EQUINE THRUSH – WHAT IT IS AND HOW TO DEAL WITH IT

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Written By Walt Friedrich

It is a condition – or more precisely, an infection – in the hoof. It is not a disease. Its elimination has been the goal of massive efforts to develop the ultimate product, as witness the vast variety of thrush-busting products on tack shop shelves. All of them do sell, and each of them probably does reduce and control the infection in some hooves – but there are a couple problems: one is that a given product may clear things up for some horses, but seems ineffective for others. And secondly, many of those hooves whose thrush does get controlled end up with a re-infection a couple months later.  Right up front, the problem is not a simple one.

Just what is this elusive infection, anyway?

Well, that’s part of the problem. The term “thrush” gets hung on just about every hoof ache or pain that comes along, but it is not necessarily just one type of microbe that’s responsible. There are enough bad guys to fill a Post Office bulletin board, including yeasts, bacteria, and fungi! The most common of the “usual suspects” is a yeast named Candida albicans, a nasty little creature, and very difficult to eliminate. In addition to albicans, there are a number of other species within the genus Candida that are known to cause human and equine infections. And to add some complication, a bacterium called fusobacterium necrophorum is also commonly held responsible for many “thrush” infections, PLUS numerous fungi in the line-up as well. The invading army that causes “thrush” can have many mercenaries, and it is asking a great deal of any one treatment to go out there and kill ‘em all.

As if that’s not complex enough, yeasts and fungi exist in both “live” and spore form. Consider the spore to be an “egg”, containing the microbe, which “hatches” when environmental conditions are favorable. Killing an army of microscopic fungi may be doable, but the spores they leave behind are virtually bullet-proof; they patiently wait for those favorable conditions to return, at which time they “hatch” and re-form a brand-new army!

Tackling the problem…then back to the drawing board

So here are we, one day, observing our horse three-legged lame, perhaps, with a gooey, stinky mess exuding from a frog. “Aha,” we think, “this is thrush and I’m gonna get rid of it.” Of course, we don’t know what organism or organisms are responsible, so we ask the guy in the tack shop for the best of the thrush killers, we buy it, then take it home and have at it. Sure enough, after a few applications, things appear to getting better, the frog is healing, the goo and the smell are gone, and our horse is happy – until a few weeks later, when we see a rerun of the problem developing. The spores have hatched and have started to party again, plus some new neighbors from the stall floor have joined them, and we’re ready to return to the tack shop to look for a newer and better anti-thrush miracle cure.

More about these nasty little critters

One of the basics we know is that we can be dealing with two entirely different entities, here – aerobes and anaerobes. Aerobes live and breathe even as do you and I, which means they need air to survive, which makes them relatively accessible to our attacks. That opens the field to most of the on-the-shelf products that we wipe on or spray on. These are the easiest to apply, and when they work, our job is easier.

The anaerobes are quite another story. They cannot live in air, consequently, when without a host, they exist in spore form, sort-of in a state of suspended animation. But those spores, along with their aerobic cousins, cover the stall floor and walls, even the very dirt we walk on, even our own shoes! It takes two things for an infection to hit a hoof: the hoof needs to be standing amid the microbes (that’s a “gimme” – if he’s in the stall, he’s standing amid them, and standing anywhere in mud or feces, it’s like he’s put out the welcome mat for infection), and the hoof needs to have some “outside doors” open – any tiny lesion on the bottom of a foot will do. Both microbes and spores get jammed into the lesion, where they get sealed in when the horse stands or walks in mud. The living microbes are already at work, and when the spores realize that there’s no air, it’s warm, it’s moist, they burst forth and join the party.

How to fight back

Now we start to see the complexity of fighting “thrush”. Topical treatments work on aerobes because we can get at them. But not so for the anaerobes. Living in an airless environment means they are buried deep in the tissues, hard for us to reach. A new approach is called for; soaking those feet in the appropriate microbe-killer long enough for the medication to soak in and do its job. A 30-minute soak in apple cider vinegar or dilute chlorine dioxide (Oxine or White Lightning, for example) will do the job on the microbes, but not their spores. For that, soaking in a product designed to kill spores is needed. There are several on the market, but the most effective may be CleanTrax, available on-line – it will kill aerobes, anaerobes, and spores.

So when you can see deterioration of the frog, and/or smell a real stink on those hooves, the “enemy” is obviously present and you can deal with it. But the real trick in dealing with it is to catch it early, before much damage has been done, and for that, some preventive measures are called for. When thoroughly cleaned, the entire bottom of the hoof is in clear view – difficult for undesirable microbes to hide. Consider forming the habit of thorough picking and wire-brushing the hoof bottom clean, a quick scrub with Dawn Detergent, every day, then spraying the entire surface with a microbe-killer; keep the foot off-ground for fifteen or twenty seconds to allow some penetration of the spray. Two very useful sprays are colloidal silver (silver ions are believed to destroy key enzyme systems in the cell membranes of these pathogens), and Usnea (a symbiosis [one organism living on another] of a fungus and an alga, used for its antibiotic and antifungal properties). Both are available on-line: consider the colloidal silver brand, “Silvetrasol”, about $20 for a spray bottle, and Usnea Tincture, about $10 for four oz., available from Essential Wholesale & Labs, among others. Mix Usnea 50-50 with water and spray daily, but Silvestrasol once a week.

Preventive medicine

Spraying is a quick and easy preventive procedure – but take it a step further and disinfect any crevices you see. For example, a healthy hoof has no crevices or clefts (the commissures don’t count), but a potential problem will show up as a cleft developing in the center of the heel of the frog. It will usually be just a slit, but if you can insert the metal tip of your hoof pick into it to any depth at all, it’s a problem in development. Left untreated, that cleft will develop into a crevice that’s as deep as your pick’s tip is long – or deeper. That means trouble is coming, and you should take countermeasures right away. Such clefts are well-protected hidey-holes for thrush-causing microbes to start their damaging work. The trick is to deposit some microbe-killer directly into the bottom of that cleft, and to do that you need a special, inexpensive, syringe (no needle). Your vet can probably provide you with one; it has a long, flexible tip that allows you to get it into tight quarters. An alternative is to buy the product, “ToMorrow”, from your local Agway, Tractor Supply, or equivalent. ToMorrow contains medication useful in treating mastitis in cow udders, hence its long, flexible tip. You can use it to deposit a pea-sized glob of medication at the very bottom of a frog cleft. You can use the mastitis treatment cream itself in frog clefts, but a better alternative is to empty the syringe, and then refill it with a 50-50 mixture of Triple Antibiotic Cream and Clotrimazole, both available on your druggist’s shelves. TA Cream is effective in combating Athlete’s Foot – a fungus infection – and Clotrimazole is a powerful treatment, especially useful in combating thrush. Added bonus is the cost for one ToMorrow syringe is only about two bucks.

The outlook is positive

And so, with all this, we’ve not yet crossed home plate – but we’re on third, waiting for the base hit that lets us score. We have a pretty good idea what causes the thrush condition. We have not yet found the silver bullet – but we’re getting closer. The thrush condition in horses is actually quite similar to the human version, and when we are able to nail it completely in humans, we should have it licked in horses, too. Meantime, we do have means to control it and make our equine partners more comfortable while we’re at it. It’s so insidious that it can slide in under the radar and our problem becomes repair rather than prevention; but to prevent takes vigilance and some effort on our part. So for our horses’ sake, keep the stalls clean, keep the floors cleared of feces, keep them clear of mud, keep that pick and wire brush close at hand and use them daily. Catch it early!

The Embroidery Horse-A True Fairy Tale

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Written By Julia Dake

Janice waited nearly sixty years for her horse. A horse was impractical to her practical parents. Riding lessons were something for a wealthy girl. Food for a horse? Out of the question. It didn’t matter that Janice begged at every Christmas or birthday for a ‘pinto paint pony’ with a ribbon in her tail, the pony never appeared. Her parents prayed Janice would ‘grow out of it’. She didn’t grow out of it but she learned to keep her dream to herself.Janice went to school, played, grew up, married and had children. She lived the life most live, soccer and play dates, wedding and funerals, movies and vacations, sadness and fear, happiness and love. She lived the normal life, the expected life and kept her dream to herself.

However, on a wall in her bedroom, in a small frame is an embroidery image of a black and white and brown horse on a little farm. Janice created the embroidery, lovingly stitching the image of the pony of her dreams with her tiny nine year old hands. She waited, no longer speaking her dream but keeping the image in the frame on the wall.

During the course of Janice’s normal life, she and her husband bought a house in ‘the country’. It was as close as she thought she would get to the life she lived amidst the threads in the frame. As Janice drove to her new home, her heart thumped, hard. One side of the road is crowded with new houses. Sidewalks and two car garages abound. On the other side of the road to her new home is the world of dreams. Horses scattered across velvet pastures, framed by beautiful white fences. All colors and sizes grazed and played.

Later in the dark quiet, Janice looked at her embroidery, trying to match the black and brown pony to one standing in the pasture. The

arge brown one, the grey or chestnut in the far pasture but none matched. None made the little thread pony come to lifeNot knowing what she would do when she found the horse but nearing sixty, she knew time to bring the embroidery horse to life was slipping away. Her health was changing and not for the better. Her husband, Tommy, who knew the tiny horse in the frame, was also suffering the changes in life. He wanted his wife to find the ‘pinto paint pony’. He wanted her to find that joy from her childhood, extraordinary and perfect.

The pressure, the desire to touch the little horse, to feel it breathe under her hand and move down the trail was becoming intense. Janice could feel the warm softness of its breath in her dreams. She heard the quiet nicker and knew the embroidery horse wanted to come to life soon.

Janice drove by the pastures every day, going to and from work, shopping, living her day. She always slowed by the fence looking, carefully, hopefully. One day as she drove home, she spotted a new horse, a black and brown and white horse grazing in the pasture. Her heart pounded in her chest. The colors of the horse sang to Janice. Without hesitation, she pointed her car toward the farm house.

The farm owner greeted her and listened while Janice talked, asking the question. ‘Is the black and brown and white horse for sale?’ No. His wife’s new mare is not for sale.

That night Janice stared at the framed pony. It danced and trotted inside the tiny fence, tossing the delicate head and calling softly. A door had been opened, the gate swung wide. It was time, if there ever would be a time. If it wasn’t the wife’s mare then there was another out in the pasture that would free the thread bound pony.

She looked in earnest at all the horses in the pastures. Each horse was considered but Janice always came back to the black and brown and white mare. She stopped occasionally to visit the farm owner and his wife, hoping the spotted mare was for sale. The answer was always the same.

A year slipped away. Another Christmas, another birthday came and went. The pinto paint pony didn’t appear. No ribbon in the tail. No soft nicker. Janice began to lose hope. The old dream darkened, quieted. She still slowed along the fence, watching the horses graze but theembroidery horse stopped prancing inside her little fence.

Life takes strange turns. Just when you think the dream is dead; you find it is only asleep. Out of reach becomes a finger-tip stretch away. And so Janice stopped at the farm one more time. The black and brown and white mare trotted in the round pen, turning and spinning, tossing her mane and calling loudly. The farm owner stood watching her. Janice quieted her heart, but hope kept whispering in her ears.

She asked the question. Her ears buzzed. Yes. The mare was for sale.

Today Janice grooms and bathes, feeling the mare breathe under her hand hoping she is taking good care of the embroidery horse. She takes riding and horsemanship lessons. She reads and questions, absorbing all she can. When she feels the sweet breath of the pinto paint on her cheek or relaxes into the rhythm as she rides down the trail, Janice makes up for the nearly sixty years of waiting.

No more keeping the dream to herself; Janice shares it with all. Friends and family visit the little mare. The barn is the first place she brings them when they arrive. The mostly non-horse people marvel at Janice’s independence, at her new found confidence. They comment that she is a different person.

Everyone admits they thought she’d grown out of it. She hadn’t. She just kept it to herself until the embroidery horse came to life and found life outside the little thread fence.

The End

Parasites: Anthelmintic Resistance

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Written By Dr. Kris Hiney

Last month we discussed management strategies that will aid in lowering the amount of internal parasites to which your horse is exposed. However, even with the best management practices available, it still may be necessary to employ chemical means to eliminate parasites. However, the use of anthelmintics (drug class which eliminates parasites) should not be done indiscriminately. A growing concern within the equine industry is the international development of anthelmintic resistance among the common parasites which infest horses. With no new drugs on the near horizon, we should take a hard look at their responsible use and our current management practices.
First of all, we should discuss how much of an issue parasite resistance might be, and what owners might have inadvertently done to help create it. It has been known for some time that ascarids and small strongyles have developed resistance to some drug classes, including benzimadazoles and the tetrahydropyrimidines or pyrantel salts, which include pyrantel pamoates and pyrantel tartrate. The other major drug classes of dewormers are the macrocyclic lactones or avermectins/milbemycins. Many horse owners would know these more commonly as the ivermectins or moxidectrin. These dewormers have been extremely popular to use because of the broader spectrum of parasites which they eliminate. Compared to benzimadozoles and tetrahydropyrimidines which kill large and small strongyles, ascarids and pinworms, the macrocyclic lactones also eliminate bots and stomach worms and moxidectrin eliminates several of the larval stages of small strongyles. Because of their broader range of efficacy, this has led many individuals to rely almost exclusively on these drugs in their management plan. However, there is a growing body of evidence that suggests that resistance issues to these drugs have begun to develop.
Ascarid resistance to ivermectin has been demonstrated in the Netherlands, Italy, Canada and Denmark. Furthermore, even within strongyles, the egg reappearance period, or the time between when no eggs are detected in the feces following deworming, to when they are seen again, has shortened from 9-10 weeks down to 5-6 weeks.  In Brazil, an increasing number of colic deaths in horses have been attributed to a growing resistance in the strongyles population.   In a recent issue of Veterinary Parisitology looking at anthelmintic resistance of horses in Finland, treatment of infected horses with ivermectin only resulted in a 52% decrease in the number of eggs found in the feces and 63% of horses had resistant parasites. Ivermectins were more effective against strongyles, but 44% of treated horses had parasites with demonstrated resistance. Comparatively, pyrantel treatment of horses infested with strongyles resulted in only a 43% reduction in fecal egg counts with 79% of horses showing resistance issues. To clarify, it is the parasite within the horse which harbors resistance, not the horse itself.
So why is resistance a growing issue? As discussed already, many individuals have relied exclusively on one type of dewormer. Eventually, as is typical in nature, organisms adapt to their environment to be more successful and to pass on their genetic code to future generations.    Essentially, once the worms adapt, or a few individuals survive a purge deworming, they are able to pass on these enhanced genetics to a future generation of worms which will also have that advantage of being immune to that drug.   If they are never exposed to a different type of dewormer, essentially the horse owner is just developing a breeding program for resistant worms! One strategy to adopt when thinking about “breeding” worms is to increase the number of refugia, or the population of worms which have not been exposed to dewormers. These would be the worms that would be in horses that were untreated, the encysted larval stages or perhaps those in the pasture. These non-exposed worms actually help to dilute out the population of resistant worms, and allow them to breed and pass on their more inferior genetics. To this end, many veterinarians now recommend that a fecal exam be performed on a horse prior to choosing to deworm. In this manner, horses which may not have worms present, are not unnecessarily dewormed. Also, a strategic deworming plan can be implemented, targeting only those horses with a significant worm burden. For example, a target concentration of 200 eggs per gram can be used.    Only horses which test to have a higher fecal egg count would be dewormed, while those horses with a relatively low burden would be left untreated, and thus increase the refugia.  This lowers our usage of anthelmintics and targets their use only at individuals which need it.
As horse owners, we may also be inadvertently contributing to resistance issues by using poor practices when we do choose to deworm our horses. Every time we under dose our horses with purge dewormers, we are creating greater tolerance in the worms. Many times owners actually under-estimate the true weight of their horse when deworming, or have a horse which spits out part of the oral dose. One easy tip for owners is to make sure there is no feed present in the oral cavity of the horse when deworming, the presence of which makes it easier to spit out the dewormer.
So what should a horse owner do? Certainly selecting only those horses which are known to be high shedders (or have a significant number of eggs present in their feces) would be ideal. However, there is very little incentive for the average horse owner to purse this type of program.   It is typically cheaper to just deworm the horse, rather than testing it first, and then follow up with deworming. More or less it becomes a personal choice of which practice to follow. If owners are unwilling to perform fecal exams, then it is imperative that they do rotate within classes of dewormers. Slow rotation strategies, which entail using a particular class of dewormer for one year, followed by a different class the following year, is an effective strategy.  Using a fast rotation program, or continually rotating between classes for every treatment is an alternative rotational strategy.   No definitive studies have been performed as of yet to suggest which strategy may be best for avoiding resistance issues. Additionally, the use of a macrocyclic lactone at least twice yearly is recommended, as these are the types of dewormers which can eliminate stomach bots. These are typically given after the first hard frost of the year, and prior to the spring thaw in the spring.
Ultimately, it is in our best interest as horse owners to employ strategic decisions about deworming our horses. A combination of management strategies and informed intelligent decisions about which horses to deworm and what products should be used. Ideally, a sound plan can be developed with your veterinarian or equine professional that serves the needs of your own horse, and the greater equine community as well.

Things I’ve Always Wanted to Know about Horses’ Hooves but Didn’t Know How to Ask

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Written By Walt Friedrich

If that fits you, then you’re in good company. Everyone with a horse or two has either been there or is there with you, right now – or soon will be. And it’s a conundrum. A hoof looks so simple; except for color, they all look very much alike. It’s so easy to take them for granted. But there are some questions:
How come some people have the guy come over every month or so and change the shoes? And how about hooves that don’t have shoes on, what’s up with that? Sometimes, instead of a shoe guy visiting regularly, there’s a guy with nippers and a rasp that comes around and delivers four pedicures on every horse. Both the shoe guy and the rasp guy look like they’re doing really intense work, hard work, and those hooves look really great when they’re done – but is all that attention really necessary? It isn’t cheap, either, getting those hooves worked on. Wild horses don’t get either guy to come around, and they survive all right. Shouldn’t a backyard horse need even less attention than a wild one – who, ironically, gets no attention at all? And even with all the guys’ visits, some hooves always seem to be in trouble, feet hurting for one reason or another. Why is that?
Now, that’s a lot to think about. Maybe I can shed a little light in the darkness surrounding this puzzling subject. We will at least get a little more familiar with hooves, I hope. Let’s start with a quick look at what makes up a hoof:
Meet Mr. Hoof
The hard covering you see wrapped around the hoof is called the hoof “wall”. It has two jobs: its outer layer – the part you see — is armor plating, so to speak, protecting the foot from outside trauma. It also has an inner layer, whose job is to provide shock absorption, stability, and some weight support for the horse.
Referring to the bottom view sketch, you see some interesting items. The flat area in the front half of the foot and extending into the sides is the “sole”, and much like the sole of your shoe, it provides protection and support.
The arrowhead-shaped area is known as the “frog”. It’s soft but firm, and provides some weight support, but it is also a shock absorber as well as a stimulator for certain tissues internal to the back of the foot, known as the digital cushion and lateral cartilages.
You also see the “heels”, flanking the back end of the frog. Note that they make a sharp “turn” as they head back toward the toe, forming what are called the “bars”, before disappearing into the bottom of the foot. That sharp turn in the wall, one of nature’s strongest constructs, forms the primary weight support for the horse. Take a sheet of paper from a small notebook, stand it on its edge, then press down on the upper edge. It bends immediately, has no supporting strength. Now fold that sheet of paper in half, stand it on its end and repeat the process; that weak sheet of paper now gives surprising resistance to your pressure. The hoof’s heels work the same way, but can support enormous pressure – more than the weight of the entire horse. And if you were to watch the heels closely from behind when the horse is walking across a rocky area, you’d see the two heels of each hoof moving up and down on the uneven rocks with each step, independent of each other; this keeps the hoof “even” as the horse walks. You could consider the horse’s hoof as the world’s first fully independent suspension system, rather like that in your automobile, with the frog acting as a shock absorber and the heels as the springs.
 
Referring to the side view sketch, the triangular-shaped bone you see is called the “coffin bone”. It is actually an inverted cone, and is attached across its front surface to the inside of the wall by a Velcro-like substance forming what is called “the laminae”, or “laminar connection”.
The two bones above the coffin bone are known simply as P1 and P2 (the coffin bone is also referred to as P3). Together, these form what is called the pastern, terminating at the upper end into what is known as the fetlock joint.
Tucked neatly into the back of the joint between P3 and P2 is a small, rod-shaped bone, whose end view you see in the sketch; it is known as the “navicular bone”.
And finally, the side view sketch shows a wad of fibrous tissue called the “digital cushion”. Note that it sits just above the frog: when the hoof is healthy, it is stimulated by the frog with every step the horse takes. A large and healthy digital cushion is vital for good foot health throughout the horse’s life.
A bit of interesting trivia: the hoof on a foreleg of a horse is the equine equivalent of the end of your middle finger. In fact, the horse’s entire foreleg matches up with your arm, bone for bone, except he has but one “finger” — the fetlock joint to the hoof — while you have five. Evolutionary deviation.
The hoof at work
 
Compare a hoof to your own foot. The hoof is actually a very small appendage, considering the bulk and weight of the horse that it supports. But the horse is a prey animal, it relies upon its sharp senses and speed to get out of harm’s way, thus its legs are comparatively skinny, allowing the horse the broadest field of view while it’s head is down and grazing. And when he runs, given a couple hundred feet head start, he can outrun any other animal on the planet. Being small, those hooves are also relatively lightweight and don’t drag him down when in flight.
Since the species lives on almost every kind of surface imaginable, the feet need to be hard, strong, and virtually bullet-proof – and they are.
Their feet need to wear well, too – considering that western-American ferals move an average of 20 miles per day, they need all that toughness, and they grow constantly and consistently to compensate for all that wear. Why don’t feral horses require trimming? It’s because the rate of hoof wear just about equals the rate of hoof growth. How convenient! When there’s more growth than there is wear, Mother Nature steps in and trims the horse by chipping away where the wall meets the ground. The result isn’t pretty, but it surely is functional, and it all grows back.
Ferals may get their 20-miles-per-day, but certainly, domestics do not — yet their hooves grow. Enter the trim guy. Horses living the barefoot life generally need attention every four to six weeks, because without sufficient movement every day, growth is greater than wear. The trimmer’s job is basically to remove the excess growth and restore the hoof to its ready-to-use condition.
Some horses are shod – but shod hooves also continue to grow. That means the shoeing farrier needs to remove the worn shoe, trim the excess growth from the hoof, then replace the worn shoe with a new one.
Shod or not, allowing a hoof to overgrow results in much more than just the loss of a nice appearance. Good foot health is likewise sacrificed – a subject to be covered in detail at another time. One common condition is the development of hoof chipping and splits. These are usually superficial conditions, correctible by proper trimming. With proper care, under normal circumstances both conditions will grow out. Remember, the wall has two layers. The outer layer is by far the most affected by chips and cracks, the inner layer not so much. That’s a good thing – it maintains the integrity of the hoof’s ability to protect, while any damage grows out with the growth of new wall.
What makes horses limp?
 
Quite a laundry list, here. Lameness can originate anywhere in the horse’s locomotive system, but most commonly in the feet themselves. We’ll talk about several of the causes.
Laminitis, one of the more common conditions, is also one of the more frightening – as well it should be. Laminitis is one of the most painful of hoof conditions, and the pain is long-lasting, even when properly treated. The Velcro-like structure that holds the wall to the coffin bone, mentioned earlier, is the laminar connection, which, like Velcro, consists of two layers that cling together tightly. But the laminae are living tissue, complete with millions of tiny blood vessels that carry nutrients to the cells that make them up. When blood flow to those cells is interrupted, the cells die, and when it happens to enough of them, the integrity of the connection between coffin bone and hoof wall is broken. That results in the very painful condition known as laminitis, with an additional danger – that of complete failure* of the laminar connection, allowing the wall to rotate away from the coffin bone, and forcing the hoof’s sole, already bearing much of the horse’s weight, to take up the added support load normally provided by the laminar connection.
Laminitis and founder are two conditions that require immediate attention by a professional. Both are treatable if caught in time, but the horse’s pain needs independent and immediate attention. Common practice is to dose the horse with an NSAID such as Bute or firocoxib, and to apply a special trim to take pressure off of the damaged laminar connection.
Abscesses can develop almost anywhere in the horse, but are most common in the hooves. An abscess is comparable to a “boil” in you and me – very painful to touch. Abscesses usually develop in hooves following a laminitis attack or founder. The dead laminar cells need to be disposed of by the body’s lymphatic system, but the infection is often so massive that the body can’t “keep up” with it well enough, and so it forms a pocket of infection. That pocket of pus and blood will eventually find a way out of the horse through a combination of normal waste collection process, and “popping” – that is, forcing its way out of the hoof, usually at the top of the wall (coronary band) or in the heel bulbs or through the sole. It is not unusual for a series of abscesses to develop after laminitis hits, as the dead laminae are cleared out. Abscesses can be dangerous if left untouched or handled improperly, and so a vet should be brought in early on to deal with them.
Bruising is caused by outside trauma. A hoof kicking forward onto a hard, sharp object may cause no visible damage, but may cause internal damage you can’t see. You’ll know it by the limp, which usually disappears after a day or two. You’ll eventually see the evidence — some old dried blood in the bottom edge of the wall when it’s trimmed. More common is bruising on the sole, caused by the horse coming down hard on a sharp stone, for example. Soles are tough, but not nearly so tough as the wall, and so you will sometimes see evidence of that trauma when you pick up the hoof. Such a condition may require some treatment to prevent infection.
Navicular is a sort-of catch-all term that describes pain in the back of the foot. It’s named after that little bone, mentioned near the end of the Meet Mr. Hoof section, above. The name, “navicular”, gets the distinction of representing a variety of back-of-hoof problems because several are connected with the navicular bone itself. However, true navicular bone problems also involve some soft tissue, such as the deep digital flexor tendon and the sheath protecting it. Pain originating at the navicular bone is referred to as Navicular Syndrome – it happens when the sheath wears through and the tendon rubs directly on the navicular bone –that rubbing happens with every step the horse takes. Fortunately, it is a curable condition.
Underdeveloped tissues, the digital cushion and lateral cartilagesin the back of the hoof need to be included here, because although their pain is comparatively unspectacular, it is real, and it’s probably the most common source of chronic pain for domestic horses. That’s because a domestic’s digital cushion and lateral cartilages are rarely fully developed to properly support an active, full-grown horse, leaving the hoof weak and accident/injury prone. The key to a horse’s foot health is movement, movement, movement, starting at foalhood, to deliver stimulation to those soft tissues. Movement is great preventive medicine, and development of those soft tissues requires it constantly. Domestics rarely get sufficient movement for proper soft tissue development. So, ride that horse! Often!
Thrush and White Line disease
 
These are actually microbial infections, but they are so common that they deserve special mention here. Thrush is actually a condition caused by a successful invasion by a number of microorganisms, especially Candida albicans; essentially, it is a yeast infection. It commonly strikes the frog, and if unchecked eventually destroys that appendage. A healthy frog is well-formed, smooth, soft but firm, and makes initial ground contact when the horse walks. An infected frog can appear to be coming apart before your eyes; it is often soft and “mushy”, receding into the back of the foot, and when probed with a hoof pick, comes apart easily. It can exude a black, smelly substance. Left unchecked, thrush can infect so deeply into the foot that it can cause serious lameness and health risk. There are a great many products on the market aimed at combating the thrush condition, many of which are effective on some horses, but not on others. The most successful treatments include soaking in Oxine (chlorine dioxide), and spraying with colloidal silver.
White Line Disease is the term often assigned to a festering sore at the edge of the sole. However, true White Line Disease is a more serious condition that exists within the hoof itself. It is caused by an anaerobic fungus that grows within the laminar connection, where there is moisture, warmth and no air. The result of such an infection is the death of laminar cells, leaving hollow spaces between the layers, allowing new fungal growth to develop. Unfortunately, the degeneration that takes place within the hoof wall is usually not visible until substantial damage has been done, making this infection a silent threat to the well being of the animal.
 
Seems like the hooves are the gathering-place for all sorts of painful events. It figures, though, since the horse’s feet are constantly at risk just by being used. Of all the common hoof problems, probably laminitis and abscessing are the most worrisome because while the horse feels the pain, you see evidence of it by the way he moves. At least you get the message of the pain early on, and can take steps to help him immediately.
Why do we shoe hooves? How about barefoot?
 
The nailed iron horseshoe seems to have first appeared in Europe about 5th century A.D. It was quickly learned that in the conditions of the time, animals exposed to domestic work that caused breakage or heavy hoof wear needed protection beyond their natural capabilities. Thus, born of necessity, the nailed-on horseshoe evolved from the early efforts at protection.
As a result, it became commonplace to shoe domestic horses, a tradition carried on through modern times. However, today the horse is primarily kept as a pleasure animal, used for everything from competitive events, through demonstrations of equine grace and prowess at shows, pleasure riding, and yes, still even farming in some communities.
Advocates of shoeing horses point out that domestic’s hooves continue to require shoeing much of the time lest they suffer damage. There is, however, a large and growing movement toward reversion to the barefoot condition. Its advocates believe that virtually any healthy horse can perform a horsey task barefoot just as well as and usually better than its shod counterpart. They cite the natural condition as being much better for the horse, and present convincing arguments and examples to support their position.
Perhaps the jury is still out. Meantime, shod or barefoot, compassion for the horse demands that we provide him with the best possible hoof care.

Equine Parasite Management

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Written By Dr. Kris Hiney

Last month we introduced you to the major internal parasites which can plague your horse. This month we will discuss management strategies that you can use to decrease the parasite load on your horse, in part through an understanding of their life cycle. We can actually use the horse’s environment to help decrease our reliance on de-wormers and do our part to aid in the battle of anthelmintic resistance.
If you remember the life cycle of our most insidious parasite, the small strongyles, you know that the tiny infective larvae hatch from eggs outside of the horse. They then use the dew or moisture present on the grass to be able to wriggle around in the blades of grass and await your horse to come along and ingest them. Since they need this moisture as part of their life cycle and to be mobile, horses housed in stalls and dry lots are far less likely to be able to pick up infective larvae. It is pasture grazing, therefore, which is the key to the strongyles’ survival. Worm larvae will tend to be located in the thicker grass areas of the pasture and down in the thatch layer, where moisture remains longer.  The highest potential for infection will occur if your horse crops the grass close to the ground.
If you observe horses natural feeding patterns, horses tend to graze pastures into areas of roughs and lawns. The lawns, characterized by short grasses,  are the areas which are cropped closely to the ground and the roughs, which have longer grass, are the areas where horses choose to defecate and avoid grazing. Obviously the larger the area in which horses are kept, the less likely they are to graze near infective piles of horse manure. This will decrease their chances of picking up larvae. As stocking density of the pasture increases, or vegetative growth decreases, such as in times of draught, the horses will be forced to eat nearer these thick areas of grass just teeming with swarms of larvae. If the grass becomes too short, supplemental hay should be provided to avoid forcing the horse to graze in the roughs. Additionally, the pasture can be mowed to keep the roughs from spreading further into the pasture.
Many people employ dragging the pasture to break up manure piles and spread them through the pasture to prevent the formation of roughs. However, if you use this strategy, you must understand that you are effectively dispersing the eggs and larvae far more thoroughly than they could ever do themselves. Even on their own, larvae can spread 4 to 12 inches from their original pile, and even further if aided by heavy rainfall. Therefore, if you drag the pasture, keep the horses off the pasture for at least two weeks. Preferably the dragging should be done in the hottest part of the year in order to expose the larvae to heat and dehydration. Cool temperatures allow the larvae to survive longer, so it is not advised to drag during the spring and fall.  If you must drag in cooler weather prevent the horses from grazing for an even longer period of time. As strongyles larvae are especially hardy and can survive winter quite easily, this is really not a good strategy for trying to kill the larvae.  Finally, if you are going to spread manure on pastures as a means of disposal, never spread fresh manure. Make sure it has been thoroughly composted before applying it to your pasture.
In an ideal world, pasture rotation allows the best management strategy to reduce strongyles infestation  in your horses. Horses grazing in fresh new pasture will avoid grazing near manure piles, and have a lower chance of re-infesting themselves. Letting pastures lie dormant will also allow any eggs or larvae present to die before horses are introduced. If space and equipment allows, putting pastures into hay production will allow parasites to die as well. Finally, if you own multiple species of animals, grazing pastures alternatively between cattle, goats and sheep will reduce your parasite burden, as the worms are host specific. Obviously all of these strategies do require a significant amount of acreage and fencing to be effective and may not work for everyone.
Remember, for strongyles elimination, heat is your friend. Only drag pastures during the hottest part of the year, and do not allow horses back onto the pasture for at least two weeks. Use separate pastures for winter pasture and summer pasture. Remember, winter does not kill the parasites. In cooler climates, parasites will not die after emerging from their dormant state until about June, May in hotter climates. If you do have a clean pasture, before you turn horses onto it, chemical deworming can prevent parasite infestation. Horses that are dewormed should be held on dry lots for several days before turning them out. This will allow all the eggs that the mature female has deposited to pass through your horse’s digestive tract. When your horses enter their new pasture, they won’t be bringing any “friends” with them!
What about the other parasites in your horses life other than strongyles? There are certainly management strategies which will help control their populations as well. For ascarid control, remember that these worms are primarily a problem for young horses. If possible and space allows, rotate which pastures house young horses with adult horses. However, even this may not be completely effective as ascarids can remain alive in the environment for several years. Essentially, if foals and young horses have been housed in a pasture, it is fairly likely that ascarids are present. Unfortunately, as ascarids don’t involve the same strategy for survival as strongyles, they can also infest the young horse in stalls and dry lots. This is typically why young horses are dewormed more frequently than older horses.
Stomach bot larvae and adult fly control are unfortunately only going to be controlled through the use of anthelmentics. The adult form can fly for miles so even if you have a great deworming program, if your neighbors do not, their flies will simply fly over to your property to lay eggs on your horse.
Tapeworms are relative newcomers when discussing parasites in horses. While not new to the horse, they are new to us, so not as much is known about them. They are believed to have a similar susceptibility to climate as the small strongyles, but may be hardier. More horses in northern climates have been exposed to tapeworms, which would indicate that these parasites are relatively cold resistant, but may have a susceptibility to heat. Therefore, follow similar management protocols as you do for small strongyles control.
From looking at the parasites life cycle and their means of infesting horses, it is clear that horses are often dewormed more frequently than is really necessary. As anthelmintic resistance becomes a growing issue in horses, we need to understand the ways in which we can manage horses to reduce their parasite burden. Next month we will tackle the issue of anthelmintic resistance and discuss which deworming strategies might be the most correct option for your horse.

Parasites: Who are you really feeding?

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Written by Dr. Kris Hiney

This month we will discuss other aspects of horse management that directly affect the nutritional status of your horse. While most horse owners are familiar with deworming their horses regularly, current recommendations from many equine practitioners are to be much more strategic with our deworming. There is a growing concern that parasite populations are developing resistance to almost all types of anthelmentics (drugs used to eliminate internal parasites). As no new anthelmentics will soon be offered to the public, this could represent a real risk to the health of our horses. In order to understand these issues, we will begin with a review of the major parasite classes in horses.
While there are many types of worms which infest horses, we will address the major classes that represent the most health risk to your horse; ascarids, strongyles, tapeworms, bots and pinworms. Ascarids, or Parascaris equorum, are a type of round worm which grow to a substantial size of 8-15 inches within the intestine. They are yellowish in color and may be occasionally seen in the feces. Despite their robust size, much of the damage created by these parasites involves their life cycle and migratory journey through the horse. Adult females pass eggs into the horse’s feces, where they spend 1-2 weeks in the environment before they are capable of infecting a new host. Horses ingest the infective eggs by grazing or eating in contaminated areas. Once inside, the larvae burrow through the intestinal lining and enter the bloodstream, where they travel to the liver. They then travel to the heart and then the lungs. Ultimately they enter the alveoli of the lungs where the horse coughs them into the oral cavity and then are swallowed back down into the stomach and intestines. The entire life cycle of the ascarid takes about three months and the journey these parasites take can cause significant damage and scarring of the tissues. A heavy parasite load of adult worms can even lead to blockage of intestines.   Young horses are the most susceptible group of horses to acquire ascarids, as well as weak, or malnourished horses. Coughing and nasal discharge in young horses may actually be a sign of ascarid infection. Older horses eventually develop an immunity to these parasites, so ascarids are primarily an issue with horses under two years of age.
Strongyles exist as both large and small strongyles, with many sub-species. The three main species of the large strongyles are Strongylus vulgaris, Strongylus edentus, and Strongylus equinus. Small strongyles actually have about 50 different species. Strongyles are also the most damaging of the parasites that horses will encounter. Similar to the ascarid, the females lay eggs which are shed in the feces. Unlike ascarids, they hatch into infective larvae that the horse ingests. The larvae molts three times before it is ready to infect the horse. The larvae actually crawl up the blades of grass in the dew. The larvae can crawl up or down multiple times waiting for a host, or even burrow into the ground when the weather isn’t favorable. Unfortunately for the horse owner, these parasites are extremely hardy and can persist through the winter.
The characteristics of the large and small strogyles life cycle make them particularly damaging. Large stronglye’s life cycle involves two stages where they migrate through the arterioles and arteries which supply blood to the intestine. Unfortunately, wherever these larvae burrow through the intestinal wall to migrate, all of them will return to one single location, the cranial mesenteric artery. Here they congregate and can cause immense damage. They can cause hemorrhaging, blood clots, or even rupture. The blood clots themselves can break free and travel further down through the blood supply to where they block blood flow and create a thromboembolic colic and even death. Oddly, enough lameness can also result from blood clots traveling to the legs as well.
Small strongyles have an additional strategy to help them survive. As they pass through the horse’s intestinal wall, the horse’s immune system is also trying to wage war against the larvae. However, the larvae are too big and travel too fast to be eliminated. The final migration of the larvae and complete maturation is actually held in check by the presence of adult strongyles in the lumen of the intestine. Essentially the adults provide feedback to the larvae that there is no room at the inn. When the larvae get that message and slow their migration, they become encysted within the intestinal wall by the immune cells. Here they can lie in wait for several years to take their turn at being the adult worms in the intestine. The horrifying reality is that when the adults die of either natural causes or by our purge deworming of the horse, the encysted larvae “wake up” and emerge to replace the newly vacated intestine. Within 6-8 weeks they will have matured and begin laying their own eggs to begin the cycle anew. Again, it is the pattern of traveling through the tissue that can cause a great deal of damage to the horse.
Relative to those bad boys, the rest of the worms which typically invade horses are mild in nature. The other major parasite classes which trouble horse owners are pinworms, stomach bots and tapeworms. Pinworms have a very simple life style compared to ascarids and strongyles. Adult females have a rather interesting feature, however. Not content to just shed her eggs into the feces, she actually deposits the eggs on the horse’s anus. This causes irritation to the horse who then scratches on anything available in the environment, effectively dispersing them. The horse then incidentally ingests the eggs, which hatch in the intestine where the larvae mature. Thankfully, these worms do little damage to the horse because their life cycle does not involve migrating through sensitive tissues. However, they can cause great irritation to the horse and robust itching of the tail head.
Tapeworms in horses can also cause reduced nutrition and potential blockages due to the preferred location in the horse’s gastrointestinal tract. The main species of tapeworm which inhabits the horse fixes at the ileocecal junction, or where the terminus of the small intestine joins into the cecum. A heavy parasite load can result in blockages, thickening of the ileocecal valve or even intusussecption, when the intestine rolls over itself due to regular peristaltic action. The tapeworm also has a separate host for part of its life cycle. While the adult parasite resides in the horse, the eggs of the tapeworm are actually ingested by a type of mite, which the horse then later ingests while grazing. There does not appear to be any age related immunity to tapeworms, as they are found in all ages of horses.
Finally, stomach bots are frequently seen in horses as well. The stomach bot, or Gasterophilus, also has subspecies, which include the horse bot fly, the throat latch bot, and the nose bot fly. The adult fly form can actually fly for several miles in search of a suitable subject on which to lay its eggs. The female hovers near the horse and deposits single eggs on one hair at a time. The eggs actually hatch into larvae within 7-10 days of being deposited. They then wait to emerge until the horse licks or scratches at the eggs. The larvae then enter the mouth and bury themselves in the gums, tongue or lining of the mouth where they hang out for a month. As they mature to later stages of larvae, they move into the stomach where they attach to the non-glandular or upper part of the stomach. The larvae live in the horse’s stomach for 9-12 months, before they and pass out into the feces. This typically occurs in late winter to early spring. There the larvae pupate and remain in the feces for several months. The flies then emerge in late summer or early fall, find mates and renew their life cycle. The damage the bots cause to the horse can occur in the mouth where they cause great irritation and even form pus pockets or cause the teeth to loosen. Large numbers of larvae in the stomach can cause blockages and erosion of the stomach lining. They, like all internal parasites, can result in reduced nutrition being delivered to the horse. An important heads up to horsemen:  when handling horses with bot fly eggs on their hair, use caution. While rare, the larvae are capable of burrowing into human skin, and if one rubs their eye after handling bot eggs, they larvae can actually invade the eye. I’m quite sure the last thing anyone wants is a bot larvae living in your eye!
Next month we will use what we know about these parasites to develop management strategies to reduce their ability to infect our horses. After that, we will discuss strategic methods in using anthelmentics in order to reduce our reliance on medications and reduce the spread of resistance in parasites which invade our horses.

Obesity in Horses: II, Balancing Diet and Exercise

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Written By Dr. Kris Hiney

In Part I of this series, we talked not only about the difficulty in removing extra pounds from our equine companions, but also the health benefits that our horse will gain from doing so. Our strategies included seeking a more mature grass hay with a lower caloric density and reducing the amount of forage offered to the horse.   The horse will probably need to be confined to a dry lot, but fed in a way to minimize boredom related to reduced  feeding time. This month’s article will look more closely at the diet of our horse, to ensure that we are reducing the calories the horse receives, but are still feeding a balanced diet that provides sufficient amounts of our other nutrients.
We will continue to use the example of our 1300 lb horse who was at a body condition score of 8 and a goal weight of 1165 lbs. The maintenance requirement for the 1165 lb horse was 17.7 Mcal per day. We decided to feed the horse at a rate of 1.5% of its target weight in order to achieve the desired weight loss. That would mean our horse would consume 17.5 lbs of feed per day. Now, because we specifically chose a lower calorie hay which is more mature, it probably is lower in other nutrients as well. In order to ensure that your horse’s amino acids, vitamin and mineral needs are met, one should look for a low calorie supplement. Fortunately many reputable feed companies produce feeds that are designed for the easy keeper. Typically these feeds will be much higher in crude protein, minerals and vitamins and are designed so that you only need to feed one to two pounds per day. This ensures that your horse will not suffer from deficiencies while we achieve the desired weight loss.
Additionally, we can accelerate the horse’s weight loss by instituting a regular exercise program. Now, assuming our horse was at a body condition score of 8, it probably wasn’t on a consistent exercise program earlier. The key in implementing an appropriate exercise program is to realize that the horse is relatively unfit and we should begin exercise carefully. Ideally the horse should be ridden or worked five to six days per week.   If this is not possible, try to institute an exercise program at least every other day. Begin with intermittent periods of walking and trotting, and slowly increase the duration of the trotting periods. You should notice that the horse is able to recover its heart rate and respiration rate more quickly during the walking recovery periods as it becomes more fit. Then you can increase the intensity of its exercise program.
Now let’s take a look at how much exercise your horse needs for increased energy expenditure. For every 45 minutes the horse spends walking per day, it will expend an additional one Mcal/d of net energy.  But what exactly is net energy? To this point in time, we have always discussed the energy needs of the horse in terms of dietary energy or DE. Dietary energy refers to the energy available in the feed once the digestibility of the feed is taken into account. When we determine how much to feed our horse, it is always based on the DE concentration of the diet compared to the horse’s DE requirements. Net energy is more specific about the flow of energy through the horse’s body. Net energy refers to the amount of energy needed to support exercise, growth, lactation, etc. after other energy losses to the horse have been accounted for. These other energy losses include the energy lost from gas production, urine, the work of digestion and the heat lost from the digestion and fermentation of the feed. The energy that is left over after all of these losses is what is available for the animal to use for other purposes.
The efficiency of conversion of dietary energy to net energy of a horse in light-to-moderate exercise is only about 40%. Therefore, if the horse expends 1 Mcal of net energy, he actually used 2.5 Mcal of DE.  Even regular trail riding will greatly help the horse with our weight loss goals, but increasing the exercise intensity will increase the calorie expenditure even more. If we use the horse’s heart rate as a guide, we can determine how much exercise they need to perform to represent significant calorie expenditure. Let’s say we would like to increase our horse’s energy expenditure to 20% over his maintenance energy requirements. Our goal for our original horse, then, is to use an additional 3.5 Mcal every day.   Our horse’s typical heart rate when he is walking is usually around 60 bpm while trotting will elevate the horse’s heart rate to around 90 bpm. This relates to 24 kcal/min and 56 kcal/min of net energy respectively for walking and trotting.    If we convert that to Mcal of DE, our horse is consuming .06 Mcal /min or .14 Mcal of DE/min. To achieve an energy expenditure of 3.5 Mcal, that would mean we would walk our horse for almost an hour a day, or about a half hour of trotting.  However, these are heart rates of horses which already are fit. For the obese horses we are discussing, the heart rates are usually higher, thus less time will need to be devoted initially to exercising these guys. Good news for them! Heart rates for an unfit horse trotting have been recorded at 120 to 140 bpm! This would correspond to about 0.25 Mcal of DE per minute. Thus only about 15 minutes per day would achieve our increase in energy expenditure of 20%. Remember, this would be 15 minutes total of trotting with intervals of walking. As the horse begins to become more fit and its heart rate lowers, he will tolerate more exercise and will need to increase the amount of time he works to continue using the same amount of calories.
Alternatively, once our horse is fit, we can also add bouts of cantering or loping to his exercise program.   A horse which is cantering typically has a heart rate between 110 and 130 beats per minute and utilizes about .25 Mcal of DE/min. If we add 10-20 minutes of cantering to our exercise program, the duration the horse needs to be ridden to achieve our target energy expenditure would be about 45 minutes per day, which is probably more realistic for most horse owners. This would include a mix of walking, trotting and loping. Combining this regular exercise program with our restricted diet will help your horse add years to his life.
Good luck with your weight loss goals.

Feeding Horses for the Prevention and Management of Laminitis

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Written By Dr. Kris Hiney

Nothing is more devastating to the horse owner than to have a treasured partner be afflicted by the painful, crippling disease of laminitis. Laminitis can be a debilitating disease that may ultimately result in the death of the horse or humane euthanization. Unfortunately there are so many factors that can manifest in development of this syndrome that it can be difficult to sort through.
To understand the development of laminitis one should really understand the physiology of the equine foot. Essentially the hard keratinized tissue which forms the hoof wall is held to the soft tissue by the interdigitation between the sensitive and insensitive laminae. The insensitive laminae (seen here in Figure 1) is formed in vertical sheets on the inside of the hoof wall. 
Figure 1. An interior view of a horse’s hoof with the soft tissues removed. 1b. A schematic of the vertical lines of insensitive laminae lining the interior of the horse’s foot.
Connecting to the insensitive laminae is the sensitive laminae, which is living tissue requiring an adequate blood supply of oxygen and nutrients to survive. When an alteration of blood flow or a vascular insult occurs inflammation or even death of the sensitive laminae can occur. The sensitive laminae ultimately stabilize the internal structures of the horse’s hoof, including the third phalanx (or coffin bone). When this stable connection is lost, the pull of the deep digital flexor tendon on the base of PIII rotates it out of place. This condition is referred to as chronic laminitis or founder.
Figure 2. The sensitive laminae which connect the hoof wall to the horse’s foot.

Figure 3. A foundered hoof where PIII has rotated out of place due to the pull of the deep digital flexor tendon.
 
There are many reasons why blood flow can be disrupted to the equine digit. Laminits is often a systemic disease which is only visualized in the foot. While digestive issues lead the list of causes of laminitis there are other physical insults which can occur as well. When procuring wood shavings from a reputable dealer, care should be taken never to include those of the black walnut tree. These shavings contain the chemical juglone, actually a toxin which can kill other plants in the black walnut environment. Other physical causes are concussive trauma, from being ridden on hard surfaces resulting in decreased blood flow to the foot, and excessive loading (i.e., one limb is severely lame resulting in extra loading to the sound limb). Endotoxemia, such as what might be seen in a mare with a retained placenta, may also result in the development of laminitis.
 Nutritionally, a whole series of gastric insults can alter blood flow to the foot.  These include a carbohydrate overload (the classic example of the horse breaking into the feed bin) which leads to an alteration of fermentation in the hindgut.  In order to prevent starch from escaping enzymatic digestion in the small intestine and escaping to the hind gut, it is recommended to avoid a starch intake of more than 2-4 g/kg of body weight per meal. Therefore, a 500 kg horse should receive no more than 1-2 kg of starch per meal.  Pasture grasses have also long been known to precipitate bouts of founder, but typically only in susceptible populations. Ponies, and horses with thrifty genotypes are the most likely to suffer from pasture-associated laminitis. It is believed to be caused by a high level of fructans, although the quantity of fructans required to cause laminitis is unknown. Fructan content is known to vary with the time of year, with a higher content seen in the spring, when most pasture-associated laminitis occurs. Horses which are susceptible to pasture-associated laminitis should also limit their intake of pasture grass in the afternoon, when photosynthesis throughout the day has resulted in a higher level of fructans in the plant. The levels of water soluble carbohydrate gradually decline through the night, making grazing in the morning relatively safer. As the majority of horses which develop laminitis due so on pasture, rather than through the owner feeding excessive concentrates, at least some thought or caution should be used when grazing horses. Ideally horses should be introduced gradually to consuming fresh grass, and susceptible horses’ grazing should be limited to when fructan concentrations are at their minimum.
If a horse does develop chronic laminitis, unfortunately there is little the owner may do nutritionally to manage the horse. Obviously exposure to pasture grasses at peak times of fructan concentration should be avoided. Also, the horse should be managed to lower body weight to decrease the mechanical load on the laminae. Low energy forage should be the primary feed for the foundered horse. However, because low energy forages will typically be deficient in protein, minerals and vitamins, it is important to ensure that the horse is supplemented with a low energy concentrate to make up for dietary insufficiencies. As these horses are often in a great deal of pain, NSAID administration may often be needed, but can also contribute to gastrointestinal upsets. Alternatives to NSAIDS, such as Omega-3 fatty acid supplementation, may help to alleviate some discomfort, without the negative side effects.
Overall, close attention to the diet of the horse, avoiding GI disturbances or causing fluctuations within the hind gut, and limiting grass intake during periods of time where fructan concentrations can be high, will hopefully prevent the horse from ever experiencing this deadly disease.

Feeding for Digestive Health

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Written By Dr. Kris Hiney 

The digestive tract of our equine companions is typically the system which most often goes awry. Colic and other digestive related upsets are the leading cause of death in the equine, but luckily can largely be avoided with careful management. If we understand the normal digestive physiology of the horse, we can avoid errors in our feeding program.
One of the most important features of a good feeding program for horses is providing an adequate amount of good quality forage for our horses. If we think about how a horses’ digestive system is designed to function, the relatively small stomach of the horse is designed to ingest small amounts of material throughout the day. This provides a constant influx of roughage to the hindgut, where it undergoes microbial fermentation. This is certainly the most healthy system and natural way of feeding horses. However, most horses managed in current stabling scenarios are meal fed, typically twice per day. While perhaps unavoidable, we try to offset this somewhat unnatural system by ensuring the horse receives enough forage for both its digestive health, and mental health as well.  Typically, horses will consume 2% of their body weight per day in dry matter. Most hays are usually around 85% dry matter (meaning they still retain 15% moisture after drying). For a thousand pound horse, that means that we should offer at least 23 to 24 lbs of hay per day. See calculations below:
1000 lbs x .02 = 20 lbs of DM
20 lbs DM/.85 = 23.5 lbs of hay as fed (or what you would actually weigh out)
Beyond just the shear amount of hay we offer, we should also think about the time the horse spends consuming that feed. If we again think about the natural feeding behavior of the horse, they eat for about 18 hours a day, continually traveling and searching for the most tender, nutritive grasses. When horses are deprived of feed, the pH of their stomach begins to drop, making them more susceptible to ulcers. In fact, a drop in pH of the stomach begins within 5-6 hours after the horse ceases eating. At 10 hours post feeding, the horse’s stomach is completely empty.
Beyond the obvious health risks this poses, the horse is unable to perform its natural foraging behavior. This encourages the development of stable vices such as cribbing, wood chewing, etc. which can be further detrimental for the horse’s health.
Therefore, our feedings should be spread out through the day to account for this.  Alternatively, we can offer more hay to our horse then the previously discussed 2% to allow them to participate in their normal desire to pick through their feed to select the most desirable parts. Realize this may increase the amount of hay wastage and economic loss. In addition, offering more hay can result in horses gaining more weight than desired if not offset by adequate exercise. If this is the case, look for hays that are lower in digestible energy (typically grass hays). However, this does not mean a decrease in quality such as the inclusion of dust, molds, weeds, etc.
In addition, the regular intake of roughage allows for a more stable population of bacteria in the gut. When the diet of the horse is radically altered, a shift in population of bacteria in the gut occurs, responding to the new environment supplied to the bacterial. This sudden shift in bacteria can result in digestive upsets, as well as development of laminitis. Therefore, any feed changes should occur gradually.  This includes the new pasture growing in the spring. Horses which are kept stalled or in dry lots should not be suddenly turned out into rapidly growing pastures in the spring. Ideally they should be introduced gradually, increasing the duration the horse has access to the pasture.
While maximizing forage intake is certainly ideal, what if you have a horse which cannot meet its energy needs through forage alone? Such horses usually fall into our moderate to heavy work category, or our lactating mares and growing babies. These horses then need to have a more calorically dense energy source, such as concentrate (or grain). When we feed a large amount of concentrate to a horse, the pH of the digestive system also changes, which may be detrimental. To avoid this, it is advisable to feed no more than .4% of the horse’s body weight in non-structural carbohydrate at any one meal. Our traditional grains such as corn and oats are abundant in nonstructural carbohydrates, which provide an excellent source of energy, but more care should be taken in feeding substantial quantities. Alternatively, we can provide feeds which are higher in rapidly digestible fibers, such as beet pulp, citrus pulp and rice bran. Many horse feeds now contain these ingredients as energy sources. In addition, rice bran is high in fat, which provides an extra boost of calories. Fat is 2.25X more calorically dense than carbohydrates, and provides a great way to increase calorie consumption with a lower risk of digestive upsets. Fat added to feeds may also dampen the increase in blood glucose seen after feeding concentrates. Finally, a horse will need less feed by weight when consuming a fat-added feed than a traditional concentrate.
One of the final considerations to maintaining a healthy digestive system of the horse is to ensure it receives adequate water every day. Horses on harvested feeds need adequate water intake to maintain the fluid environment of their digestive tract. If forage is higher in fiber and less digestible, it is imperative that the horse receives enough water to keep digesta moving normally through the tract. Most horses consume at least ten gallons of water a day. It is ideal to provide more water than the horse consumes (i.e., the bucket should not be empty before refilling).  Also be sure that, in the winter, the horse has access to water. In cold environments rapidly freezing water may lower a horse’s overall intake and make him at risk for impaction colic. Using bucket or tank heaters or a more frequent watering schedule will ensure that everything keeps moving regularly through your horse!
Following these simple guidelines for feeding will help avoid costly veterinarian bills and keep your horse healthy, both mentally and physically.

Everybody Admires a Well-Turned Leg…

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Written By Walt Friedrich
 …especially when it’s on a horse! Same goes for a pretty foot, also especially when it’s on a horse. I’m going to talk a little about horses’ legs and feet here, but I’ll refer to the feet as “hooves” for the sake of both accuracy and clarity. Know how you think of your foot as everything from the heel to the toe? If we do the same when referring to a horse, we’d be talking about fully the bottom half of an entire visible leg! (More on that a little later.) His hoof is the hard shell at the very bottom of each leg, plus its contents.
But the hoof, simple as it looks, is more than just a hard shell on the end of a horse’s leg, it’s actually a very complex system with a number of movable parts that all need to work together. And I do mean work – a feral (wild) hoof is in actual work typically twenty hours per day, seven days per week, all year long, for many years. With that kind of usage, the hoof had better be well-designed, well-built, tough, strong, and self-rejuvenating. If a horse moves twenty miles every day, and lives for twenty years, he puts 150,000 miles on each hoof over his lifetime, and even at the end most of those hooves are still functional! Only his teeth and jaws give his hooves a run for the money, so to speak, and they don’t support all that weight while they’re doing it.
Here’s a little food for thought: Enough fossilized remains have been studied that we know something of how today’s horse has evolved over the millennia. For example, vestigial bones in a horse’s leg suggest that that big old hoof is actually the equine equivalent of the last joint in your middle finger!
Let’s follow the finger analogy: his hoof is part of an “assembly” consisting of three bones, each articulating with its neighbors, and whose joints are held together with extremely strong and tough ligaments. Each of these bones moves with respect to its adjoining bone(s), controlled by tendons at the ends of muscles. Those tendons are encased in sheaths, to keep them positioned properly. You and I call this three bone assembly a “finger” – but on a horse, they’re known as the “pastern”. The last bone in the set, the bone that is encased in the hoof capsule itself, is known as the “coffin bone” – though there’s nothing at all eerie about it.
But let’s get back to that well-turned leg and examine it, top to bottom. Because they look so different, you’d never think that a horse’s foreleg and your own arm are very much alike – but they actually are, as you’ll now see. Remember the old song, “Dry Bones”? Let’s play an equine version of it — you can follow it on the adjoining sketch, and you’ll see how it relates to your own arm, step-by-step:
His shoulder blade’s connected to his upper arm bone —
 Technically, that’s his scapula connecting to his humerus – both are buried inside his body, so you can’t see them;
His arm bone’s connected to his elbow bone —
Which, finally, you can actually see (but probably have never noticed). It’s very easy to feel, though — run your hand up the back of a foreleg, and just as you get to his torso, you’ll feel a hard, round knob – that’s part of his elbow;
His elbow’s connected to his forearm bones —
Radius and ulna, that is – his forearm is the top section of his leg that’s visible to you and me;
His forearm’s connected to his wrist bones —
These are a collection of small, vestigial bones called the carpals, the “wrist” joint forming what most of us call his “knee”, because it’s in the middle of his leg and it bends forward like our own knees;
His wrist bone’s connected to his hand bone —
— by way of the one carpal bone that survived the evolutionary process to become his “lower leg”, which is actually the equine version of your hand. It’s called the Cannon bone;
His hand bone’s connected to his knuckle bone —
That joint is called his “fetlock”, the equivalent of your middle finger knuckle;
His knuckle bone’s connected to his finger bone —
Which, as we have learned, is his three-boned pastern.
Now, that’s the leg of the horse!
To help you orient yourself, that well-turned leg is vertical down to the fetlock, at which point his pastern takes an angle of 30 degrees, give or take, forward.
Let’s not omit his hind leg: the hoof is pretty much the same as those in front, right up to the fetlock. The long bone that extends from there half-way up his leg meets the joint we refer to as the “hock” – which is analogous to your heel and ankle joint! Continue upward to find his knee, which you won’t see unless you look very closely – but you can find it by running your hand up the front of his back leg, and just as you reach the torso you’ll feel the bony knob that is part of his actual knee. His thigh bone is inside his body, attaching to his hip.
Two incidental points of interest: one, his hind leg, from his hip down, appears longer than his foreleg, which leads us to question how he can run so smoothly. If they truly are longer, you’d expect many more steps by his forelegs than his hinds in order to keep up. But remember, his “upper arm” bone is buried inside his body so you can’t see it; furthermore, a horse has no collarbone (clavicle) to lock his scapula in place, as do you and I, so effectively he has an extra “leg bone” in his fores, which makes front and hind legs essentially of equal length. And the second point, the “cowboy tale” that you can predict the adult height of a newborn foal by measuring the distance between his “knee” and fetlock, and substituting “hands” for “inches”, turns out to have some basis in fact. It’s not an exact science, but as empirical evidence, observe a newborn standing beside his dam: his lower leg (cannon bone) will be close to the same length as his dam’s, and will grow but little more – except in girth, as it develops muscle. That makes it a fairly reliable predictor of adult height.
Whew. Congratulations, if you’ve stayed with it thus far.
Now let’s get to the hoof. We’re going to take something shaped roughly like a slip-on shoe (his hoof) and stuff it full of several interesting items, the items that make up the hoof’s “innards”.
We are all familiar with the shape of the hoof – rather like half a cone, with no top. Well, the coffin bone itself is shaped in very much the same way, attached to the leg’s bony column at an angle so its base can sit flat in the hoof capsule. It tucks neatly into the front section, and fits like a glove. The back half of the capsule contains a large wad of very tough, fibrous tissue, known as the “digital cushion” – flexible as well as tough, as it supports the horse from directly under the bony column of the leg, and it absorbs the shock when the hoof lands. The digital cushion is held firmly and tightly in place by a “belt” of even tougher material known as “lateral cartilage” – it “cups” the digital cushion from underneath, behind and both sides.
All we need to hold it all together is to sort-of glue the coffin bone to the inside of the capsule around the toe. That gets done by Velcro-like layers composed of billions of cells forming what are called “laminae”. One layer of laminae is part of the coffin bone, the other layer is part of the hoof wall; these two layers interlock like Velcro, and these form one of nature’s strongest bonds.
Finally, what’s underneath the hoof? At the very back, the wall forms two ultra-strong columns, called the “heels” – one on each side – capable of slight sideways and vertical movement to stabilize the horse when he’s moving. Between the heels and stretching toward the toe sits the “frog” — triangular-shaped, tough fibrous tissue that provides both support at the back of the hoof and stimulation for the digital cushion, immediately above it. And what’s left, covering most of the bottom of the hoof, is the “sole”. It holds everything together, and in conjunction with the wall and heels, provides the total support for the horse’s entire weight – for an average horse, that amounts to a load in the area of 200 to 300 lbs per hoof, just standing; imagine how much greater when the horse is walking, running, jumping…
Tying it all together is the blood supply. And it is RICH. It has to be – it’s the only protection the hooves have from the cold, and that protection is superb. The hoof’s components, together, are very demanding of constant, steady blood flow. They get help from what’s known as “hoof mechanism”; because of the hoof’s architecture, its blood supply is cut off for an instant with every step the horse takes, allowing a momentary pressure build in the arteries feeding the hoof and a small pressure decrease in the hoof itself. But as the hoof completes each step and raises off the ground, that blockage is released, and the built up pressure forces a spurt of blood flow through the hoof. The hoof itself also expands slightly as it takes weight with each step; that forces blood through the hoof, and when the hoof is raised, the expansion relaxes, allowing the blood pressure in the hoof to restabilize. These two actions are synchronized, with the result that each hoof is referred to as a sort-of auxiliary heart – that means five hearts working to pump blood with every step the horse takes. The laminae in the hooves especially require a strong and steady supply of rich blood, and Nature’s design provides it for them.
While the hoof and the horse date back into antiquity, you might note that the hoof is also the first four-wheel independent suspension system on the planet. The shock absorbers are the digital cushions together with the frogs, and the springs are the heels, working independently of each other. That’s why when his feet are healthy, he can stride fast across a path of rocks – each heel retracting and returning as necessary on the uneven terrain.
So you see, those four little hooves – little in comparison to the bulk and weight of the rest of the horse – actually do wonderful work, far greater than their own size and weight. But then, that sort of thing is true of the horse in general.