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I recently uploaded a new lecture to our online education courses; Equine Metabolic Syndrome.  I worry a little that the while the subject matter is one that most of my readers and students should know, the name may be confusing. Do you know what Equine Metabolic Syndrome means? Do you know about Insulin Resistance and what it means for your horses and their health?  It's when an overweight or obese horse develops a condition related to the obesity. They have abnormal fat deposition, exercise intolerance (lethargic and out of shape) and can develop serious medical conditions like laminitis. It's a little bit like Type II Diabetes in humans, but not close enough to use the same nomenclature (cause that would make it too easy for all of us).  While its something that has been going on in horses for as long as we’ve been putting them in stables and supplementing their feed but its something the scientific community has only been investigating for the last handful of years. And because the syndrome is old but the research is new, there is a lot of misinformation out there about why horses are fat and what we can do to fix it. One of the myths I have the hardest time debunking is that of Hypothyroidism. When people tell me their horse is hypothyroid I think of that line from A Princess Bride, “You keep using that word. I do not think it means what you think it means.” So let me tell you the schpeal that I give clients and other vets who call me for advice.

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Hypothyroidism in a dog.
Back in the day, well not too long ago, people would notice that they had a horse that had become overweight and lethargic and they wanted to know why. In people and in dogs hypothyroidism is a real, documented disease and is somewhat common. Humans with thyroid dysfunction are fatigued, weak, irritable and gain weight, or have trouble losing weight. Dogs will become dull and listless, reluctant to engage in their normal activities and will gain weight despite no change in appetite or feedings. So it would only make sense that if your horse was now dull and pudgy that hypothyroidism would be the answer. So we started testing horses thyroid hormone levels and guess what? Sometimes they were low. ">Problem solved!!!  And thus hypothyroidism was blamed for a variety of equine problems such as obesity, laminitis, anhidrosis (inability to sweat), recurrent rhabdomyolysis (tying-up) and poor fertility.  But here’s the problem with that theory…. Thyroid hormone levels that we measure in the blood may not tell us about true thyroid function. And who cares what the numbers from the lab say if the thyroid gland itself is functioning properly and doing its job to aid in growth and regulation of metabolism? We also know that certain medications (Bute & dexamethasone), strenuous exercise and diets high in energy, protein, zinc and copper will falsely alter the levels of circulating hormones in the bloodstream. The only way to know about how the thyroid functions is to perform thyroid function tests, which are rarely done in the field because the medications needed to stimulate the thyroid (to prove to us that its working) are not readily available. But when horses that are showing the “classic” signs of hypothyroidism, and have low thyroid hormone levels are tested for true thyroid function, they are found to be normal. Researchers have even tried to prove this association by removing horse’s thyroid glands to see what happens. Well what doesn’t happen is they do not become obese and they do not develop laminitis.

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“But I don’t understand!” you say. “I had a hypothyroid horse and we treated her and she got better! Was my vet wrong?” Well, yes and no. For all those years, we have been treating your horses correctly, using all of the knowledge that we knew at the time, but we were doing it for the wrong reasons. It has only been within the last few years that the veterinary community has come to define Equine Metabolic Syndrome. EMS is an endocrine disease of horses that is characterized by insulin resistance, meaning your horse’s cells don’t respond to insulin they way they should and the energy (glucose) they consume can’t be metabolized properly. It’s similar to Type II Diabetes in humans, in that it is often a result of obesity, rather than a cause. Some horses are more predisposed to being overweight, “easy keepers.” Obesity leads to insulin resistance, which in turn makes weight loss even harder to achieve. Horses with EMS are more prone to episodes of laminitis because of alterations in glucose and insulin in their blood streams. Many “hypothyroid” horses that have normal thyroid function will test positive for EMS and insulin resistance.

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“So why does treating with thyroid medication make these horses better if they don’t have a thyroid problem?” you say. Excellent question! Well thyroid supplementation causes an increase in metabolism. By increasing the horse’s metabolism they are able to loose weight and correct their insulin resistance. It works so well that researchers are now recommending treating these types of horses with a much higher dose of thyroid supplementation, a “supraphysiologic dose.” So while we have been doing the right thing all along, we only now understand why it was working. It is important to understand one other big difference. True hypothyroidism, in dogs and people, will require life long treatment. Horses who have been successfully treated for EMS do not, and unnecessary treatment with thyroid supplementation over extended periods of time is not only a waste of money, but also a potential health risk.

   So if you have a horse that is slow, sluggish and fat, or one that has been previously diagnosed as hypothyroid, learn more about Equine Metabolic Syndrome by taking our online course and talk to your vet about what you can do to test and treat this very common condition.

 
 
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   I love food. I love food and I love to eat. I love everything about the act of consuming nutrients (even those that aren’t so nutritious). I love the look of food, the smell, obviously the taste, that feeling you get when you’re so full that you want to curl up and take a nap. I love it all (except maybe the cooking and cleaning, but that’s a tale for another post). The old saying goes, “The way to a man’s heart is through his stomach,” and that definitely holds true for me. In fact, after a few weeks of talking and spending time together, a friend of a guy I had been seeing asked why things weren’t more serious between us, my reply was, “He hasn’t bought me dinner yet.” That night, I was taken to dinner and last week we tasted food for our upcoming wedding. I am wholly motivated by food. But can the same be said for our animals? Or dogs? Cats? Horses? Is the ‘carrot on a stick’ really the way to go, or is a good scratch behind the ears enough of a reward for Fido?

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Food and Contact Bonding
    We know that in forming relationships and bonds there are two things to consider; the food bond (which obviously is very strong for me) and the contact bond, the real bonding that occurs through physical contact. These ways of bonding are most evident when you look at an animal mother and her newborn. There is a lot of licking and nuzzling (contact bonding) and there is also the food bonding of nursing. So which is stronger? Studies have shown in humans and cats, tactile contact creates a true bond and we sometimes assume that since the taming and domesticating of animals involves so much physical contact that it is important to the bonds we form with our horses. Studies have shown that when horses are groomed, their heart rate decreases (and anyone who uses their horse as their therapist knows, the groomers heart rate decreases too; think of it as a Reverse-Umbrella Study). So is grooming enough of a positive reinforcement to train a horse?

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Inter-individual bonding.
French and Polish researchers collaborated to find out the answer. They took 20 Konik horses, a primitive breed originating directly from the wild Tarpan horse who were raised in semi-natural conditions for the first 1-2 years of life. Horses were then trained to respond to the command “reste” by remaining still for a given period of time. Essentially they were teaching these horses to ‘Stay.’ One group of horses was rewarded with food and the other group was rewarded by vigorous scratching on the withers, similar to the way horses groom each other in the wild. The researchers attempted to train the horses to ‘stay’ for longer and longer periods of time throughout the study. The training lasted for 6 days. The other portion of the experiment investigated the human-animal bond by placing a horse in an open space with a human standing stationary in the center. They measured the time it took the horse to approach the human and the total time the horse spent interacting with the person.

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FR- Food Reward; GR-Groom Reward
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  Here’s what they found: Horses that were rewarded with food were far more successful at learning the task and reaching the highest level (1 minute of ‘staying’) with 9/10 horses completing the training. Only 4 of 10 horses that were rewarded with physical contact were able to stay for the full minute. Also, the food-rewarded horses had a much steeper learning curve than the other group. In fact, the learning curve of the ‘scratching’ horses plateaued after Day 2 and after that no improvement was seen. Now these results aren’t too surprising to me. Like I said, I love food and I would surely learn a task much quicker if I was offered cheesecake as opposed to a massage.     What did surprise me was how food-rewards had an effect on the human-animal bond. When placed in a paddock with a motionless human, and no rewards were offered for any actions, horses that had been trained with treats approached the person much faster (less than 50 seconds) than the contact trained horses (nearly 3 ½ minutes!). These horses also spent much more time interacting with the human (2 minutes vs 30 seconds). Summarizing their study, the investigators said, “Using food rewards had beneficial effects on horses' attachment to humans and facilitated learning, whereas the tactile contact was clearly not perceived sufficiently positively, neither for bonding to occur, nor for enhancing learning.”

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    So there you have it. The quickest way to a horse’s heart IS through his stomach. I’ve always known that I have a special connection with the equine species, and now I know what it is, our love of food.
    Now that being said, don’t go and throw out your brush box and buy a 50lb bag of carrots. There are still many benefits to physical contact with your horse, for both him and (maybe even more importantly) you. Spending time in close contact with your horses helps you learn more about them, what they are thinking, what they are feeling. The Umbrella Study showed us that horses can read our silent cues, but the more time we spend in the barn and in the saddle, the better we will be at picking up our horses cues.

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   I also don’t want to promote feeding your horses hand-fulls of molasses covered treats every time he picks his hoof up to be picked out or stops when you say “whoa.” Many packaged horse treats are high in starches and sugars and can lead to carbohydrate overload which leads to a whole host of problems like colic and laminitis. Even buckets full of healthy treats like carrots and apples can be too much of a good thing and throw off the nutrient balance that your hay and grain provide. And sadly (as I have learned from a lifetime of balancing my love of food and my love of being able to see my toes) weight loss and gain is all about calories in and calories out. Obesity is becoming a huge problem in our horse population and diseases like Metabolic Syndrome and Insulin Resistance have been directly linked to the increased incidence of laminitis and other medical ailments.
So keep on brushing and hugging your horses but remember, if you really want to get him to do something, try some treats (as long as its in moderation).

 

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