Dealing with Old Lower Leg Problems

It’s difficult enough to support the mass of a horse on a tiny column like the leg if it is a   rigid structure.  When it also has a moving part (the fetlock), the problem becomes much more complicated.

Exaggerated flexion of the fetlock is an easily seen outward indicator of the force being applied to the leg.  This occurs when speed is added to the mass of the horse, as in racing,

Injured, but a winner to the end: Xcellent is victorious in the Trentham Stakes on Saturday, in what was to be his last race.

also in dressage movements requiring suspension, cutting/roping, takeoff and landing from jumps, negotiating hills or uneven ground and sometimes plain old horseplay.

It is the soft tissue structures of tendon, ligament and dense investing fascia that allow the horse’s lower leg to function as it does.  Damage to the extensor tendons, suspensory ligament or any of the myriad other supporting and reinforcing structures is very common.

Once damaged, they never completely regain their normal strength and flexibility but with a little extra care many horses can continue to be athletically active, even at their preinjury level.

STRETCH

Once the healing period from an acute injury has been successfully completed, you need a strategy for reducing the risk of reinjury.  Passive stretching as part of warm up is a good idea.  The flexor tendons are attached to muscle bellies.  Increased tension is common when injury has occurred and can be gently relaxed by stretching.  Even pure connective tissue/ligament injuries can show contraction that may respond to gentle stretching and massage.

Absolutely meticulous attention to hoof balance, regardless of barefoot, shod or type of shoes, is an absolute must.  Every effort must be made to ensure that the leg is loaded evenly.

Physical fitness and good balance (neuromuscular conditioning) are two of the best guardians against reinjury.  Introduce work slowly but with steadily increasing increments.  Avoid unfavorable ground conditions whenever possible.  Do not ask for sudden, sharp movements or speed changes but introduce elements that challenge control and balance, like ground poles.

Finally, use the best and cheapest therapy there is – heat and cold.

ICE

Like massage and stretching, warmth encourages tissue relaxation.  Standard wraps, sweat wraps and neoprene can all be used to advantage when the horse is stalled.

It’s impossible to overemphasize how important ice can be to the horse coming back from an injury.  Apply ice to the previously injured area as soon as possible after exercise stops and maintain it for a 30 minute cooling period.  Ice slows excessive blood flow and/or inflammatory enzyme activity that often result in annoying periods of  intermittent heat and edema as you bring the horse back into work.  I use it faithfully after every work regardless of intensity.

Investing these few extra minutes can mean a smooth uneventful rehab and maximize your chances of avoiding reinjury.

Eleanor Kellon, VMD

Posted in Equine Nutrition | Tagged , , , , , , , , , , | Leave a comment

Herbs for Topical Use

If you haven’t tried herbal products for skin and coat use, you really should.  Not because they’re herbal or natural – because they are effective!

Chemicals are chemicals whether they are inside a plant or in purified form.  Many effective pharmaceuticals were isolated from or based on chemicals in plants.  One thing that makes herbals distinctive in their effectiveness is a low side effect profile.  This is related at least in part to the fact that for every active constituent in a plant there will often be another that has an opposite or moderating effect.

Black mortar and pestle with fresh picked herbs, over white background.

The topical use of herbs has a very long history and is easier to validate than systemic use simply because the results can be readily seen.  The following are some common topical herbal ingredients and their actions.

Tea Tree (Melaleuca) Oil:  Most people have heard of tea tree oil because its use is so widespread.  Tea tree oil is extracted from Melaleuca alternifolia, a small tree/bush native to Australia. It has a pungent, camphor-like aroma.  At least 98 components have been identified in the oil.  Tea Tree oil is only needed in low concentrations and excels in antiseptic properties with activities even against antibiotic resistant strains and fungi.

Calendula officinalis:  Calendula is the common marigold.  Its use on skin dates back at least 600 years.  They were heavily used in wound dressings in the American Civil War and World War I.  Formal research has documented that Calendula stimulates fibroblast activity in wound healing, assists with closure of pressure sores and has anti-inflammatory effects.

Comfrey (Symphytum):  Comfrey is a small flowering herb native to Europe.  Written history of its topical use dates back to ancient Greece although use was estimated to date back considerably before that.  A major component is allantoin, which is documented to speed wound healing and has both anti-inflammatory and antimicrobial effects.  Inulin adds to its soothing effects.

Lavender:  Everyone recognizes the scent of lavender.  The flowers and oil are used.  You may be more familiar with lavender being used as a fragrance to induce calming, an effect that has been proven by formal research. There is also a long history of topical use.  In addition to gentle support of circulation, lavender has healing and anti-inflammatory properties.

Rosemary and Thyme:  Not the Simon & Garfunkel album, and not your Thanksgiving turkey either!  These common edible herbs are also used topically both for their wonderful aroma and the mild antimicrobial effects they have.

Plantain:  Plantain is a member of the banana family.  It’s long, fat leaves can be used to make a poultice for wounds or skin irritations.  Like Comfrey, it is rich in allantoin.

Whether herbal or not, any topical can cause a skin reaction.  If you know your horse is prone to sensitivities, do a test of any product before using by applying a small amount to either the back of the pastern or the inner hind leg just above the hock.

A variety of skin issues from wounds to itching can be helped with topical herbals.  They are pleasant to use and typically inexpensive.  Definitely worth a try.

Eleanor Kellon, VMD

 

Posted in Equine Nutrition | Tagged , , , , , , , , , , , , | Leave a comment

L-Methionine – A Vital Amino Acid

Considering all the important tasks L-methionine performs it’s perplexing you don’t hear or read more about it.

L-methionine is one of the essential amino acids, meaning the horse must get his supply from the diet because the body cannot manufacture it.  Methionine is a structural amino acid which means you can find it in all proteins in the body, from skeletal muscle to hemoglobin, antibodies and enzymes.  Methionine is also required for the initiation of building proteins in the body.

CRACK

Insufficient methionine can play a role in crumbling and cracking hooves.

Methionine can be converted to the other two sulfur containing amino acids, cysteine and cystine.  Sulfur bonds between cystine amino acids strengthen the structure of hooves, hair, tendons and ligaments.

Methionine is required for the production of:

  • Taurine – central to health of the heart, nervous system and eyes
  • L-carnitine – a carrier that is necessary to burn fats for energy
  • Metallothionein – a protein which binds excess dietary minerals, and toxics, and carries them back into the bowel for excretion
  • creatine – the carrier of high energy bonds for muscle contraction
  • glutathione – the body’s master antioxidant

Methionine also functions as a methyl group donor by being the precursor for SAM.  Transfer of methyl groups (transmethylation) is involved in a host of body functions including:

  • Detoxification reactions in the liver
  • Production of epinephrine
  • Regulation of the activity of DNA
  • Production of the active form of the vitamin folic acid
  • Recycling of methionine
  • Regulation of the immune response
  • Recycling of glutathione into an active form

More is never better even with a nutrient this important but unfortunately we really don’t even know what the equine methionine requirement is!  A look at the most common things fed to horses quickly shows they are mostly on the low end for methionine:

METHIONINE FEEDS

Hays also vary in methionine content quite a bit, based on both their protein content and the type of hay.

The current best guess for methionine requirement in adults is that it is 1/2 to 1/3 of the lysine requirement.  If your horse has outward signs consistent with inadequate methionine such as weak hoof structure consider supplementing with 2500 to 5000 mg of methionine/day.  This is commonly paired with 7 to 10 grams of lysine, another amino acid that is often deficient.

Eleanor Kellon, VMD

 

 

Posted in Equine Nutrition | Tagged , , , , , , , , , , , , , | Leave a comment

Flagging Energy

A common concern this time of year is horses that lack energy for exercise.  There are no apparent health or lameness issues but the horse is either “flat” or starts out well but hits a wall that is at a level of exercise below where they normally perform. What’s wrong?

Is it just too hot?

Could be!  The horse is a very large animal and this makes it difficult to dissipate heat.  Horses expected to work in the heat should be gradually accustomed to it by step wise increases in work duration and intensity.  An important adaptation that occurs is development of an extensive system of blood vessels in the skin.  These supply the sweat glands and also radiate body heat from the hot blood on the surface to the  surrounding air.

HUMIDITY

Conditions can be dangerously hot even for accustomed horses.  A good rule of thumb uses a heat index calculated by adding the temperature (in Fahrenheit) and the relative humidity.  If 120 or less, no barrier to heat dissipation.  If over 150, especially with high humidity, the horse will have some difficulty cooling. Over 180, cooling mechanisms are severely compromised and the horse should not be worked.  Flagging energy and slowing down will be the first sign your horse is overheating.  Heed it.

Is fluid topped off?

Exercise research has documented that as little as 2% dehydration will compromise performance.  Work at low and moderate speeds will be affected more than high intensity efforts. This level of dehydration occurs even before you can detect a problem with the skin pinch test so it’s easy to see how dehydration can easily be a problem with work in the heat.

Providing plenty of fresh, clean water whenever the horse wants it is obviously important to avoiding dehydration but it’s not the whole story.  To retain that water in the body the horse needs adequate sodium.  The major electrolyte lost in sweat is sodium and it is also highly deficient in both hay and concentrate feeds.

SALT BLOCK

I use a 2-2-2 rule to help guard against dehydration – 2 oz of salt the night before a competition or heavy work, 2 oz the morning of and replenish with an electrolyte supplement correctly balanced for sweat if work is longer than 2 hours.

Is the gas tank full?

Many people today are feeding diets designed to limit starch and sugar intake.  There is a lot to be said for this but it can sometimes backfire if the horse is in regular work.

The major fuels for muscle work are fat and glucose, with branched chain amino acids also contributing.  The fat for muscle work is liberated from fat deposits throughout the body and there is never a shortage.  Glucose is taken from the blood but primarily from glucose stored in the muscle as glycogen.  Glycogen in the liver is also used to keep blood glucose normal. Glycogen stores are limited so this is the fuel with the potential to limit work.  Fat cannot be used to replace glucose. There is always a baseline requirement.

Glycogen stores are lowered by work and need to be replenished.  The very low sugar and starch diet may not be able to keep up with losses.  Timed feedings can get maximum benefit from a higher carbohydrate meal and also avoid aggravating insulin resistance.  Feed 1 to 1.5 lbs of beet pulp (dry weight) with 1 to 1.5 pounds of plain oats within the first hour after work is finished.

beet pulp shreds

OATS

There is a window after exercise where muscle takes up glucose very readily.  Even insulin resistant horses can receive extra carbohydrate in that time frame.  The oats are easily digested to glucose to begin replacing glycogen.  The beet pulp is fermented to acetate which is more slowly released and can be used instead of glucose for energy functions, freeing up glucose for glycogen.  Studies have confirmed acetate supports the glycogen replacement process.  As a plus, you can get water and electrolytes into the horse at the same time – which research has shown is also important for replenishing glycogen.

The above three issues account for the vast majority of horses with energy issues in the summer.  If you are having problems, consider them first.

Eleanor Kellon, VMD

 

Posted in Equine Nutrition | Tagged , , , , , , , , , , , , | Leave a comment

Care of the Cushing’s Horse

Since the 1960s when reports of equine pituitary adenomas and their systemic consequences appeared in the literature, our understanding of Cushing’s disease (pituitary pars intermedia dysfunction or PPID) and the insulin resistance it causes has grown tremendously.  Despite this, there is still outdated information out there that does a real disservice.

PPID

photo from ecirhorse.org

For example:

Why do horses get Cushing’s? We don’t know. Not true. Horses get PPID because of oxidative damage to nerves in the hypothalamus of the brain.  These nerves normally produce dopamine which controls the output of POMC-derived hormones, like ACTH, from the intermediate lobe of the pituitary.  What we don’t know is why some horses develop this damage and others don’t – or at least they don’t develop it in severe form before they die of other causes.

Good general management (diet, farrier, teeth, wound care) is more important than medication.  I would have to also consider that false.  Those things are extremely important but they do nothing to control the hormonal upheaval that the disease causes or to prevent the consequences of that.

ACTH does not cause laminitis.  ACTH levels alone are not predictive of laminitis. ACTH may be present in a form that is not highly biologically active.  However, high ACTH and the other POMC derived hormones are directly responsible for causing or worsening the insulin resistance that eventually can result in laminitis.  If they are not controlled, no amount of dietary management and hoof care will prevent the laminitis.

You shouldn’t expect a treated horse to live longer or even avoid PPID related problems.  In a study of 217 diagnosed and treated horses followed for 4.6 years (only 44 were actually followed), 50% were euthanized for Cushing’s related problems.  What you’re not told is that some of these horses were treated with cyproheptadine which has since been shown to be ineffective.  There is also no mention of the dosage of pergolide used and whether or not it was sufficient to control the ACTH (and other hormones; ACTH is a marker for uncontrolled intermediate lobe hormonal output).

Because brand name pergolide is expensive, for many years it has been suggested that all you should expect to call a treatment “successful” is improvement in symptoms and/or blood work – not normalization.  I personally set the bar much higher.

I have been closely following and working with PPID horses for 15 years.  Laminitis is by far the worst consequence of PPID and the focus has been on preventing that.  This takes the form of keeping ACTH in normal range (which usually IS possible with adequate dosing in the vast majority of cases) and a low sugar and starch, mineral balanced diet to further support control of insulin resistance.  Hoof care is critical to rehabing the laminitis horse.  Once stable, regular exercise is encouraged.

Good general horse care but no medication or serial testing to make sure medication dosing is effective is not adequate treatment in my book.  In fact, it’s no treatment at all.

Eleanor Kellon, VMD

Posted in Equine Nutrition | Tagged , , , , , , , , , , , | 2 Comments

Modern Day Equine Urban Legends

We can all think of at least one old horse care myth that has been debunked but they continue to be generated to this day.  One of the most persistent is that fructan causes pasture associated laminitis, but I’ve discussed that twice and won’t go into it again here.

What I have in mind now is something I keep hearing and reading with increasing frequency – that unlike humans, horses do not produce saliva unless they are eating.

SALIVA

from:  Dressagedifferent.com

If this was the case, when you insert a finger into the horse’s mouth when it is not eating  it would feel bone dry.  It doesn’t.  Horses with choke wouldn’t drool.  Horses engaged with the bit wouldn’t foam.  It’s just common sense that this isn’t true if you just think about it a little bit.

It’s true that the largest salivary gland, the parotid, only secretes when the horse is chewing food but the horse has two other major salivary glands and thousands of individual microscopic clusters of saliva secreting cells lining the oral cavity.  These do secrete constantly to keep the mouth moist and that saliva is swallowed.

The second is also GI related; that ranitidine is the preferred drug for treating hind gut acidosis/ulcers.

Ranitidine (Zantac) binds to acid secreting cells in the stomach to block stomach acid secretion.  It will have no effect in the hind gut for the simple reason that there are no acid secreting cells in the hind gut.

Hind gut acidosis itself is a bit of an urban legend that is being used to promote the sales of a variety of supplements.  The alleged acidosis is also claimed to be responsible for a variety of behavior changes and vices.

Acidosis refers to pH.  A pH of 7 is neutral, below 7 acidosis, above 7 alkalosis.  However, in medical terms, e.g. referring to the blood pH, acidosis is any time the pH is below the range of pH normally found.

The pH of the cecum, the first portion of the hind gut, reflects diet and normally ranges from the low 6’s to the low 7’s. The lining of the intestine has to be able to tolerate a range of pH to allow for variety in the diet, including plant material. Fecal pH is often used as a marker instead but is a poor measure of the cecal pH and is always more acidic. Consider these facts from research:

  • horses on pasture of ryegrass and clover had fecal pH of 6.18 while those on high grain feeding, haylage and minimal hay had higher pH.  No symptoms.
  • feeding 2.17 kg (4.77 lbs) of pelleted barley twice a day reduced the fecal pH to 6.39 from 6.74. No symptoms.
  • horses maintained on pasture and fed up to 6.12 kg of oats/day in two meals had no significant changes in fecal pH.  No symptoms.
  • a pelleted 70% corn and oats diet vs hay produced a lowest cecal pH of 6.12 vs 6.75 for the hay diet. Pellet fed horses spent more time chewing wood but there was little effect of neutralizing cecum pH with sodium bicarbonate and time chewing wood was not correlated with pH.  No other symptoms.
  • Weanlings fed a high sugar/starch supplement had fecal pH 6.94 vs 7.99 for high fat and fiber and diet had no effect on behavior or vices.  Behavior was monitored by cameras.  Note: The pH values are higher than adult because weanlings do not yet have full fermenting capacity in the hind gut.

In contrast, horses that develop laminitis after experimental pure fructan overload have a cecal pH of 4.3.

Unless you are feeding a diet that is greater than 70% grain it is unlikely your horse has a hind gut pH that is low enough to produce any symptoms, let alone need a supplement to correct it.  There are individual differences in tolerance for high sugar/starch intake but an invariable sign will be soft manure.  I’ve seen this many times in racing barns and the fix is to feed smaller meals.  There are no changes in behavior, signs of colic or performance effects.

There are enough things that can go wrong with our horses.  We don’t need to conjure up any more.

Eleanor Kellon, VMD

Posted in Equine Nutrition | Tagged , , , , , | Leave a comment

Do Any Horses Benefit from Grain?

The current wisdom is that all horses should be fed forages only and never any grain.  While it’s certainly true that most horses do not need grain calories and are better off in many ways on a forage diet, there is still a place for grain in some circumstances.

feed

Glucose is the most important fuel for all cells in the horse’s body.  There is a baseline minimum requirement for glucose without which all cells would die.  Glucose is so essential the horse’s body is equipped to produce it from other substances if dietary levels are low.

Muscle cells do pull glucose from the blood when working but they cannot get a sufficient amount this way. They are heavily reliant on glucose stored inside muscle cells in the form of glycogen.

With exercise, fat, amino acids and glucose are burned.  The relatively percentages depend on the intensity of the exercise but can be influenced to some extent by diet and level of fitness.  However, the bottom line for both high speed work and endurance type work (as well as draught work back in the day) is that glycogen stores are the limiting factor.

Racing, eventing and endurance are the sports where horses are most likely to face limited exercise capacity related to insufficient glycogen.  Horses doing less strenuous work may be just fine with lower levels of glycogen in their muscles.  As you might expect, signs of insufficient glycogen include inability to continue performing beyond a certain distance/time duration with slow work and inability to meet speed targets with faster work.

A study presented in 2014 (ICEEP) showed that even with high calorie intake from fat (23% of the calories) horses receiving only 18% of their calories from sugar and starch were unable to replace glycogen stores after heavy exercise while those receiving 36% and 43% did.  Unfortunately, we don’t know if levels lower than 36% may have also been adequate.

What does this look like in a diet?  For a 500 kg horse getting 1.25% of body weight in a high quality grass hay you would have to feed about 4 kg of oats or 2.6 kg of a mixed grain sweet feed.  If the real requirement is only about 25% sugar/starch this would drop to around 2.7 kg of plain oats or 1.8 kg of mixed grain sweet feed and hay fed should be increased to closer to 1.37% of body weight. (Numbers are approximations.)

This of course is how countless generations of caretakers have fed high performance horses.  It probably holds true for the upper level international endurance horses as well, at least during replenishment periods after races or heavy training.

The bottom line is that while grainfree, high forage diets make sense for most horses, grain is not poison and has a place in the diets of our upper echelon performance horses.  From ancient Rome to pony express mounts to today’s elite equine athletes, grain is the concentrated fuel they need to keep going.

Eleanor Kellon, VMD

Posted in Equine Nutrition | Tagged , , , , , , , , | Leave a comment