaps and reduces overeating to simply obtain enough nutrients.
  • Avoid processed foods. These can contain inflammatory preservatives and omega 6 fatty acids (typically from soybean and corn oils).
  • Feed whole foods free of additives and toxins.[xi] Whole foods can include non-GMO beet pulp, alfalfa, hay pellets, copra meal, split peas, hemp seeds, ground flaxseeds, chia seeds, blue-green algae, and various fruits and vegetables. Limit soybean meal — the long term impact of isoflavones (the phytoestrogen found in soy) on the thyroid gland is controversial.
  • Feed a variety of protein sources by mixing grasses and adding whole foods. When only one or two sources of protein are fed, the excess amino acids can be converted to glucose, potentially increasing insulin.
  • Eliminate excess sugar and starch. These include sweetened feeds, cereal grains, wheat middlings, and rice bran. They raise insulin as well as triglycerides. Triglycerides can bind to leptin in the blood stream and prevent it from signaling satiety to the brain.[xii]
  • Avoid high-omega 6 oils. They are highly inflammatory (e.g., soybean, vegetable, corn, wheat germ, and safflower oils).
  • Increase omega 3s. Feed ground flaxseeds or chia seeds. Fish oils can be included in cases of high levels of inflammation.
  • Add antioxidants. These include vitamins E and C, beta carotene (vitamin A), lipoic acid, grapeseed extract, green tea extract, spirulina,  as well as herbs including turmeric, boswellia, and ashwaghanda (which is particularly useful in combatting stress).[xiii]
  • Avoid prolonged use of H2 receptor blockers and proton pump inhibitors. They can interfere with the body’s ability to absorb nutrients and create rebound acid production upon removal.
  • Add a probiotic for digestive health. Horses who graze on pasture will naturally consume a variety of microbes. Hay-based diets, however, may not offer enough microbes for proper digestion of forage.  Stress can also disrupt the horse’s normal microbial flora.
  • Allow for movement. Exercise increases insulin sensitivity and lessens inflammatory cytokines.[xiv] It has also been shown to directly reduce hypothalamic inflammation.[xv]
  • Limit grazing muzzles. They can defeat the purpose if they cause stress. They should be limited to no more than 3 hours per day because the digestive tract needs more forage than they allow.
  • Consider slow feeders. Not all horses require them, but they are helpful initially to allow for slowing down intake.[xvi]
  • Keep stall confinement to a minimum, if at all. Horses who have room to roam can be as fit as those who receive daily focused exercise, and they are under far less stress.

Free-choice hay costs less

Many barn owners are reluctant to feed hay free-choice because of the apparent expense involved in purchasing more hay. But in actuality, horses who are permitted to self-regulate their intake will eat less. It’s only when several hours lapse between feeding that they eat very quickly and consume everything in sight. But when they get the message that hay is always available, that they can walk away from it and it will still be there when they return – then, and only then will they eat just what their bodies need to maintain a healthy weight. They will actually eat less than before.

Can your horse ever graze on fresh pasture again?

Absolutely! Living, healthy grass is the best whole food around. Grazing in the open air is the best stress reducer your horse can experience. The amount of grazing depends on your horse’s individual condition. Yes, pasture can be high in sugar and starch but it can vary depending on the month, the time of day, level of rainfall, sunlight, etc. Get to know your pasture grasses.

Bottom line

Turn off the body’s fat-hoarding response by taking measures to reduce stress. Combine this with an anti-inflammatory diet and increased movement, and your horse’s brain will regain its ability to respond properly to leptin. Taking off weight will become much easier.

For permission to reprint this article, in part or in its entirety, please contact Dr. Getty directly at gettyequinenutrition@gmail.com.

Juliet M. Getty, Ph.D. is an independent equine nutritionist with a wide American and international following. Her research-based approach optimizes equine health by aligning physiology and instincts with correct feeding and nutrition practices.

Dr. Getty’s comprehensive resource book, Feed Your Horse Like a Horse, is available at www.GettyEquineNutrition.com–buy it there and have it inscribed by the author. Or get it at Amazon (www.Amazon.com) or other online retail bookstores. The seven separate volumes in Dr. Getty’s topic-centered Spotlight on Equine Nutrition series are available with special package pricing at her website, and also at Amazon in print and Kindle versions. Dr. Getty’s books make ideal gifts.

Find a world of useful information for the horseperson at www.GettyEquineNutrition.com: Sign up for Dr. Getty’s informative, free e-newsletter, Forage for Thought; browse her library of reference articles; search her nutrition forum; and purchase recordings of her educational teleseminars. Reach Dr. Getty directly at gettyequinenutrition@gmail.com. She is available for private consultations and speaking engagements.

This spring! On May 2, 2015, hear Dr. Getty address issues in horse nutrition at the Kirkland House Foundation in Delta, British Columbia, sponsored by “Hay…Girl!” For more information on this event, contact Pam Janssen at precioushaygirl@gmail.com or call 604-961-7265.

[i] Block, J.S., He, Y., Zaslavsky, A.M., et. al., 2009. Psychosocial stress and change in weight among U.S. adults. American Journal of Epidemiology, 170, 181-192. Also, Gabriel, J., 2008. The Gabriel Method. Atria Books.

[ii] Getty, J.M. 2014. Restricting forage is incredibly stressful. Choose a different method to help your horse lose weight. http://gettyequinenutrition.biz/library/restrictingforageisincrediblystressful.htm

[iii] Tiley, H.A., Geor, R.J., and McCutcheon, L. J., 2007. Effects of dexamethasone on glucose dynamics and insulin sensitivity in healthy horses. American Journal of Veterinary Research, 68(7), 753-759.

[iv] Freidman, J., and Halaas, J., 1998. Leptin and the regulation of body weight in mammals. Nature, 395, 763-770.

[v] Wisse, B., 2004. The inflammatory syndrome: The roles of adipose tissue cytokines in metabolic disorders linked to obesity. Journal of the American Society of Nephrology, 15(11), 2792-2800.

[vi] De Git, K.C., and Adan, R.A., 2015. Leptin resistance in diet-induced obesity: The role of hypothalamic inflammation. World Obesity, (16(3), 207-224.

[vii] Farias, F.H.G., 2007. 11Beta-Hydroxysteroid dehydrogenase activity in feline, equine, and Ossabaw swine adipose tissue. Master of Science Thesis, University of Missouri-Columbia. Also, Morgan, S.A., Sherlock, M., Gathercole, L.L., et al., 2009. 11Beta-Hydroxysteroid Dehydrogenase Type 1 regulates glucocorticoid-induced insulin resistance in skeletal muscle. Diabetes, 58(11), 2506-2515.

[viii] Getty, J.M., 2014. Equine Digestion – It’s Decidedly Different. http://gettyequinenutrition.biz/TeleSeminars/TeleseminarBooks/SpotlightonEquineNutritionTeleseminarSeries.htm

[ix] Lestelle, LR., Earl, L.R., Thompson, Jr., et.al., 2011. Insulin-glucose dose response curves in insulin sensitive and insensitive mares and effect of overnight and long-term feeding regimen. Journal of Equine Veterinary Science, 31, 285-286.

[x] Getty, J.M., 2015. Do you need to analyze your hay? http://gettyequinenutrition.biz/library/doyouneedtoanalyzeyourhay.htm

[xi] Berkseth, K.E., Guyenet, S.J., Melhorn, S.J., et. al., 2014. Hypothalamic gliosis associated with high-fat diet feeding is reversible in mice: A combined immunohistochemical and magnetic resonance imaging study. Endocrinology, 155(8), 2858-2867.

[xii] Banks, W.A., Coon, A.B., Robinson, S.M., et. al., 2004. Triglycerides induce leptin resistance at the blood-brain barrier. Diabetes, 53(5), 1253-1260.

[xiii]Schell, T., DVM, 2015. Reducing the effects of stress and anxiety of health with ashwaghanda. Nouvelle Research www.nouvelleresearch.com

[xiv]Liburt, N.R., Fugaro, M.N., Wunderlich, E.K., et. al., 2011. The effect of exercise training on insulin sensitivity and fat and muscle tissue cytokine profiles of old and young Standardbred mares. Journal of Equine Veterinary Science, 31(5-6), 237-238.

[xv] Yi, C.X., Al-Massadi, O., Donelan, E., et. al., 2012. Exercise protects against high-fat diet-induced hypothalamic inflammation. Physiology & Behavior, 106(4), 485-490.

[xvi] Getty, J.M., 2014. The correct way to use slow-feeders. http://gettyequinenutrition.biz/library/thecorrectwaytouseslowfeeders.htm

Self Inflicted Pain

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Dear Julie,
My 11-year-old horse recently started biting at his sides—digging deep and mutilating his skin and hair coat. Before I bought him last year, he was gelded and was away from other horses during his healing time. That’s when this strange behavior started. When I purchased him, the former owner barely mentioned the behavior. He just told me if you rode him each day, he’d be too tired to bite his sides. At my place, we keep him turned out with a larger herd. He exhibits the behavior when he’s around his buddies—not only when he may feel lonely. The horse is so sweet to people. He’s kind and respectful. He’s just terrible to himself. What can I do to help him? Why is he doing this?
Bit To Pieces

Dear Bit To Pieces,
Horses that self-mutilate (bite at their own flesh causing open wounds) are generally either in severe pain or experiencing severe stress. Have your veterinarian evaluate your horse to rule out any pain that may be causing the habit. You may also consider having an equine chiropractor (a veterinarian specially trained in spinal alignment) check your horse’s back and range of movement. If you resolve the pain or take away stress, the behavior should go away. That sounds easy, right? However, I wonder if your horse may be hurting himself because of pain or stress he experienced in the past. He may have felt stressed and frustrated when he was isolated at another barn. That stress-time behavior may have become habitual—meaning your horse may not feel pain or stress now, but he has the undesirable behavior nonetheless. If that’s the cause, your horse may need some time to realize he no longer needs the stress-relieving behavior. An interesting note, some research indicates that self-mutilation is related to Tourrettes Syndrome in humans. That link may explain why some horses continue to harm themselves long after a prompt is present.

I have seen a handful of self-mutilators in my training career. I’ll never forget the little mare that had been in training with a brutal hunter-jumper trainer who rode her in draw reins with her nose cranked to her chest. She began to bite her chest while being ridden. Both sides of her shoulders dripped with blood at the end of every course of jumps. Eventually her owner figured out that she was in pain and under stress because of the trainer’s methods. The owner removed the horse from the trainer’s barn and the problem behavior went away. Unfortunately, that trainer is still in business—or so I’ve heard. The other horses I’ve known were stallions with exacerbating medical conditions that caused them great pain. When the horses were brought back to a healthy condition, the self-mutilation went away.

To stop the flesh-eating behavior, you can put a neck cradle on your horse to prevent him from reaching to his sides or legs with his mouth. A cradle is made with dowels strapped together and buckled around his neck when he is alone in his stall. Look for a cradle in any vet catalogue’s bandaging section. It’s not a good idea to have a neck cradle on your horse when he’s turned out with other horses—he won’t be able to turn away from dominant horses or defend himself. Other horses may also become tangled in the cradle. Keep in mind, this cradle can stop the behavior, but not the horse’s desire to self mutilate. It’s important to find a way to help your horse inhibit his desire while his body begins to heal.

Dr. Katherine Houpt from Cornel University has researched self mutilation extensively. In her book, Domestic Animal Behavior for Veterinarians and Animal Scientists she says “self-mutilation is a very common behavior problem. Although it occurs in both sexes, it is much more common in stallions. The behavior consists of biting at or actually biting the flanks or, more rarely, the chest. The horse usually squeals and kicks out at the same time. The signs mimic those of acute colic, but can be differentiated because self-mutilation does not progress to rolling or depression and is chronic. The cause of the behavior is unknown, but because it usually responds to a change in the social environment it is probably caused by sociosexual deprivation. Most breeding stallions do lead similarly deprived lives in that they are kept in stalls in isolation from other horses, particularly from mares, but do not self-mutilate. Castration usually, but not always stops self-mutilation.” I got my copy of Houpt’s book from Knight Equestrian Books by calling 207-882-5494.

It sounds like you’re on the right track when evaluating your horse’s psychological needs. You said you have him turned out with other horses. That social arrangement—much different than his sole time in a stall–may help the behavior disappear after he becomes more comfortable with the herd. If health problems have been ruled out, your best recovery bet is to experiment with different herd arrangements until your horse feels comfortable and realizes chewing on his sides isn’t necessary any more. I wish you the best of luck!

Until next time,

Julie Goodnight

Issues From The Saddle: When To Start A Colt Under Saddle

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Question Category: Issues from the Saddle

Question: My granddaughter and I started our yearling colt this year. He was schooled in halter. We’ve had a saddle pad and surcingle on him. He is used to the English saddle and carries a sweet iron bit beautifully. We can turn him with the bit from the ground as well as back him up. I want to start ground driving him soon. He seems to enjoy all this including a trail course we set up for him. He took reserve in yearling halter and reserve in trail in hand. We have lunged him, trailered him, clipped him (needs work on this). I guess I just want to know if we’re pushing him too much. We are not going to actually ride him until late next year (lightly) then send him to WP trainer as a 3 year old. I would appreciate any input you can give me.

Thanks in advance. Barb

Answer: Barb,

I am assuming that your yearling is now in his 2 y/o year. It is good that you are concerned about pushing him too much and as long as you have that concern, it probably will not happen.

The problem with starting horses too young is two fold. First, there is physical immaturity and methods such as round penning and longeing are way too physically stressful for his immature muscular-skeletal system. The second problem is mental immaturity (short attention span) and the risk of putting too much mental pressure on him and causing resentment to working.

As for the physical problem, as long as you do not round-pen or longe the colt much or ask him to pack around heavy weight, you can avoid this problem. Working at the trot and especially canter on a small circle at too young an age can cause permanent damage to his physical soundness. So you should definitely avoid this type of work. The mental maturity is much more difficult to avoid. Generally, by the time you realize that you have pushed the colt too much, it is too late and he is already sour.

To avoid mentally stressing the colt, make sure your sessions are very short, 10-15 minutes, and very fun for him with lots of variety. Remember, colts of this age are supposed to be playing with the herd out in the field and learning the socially accepted rules of the herd. So make sure he gets plenty of time to play in the herd and that his work is more playful with lots of rewards. If he is kept confined in a stall, the chances of burnout greatly increase.

Starting to ride him as a ‘long’ two-year old is a great idea. As long as you don’t overwork him in the meantime, I think you will be fine. My specialty as a trainer is starting colts and through the years, I have learned that there is a huge difference between a 2 y/o and a 3 y/o, not only physically, but especially in the mind. I prefer to start horses as a 3 y/o, unless there is a compelling reason to do otherwise, such as sales or competition.

As long as your colt is bright eyed and happy to see you, keep doing what you are doing. Keep a close eye for him beginning to resist or dread his work sessions and know that is an early warning sign to back off. Don’t expect too much from him, especially when it comes to his attention span and give him lots of mental breaks in your work session. Good luck!

Julie Goodnight

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