Conditioning The Older Horse

I remember quite well the time when a show horse over the age of 8 or 10 was considered “old”.  Those days are long gone as the experience and levelheadedness of older horses has become appreciated.  Nevertheless, there are some special considerations with exercising an older horse.


It’s a win-win when an older horse can get basic conditioning taking care of a novice rider. [Photo NickaJack Farm]

What constitutes “old” can be highly variable.  One of my favorite mounts, a grade palomino named “Snoopy”, was being used to pony pretty fractious racehorses at the trot and canter across open farm fields when he was 35.  For most horses though, when they hit their late teens to early 20s there are age related changes that need to be taken into consideration.

The best way to keep a horse going well into their teens and twenties with no special conditioning considerations is to keep them moving all year.  Layoffs longer than 4 weeks are associated with measurable changes in muscle mass and fiber type, muscle biochemistry, exercise capacity, etc.. Regular formal exercise, even at a reduced intensity, will largely prevent this.

Whether barefoot or shod, start with a meticulously maintained physiologically sound trim.  A properly functioning hoof is a major shock absorber while one that is not in correct form creates abnormal stresses on the joints and tendons/ligaments.

One age-related concern is sarcopenia, loss of muscle mass.  This is largely preventable and even reversible with exercise but there is also a nutritional component. In both humans and horses, exercise effects are magnified by supplementation with either high grade protein (whey) or specific amino acids (lysine, threonine) even if the diet is not obviously protein deficient.  This is cheap insurance, especially if you go the essential amino acid route with 10 to 20 g of L-lysine and 2.5 to 5 g of L-threonine supplemented.

As the horse ages, tendons and ligaments become less flexible and repair capacity diminishes, to the point that it is “normal” for aged horses to have core lesions in their flexor tendons.  Older horses with Cushing’s disease are at particular risk because this weakens tendons and ligaments.  Avoid extreme up or down inclines, speed work over rough ground, slides, etc..  Conditioning cannot reverse these changes but a fit horse with good muscle tone and flexible joints is far less likely to have an injury.

Speaking of joints, few horses that have led active lives reach their later years with no issues.  Things like ringbone and hock changes are extremely common.  These may interfere with activity at times but the best management for joint issues is to keep the horse moving.  Exercise stimulates the production of growth factors and antioxidant defenses which help protect the joint cartilage.

If you find yourself faced with the task of conditioning an older horse after a long layoff, let take it slow be your mantra. Never push the horse to the point of heavy sweating and heavy breathing.  Avoid very rough ground and extreme inclines. Long walks are a great place to start. Introduce trotting in 5 to 15 minute increments and no cantering until that is well tolerated.  As with any horse, routinely check the legs for heat or swelling and palpate muscles.  Remember a negative change in attitude is often caused by pain.

Riding an older horse is one of life’s greatest pleasures.  With a little extra care and attention to detail, an older horse can continue to serve for a very long time.

Eleanor Kellon, VMD

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Delayed Shedding

Are other horses shedding like mad while yours remains woolly? Are there patches of hair that refuse to budge? Has the coat taken on a stark mustard-like color? If so, you have delayed shedding.

Delayed shedding with the bleached out coat can also be seen in foals

In older adults, the most common cause of delayed shedding is PPID – pituitary pars intermedia dysfunction, aka Cushing’s disease. The coat may also be curly and long “guard hairs” may be present on the head or belly. PPID can have serious consequences including impaired immunity, muscle loss, tendon/ligament breakdown, diabetes and laminitis.  If you suspect this, get your veterinarian involved.  The treatment is the medication pergolide.

Parasitism can cause delayed shedding and is a particularly common cause in foals.  Foals normally shed their baby coat within 3 to 4 months. The body gives nutrient preference to the key organs. As a result, alterations in the coat (and hooves) are common outward manifestations of the disrupted nutrient supply caused by parasites. This is also often accompanied by an abdominal girth out of proportion to the rest of the body. Treat with deworming drugs appropriate for the involved parasites and be sure to repeat a fecal exam 2 weeks after treatment.

Surgical removal of the thyroid gland to induce hypothyroidism delays shedding. A situation of similar severe hypothyroidism rarely, if ever, occurs under normal circumstances but thyroid function can be impaired in what is called “euthyroid sick syndrome”.  In this condition, the stress of a chronic health problem causes the body to suppress thyroid function to lower metabolism and conserve nutrients for  whatever the chronic challenge may be.  It will improve spontaneously when the underlying problem is treated.

Thyroid function can also be impacted by deficiencies of  iodine and/or selenium in the diet. Iodine is essential for the production of thyroxine hormone, T4. Selenium is needed to convert  T4 to the active form, T3.  Goitrogens in the diet can interfere with the utilization of iodine to manufacture thyroid hormones. These include nitrates from water or forage, raw soybeans, cabbage, kale, rape and turnips.

Horses that are stall-bound and getting little to no exposure to sunlight and exercise commonly are slow to shed. Light is a potent trigger and exercise improves blood flow to the skin and activation of sebaceous glands helps move out the old hair. Getting the horse out and moving is one of the best ways to speed up shedding.

Finally, malnutrition in general interferes with the normal cycle of hair production. There’s no problem in spotting an undernourished horse but  deficiencies of specific key nutrients could also cause delayed shedding. These include essential amino acids, zinc, vitamin Abiotin (and other B vitamins in horses with intestinal disease) and omega-6 essential fatty acids.

If you notice delayed shedding, don’t ignore it. Consult your  veterinarian and a nutritionist you trust to get to the bottom of the issue.

Eleanor Kellon, VMD


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Any Horse In Regular Work Is A “Performance” Horse

“Performance horse” makes us think of things like speed work, endurance, upper level eventing and showing, but it’s much more than that.

These are performance horses too.

Let’s define performance horses as those being asked to perform work in excess of their regular activity. Feral horses travel as much as 20 miles per day in search of adequate food, water and salt. If you consider that as a baseline, horses grazing on good pastures or standing around in a stall or paddock all day have a long way to go to match it. Not so for a horse being ridden.

Keeping things at the walk for a moment, the feral horse is doing a lot less work than one carrying a rider.  If you doubt that, try going about your daily activities  wearing a back pack containing 1/5 of your weight. Carrying weight roughly triples the energy burned. An occasional stroll through the fields is one thing but if your horse is regularly doing trail rides, he’s a performance horse. So is a horse or pony taking care of beginner riders several hours a day.

Obviously there is a difference between those horses and a horse in endurance training or any other extremely strenuous effort but they are more alike than you might think in the ways their bodies have to adapt.

As always, calories is the easy part. Increased calorie requirements depend on the individual  metabolism  (e.g. Thoroughbred versus air fern Morgan), duration and intensity of exercise. Your, or your trainer’s,. experience with the individual and work type will determine how much to feed.  The bottom line is always to maintain an appropriate body condition score.

However, when the speed of the work increases to trot or canter on a regular basis, this requires an adaptation of the muscle metabolism above and beyond what is needed by a feral horse moving around primarily at the walk.  Carrying weight and advanced movements also increase demands on the muscle compared to what the horse’s genetics provide at a baseline.

A robust response to the demands of exercise is facilitated by a targeted blend of key amino acids, minerals, vitamins and metbolites plus adaptogens to support a balanced stress response. Some horses struggle in specific areas such as breathing or have muscular challenges like meeting training milestones or muscular bulk.

Whatever the issue, there is supplemental support to help.

Eleanor Kellon, VMD


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Introducing Spring Pasture

Spring grass is mother nature’s panacea for winter’s nutritional hardships and the huge demands of pregnancy and lactation.  However, rangelands utilized by feral horses usually bear little resemblance to the fields of domesticated horses and even in the spring their diets also include high fiber items like shrubs. Unlimited access to powerhouse grasses can cause some problems.

Spring pastures are horse heaven.

Young grasses are low fiber, very high protein and higher in rapidly fermentable carbohydrate fractions than more mature growths.  This can lead to a variety of hind gut digestive upsets including bloating, varying degrees of manure softening/diarrhea and in some cases colic.  This can be avoided by careful introduction to the new grass.

Given the option, every horse will gorge on the succulent young grasses and largely ignore anything else you try to get them to eat – including grains in many cases!  When their large intestine is packed full of the rapidly fermenting grasses it produces conditions that do not favor proliferation of fiber fermenting organisms.  To balance this out, keep the horses off the grass for 18 to 20 hours per day with access to good hay. When the pasture is particularly dense it may need to be longer than this.  Gradually allow longer grazing periods always keeping a close eye on manure. Grazing muzzles are also useful.

Supplementing with probiotics containing live yeast cultures is also beneficial. Yeast have been documented to help avoid the large changes in the colonic environment that have a negative impact on fiber fermentation.  It is also useful to feed a source of easily fermented soluble fiber to further support the fiber fermenting organisms.  Psyllium and beet pulp are particularly good sources.

Spring grasses can also be low in magnesium and sometimes other major minerals such as calcium as well.  Sodium levels are typically quite low.  Combinations of these factors may interfere with digestion or intestinal motility and can even result in electrolyte disruptions such as thumps.  Magnesium sensitive horses can also show increased nervousness and muscular twitching. EPSM horses often have noticeable increase in symptoms which could be from low magnesium intake and/or high sugar and starch in the grass.

Speaking of sugar and starch levels, insulin resistant horses are at extremely high risk of developing laminitis. It may not be a full blown laminitis every year but there will always be damage to some degree. There is no way to prevent this, no supplement or management approach that makes spring pastures safe for IR horses.

If reaction to low magnesium is suspected, supplement with 5 to 10 grams/day.  All horses should also receive a minimum of 1 oz of table salt/day in their feed.  If  free choicing salt, use a coarse granular rather than salt blocks, fed in a covered feeder.  Daily formal exercise is particularly important for EPSM horses on lush spring pastures. If worsening symptoms persist, pull them off pasture until it has matured.

There can definitely be too much of a good thing with high quality spring pastures. Controlled intake and a few intelligently selected supplements will help your horse get maximum benefit without the drawbacks.

Eleanor Kellon, VMD

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Diagnosing Allergies

If I asked you if horses can have food allergies, your immediate response would probably be – Sure, why not? That may well be true but you could be surprised to find out that a true food allergy has never been formally proven in a horse.

Seeds, nuts and grains are among the most common food allergies in other species

A food allergy is defined as an unpleasant or dangerous reaction to the ingestion of a food. It can range from life-threatening immediate anaphylactic reactions to hives or swelling and tingling in the mouth or lips.  People may develop eczema and dogs often have itchy and inflamed ears, faces and/or paws.

Gastrointestinal symptoms may also be involved, such as abdominal pain, bloating/gas, vomiting or diarrhea although these may be symptoms of food intolerances rather than true allergy. For example, horses may be particularly susceptible to food intolerances because of the extensive fermentation in their hind gut.  The microflora of each horse is unique so the way they handle fermenting any given food may be different.

For all the horses you hear about  that are supposed to have feed allergies you would think that someone would have published on the problem by now.  A major difficulty is diagnosis. In humans and dogs it is well established that skin testing by scratch, patch or intradermal testing has at best 60% accuracy while blood testing for IgE levels is even worse. You might as well go through the list of possible allergens flipping a coin.

Despite this, blood testing for equine feed allergy is widespread and of course the companies claim it is useful. Are horses really different?  A 2016 study (DuPont et al) used a commercial testing service to do blood IgE allergy testing on 17 healthy ponies and tests were repeated twice to look at consistency of results.  They found 10 of the 17 tested positive for one or more food allergy but only 3 tested positive twice and only 1 tested positive twice for the same allergy.

Ponies with positive IgE tests were further tested with the “gold standard”, a challenge test where they were fed the identified offending food for 14 days and serum amyloid A levels were also monitored. Serum amyloid A is a very sensitive marker of inflammation.  There were no abnormalities in blood work or symptoms during the provocative trial.

A 2001 study (Lorch et al) looked at horses with known skin or lung allergic disease and compared reactions on intradermal testing to 3 different blood allergy assays. They concluded “None of the 3 serum allergy tests reliably detected allergen hypersensitivity compared with the intradermal testing”.  Morgan et al 2007 also confirmed IgE testing was not worthwhile for skin allergies and Tahon et al 2009 found the same poor reliability of blood testing with RAO/”heaves”.

If only by chance, the blood IgE tests are bound to get it right sometimes but research really does not support their use as a diagnostic tool.  Too many people are unaware of this and agonizing unnecessarily over what to feed their horse based on a host of positives on IgE testing.

Positives for IgE antibodies can represent “sensitization” rather than an actual allergy. This just means the immune system lining the GI tract has been exposed to that allergen. Since horses commonly have breaks in their lining from parasites, these exposures happen all the time. It doesn’t mean there will be an allergic reaction.

The horse cannot be allergic to a food he has never been exposed to so if you see positives for things you never fed you can write that off.  Also realize that when showing the signs you suspect are a food allergy it has to be something he is eating when he has the signs/syhmptoms.  In other words, if the horse shows allergy signs when eating only hay and has a positive test for corn, corn is not your problem.

The best way to get to the bottom of food allergies is list hay/grass type(s) and food ingredients for all feeds and supplements. Start the horse on a hay only diet of a hay type he has never eaten before. If symptoms resolve, start adding back individual foods (e.g. oats only) one at a time allowing 2 weeks between additions.  If you add an item the horse is allergic to or does not digest well, symptoms will return.

Eleanor Kellon, VMD

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Support Of Normal Sweating

Horses exercising in the heat quickly develop high body temperatures. The overheating can become life-threatening if they don’t have efficient ways of dissipating the heat.

There are several ways heat leaves the body:

  • Radiation: This is transfer of heat energy to the air surrounding it. Veins in the skin dilate during exercise,  bringing more hot blood to the surface.
  • Conduction: Transfer of heat to a solid or liquid in contact with the body.
  • Convection: Moving air crossing the body picks up heat and removes it (e.g. a fan or breeze)
  • Evaporation: Water/sweat on the surface of the body is heated then evaporates. Sweating is responsible for 85% of the heat loss during exercise.

The horse produces from 1 to 4 gallons of sweat per hour when exercising, and more in the cool down period after exercise.  The first requirement for keeping this cooling mechanism going is plenty of water.  The production of sweat is triggered by release of epinephrine.  The release of sweat also involves purinergic receptors which are activated by either adenosine or its products – ATP, ADP, UDP. Once activated, calcium ions are released and sweat production begins.

Making sweat also requires a steady supply of electrolytes – sodium (Na), potassium (K) and chloride (Cl).  Start with a generous amount of hay or pasture (for K and Cl) plus 2 oz of plain salt/day (Na, Cl).  For horses sweating heavily or working more than 2 hours, add a properly balanced electrolyte. Always match electrolyte supplementation to the horse’s sweating. Giving too much can actually worsen dehydration.

As important as electrolytes are to sweating, you cannot increase sweating by feeding more electrolytes. Many things have been tried to support good sweating in horses and about the only universal truth is that nothing works all the time, or even most of the time. I have had the best results with a combination of 1 scoop each of L-leucine (9.85  grams) and Jiaogulan (7 grams) twice a day.

The protein in sweat, latherin, is almost 25% leucine. Jiaogulan is an adaptogenic herb. Adaptogens help maintain a normal and balanced output of stress hormones, including epinephrine.

Efficient sweating is your key to maintaining performance and preserving health in the heat. Do your best to support it.

Eleanor Kellon, VMD

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Why Vitamin E and Selenium Are Given Together

Vitamin E and selenium are nutrients familiar to most horsepeople.  They are among the most common deficiencies in unsupplemented animals – and also the only two where deficiency diseases are still routinely seen.

Endurance champion “Squiggle” and owner/rider Carol Layton

E and Se are often supplemented together but contrary to popular belief they do not actually work together, nor is their absorption from the intestinal tract connected in any way. 

E and Se are both important antioxidants but are active in different portions of the cells. E works to shield fats within membranes surrounding the cell and structures within the cell from oxidative damage.  Se, as part of the glutathione peroxidase enzymes, helps protect from free radicals in the internal watery portions of cells. Free radicals are a by-product of cells generating energy for work or cell division and of immune system activity. Processing toxins can also generate free radicals.

Vitamin E and selenium status is documented to significantly impact:

  •  The nervous system
  • Muscular function
  • Fertility/sperm quality
  • Antibody levels in colostrum
  • Immune function
  • Red blood cell integrity in exercising horses
  • Heart health

Selenium is also integral to the enzyme which converts the inactive form of thyroid hormone (T4) to the active T3.

In most areas of the US and Canada, and many other places around the world, selenium is barely adequate to frankly deficient.  Horses not being maintained on pasture have extremely low levels of vitamin E in unsupplemented diets. E levels in fresh grass are good but not hay or dried feeds. E added to feeds or multi-ingredient supplements often acts more like a natural preservative than a supplement because even stabilized forms of the vitamin can break down easily.

Horses absorb inorganic selenium (e.g. sodium selenate) well but absorption of this form may be reduced by high levels of competing minerals in the diet. For this reason, some or all of the selenium supplement should be in the form of high selenium yeast.

Because E is a fat soluble vitamin it is best given dissolved in fat. If your supplement is powdered E, or an E-Se combination mix it into some oil or sprinkle it on top of oil that is top dressed on the feed.

E and selenium are two of the most important and the most often deficient nutrients in the horse’s diet.  Make sure your horse’s intake is adequate. If unsure if your diet is supplying sufficient amounts, request blood tests from your veterinarian.

Eleanor Kellon, VMD

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Make Quick Work Of Shedding

We’ve all been there, slaving away with a curry or shedding blade on one spot for 30 minutes and there is just no end to the hair.  Truth is that elbow grease will always be an inevitable component of getting through the spring shed but there are some things that can make it quicker and easier.

There’s a gleaming coat under all that winter hair

In my experience, shedding goes much quicker in horses that are being worked.  As little as 30 minutes/day lunging or ponying will greatly increase shedding rate. The likely explanation is that the exercise increases blood flow to the skin, thus stimulating the hair follicles.  Conversely, not exercising the horse can lead to them holding onto the winter coat much longer.

Shedding is under hormonal control but also requires adequate nutritional support to grow the new coat.  There is no nutritional requirement for fat other than the essential fatty acids but coat quality is definitely improved by fat supplementation after a winter of dry hay (which has only 50% as much fat as fresh grass).  Cold pressed, unfiltered fat that still retains all its inherent antioxidant content is especially helpful.

If you notice the skin is particularly dry and flaky consider supplementing with vitamin A (40,000 IU/day) and zinc (300 mg/day) until your pasture grass comes in.  If also having problems with dry, poor quality hooves you can try adding biotin, 25 mg/day (all doses for an average size horse). Biotin is a B vitamin equally important for skin, coat and hooves.

Clipping the horse is one way to bypass the saga of shedding time, but it doesn’t do anything to change the health of the skin and hair or the timing of the winter coat shedding and the vibrant new spring coat coming in so you may be stuck with a coat that is shorter but dull for a while.

One thing I can recommend 100% as a godsend with shedding is a vacuum.  The upper level equine vacuums do a fantastic job but you can even benefit by putting your wet-dry Shop Vac to double duty.  They effortlessly lift the loose hairs and dead skin cells.  Turn it on in the barn without using it to desensitize jumpy horses but you will see that even sensitive types learn very quickly that it feels good.

On a final note, if you have an older horse that is slow to shed remember this is a classical symptom of Cushing’s disease/PPID, a hormonal disorder of senior horses.  The advanced Cushing’s coat is long and often curly but in earlier stages you may see only long guard hairs or patches of longer hair. Left untreated, PPID can cause disastrous issues with laminitis but it is very amenable to the correct medication.  If you suspect this, get your horse tested.

Eleanor Kellon, VMD


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Lose Your Fear Of Selenium

It’s never bad to be aware of things that may be toxic to your horse, but precautions can be carried too far if you don’t know the details.  Yes, selenium is a potentially toxic mineral (they all are) but deficiency is much more common.


            USGS Map of Soil Selenium in USA – Light = Low

An owner contacted me because she had a hay selenium assay done which showed she was feeding about 3 mg per day from the hay but she was horrified to realize the horse had been receiving another 2 mg per day on top of that.  The bare minimum requirement for an average size horse is 1 to 2 mg/day.

However, bare minimum requirements are a long way away from toxic and even the 5 mg/day is considerably below any intake that would be dangerous.  It is estimated an average size horse would need to take in at least 20 mg/day to be at risk for chronic toxicity – i.e. toxicity that takes weeks to months to show up. Acute toxicity takes over 1500 mg/day.

Naturally occurring chronic toxicity can occur with hays having over 5 ppm selenium ( = 50 mg in 22 lbs of hay) but this is rare.  Natural toxicity is more likely in animals grazing on very high selenium soils where wild selenium accumulator plants, which contain several hundred ppm selenium, are growing.  The highest selenium soils in the USA occur in pockets of Wyoming and South Dakota.  These soils are high saline shales with an alkaline pH.

Acute toxicity causes a neurological derangement called “blind staggers” and is fatal.  Chronic toxicity, “alkali disease”, causes loss of mane and tail hair plus disrupted hoof growth resulting in separation of the hoof capsule at the coronary band.  Another symptom of selenium toxicity is a DMSO or garlic-like odor on the breath.  Recovery from chronic toxicosis takes up to 10 months if the hooves slough off.  Again, both of these are rare.

Severe selenium deficiency causes white muscle disease, with degeneration of skeletal and heart muscle.  This is usually seen in foals but can also affect adults.  Adult deficiency has also been linked to atrophy of the cheek muscles and swallowing difficulty.  A link to tying-up has not been confirmed but wild animals with deficiency develop extensive muscle breakdown when they are chased in attempts to capture them.  Many studies have shown how selenium protects the muscles, lungs and red blood cells from damage caused by free radical generation during exercise. Selenium also plays critical roles in the normal functioning of the immune system and is needed for generation of the active form of thyroid hormone, T3.

It’s important to realize that the selenium dose in supplemented grains or vitamin/mineral supplements, which is regulated by law, is not going to cause toxicity even if intake from hay is already adequate.  There is a lot more to worry about from deficiency than toxicity. If you have any concerns regarding whether your horse’s selenium intake could be toxic, consult your veterinarian.  Selenium status is easily checked with a blood test.

Eleanor Kellon, VMD




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Omega-3 Fatty Acids in Equine and Canine Nutrition

These “good fats” must come from the diet and are essential for health.

All mammals need omega-3 and omega-6 fatty acids in their diet. The ratio between them is also important.  Like the modern human diet, canine and many equine diets are heavy on omega-6. If you have frequent online equine presence you have probably heard of Chia seeds as the next latest and greatest equine supplement, a good source of omega-3 fatty acids.   Fish oil has also been promoted as a superior omega-3 source for horses and is touted as good for dogs. How do you choose?

Horses grazing fresh pasture get good levels of omega-3 but it is rapidly lost in hay.

The horse’s natural diet, grass, has an omega-3 to omega-6 fatty acid ratio of around 4:1.  The same is true for browse foods the horse might eat, like leaves and buds.  When grass is cut, dried and baled as hay, the fragile omega-3 fatty acids are lost.  Other common diet elements like grains, brans and vegetable oils, are very high in omega-6 fatty acids, all leading to a deficiency of omega-3.

Dogs evolved with a very different diet than they have now. The meat of grass-eating animals has an omega-3:omega-6 ratio of about 1:6. However, the advent of modern high grain feeding for animals and birds in heavy production situations has led to ratios as low as 1:20. Plant sources of omega-3 provide alpha-linolenic acid while animal sources also contain some DHA and EPA omega-3, which are the most active forms.

Flax seeds, and flax seed oil, with an omega-3 to omega-6 ratio of 4:1 have been the traditional fatty acid supplement for horses.  The omega-3 linolenic acid and omega-6 linoleic acid cannot be manufactured in the body and have to come from the diet. Omega-3 and -6 fatty acids are also essential for dogs.

Compared to flax, Chia has a similar to somewhat lower ratio of omega-3:6, depending on where you are reading, and is also a reasonable source of omega-3 but there are claims by some it is superior. It’s not. It has been claimed Chia is more convenient because it doesn’t require grinding but recent research has found this is not true – it also needs to be ground.

It is said flax seed can cause cyanide poisoning because it contains cyanogenic glycosides.  Cyanogenic glycosides are common in plants with over 2500 species containing them.  Some frequently consumed human foods like lima beans and almonds contain higher levels than flax seed.  Green flax seeds have higher levels and should be avoided but there has never been a report of cyanide toxicity from flax in any species.

Chia is claimed to have a higher protein level than flax seeds but in reality they are virtually identical.  The protein in both types of seeds is very high quality and contains all the essential amino acids.

Estrogenic lignans in flax seed are said to be a negative.  It’s true the lignans can bind to estrogen receptors but they do not have any estrogen-like effects. In fact, they can protect against high levels of estrogen by shielding the receptors and are classified as anti-estrogen. Oats and barley contain the same lignans.

The oils of some fish are very high in omega-3 fatty acids, including DHA and EPA, and they cause higher blood levels of DHA and EPA than feeding plant fats high in their precursor alpha-linolenic acid.  Fish oil is obviously not a natural part of the equine diet – nor of dogs for that matter but they would normally get DHA and EPA in their diet unlike horses.

Why feed fatty acids? The immune system uses them to synthesize signalling molecules. The omega-6 fatty acids predominately are made into inflammatory signals while the omega-3 are antiinflammatory. Both are required for robust immune reactions. Omega-3s are also important in brain development, behavior and eye health. Horses not on fresh pasture will have a dietary deficiency of omega-3. Most dogs will as well unless they are on diets of grass fed animals and fatty fish.

Which to use?  DHA and EPA from fish oil bypass the normal pathways for their production from the plant omega-3 alpha-linolenic acid and are found in fish and meat fat. Fish oil should only be used in recommended amounts to avoid interfering with normal immune function but is certainly useful, especially in dogs, for balancing out the high omega-6 diet. Judicious amounts may also be helpful in horses but since it is foreign to their normal diet it is wise to primarily rely on flax seed for omega-3 supplementation. Chia is fine too but there is no truth to the idea it is superior – and it costs more.

Eleanor Kellon, VMD


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