Horse Care

Changing Horse Feeds & Forage Safely:

By khan.

When making seasonal adjustments to your horse's diet, you'll need to give his digestive tract time to adapt.

During the fall, the microbes in the horse's digestive tract need time to adjust to nutrient changes in the grass, the addition of hay to the diet, and any fallen leaves the horse consumes. Watch for signs of digestive upset.

Horses have evolved to handle a wide variety of vegetation in their diet, but with a few key differences between the feral horse and the domesticated horse. A horse ranging freely in search of food consumes nutrients such as carbohydrates and fats in a very diluted form because grasses and other plants are at least 75% water. Wild horses also get a lot more exercise than domesticated horses, which is important to good gut function. We don't really know exactly why, but research bears this out.

The dilution factor is important because most gut upsets in the horse are related to the large intestine. The horse's large intestine is essentially a fermentation vat-like the four stomachs of a cow. Nutrients are first broken down by the bacteria and protozoa that live in the hind gut. The byproducts of that breakdown are actually what the horse then absorbs and turns into proteins, fats, and carbohydrates that the body can use.

Seasonal Diets

• Be aware that cool or wet weather can change the nutritional balance of fall grasses.
• When switching from pasture to a hay-based diet, do so gradually.
• If you choose to supplement with grain, introduce small amounts slowly.
• When making any dietary changes, watch for signs of digestive upset.
• Use the same precautions when switching to different cuttings or varieties of hay as you would when changing or introducing grain.When a large "load" of fermentable food hits the hind gut all at one time, if it is different from what the organisms are accustomed to handling, the result can be a rapid increase in the "bugs" that prefer that type of nutrient. This, in turn, can change the chemistry in the intestine and cause other forms of bugs to die off. Consequences for the horse range from poor utilization of feed (or some portions of it) to gas, mild distention, diarrhea, or full blown colic.Each specific type of organism (and there are hundreds) will need a specific type of food to survive. Some are better at using complex fibers. Some like simple sugars. Others will thrive on high protein. Still others will be intermediate forms and will further break down the products produced by other types of organisms. When the organisms receive a constant flow of foods to ferment in a high volume of fluid, they can adapt to changes much easier.

If the large intestine becomes too acidic, as it can if unusually high amounts of sugar, starch, or complex plant sugars enter it, the lining can actually be damaged and bacterial toxins absorbed into the body. This can make the horse very ill. It can even cause laminitis.

Most people know you shouldn't start, increase, or change grains rapidly. This is one of the most dangerous things you can do in terms of risking intestinal upset. However, what you may not realize is that changes in hay can be bad, too.

At this time of year, many of us begin to supplement pasture with hay and grain. Make dietary changes slowly, and be sure to balance the vitamin and mineral content of the ration.

The large intestine is the major site for breakdown of hay. Even if you always feed the same type of hay, such as timothy, Bermuda grass, or alfalfa, not all hay is created equal. Different cuttings, under varying growth conditions and even different strains of the same type of forage, can vary by 100% or more in the level of rapidly fermentable nutrients they contain. Changing hay types risks dietary differences in both the levels and relative proportions of fermentables your horse's system must adapt to.

Even rapid changes in pasture plants can cause problems for your horse if their composition changes too much. This is especially true in the spring and fall when grasses are growing (or regrowing) at a rapid rate. Young growths of grass are lower in slowly fermented fiber types and can have wide swings in the amount of simple carbohydrate they contain. Very high protein levels in young, growing pastures can also cause gut upset.

These guidelines can help you prevent feeding-related gut upsets:
• Introduce grain feeding gradually, no more than 1 pound per feeding.
• Allow three days between each increase in grain to enable organisms to adapt.
• Don't feed more than 4 pounds of grain at one time.
• Make changes in hay gradually, replacing from 10% to 25% of the old hay with the new variety; increase every three days.
• Accustom horse to lush pastures gradually, especially if grass is growing rapidly (spring and some fall conditions).
• Keep hay available for horses on young growths of pasture grass to provide complex and slowly fermented fiber which the grasses may be lacking.

Alternative Therapies

Homeopathic First Aid Kit for Horses

Holistic veterinarian Madalyn Ward describes how five basic homeopathic remedies can help you care for your horse. From the editors of Practical Horseman magazine. 

Posterior pectoral muscle tightness in your horse's girth area may be the cause of your horse moving poorly, says a top equine sports massage therapist.

Loosen Tight Posterior Pectoral Muscles in Your Horse’s Girth Area with Equine Sports Massage:

Your horse used to enjoy his work, but now he pins his ears and sucks back when you ask him go forward. He balks when you ask for the canter and has trouble picking up the correct lead. He doesn’t seem lame—but he doesn’t seem right. What’s up?

While a number of causes can underlie these signs, in my work as an equine sports massage therapist, I’ve found that one is especially common: Tight muscles in your horse's girth area. In this article, I’ll tell you how to figure out if your horse has this problem, and I’ll outline some simple steps to solve it using equine sports massage.

The Problem
The specific muscle involved is the posterior pectoral, one of three pectoral muscles that help move the foreleg. This flat, triangular muscle lies against the rib cage behind your horse’s foreleg. It fans away from a point on the back of the humerus (the large arm bone below the shoulder) to points along his rib cage and sternum (breastbone) at the midline of the belly. When this muscle contracts, it pulls the leg back. Other muscles contract to move the limb forward—but the leg can’t swing forward freely unless the posterior pectoral relaxes to let it go.

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Simple muscle tightness here is a very common cause of shortened strides. If the posterior pectoral is tight, it doesn’t release the leg easily, so forward motion is inhibited. Hind limb motion may be affected, too, as a horse’s front and hind always move in synch. Your horse may be “girthy,” objecting when saddled or mounted or moving with short, stilted steps. In extreme cases, a horse may even rear to resist going forward. Often, though, the signs are subtle. Because your horse is uncomfortable reaching fully forward in front, he may:

• have difficulty going up or down hills;
• be reluctant to pick up a lead or tend to swap off or cross-canter;
• hang a leg over fences;
• have difficulty with banks, drops and ascending oxers—obstacles that require extra “reach” in front;
• show reluctance when asked for lengthenings or tempi changes; and
• tire quickly, because he has to work against the tightness to go forward.

When a horse shows any of these signs, it’s not difficult to find out if the posterior pectoral is involved. Perform this simple check on each side of your horse: Stand at his shoulder and run your hand, fingers flat against his side, over the area behind his elbow. (This is a sensitive spot, so be aware that your horse may move away or even kick out, especially if he’s sore.) If the muscle is relaxed, this area will feel flat and soft. If it’s tight or in spasm you’ll feel a knot—a lump in the shape of a small hot dog, across the muscle (perpendicular to the ground).

Work It Out

To look for tightness or spasms in the posterior pectoral muscle, I stand at the horse's shoulder and use a flat, relaxed hand to stroke and press down toward the ground. I am feeling for bunched tissue or a soft, small hot-dog-shaped vertical lump.

A simple massage technique helps the muscle relax. Standing behind your horse’s shoulder, put the flat of your hand against his side just behind his elbow. Keep your hand relaxed. Using soft, moderate pressure with the entire palm or back of your hand, gently work along the muscle for a distance of about one-and-a-half hand lengths. Your horse will tell you—by moving away, pinning his ears or giving other signs—if the pressure is too strong. Typically the knot releases in just a few minutes. Then the muscle feels soft and pliable, and your horse relaxes.

A correctly placed saddle sits behind the horse's shoulder blade and leaves space between the foreleg and the girth, ­allowing for full use of his pectoral muscle and shoulder.

Follow the massage with exercise, which completes the treatment by activating and lengthening the muscle fibers. Cantering is especially helpful for this. To really solve the problem, though, you need to figure out what’s causing the tightness. Here are six prime suspects, and the fix for each:

• Saddle placement: Incorrect saddle placement is the most common cause. Too often, the saddle is put on too far forward, so the girth passes right behind the elbow. Girth pressure there pinches the muscle and provokes spasms. The fix: Because every horse’s conformation is slightly different, it’s hard to make hard-and-fast rules for proper saddle and girth position. But you’ll generally be safe if you place the saddle so that it doesn’t sit on his shoulder blade and interfere with the action of the shoulder and so there’s space between his girth and his foreleg.
• Girth length: A short girth like those used in dressage sometimes causes the posterior pectoral to tighten, particularly if the buckles line up right on top of the muscle. The fix: Switch to a longer girth, and see if that ends the problem.Girth type: A narrow girth concentrates pressure on a smaller area than a wide girth does and is more likely to cause problems. The fix: Try a wider girth. Fabric is a good choice, at least for schooling. I think it’s more comfortable for the horse than leather. Elastic at one end of the girth is also good, because it allows a little give. Elastic at both ends may be too much if it allows the saddle to shift.
• Work: Performing the same maneuver over and over—cantering endless circles, for example, or overdoing lengthenings—can lead to tightness in the girth area, as well as in other muscles. The fix:Vary the work, changing gaits and directions often.
• Footing: Working in deep footing tires your horse and contributes to muscle tightness. The fix: Limit the amount you do in deep footing.
• Hidden problem: Sometimes the real cause isn’t at the girth area at all. Your horse may have a problem in his lower leg or foot, for example. He tightens the posterior pectoral to protect his sore leg by limiting the range of motion. (In orthopedic medicine, this is called “protective splinting.”) Then the muscle goes into spasm. In cases like this, the knot often doesn’t resolve quickly with simple massage, and the problem doesn’t clear up with changes in tack and work routines. The fix: No simple fix here; a veterinarian and/or farrier needs to assess your horse.

To massage a tight posterior pectoral muscle, use a relaxed, open palm or the back of your hand, moderately pressing and stroking down toward the ground. If your horse moves away or reacts adversely to this, you may be using too much pressure. Try again, with less. If he continues to act uncomfortable, call a professional massage therapist.

Correcting the underlying cause of the tightness should allow your horse to move freely again. In addition, some simple stretches and changes in warm-up routines often help horses who have this problem.

• Before you mount, stretch your horse’s pectorals by drawing his front legs forward, one at a time. Grasp a leg behind the knee, lift it so that the forearm is almost parallel to the ground and gently pull it forward (see photos page 66). (Don’t grab the pastern and pull the whole leg out. That stretches his leg tendons.) Repeat with the other leg. If your horse has tightened his posterior pectorals in response to girth pressure, this will help release them. Do this stretch once or twice on each side, as tolerated by your horse.
• Warm up with work that encourages your horse to lengthen and stretch these muscles. Cantering is the most concerted exercise for lengthening. (That’s why the trot always feels so much better after a canter.) Walking up hills is also excellent.
• When you untack after work, repeat the foreleg stretch described above. It will help release any lingering tightness.

By identifying tightness in your horse’s posterior pectoral muscle and working to loosen it, you will be able to help him move more freely—and happily.

Jo-Ann Wilson is a licensed massage therapist, teacher and researcher whose clinical practice includes humans as well as horses. Her equine practice spans all disciplines—from international competition horses to backyard pleasure horses. She worked at the 2000 Olympic Games in Sydney as the sports therapist for the United States Equestrian Team’s eventing squad, winners of individual gold and team bronze medals. Based in Searsmont, Maine, Jo-Ann was a longtime associate of the late Jack Meagher, a pioneer in the field of sports massage therapy. She partnered with him in Wilson and Meagher Sportstherapy, which offers training programs in the Meagher method of sports massage. Jo-Ann has also produced an educational sportsmassage DVD, available this fall. Information on the programs is available online at.

How to Evaluate a Weanling

Use these tips to evaluate the quality of a weanling to buy or for other consideration.

By observing how a weanling behaves toward other horses, you

You've got your reasons for having your eye on horse weanlings right about now and wanting to evaluate them.

Maybe you're a breeder, as I am, with a built-in interest in knowing how to assess what you've raised. Or, you could be a potential buyer, eager to bring home a young horse you can raise and train as your "forever" partner. Perhaps you're in the market for a show prospect, with intent to resell at some point. Maybe you just enjoy challenging yourself to improve your eye for horses.

The trouble is, a lot of people can't look at a baby and see anything but cute. This occurs with buyers and breeders alike, at all levels of the weanling market. If this is where you are, I'm here to offer a hand.

In the breeding/training business I operate with my husband, Roger, I deal with weanlings virtually every day. Not only do we breed, raise, train and sell our own, we also work with our customers' weanlings, and consult with them on buying and selling. And, because we run a training program designed to give these young horses a great head start on basic skills (learn more at , I also get plenty of hands-on, eyes-on experience at finding out how those adorable babies turn out as they mature. This gives me a body of knowledge you can draw on.Strictly personal, or otherwise? Are you trying to find a horse you'll keep as a personal partner for the rest of his life, with no plans to ever compete or breed him? Or, are you looking for a prospect you'll eventually show, breed, and possibly resell?

Impulse Protection: To protect yourself from falling for cuteness (or any other single trait, like coat color or a temptingly low price), establish some initial objectives. These will be your touchstones, helping you to stay objective as you look at your own stock, or someone else's. Ask yourself these questions:

When buying or retaining a weanling strictly for your own purposes, you get more leeway to suit yourself than you do in the other circumstance. You don't have to be as fussy about pedigree, for instance, or about some of the other factors that add show, breeding or resale value. (More on that later.)

What's your goal, and at what level? I think it's safe to say that everyone who's looking at weanlings wants to end up with one who'll grow up to be a healthy, balanced, correct and good-tempered individual. But beyond that, many points of evaluation depend on the goal you have in mind for the horse, and at what level.

For example, you wouldn't look for the same things in a Western pleasure prospect as you would in a barrel or roping prospect. And you don't necessarily have to be as insistent on eye appeal or quality of movement in a 4-H project weanling as you do in one you'll aim at world-class competition or profitable resale.

What level is your eye? If you intend to shop unassisted, particularly for a show prospect, the level of your eye--in other words, the level of horses and competition you're used to seeing--needs to match or exceed the level of your goal.

Suppose your goal is to compete in one of next year's yearling longe-line futurities at a major show. If you've only known the weanlings in your neighbor's pasture, chances are, you won't know what to seek, or how to recognize it, in a competitive longe-line prospect. If you've never been to your breed or sport's biggest show, yet want a weanling who could compete there some day, your eye and goal are out of sync. In cases like these, I recommend you get experienced first-hand help.

Pedigree Power
Let's say you've established your core objectives and have done some preliminary shopping based on that foundation. You've come to me with a list of the weanlings who have caught your eye. (Or, you may want my help in evaluating what you've raised.) Where would we go from here?

My first consideration for each candidate would be, "What does he look like on paper?" To the degree that your budget will allow, you want the close-up relatives on a pedigree to have proven aptitude and ability in whatever it is you want the weanling to be able to do.

Not only does this boost your odds of getting the kind of horse you want, it also contributes to a horse's resale value--critical, if resale is part of your overall plan. The higher you rank resale as a goal, and the higher the competitive level, the more particular you have to be.

Dentistry

Common Equine Dental Problems

Here's how to recognize dental malformations and abnormal wear patterns in horses. By Christine Barakat for EQUUS magazine. 

Common Equine Dental Problems

When your veterinarian begins describing your horse's oral anatomy--or what might be abnormal about it--you may feel as if you need an interpreter. Sure, some terms such as "overbite" and "underbite" correspond roughly with those in human dentistry and are easy enough to understand. But visualizing a "wave mouth" or a "step mouth" can be difficult. Even if your veterinarian helps you peer into your horse's mouth, it can be tricky to recognize bite or wear abnormalities, particularly when they affect the teeth in the farthest reaches of the mouth. To help you become a better partner in your horse's care, we've illustrated the most common equine dental abnormalities. If you review them now, the next time your veterinarian visits for a dental exam, you'll know exactly what he's talking about.Here's how to recognize dental malformations and abnormal wear patterns in horses.

Malocclusions
Malocclusions that stem from jaw conformation are nearly always present at birth but are not necessarily inherited. Minor malformations may have no effect on a horse's immediate ability to eat, but all misalignments eventually affect the wear pattern on other teeth, making regular dental care essential.

An overbite (parrot mouth, brachygnathism) is a congenital deformity in which the upper incisors overlap the lower incisors.

An underbite (monkey mouth, sow mouth, prognathism) is a deformity in which the lower incisors extend beyond the upper incisors.

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Dorsal curvature (frown) occurs when the outer corner upper incisors grow longer than the opposing teeth below. In ventral curvature (smile), the outer corner lower incisors grow longer than the opposing teeth above. Both misalignments are usually caused by retained baby teeth or abnormal chewing.

A diagonal bite may result from a malocclusion or pain in the cheek teeth that causes a horse to grind feed primarily in one direction.

Abnormal Wear Patterns
The following dental problems and abnormal wear patterns require the attention of a veterinarian.

Hooks--sharp protrusions that develop on teeth when an overbite, underbite or other dental deformity causes an imperfect meeting of the top and bottom arcades. Most common on the upper first cheek tooth and lower last molar.

Ramps--typically premolars with a surface that slopes like a ski jump. Ramps can cut or scrape the tongue or cheek, especially when a horse is bitted.

Step mouth--a cheek teeth row with one molar that has grown unopposed so it juts above the rest of the arcade. A gap in the opposite molar lineup usually initiates the abnormality.

Wave mouth--a severely restricting abnormality that occurs when two or more teeth in an arcade are high, creating a series of ascending and declining grinding surfaces.

Shear mouth--a dental configuration in which the molars' grinding surfaces are worn at a sharp 60- to 75-degree angle. Normally, the angle is 15 degrees.

Deworm Your Horse with Clinton Anderson

By SOHAIL KHAN

thee process with top trainer/clinician Clinton Anderson’s proven technique.

Deworming is one of the basic elements of good horsekeeping. It should be a worry-free, routine practice that takes place several times a year.

Is your horse difficult to deworm? If so, he may have had a bad experience being dewormed or doesn’t like the taste of the dewormer.

Top trainer/clinician Clinton Anderson explains that most deworming issues aren’t the horse’s fault; it’s the owners’ approach to the process.

“Avoid sneaking up to your horse and jamming the dewormer in your horse’s mouth,” Anderson says. “Also, don’t walk straight up to your horse, hang on to the halter really tight, then jam the syringe in his mouth. You’ll make him defensive.

“Keep in mind that horses are prey animals,” he explains. “If you approach him and stick the dewormer in his face, like a predator, then he’s going to stick it back in your face and say, ‘Get lost!’

“On the other hand, if you walk up to your horse and kind of act casual about it, pretty soon, you’ll notice that a lot of his defensiveness will go away and he won’t be worried about getting dewormed.”

A horse that’s good to deworm will stand still with his head down, body relaxed, and ready to accept the deworming procedure, because he realizes that you’re not trying to hurt him. Here’s a step-by-step technique to deworming the right way.

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Step 1: Desensitize the Airspace

Use the dewormer to desensitize the airspace around your horse’s head. If he won’t accept the dewormer in the airspace around him, then he won’t accept the dewormer in his mouth. Desensitizing works, because you’re doing the opposite of what he expects you to do — that is, he expects you to deworm him, but you won’t in this step.

Stand on your horse’s left side, so you’re out of his way if he tosses his head or strikes at you. Wave an empty deworming syringe back and forth around his entire head and muzzle, keeping it eight inches away from his muzzle.

When your horse keeps his head still, immediately stop waving, retreat, and rub his head with your other hand. Repeat this step until he keeps his head still for the entire time that you’re moving the dewormer.

“If he isn’t relaxed at this point, don’t go to the next step.” says Anderson. “Your horse must be relaxed for this to work.”

Step 2: Desensitize to the Syringe

Desensitize your horse to the touch of the deworming syringe. You want him to understand that he can be touched by the dewormer without actually getting dewormed.

Starting at your horse’s withers, rub an empty deworming syringe all over his body. Work back toward his withers, and onto his neck and jaw. If he throws his head or moves away from you, continue rubbing until he stands still and relaxes, then retreat.

Rub the deworming syringe all over your horse’s face, continuing to use the approach-and-retreat method. As he becomes desensitized, gradually rub the dewormer down and around his muzzle.

“When you rub the dewormer around your horse’s nose and face, don’t rub it real slow like you’re sneaking around him hoping that he’ll stand still,” says Anderson. “Instead, rub vigorously. He’ll think, Man, you’re an idiot, you don’t even know where my mouth is.”

When your horse relaxes, and keeps his head and feet still, retreat the dewormer, and rub his head with your other hand.

“You’re trying to establish a starting point,” says Anderson. “You want him to realize that the quickest way to get rid of the dewormer is for him to stop moving his feet, and to relax his head and neck.

“When he does so, take the dewormer away from him, and rub his face with your other hand. Keep doing this until you can rub the dewormer all over him, and he doesn’t move.”

Step 3: Coat the Syringe

Repeat Step 2, then coat an empty deworming syringe with something sweet, such as honey, molasses, or sugar. This sweet coating will help teach your horse to accept the deworming syringe in his mouth — it’ll help him disassociate the bad taste of dewormer with the deworming process. (Give your horse a taste for the sweet coating by putting a little of it on his feed every night.)

Stand on your horse’s left side, and ease the dewormer into the corner of his mouth. Keep the dewormer in his mouth; if he throws his head, raise your arms. If he steps backward, move back with him.

As soon as your horse stands still, lowers his head, and relaxes, remove the syringe and rub his face with your other hand.

Patiently repeat this step until your horse stands still.

Step 4: ‘Deworm’ with Honey

‘Deworming’ your horse with honey makes him think that whatever is in a deworming syringe tastes good.

Fill the empty dewormer with honey, then wave and rub the syringe around his nose to ensure that he’s desensitized to it. Then place the honey ‘dewormer’ in the corner of his mouth, and slowly ‘deworm’ him by letting him lick the honey off the syringe.

Repeat this step over the course of several days.

Step 5: Deworm Your Horse

When your horse accepts the deworming syringe in his mouth, you can actually deworm him. Repeat Steps 1 through 4 until he shows no defensiveness towards the dewormer. Then get a real dewormer, and put a sweet coating on the outside of the syringe. Put the dewormer in the corner of his mouth, and empty the syringe. Wait for him to digest the dewormer, and immediately follow up with a honey dewormer.

“Always leave your horse with a positive taste in his mouth,” says Anderson. “If you just give the bad-tasting dewormer and walk away, the last thing he remembers is a foul taste.”

Step 6: Follow Up

Over the next three or four days, ‘deworm’ your horse with honey to remind him that deworming doesn’t have to be a horrible experience. Be sure to desensitize him by waving and rubbing the syringe around his nose before putting the honey dewormer in his mouth.

Step 7: Repeat the Process

Deworm your horse with honey once a day for four days before the next scheduled deworming. Follow up by ‘deworming’ him with honey once a day for four days after the deworming. You’ll then leave him with a positive deworming experience. In time, you should be able to just walk up, deworm your horse, and walk away.

Clinton Anderson grew up in Queensland, Australia, learning to ride as a teenager and training with many of his country’s top horsemen. In 1997, he relocated to the United States to perfect his Downunder Horsemanship program. Under Anderson’s guidance, horses learn to respect and respond to their handlers, developing willing partnerships.

One Simple Tip for More Effective Deworming

By the Editors of KHAN MUHAMMAD KHAN.

Try this trick to ensure your horse gets the most out of his deworming mediation,A least 10 minutes before you administer dewormer, restrict your horse’s access to forage or grain. That way, he won’t have a partially chewed wad in his mouth to get in the way of the dewormer or to aid his efforts to spit it out.

You may be quite adept at squirting paste dewormer into your horse’s mouth. But even with the best technique you won’t succeed in delivering the medication if you don’t make sure his mouth is empty first.

Either remove his hay and grain or tie him so he can’t reach them. If you suspect he’s still concealing a last bite, carefully open his mouth by placing your fingers in the toothless bars, as you would if you were inserting a bit. A little thumb pressure against his tongue will encourage him to swallow. If necessary, use a catheter-tip syringe to flush his mouth with water.

When you’re sure that your horse’s mouth is empty, deliver the medication and watch for a moment or two to verify that it doesn’t come back out. Dewormers are formulated to be extra sticky and cling to the roof of the mouth, so it’s unlikely any will escape.

The Skinny on Tapeworms

By HAMEED KHAN.

Tapeworms may not be completely harmless to your horse but they are easy to control.

While grazing, horses can ingest mites containing tapeworm larvae.

If you had to live as a primitive animal, being a tapeworm wouldn't be so bad. Imagine a perpetual vacation at a Caribbean resort, where you have nothing to do but bask languidly in the sun, while an unending stream of wait staff carries to you all the food and drink you desire; you don't have to move a muscle as you dreamily contemplate the poor blokes struggling to meet their deadlines back at the office.

That's not far from a tapeworm's existence. Unlike most animals, who spend their lives evading predators while battling for food, mates and territory, tapeworms spend their adult lives in warm environments safe from predation, bathed in a continuous stream of nutrition.

OK, the scenery may be nicer on the beach than inside a horse's intestine, but tapeworms don't have eyes, anyway. The point is that tapeworms live a pretty stress-free life, and it's really in their best interest to avoid damaging their host-injuring the horse would mean jeopardizing their only source of survival. In fact, tapeworms are among the least dangerous internal parasites your horse can have. "There have been some studies that have been able to correlate the presence of tapeworms with certain disease signs but most horses probably don't suffer anything remarkable," says Craig Reinemeyer, DVM, PhD, a parasitologist with East Tennessee Clinical Research. "If you were leaning over the fence looking at a horse with tapeworms, you probably wouldn't notice anything at all wrong with him."

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When they do appear, the outward signs of tapeworms-frequent mild colics, unthriftiness, mild diarrhea-are easy to miss or to mistake for other conditions. But if a horse is consistently "off"-dull coated, not gaining weight as fast as he should, colicking frequently-and all other physical maladies have been ruled out, tapeworms may be the culprit.

The generally benign nature of tapeworm infections is good news because many horses have them. "Surveys here have shown that 50 to 60 percent of horses that died from various causes and were necropsied here also had tapeworm infections," says Eugene T. Lyons, PhD, a parasitologist with the University of Kentucky's Gluck Equine Research Center. That infection rate has been consistent over the past few decades. In separate surveys published in 1983 and 2000, Lyons and his colleagues found the tapeworm Anoplocephala perfoliata in 54 percent and 52 percent of the horses they examined in Kentucky. Infection rates vary from region to region, however. "We find tapeworms in as few as 5 percent to as many as 25 percent of the different populations of horses we study," says Reinemeyer. "But we have found individual farms where the rates can go to 60 percent or higher."

A Tapeworm's Life

Because tapeworms pose a relatively small threat to horses, they have received much less research attention than more dangerous worms, such as strongyles. "We know so much about other parasites and so little about this one because it usually doesn't cause serious problems," says Lyons. "It's also difficult to reproduce the tapeworm life cycle in study conditions."

Researchers do know how the tapeworm's life cycle works. An adult tapeworm consists of a head-that attaches to the intestinal wall with a set of suckers-and a segmented body; each segment contains within it a complete set of reproductive organs that can produce eggs independently. As the worm grows, the lower segments separate and their eggs are carried off in the passing stream of digesting food on their way out of the horse's body. Once on the ground, the manure is broken down with the help of oribatid mites; the mites ingest the eggs, which develop into larvae inside their bodies. If the larvae-carrying mites crawl up onto the grass and are eaten by a grazing horse, the tapeworm larvae will settle into a new host.

But many questions remain. "In a site where tapeworms are common, some in a herd will have them and some will not. No one knows why," says Reinemeyer. "Acquired immunity probably plays a big role, and like any type of immunity, some will develop it better than others." Age doesn't seem to matter; tapeworms have been found in horses young and old. "But we've never found any in a horse younger than nine months, so we don't even bother to look anymore," he adds. "We don't really know why."

What Harm Do Tapeworms Do?

No one is quite sure how much--if any--harm these tapeworms inflict on a horse's gut. A. perfoliata, which is by far the most common of the three tapeworm species known to infect equines in the United States, is too small to physically block a horse's intestine, even in relatively high numbers. Its adult size is only 5 to 8 cm long and 1.2 cm wide. And a worm that size isn't likely to "rob" your horse of enough nutrition to seriously affect his health, either. But they can do some damage. "They cause inflammation of the intestinal wall at the site of attachment," says Reinemeyer. "Can it be fatal? In rare cases, yes." A. perfoliata is most likely to attach to the horse's intestine near the ileocecal valve, the point where the small intestine empties into the cecum. "The supposition is that the worms favor that location because the material from the small intestine is very nutritionally rich with sugars and proteins that have already been broken down into forms that may be better absorbed," says Reinemeyer.

Concentrations of worms at that small opening-at about 5 cm in diameter, the ileocecal valve is one of the narrowest points of the horse's gastrointestinal tract-are associated with several health problems. A British study published in 1998 showed that horses with tapeworms were 22 percent more likely to experience spasmodic colic and 81 percent more likely to experience an impaction colic at the ileocecal valve. In rare cases, the inflammation can also cause ulcerations of the intestine, leading to peritonitis, an infection of the abdominal lining. Tapeworms are also believed to contribute to a thickening of the intestinal wall, as well as ileocecal intussusception, a condition where the end of the small intestine "telescopes" through the valve and into the cecum. "The gut basically crawls inside itself, pulling itself inside out, like when you pull off a stocking," says Reinemeyer. "When that happens, the inside layer is squeezed by the outside layer, and it can cause painful colics."

Although researchers have been able to connect the presence of tapeworms with increased prevalence of these conditions, they don't know exactly how the worms cause the problems, if indeed they do. After all, horses can develop these types of colics without worms, and many who carry tapeworms all their lives show none of these signs. "We see many older horses who have a high wormload and yet never developed any pathological changes," says Lyons. "Just because the worms are there doesn't mean they are causing problems. But people should be aware that they sometimes have been associated with serious detrimental effects, especially in younger horses."

While grazing, horses can ingest mites containing tapeworm larvae.

A complication of tapeworm research is the fact that most of the data about tapeworms are derived from counting them in dead horses. In living horses, it's difficult to know whether tapeworms are present because their eggs are notoriously hard to find in standard fecal float tests, which analyze the number of parasite eggs that come to the surface when a manure sample is mixed with a dense salt solution. "Their eggs don't float very well," says Lyons. In addition, tapeworms release eggs only intermittently, so the fecal exam would have to be repeated every day for several days. All of which means that the presence of tapeworms can easily go undetected unless the horse is carrying a particularly heavy load.

"The number of worms in a single horse can reach the high hundreds-800 or 900," says Reinemeyer. "We commonly find as many as 150, but the average is probably less than 100. But no one has been able to prove an association between the number of tapeworms and the onset of disease."

Risk Factors

Horses get tapeworms by ingesting oribatid mites that carry tapeworm larvae. Oribatids are a superfamily of mites that live in different ecosystems all over the Earth, including Antarctica, and they play a vital role in recycling organic wastes. "Their job is to help improve soil fertility by eating organic matter, excreting it, and mixing it up within the soil," says Merijo Jordan, DVM, a graduate student at the University of Florida who has studied the tapeworm life cycle. "They are little decomposers." About 7,000 species of oribatids are thought to live in the United States, says Jordan, but only 14 genera are known to act as intermediate carriers of A. perfoliata eggs.

Oribatid mites are present in every grassland in the country. "Usually, when we are doing a study we can find 30 to 50 species on a pasture in a temperate zone," says Jordan. In her studies in Florida, Jordan has counted a range of different species in the upper teens and lower 20s. "Generally, about half are suspect carriers." But the mites themselves pose no threat for horses. Oribatids are free-living animals, not parasites; they live on every pasture, whether or not the tapeworm eggs are present. Nevertheless, tapeworm infections are likely to be more prevalent under climate conditions that favor larger populations of the mites, so researchers are working to understand the living conditions oribatid mites like best.

"Temperature and humidity are thought to rule where the mites live," Jordan says. "In the dawn and dusk, they seem to like to move up onto the grass. In the heat of the day, they will be down in the top layer of soil, and when it's really hot or really cold, they'll go down deeper into the soil." But Jordan cautions that these behaviors are not absolutes, and pulling a horse off pasture at certain times of the day is not likely to have any effect on whether he will ingest the mites. As of yet, there is still no absolute way to predict what time of the day or what season of the year the mites are most likely to be active-and the most likely to cross paths with grazing horses.

"We're also still trying to figure out how humidity affects oribatid populations," says Jordan. "Most of the work seems to be in the temperate regions. The mites are probably not as prevalent in the arid climates, but no one has proven it." Reinemeyer suspects that horses in the West and Southwest, where larger ranges are more common, are less likely to graze over areas tapeworm eggs have been deposited. "In my studies, we've never seen tapeworms in horses from those regions," he says. "That's not scientific, but my general impression is that they are more likely to occur in horses from the Eastern pastures and on the West Coast."

Because the mites live in green grass, it seems likely that horses on pasture are more at risk of encountering tapeworms than are horses kept stabled and fed only hay and grain. "But some confined horses could still be at risk, especially if they are fed green chop recently cut from outside," says Reinemeyer. "There is also some evidence that round bales, because they sit outside, may still provide a reasonable habitat for mites, especially if the bales sit on the ground, where the hay may still harbor moisture."

Deworming Strategies

The first equine dewormer formulated specifically to control tapeworms was recently approved by the Food and Drug Administration and should be available to the public by the end of the summer. Zimecterin Gold, manufactured by Merial, controls 61 species of equine parasites, including tapeworms. The new product combines two active ingredients, ivermectin, an anthelmintic agent common in many equine dewormers, and praziquantel, a drug used to control tapeworms in dogs and cats. According to Merial, Zimecterin Gold can be included in any deworming rotation program. "We recommend treating for tapeworms at least twice a year," says Duane Maye, DVM, product manager for Merial. "The fall and spring are good times to treat for tapeworms, But you could use it at any point in the year." Zimecterin Gold will be available through veterinarians, tack and equine supply catalogs.

Tapeworms are rarely a problem for horses, so they haven't received a lot of attention, but they may occasionally cause serious trouble. Tapeworms are sometimes the culprit in horses who mysteriously fail to thrive or develop frequent digestive problems, and it may be wise to consider taking preventive action against these worms, even if you're not sure whether they're present. "Unlike other parasites, which can really cause serious problems, we can't predict what tapeworms will cause," says Lyons. "But there's always a potential for trouble. We don't want people to overreact, but this is a problem we want people to be aware of."