The Best and Safest Way to Help Your Horse Lose Weight with Dr Juliet M. Getty, Ph.D.

This article is from the November 2020 Horse Deals magazine.

Rules toward safe weight loss

Is it your horse’s fault if he’s an “easy keeper”? A horse, like a person, has his own metabolic rate and genetic tendencies. Add in a lack of exercise, too many treats, overfeeding, even stress, and the easy keeper is at risk for hormone imbalances, arthritis, and laminitis. Certainly, the overweight horse will not perform at his peak.

Too much fat leads to insulin resistance (a hormonal disorder also called metabolic syndrome), which is like Type II diabetes in people, and equally serious — an insulin-resistant horse is a strong candidate for laminitis. Watch for fat accumulation above your horse’s eyes, on his rump, along his neck (“cresty neck”), or in a fatty spinal crease down his back. All overweight horses have some degree of insulin resistance, so feed the easy keeper with that assumption to be on the safe side.

The first step in any weight management program is to have your horse thoroughly examined by your veterinarian, including a complete blood count and chemistry panel tests, to rule out any underlying medical disorders. Then take a hard look at your horse’s feeding and exercise regimens.

Rule #1

Reducing calories is fine, but taking away forage is not the way to help your horse lose weight.

In fact, it does just the opposite—more about that in a moment. For the most part, healthy horses become obese because they are given concentrated feeds—even ones promoted for weight loss (which, in fact, add calories).

Concentrates are no substitute for forage. Use them only as carriers for supplements or to provide a small meal to satisfy your horse while others are eating.

Rule #2

Avoid feeding cereal grain and sugary treats.

“Grain” is commonly used to describe any concentrated feed, but it really means cereal grains, such as oats, corn, barley, wheat, etc. or pelleted feeds that contain cereal grains. Stay away from these. Fortunately, there are many safe, low starch feeds made from other ingredients (alfalfa, soybean meal, flax, and beet pulp).

The high sugar in carrots and apples increases blood insulin levels. Avoid offering them, as well as any commercial treats made from cereal grains and molasses.

Rule #3

Consider an all-forage diet.

Depending on your horse’s age, workload and condition, an all-forage diet can be very healthful. You may not need to feed any concentrate at all. But have your hay tested for sugar, fructan, and starch levels. Strive for a ESC (simple sugars) + Starch level of less than 10% on a dry matter basis. And if feeding only hay, a comprehensive vitamin/mineral supplement is important to add, in order to fill in the nutritional gaps created when fresh grass is cut, dried, and stored to make hay.

Be careful when feeding high-calorie hay such as grain hays (oat, crested wheatgrass, rye) and grass/legume combinations (timothy/alfalfa mixes). Alfalfa is a wonderful feed, but it’s higher in calories than grass, so limit it to no more than 20% of the total forage ration.

Alfalfa boosts the protein quality in the forage mix. High quality protein maintains immune function; protects the vital organs; keeps bones, muscles and joints strong; and builds healthy hooves, skin, and hair. Low-quality protein is unusable and can be stored as fat.

Rule #4

Feed forage, free-choice.

All horses, regardless of their weight condition, should have forage at all times. Yes. 24/7. Your horse’s digestive tract is designed to have forage moving through it consistently throughout the day. Horses allowed to graze freely, will self-regulate their intake and eat only what they need to maintain condition.

Sure, your stabled horse “inhales” every speck of available hay now — he is storing up until his next feeding. So, give him all he wants. The free-choice adjustment takes about a week, during which the horse may initially overeat, but he will soon trust the hay to be there, and will moderate his consumption. At that point, you can measure his regular intake to make other feed calculations. And look for a bonus: Fed free-choice, horses also generally become calmer and more tractable.

Rule #5

Choose safe grazing times for the insulin-resistant horse.

Grass has the lowest sugar, fructan, and starch levels in the early morning. As grass is exposed to sunlight, it produces more NSC, making the late afternoon the most hazardous for the easy keeper. Grass is also more dangerous in the early spring and late fall when the thermometer dips below 4.5°C overnight, raising the NSC levels.

A grazing muzzle may seem ideal, but it can be counterproductive by causing stress and slowing the metabolic rate. So watch your horse; if a muzzle is frustrating him, it’s not helping.

Rule #6

Add or increase exercise.

Exercise reduces insulin resistance, builds muscle mass and burns more calories. And, since muscle is more metabolically active than fat, more muscle means more calories burned.

Rule #7

Avoid long term usage of thyroid hormone replacement.

The synthetic supplement levothyroxine sodium (“Thyro-L”) may be appropriate for the horse with chronic laminitis who can’t be exercised. However, usage beyond 6 months is not advised; the horse should be weaned to promote resumed thyroid gland function.

Rule #8

Don’t forget key supplements.

Live grass offers an abundant supply of vitamins and minerals, but the nutrient content in hay diminishes over time. Minerals remain, but vitamins are very fragile, so hay-only diets require supplementation. Offer these in a small, non-starchy carrier meal. Avoid supplements with a molasses base.

Most comprehensive products contain a balanced mixture of vitamins and minerals. If your horse’s diet contains more than 3.6kg of alfalfa, choose a supplement designed for alfalfa-based diets; it will be lower in calcium.

A caution about iron: Too much may increase insulin resistance as well as depress immune function; besides, forage is iron rich, making supplementation unnecessary.

Three nutrients are commonly under-supplied: vitamin E, omega-3 fatty acids, and magnesium.

Magnesium: Magnesium helps lower circulating insulin levels, which allows your horse to burn fat, rather than store it.

Vitamin E: Vitamin E and selenium work together; however, selenium can be toxic at relatively low levels, so be sure to evaluate the selenium content of the total diet before supplementing.

Omega 3 fatty acids: These unsaturated fatty acids are necessary for proper immune function, joint health, and hoof and hair condition, and they also regulate blood insulin levels. Although high in fat calories, flaxseed meal in small quantities provides unparalleled support for your horse’s health.

The critical secret: Restricting your horse’s forage intake makes him fat!

Restricting forage (hay and/or pasture) intake lowers your horse’s metabolic rate, slowing calorie expenditure and leading to weight gain. Constantly eating good forage stimulates the metabolism, thereby promoting weight loss.

Hunger and pain are extremely stressful. Acid flows continuously in a horse’s stomach; without forage to process, acid causes ulcers and perhaps colic. This kind of stress releases the hormone cortisol, which increases insulin levels — which leads to fat storage, which leads to more insulin, and so on, in a vicious cycle that makes the horse fatter. Elevated insulin levels also can cause the damaging liver condition hyperlipemia; ponies, miniature horses, donkeys, and mules are particularly prone to this, but no horse is immune.

Excess weight hinders the easy keeper’s life quality. With just a little extra attention, you can help your horse achieve and maintain ideal weight and with it, optimal well-being — and that is a gift sweeter than sugar.

with Dr Juliet M. Getty, Ph.D.

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