“Natural is Better” Wars

There are so many labels available to describe the individual interests in this debate that it’s very difficult to even frame a simple sentence that describes it. A workable approximation for my purposes here is to define “natural” as substances that exist in a form that can be found in nature.

This blog topic was inspired by reading an article on the holistic treatment of Cushing’s disease – PPID, pituitary pars intermedia dysfunction. I actually agreed with many of the approaches suggested but it was conspicuously lacking the one thing that prolongs, often saves, the lives of these horses – the medication pergolide.

Ironically, pergolide is derived from a natural substance, the fungus ergot. It’s core structure is based on the ergot alkaloid ergoline. Ergot in its natural form is highly toxic, causing potentially life-threatening gangrene, convulsions or hallucinations.  The development of pergolide took a chemical found in this naturally occurring fungus and refined it to produce something which is life-saving for a PPID horse.

Pergolide is a perfect example of where “natural” is not better.  The naturally occurring alkaloid is far too toxic but it can be modified to make a drug that is far safer and highly beneficial.  Many drugs are actually modifications of naturally occurring substances, some stronger and some weaker than the resulting pharmaceutical. Aspirin is another one, a modified form of the salicin found in White Willow Bark and Meadowsweet.

I use a LOT of natural substances instead of drugs. They can be just as effective, if not moreso. Examples are chondroitin sulfate and Spirulina with hyperreactive skin and airways, Jiaogulan for circulatory support in laminitis, acetyl-L-carnitine for muscle metabolism, L-leucine/HMB for building muscle bulk (instead of anabolic steroids).  Natural substances can even be more effective, or just as effective but without certain side effects.

The flip side, as above, is that phamaceuticals can also be far more effective, even safer, in some instances. This includes vaccinations, dewormers and antibiotics where there are no natural alternatives equivalent in effectiveness and safety.  In fact, advancements in those three areas are largely responsible for the dramatic increase in the horse’s average lifespan over the last 50 to 100 years, human too for that matter.

Some natural remedies are not only totally ineffective but also toxic. The current craze of using cobalt instead of EPO to boost red counts in racehorses is a perfect example.

The bottom line here is that “natural” has a lot to offer but it is not always better or  effective and can be toxic.  The intelligent approach is to take advantage of the best of both worlds, weigh all your alternatives for every situation in terms of risk versus benefit. Your horse will benefit.  Be WHOLE-istic.

Eleanor  Kellon, VMD

 

 

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Little Recognized Early Signs of Cushing’s Disease

The classical signs of Cushing’s Disease in horses (pituitary pars intermedia dysfunction/PPID) of poor topline, sagging belly and long curly coat that fails to shed are only evident fairly late in the condition.  If your horse is in his teens there are changes you need to know could be linked to early PPID.

The unexplained appearance of new issues in a teenage horse may be signs of early PPID

A sharp increase (doubling is common) in water consumption and urine production mid August or September is a common sign.  This correlates with the normal seasonal increase in ACTH hormone which is exaggerated in early PPID horses.  It is often mistakenly assumed to be related to hot weather.  There will also be a proportionate increase in urine production, which you would not see if the horse was drinking more because of fluid loss in sweat.

The development of regional fat accumulation in the hollows above the eyes, along the crest, withers, rump, tail base or chest wall is a marker of insulin resistance rather than PPID but if this appears for the first time when the horse is in his/her teens early PPID should be suspected as a cause.  If loss of topline definition or muscle bulk in general is also occurring this further increases the index of suspicion.

Tendon or suspensory “breakdowns” unexplained by a known accident or heavy exercise can also be a sign of early PPID.  Elevated levels of cortisol are catabolic, interfering with the building, maintenance and repair of all protein tissues, including the proteins of connective tissue like tendon and ligament. Hofberger et al 2015 examined suspensory ligaments from horses with PPID compared to non-PPID aged horses and found clear abnormalities similar to those seen with DSLD (degenerative suspensory ligament desmitis) in Peruvian Pasos.  Grubbs et al presenting at the 2017 Equine Endocrinology Group conference also found that 39% of sport horses over the age of 10 with suspensory desmitis tested positive for PPID.

An even more devastating manifestation of early PPID can be fall laminitis.  This often occurs with no dietary change or other obvious precipitation, in animals on pasture or not. The horse may or may not have a prior diagnosis of insulin resistance.  It is caused by the sudden and dramatic rise in ACTH which occurs seasonally and the IR it causes.  Levels actually start their rise after the Summer Solstice but show a sharper rise beginning late August and peaking end of September.

If you suspect your horse may have early PPID, testing is fairly simple. A baseline (endogenous) ACTH hormone is best tested during the seasonal rise as levels may be within normal other times of the year.  These horses are good candidates for a TRH stimulation test if done outside the time of the seasonal rise.  TRH causes a significantly greater rise in ACTH in PPID horses than normal horses. Blood will be drawn before giving TRH and 10 minutes after.

The sooner the disease is diagnosed the easier it is to treat. Pergolide mesylate is highly effective in most horses and hopefully soon even horses continuing to compete can be treated. In July of this year, the USEF Board of Directors approved a panel to study the controlled use of pergolide mesylate in horses competing in sanctioned events.

Eleanor Kellon, VMD

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Minerals and the Insulin Resistant Horse

Minerals have direct and indirect involvement in virtually every action in the body, and have important effects on Insulin Resistance (IR) or its consequences. IR is different in the horse than in the human, but the same basic principals apply.  There is evidence of activated antioxidant defenses in the tissues of IR horses.

Building the horse’s own antioxidant basic defenses is most effective. This includes the SOD, catalase and glutathione peroxidase enzyme systems as well as the antioxidants glutathione, CoQ10, carotenoids and vitamin A, flavanoids, vitamin E and C. Glutathione is particularly widely distributed.

SOD absolutely requires copper and zinc. Catalase requires iron which is not an issue as the typical equine diet supplies plenty of iron.

Glutathione activity depends on Selenium, a very common deficiency.  Selenium is also essential for the generation of the active form of thyroid hormone, T3, from T4.  Selenoproteins, important to immune function, are just beginning to be looked at in depth. Both IR and PPID horses are prone to inflammatory and allergic-type immune reactions rather than using the more sophisticated arm of the immune system.

Zinc is a commonly deficient mineral. Low serum Zinc is associated with IR and type 2 diabetes in humans and rats. Supplementation of Zinc supports  defenses against type 2 diabetes in rat models. Exactly why has not been determined. It is known that Zinc is important on several levels, involved in insulin release and sensitivity as well as being an antioxidant in SOD.

Like Zinc, Copper is critical for SOD function. Copper deficiency causes IR and fatty liver in rats. Low liver Copper is found in human fatty livers. Deficiency is also linked to higher liver iron in IR, a known problem in IR horses too.

Magnesium has been associated with IR for forty years with hundreds of human papers dedicated to the subject. Magnesium is not a treatment, but by correcting a deficiency it makes the disease easier to control.

Magnesium dietary intake and magnesium status – whole body levels – are both associated with strong defenses against IR and they deteriorate when someone develops IR. It becomes a cycle you need to stay on top of to allow stabilization.

A 2013 study included almost 2000 non-diabetic subjects followed for 15.6 years. 1 Magnesium intake was a “significant protective factor” against type 2 diabetes, including progression from IR to diabetes. Researchers could predict who would most likely become IR by looking at their magnesium levels.

Magnesium increases insulin receptor number and sensitivity in experimental rodent IR. Magnesium deficiency interferes with insulin signaling. Deficiency has also been linked to activation of allergic and inflammatory reactions.

Iodine is essential to production of thyroid hormone. Low iodine status has been identified in human patients with type 2 diabetes. Normal thyroid function is required for insulin sensitivity.

IR horses may also have low thyroid hormone levels in some cases. This is probably euthyroid sick syndrome, meaning it is an effect rather than a cause. In most of these horses, with correct levels of Selenium and Iodine, and control of IR, the levels will rise again. Low thyroid is not a primary part of the syndrome but can make some horses very depressed and lethargic. Thyroid supplementation can be used but by addressing the above you will not need supplementation long term.

Chromium has been important for people probably due to processed foods being stripped of many essential minerals. It is required for a normal cellular response to insulin. The exact dietary requirement is unknown, but supplementation in IR horses is not helpful in most cases. Grass absorbs chromium very efficiently and soil levels are abundant in most areas. We have observed a problem only when horses are eating hay grown on alkaline soils where the plants may not absorb the chromium as readily. 

It’s not as fancy as a pricey magic bullet supplement but the best place to start supporting your IR horse on a low sugar and starch diet is with balanced intake of key minerals.

Eleanor Kellon, VMD

 

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What Can You Tell By Just Looking at Hay?

There’s a lot you can’t tell by looking but appearance does yield some useful information.  Just the type of hay is a helpful start.  Legumes (clover, peanut, alfalfa) are always high protein and calcium.  Bermuda will be low protein unless fertilized.  Ryegrass and grain hays tend toward high sugar, plus starch in the grain hays.  Contrary to popular belief, there is no type of grass hay guaranteed to be low sugar and starch.

Seed heads are the easiest way to identify a grass hay. Timothy’s fuzzy, long seed heads look like a green or beige caterpillar.  Bermudagrass seed heads resemble the spokes of an inside-out umbrella. Teff grass seed heads are a bouquet of long, graceful sprays with the multiple thin straight strands having a chain of individual seeds.  If you don’t know what to look for, take a sample of the hay, including seed heads, to your local agricultural extension office.

Orchardgrass seed heads have a tree-like branched shape with seeds clustered in a tuft    or fan configuration at the end of each branch

Ideally you want an obvious green color.  Color isn’t necessarily a deal-breaker if you know why the hay is yellowed instead of green. It may be old, sun bleached or rained on after cutting.  All yellowed hay is low in the vitamin A precursor carotene.  If only sun-bleached, the inner layers will still be green and loss is minimal. If old and yellow throughout it will also be very dry and the leaf/blade portion more likely to crumble and be lost, greatly reducing nutritional value. Rained on hay will have lower sugar, thus lower calories, and lower (but likely still adequate) potassium.

Seed heads also yield clues to likely calorie and sugar/starch content.  If no seed heads or they are very green and firm, seed has not yet set (this is called “boot stage”) and sugar/starch will be higher. Seed heads that are tan but still contain seeds will contribute to the overall caloric value of the hay, while old empty seed heads belong to very mature grasses with likely lowest sugar/starch, calories and protein.  You also want to see a large proportion of leaf/blade  material compared to stiff stems.

Bales that feel unusually heavy for their size are often high moisture, moldy or contain stones/dirt. Always open a few bales even if you have to buy them first.  Never buy hay that feels moist or warm on the inside.  It’s going to mold.  It should have a fresh, “sweet” hay aroma.  No or off odor indicates molding or very old hay.  When you open a bale, there should be no puff of fine dust. This may be dirt or it may be molding. You don’t want either. Obvious molding, chunks of dirt, stones or other foreign material, and presence of weeds are all reasons not to purchase.

If a hay has passed the important visual assessment you will still need hay analysis to get in-depth nutritional information.  Calories (DE – digestible energy), crude protein and important mineral levels are all part of the analysis.  Sugar and starch levels can be obtained.  Hay (or pasture) is by far the major part of most equine diets.  The critical information you need to identify and correct deficiencies and/or imbalances can only be obtained from an analysis.

Eleanor Kellon, VMD

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Making Sense of Feeding Sulfur

You have probably read at least one article talking about sulfur in the body as indispensable for protein production, integrity of skin/hair/hooves and nails, enzyme action, some B vitamins, production of substances like chondroitin sulfate and elimination of toxins. All of that is true, and more, but confusion reigns about how you should supply it.

Elemental inorganic sulfur is a brilliant yellow mineral.

If you are from Australia or South Africa you may have been told horses should be supplemented with inorganic elemental sulfur.  Regardless of where you are from, you probably have read that MSM or DMSO are sources of organic sulfur that will be available to perform all the important roles of sulfur in the body. Both are incorrect.

Horses may utilize small amounts of the sulfate ion present in their diet and water but their main source of sulfur, and the only form utilized by proteins and insulin, is the sulfur containing amino acids, the most important of which is methionine which can also be converted to cysteine and from there to cystine – the other two structurally important sulfur amino acids. The horse cannot make methionine from sulfur or MSM/DMSO, it has to be present in the  diet.

Sulfur bonds/crosslinks maintain structural integrity in protein hormones like insulin as well as the keratin in skin, hair and hooves.  These bonds don’t come from sulfur being inserted into the structure.   They occur between the sulfur groups of two cystine amino acids.  The sulfur needed to make sulfated compounds like chondroitin sulfate comes from the desulfurization of sulfur amino acids.

As an aside, ruminants like cows or goats can benefit from elemental sulfur because the organisms in their forestomachs will use it to make methionine just like plants do. When the bacteria pass into the stomach and small intestine, the methionine will be absorbed.  Horses ferment their food in the hind gut, where absorption of amino acids is minimal – if it occurs at all.

The true equine requirement for methionine is unknown but is probably between 1/4 to 1/3 of the lysine requirement.  Forage is the major source of methionine.  The National Research Council has recommended a sulfur intake of approximately 0.15% of the diet dry matter, although there is evidence this may be inadequate.  (Note: About 90% of the sulfur in a hay analysis is incorporated into plant protein amino acids.) Good quality hay grown on soil with adequate sulfur should meet the requirements of at least maintenance and low level exercise if there are no special needs but there is a mounting problem with this.

Sulfur was routinely incorporated into plant fertilizers until increasing industrialization began sending large amounts of sulfur into the air. This “acid rain” provided an excellent source of free sulfur for plants but caused many other problems.  Sulfur emissions have been tightly regulated since the 1980s and 90s, with the result that soil sulfur is dropping.  A hay analysis crossed my desk this week that had only 0.04% sulfur.  These hays will have low protein, low methionine and the potential for high nitrate levels.

Taurine is another sulfur amino acid ultimately derived from methionine that plays many important roles in the nervous system, detoxification, liver function and metabolism.  Increased levels may be needed by horses with abnormal glucose metabolism to support the body in avoiding harmful interactions of glucose with body tissues, including nerve damage.  Taurine also helps maintain neurotransmitters responsible for a stable, happy mood.

When methionine intake is known to be low, or suspected from things like poor hoof quality, supplementation of 5000 to 10,000 mg (5 to 10 grams) per day for the average size horse is reasonable.  For situations that may benefit from taurine support, this can be supplemented directly in similar amounts.

Eleanor Kellon, VMD

 

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What Is Restricted Feeding?

On one level, it’s exactly what it sounds like – restricting what you feed your horse. The devil is in the details though.  Exactly what is being restricted, why, how much?

Some people use restricted feeding and slow feeding synonymously.  In that case, the horse is restricted in how fast they can eat.  This may or may not end up also reducing how much they eat.  Some horses become very adept at eating from small hole nets or slow feeders. Others simply spend more time eating. Either way they can end up eating as much as they did before.

In most cases restricted feeding refers to limiting how much the horse is given to eat. That may mean just cutting back on grain or pasture time but usually means the horse’s daily calorie intake from all sources is controlled to maintain a healthy weight.  Situations where this is necessary include overweight horses needing to trim down, insulin resistant horses that will eat too much and horses on forced stall rest for an injury.

Contrary to what you may have heard, restricting caloric intake is not the most stressful thing you can do to your horse.  It is not cruel and will not cause health problems when done properly. While some advocate extreme calorie restriction, especially when trying to get weight off a horse, this really isn’t necessary.

A grass hay with under 10% sugar (ESC) and starch combined, protein 9+% can usually be fed at a rate of 1.5% of current body weight or 2% of ideal body weight, whichever is larger, to achieve the desired weight.  Use a slow feeding set up and break this up into multiple feedings. If the horse is able to be regularly exercised they can eat even more.

It’s worth mentioning here that these guidelines also work for insulin resistant horses most of the time.  It’s not so much that they gain weight easily but rather that they eat too much. When a horse is not losing weight at the above level of feeding a calorie count using the actual digestible energy from the hay analysis usually reveals the hay has higher than average calorie density. There are some individuals that need more stringent restrictions but they are the exception rather than the rule.

Don’t worry about the gut being “empty” if the horse is not constantly eating.  It takes the stomach a bare minimum of 2 hours to empty, usually much longer.  Running out of hay for a couple hours also does not guarantee stomach pain, “stress” or ulcer formation.

As for feeding the organisms in the hind gut, food takes about 2 days to finish traversing the hind gut.  It is not true the horse’s cecum won’t empty without a constant flow of food to push the contents along.  Just like everywhere else in the intestinal tract, food is mixed and propelled along by muscular contractions which occur at set intervals.  The time food spends in the cecum depends on particle size and ranges from 2 to 48 hours (Argenzio 1974).

Whether it’s a human, a horse or the family dog or cat, weight control still boils down to calories in versus calories out.  Horses that are overweight or have sharply curtailed activity need to have their calories counted.  Horses which overeat for medical or temperament reasons also need to have calories restricted. Restricting calories to those needed to maintain a normal weight is not extreme. It’s really that simple.

Eleanor Kellon, V.M.D.

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Protein for the Active Horse

Protein is the most expensive ingredient in a diet. Equine nutritionists are trained with the same mindset as nutritionists working with other livestock.  Cost is a consideration; return for the investment.  This often results in recommendations being the minimum you can get away with rather than the optimum for health and performance.

Wikipedia

For example, recommendations for broodmares are focused on getting a live foal on the ground but there is convincing research the current guidelines need adjustment.  In a series of studies published 1997 and 1998, Van Niekerk and Van Niekirk found mares receiving quality protein (higher total protein and essential amino acids) ovulated sooner in the spring transition, had higher progesterone in early pregnancy and lower rates of early loss. Foals from mares fed recommended levels of protein were 25% smaller at weaning than mares on a higher protein intake. Tanner et al 2014 found weanlings fed the recommended level of crude protein and lysine incorporated less protein into their tissues than those fed at a higher protein intake.

With exercising horses, the prevailing wisdom is often that higher protein intakes may actually be harmful but Oliveira et al 2015 have solid data to the contrary. Horses in eventing training fed 2.25 grams of crude protein/kg of body weight showed improved nitrogen absorption, more absorbed nitrogen retained as protein and even improved fiber digestibility. The current recommendation (NRC Nutrient Requirements of Horses 2007) is only 1.72 grams crude protein/kg of body weight for horses in heavy exercise, a 31% difference.

Since we know very little about the horse’s dietary requirements for essential amino acids, it’s quite possible the same effects could be achieved simply by increasing intake of key amino acids (the building blocks of protein) rather than large increases in protein across the board. However, we only have good information for a few of the 10 to 12 essential amino acids and wouldn’t really know where to start.

When the horse absorbs protein, it is first broken down into amino acids which are then reassembled into proteins inside the body.  In addition to building muscle, protein/amino acids are needed for the framework of bone, tendons, ligaments, enzymes and hormones.  Creatine, which stores high energy in muscles, is a protein. Carnitine is needed to carry fats into the mitochondria to be burned and its metabolite, acetyl-L-carnitine, is a critical regulator of energy generation.  Carnitine synthesis requires lysine and methionine. Glutathione, the major antioxidant in muscle, is a protein. The list goes on.

How do current diets measure up to the higher, probably more optimal, protein intake?  A 500 kg (1100 lb) horse eating 10 kg (22 lb) of an 11.25% protein hay would meet the higher protein intake for heavy work but since you would need to feed considerably more hay on a hay only diet (close to 30 lb) the hay would only have to be about 8% protein.  Any good hay would likely meet this crude protein requirement.  Ironically, if you feed grain and less hay your deficit is probably larger because a lb of grain contains 2 to 3 times the calories but not 2 to 3 times the protein.

The only way to know precisely how your horse’s diet measures up would be a formal diet analysis.  As a rule of thumb, to close the gap on what could be as much as a 30% deficit in protein intake try adding 50 grams of protein (e.g. 100 g of a 50% protein supplement) from a mixture of flax seed (about 30% protein), soy and whey protein plus a supplement of L-lysine, L-methionine and L-threonine (10-5-2.5 g), especially if you are seeing an indication your horse’s muscle function could be better.  This includes issues with muscle bulk, speed, endurance, topline definition or muscle soreness – all very common complaints with active horses.

Eleanor Kellon, VMD

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Late Summer Weight Loss

Weight loss in late summer is a fairly common problem. It can have many different causes and pinpointing the reason is obviously central to successful resolution.

from: University of Minnesota

Cumulative effects of dehydration is a common cause. With mild dehydration the horse’s body will pull water from the tissues into the blood to restore normal concentrations of sodium and other solutes.  Since the drive to drink from the brain ultimately originates in higher osmotic pressures in the blood, the brain thinks that all is well and the end result is tissue dehydration and weight loss.

Inadequate sodium intake is the most common cause of dehydration.  If you don’t know for sure how much salt your horse is taking in, and that the amount is adequate for baseline needs + sweat losses, there’s a good chance this is the problem.  As a start, provide 2 oz of salt plus an additional oz of salt or a dose of balanced electrolyte providing at least 10 grams of sodium for each hour of formal work.

With the trend today of reduced deworming frequency, parasites can sneak up on your horse between the common routine interval dewormings in the spring and fall.  Activity of all types of parasites is increased in the warm weather and you have the added threat of stomach bots in fly season. Waiting until the first solid freeze to deworm for bots ensures there will be no further transmission but by then larvae picked up early in the season have abraded the stomach and grown quite large (each up to 3/4 inch long).

from: University of Florida

Does anyone really believe a stomach full of bots causes no problems?

Abdominal distention or coat changes are additional clues but won’t necessarily be present. Bot infestations are not detectable on fecal exams and tapeworms rarely are. Fecals are best for strongyles but manure must be freshly passed and kept cool until examined or the eggs will hatch. Mailed in fecals are a waste of time and money. When you deworm, be sure not to underdose. Underdosing is the major cause of resistance to deworming drugs.

Another issue in late summer is declining pasture quality. Even if still green, mature grasses drop in caloric value and protein. More succulent and higher protein clovers often do not tolerate high heat well. Weight loss can begin long before pastures appear “dead”. Supplement with a high quality grass hay or  grass with up to 10-15% alfalfa. A sure sign your horses needs supplemental hay is when they begin eating it.  Most horses will choose good grass over good hay any time.

Horses in their teens that begin losing weight late in summer/early fall with no apparent reason may be early cases of PPID – pituitary pars intermedia dysfunction, aka Cushing’s disease.  There is a natural rise in ACTH and other hormones from this area of the pituitary which occurs at this time.  In normal horses it is small and of no consequence but early PPID cases have an exaggerated rise.  Weight and muscle loss is one of the consequences. Blood tests are needed for diagnosis.

Weight loss can also be a nonspecific sign of many significant disorders.  If the horse does not respond to addressing the more common issues, always involve your veterinarian.

Eleanor Kellon, VMD

 

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Feeding Yearlings

Whether you are prepping for sales and halter classes or trying your best to raise a healthy and sound youngster, careful attention to nutritional needs is a key component.  Yearlings should not be fed like little adults.

This handsome devil is a Beneteau colt that was selling at the 2015 Australia Magic Millions Perth Yearling sale

An easy way to see this is to compare their calorie needs on a Mcal/kg of body weight basis and their protein and mineral needs as grams or milligrams/Mcal of diet.  Those second numbers show you how nutrient dense the diet needs to be.

Compared to the adult maintenance, the yearling needs 113% more calories, 186% calcium, 134% crude protein, and 134% L-lysine.  Although the NRC has not gotten around to recognizing it officially yet, formal research such as vanWeeren et al 2003 shows an effect of copper on healing of osteochondrotic lesions, as did Dr. Knight’s original work in 1990. Feeding three times the current NRC minimum requirement is safe and cheap insurance. Other trace minerals are increased proportionately to keep them in balance.

If you have a properly formulated weanling diet in place this will also meet all the needs of the yearling simply by adjusting calories.  If the horse starts to get too fat, cut back the diet but add 1/2 to 1 lb of a 25% protein and balanced mineral supplement to keep up the nutrient  density.

The usual advice for feeding weanlings is a 50:50 diet of pasture or high quality hay and a  commercial concentrate, by weight of each.  The first thing I check is the fat content.  In a 1999 study by Hoffman et al, young horses fed as little as 1 to 1.4 kg (2.2 to 3 lbs) of an average 10.4% fat concentrate twice a day, with pasture, had reduced bone mineral  density despite mineral intakes that were at least 200% of requirements.

Fats form insoluble complexes with calcium and magnesium. Fiber binding some minerals was also mentioned but is far less likely as a cause since horses raised on pasture get more fiber than this. Added fat in the supplement from the study above amounts to about 10 oz of oil. Unfortunately, many feeds labeled for use in yearlings have too much fat. This also increases calories and results in just the concentrate providing all calories required, if not more, and a fat youngster. This leaves no room for hay and sets the stage for wide hormonal swings, digestive upset and impaired development of the GI tract and its microbes.

Commercial growth feeds do a good job with minerals but don’t correct imbalance issues in the hay or pasture. Protein provided is 60 to 65 % of minimum requirement with  most or all lysine being met, depending on the product.  If hay is at least 8.5% protein, it will fill in the additional protein.  All of this assumes you feed the full recommended amount, typically as much as 7.5 lbs/day for a 650 lb yearling.  If he backs off the recommended minimum 1% of body weight in hay or gets too heavy (and they will with those high fat feeds) you will have to reduce it – and with that the protein and minerals also go down and will have to be added back in.

An alternative approach is a simple concentrate you mix yourself instead of the commercial feeds, adding a separate concentrated mineral mix and protein as needed. For example, by weight, 1 lb beet pulp and 2 lbs high grade oats with 1 oz of flaxseed per pound of mixture is balanced for calcium and phosphorus, about 12% protein and contains about 65 to 70% of the calories of high fat yearling feeds.  Ingredients also meet or exceed the % lysine required in protein for yearlings.  Other combinations of high calcium (alfalfa, clover, beet pulp) and high phosphorus (grains, brans, seeds) can be used to get a balanced Ca:P ratio.

For a 650 lb yearling, combine 7.5 lbs of good quality grass hay with 7.5 lbs of oats/beet pulp mixture, 2 cups of ground flaxseed (all daily totals) and 1 lb/day of a high quality 25% protein and balanced concentrated mineral supplement. Look for a blend of milk and vegetable protein, 4.5 to 5% calcium, at least 350 ppm copper and 875 ppm zinc with lower manganese.

If needed, an additional 2 to 4 oz of oil can be added for coat conditioning. Boost protein for low protein hays or pastures using a protein supplement without the added high levels of minerals.  When more calories are needed, increase all elements of the diet proportionately – e.g. pound each of concentrate and hay, 1 oz flax, 2 oz protein/mineral supplement.

Attention to detail will get you the well developed, muscular rather than fat, shining and structurally sound young horse you are wanting.

Eleanor Kellon, VMD

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You Can’t Always Follow Your Gut With An IR Horse

Following your gut instinct is good advice in some situations but gut, and even good old common sense, can also be wrong.  This is where fact and science come in.

Correctly caring for a horse with insulin resistance takes some major lifestyle changes. It is up to the caretaker to implement those changes. This can be a major advantage for the horse, who doesn’t have to rely on his own will power, or it can throw any number of obstacles in his path.

We hear things like ‘The horse can’t possibly be happy without pasture’, despite the fact that millions of horses around the world are; many of which do not even have pasture as an option. Another is that they can’t possibly be healthy on a diet restricted in amounts or types of food, when in truth it is the human imposing their own emotional reaction to that possibility on the horse.

Most dangerous are objections that sound like they are based in science when they are not. One is that not permitting an IR horse 24/7 access to food will cause stress and a cortisol increase that will actually make him worse.  This has a ring of truth to it, but it’s wrong.

Sticker et al 1995 fed mares either 100% of requirements or restricted calories by 50%.  The restricted mares had a drop in cortisol levels.

DePew et al 1994 fasted mares and stallions for 19 hours then fed a pellet and hay meal. Cortisol rose after feeding and did not change in response to fasting for 19 hours.

Glunk et al 2015 fed adult Quarter horses a restricted hay diet of 1% of their body weight either as loose hay or from slow feeder nets, divided into two feedings with 15 hours between the afternoon and morning  meals.   The floor fed horses finished their meals much quicker.  There was no difference in cortisol levels between the two types of feeding. Cortisol dropped in both groups over the 28 day trial despite the markedly restricted feeding and weight loss. [Horses were sampled every 30 minutes after meals and hourly between feedings.]

Storer et al fed both normal and hyperleptinemic (IR) mares either constant pasture, free choice hay or hay and pellets only once daily.  The mares fed only once daily had an expected exaggerated insulin and glucose peak after feeding but their cortisol levels were lower than the mares with constant access to hay or pasture at all testing times.

Freestone et al 1991 did find small (but not statistically significant) rises in cortisol in ponies fasted 24 to 72 hours, consistent with the tendency of ponies, but not horses, to develop exaggerated release of fat into the bloodstream with fasting. The metabolism of ponies (and minis, donkeys) is distinctly different from horses.

What about the fact that feral horses spend 18 to 20 hours a day eating? This observation does not automatically mean horses have to spend this much time eating to be metabolically healthy.  You have to remember that grass is over 70% water while hay is typically around 10% and a much more concentrated calorie source than pasture.  They have to spend that much time eating native pasture to get enough calories.

By all means feed your insulin resistant horse with a slow feeding set up to avoid long gaps with no food that might lead to insulin peaks and also just to keep her busy but don’t worry that going without food for even short periods will increase cortisol and make IR worse. Research has proven that’s simply not the case. In fact, in study after study a drop in cortisol has been found with fasting or restricted feeding of horses.

Eleanor Kellon, VMD

 

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