August  2005

Idaho’s Hidden Creek Ranch
Offers Riding and More by Susan Seligman... 8
Laminitis: New Ideas on a Devastating
Disease by Doug Thal, DVM... 10
Show Clothes: Balancing Trend and Tradition by Christina Fleming.. 12
Focus on Mules by Sophia Sarember... 13
Western Fashion Forecast by Suzanne Drnec 14
A Horse Of Course by Don Blazer... 16
Carbohydrates: One of the Basics of Diet
by Heather Smith Thomas... 33

d e p a r t m e n t s
NM Quarter Horse Association Newsletter . . . . . . . . 22
Stallion Showcase  . . . . . . . . . . . 18
News Briefs . . . . . . . . . . . . . . . . 26
Calendar of Events . . . . . . . . . . . 34
Breeders Directory. . . . . . . . . . . .46
Instructor/Trainer Directory . . . . .46
Classified Advertising . . . . . . . . . 47
Equestrian Property . . . . . . . . . . .53
Classified Advertising/Subscription Information. . . . . 62
Advertising Rates & Information..  62

Laminitis: New Ideas on a Devastating Disease Part One


Laminitis (known by horsemen as founder) is a disease of the feet that is a common and serious form of lameness in equines (horses, donkeys, mules). The disease is
among the most costly to the equine industry. It causes severe and debilitating lameness, loss of use and often necessitates euthanasia. It is a very frustrating disease to deal with. It can seemingly come out of nowhere, or can follow as a sequel to other serious diseases which might themselves have been treated successfully and resolved.

The mechanisms of laminitis have been studied intensively for many years but there is still much that is not understood. Recent findings have contributed more to our understanding. The purpose of the first part of this article is to define
what laminitis is and current ideas on how it happens.
The next part will discuss some mainstream approaches and new ideas with respect to treatment and prevention.

The Signs of Laminitis Laminitis typically results in very severe lameness which is usually worse in the forelimbs than hind limbs. Anyone who has witnessed a horse with laminitis is unlikely to forget it. In an effort to avoid bearing weight on the very painful front feet, horses show a characteristic stance with the hind limbs pulled far under the body and the front feet far out in front. They may lie down
to get off the feet entirely. Less painful laminitis often results in a horse that looks like he is “walking on eggshells.”

How Foot Structure Relates to Laminitis
While other grazing animals may get laminitis, none show the dramatic signs that
equines do. In order to understand the mechanism of laminitis, it is important to understand the basics of equine foot structure. Equines are the only family of mammals that have evolved to walk on the tip of one finger (digit). The equine foot is a real miracle of engineering. The entire weight of the horse is borne by the coffin bone, which is suspended above the sole of the foot by its attachments to the outer hoof wall. This unique attaching layer is called the laminar layer. 

 The real key to understanding laminitis is to understand that a mechanism exists in the normal foot which allows the coffin bone to be securely suspended by the hoof wall, but also allows the hoof wall to slide over the bone as it grows. The coffin bone (pedal bone, or P3) is attached to the outer hoof wall by the laminar layer. You can see the laminar layer on the sole of a newly trimmed foot as the "white line," just inside the outer hoof wall. Microscopically, the white line can be seen to be made up of two layers of laminae, one that is attached to the outer hoof wall and one attached to tissues firmly glued to the underlying coffin bone. The attachment between these two laminar layers is an active process involving thousands of interconnected and branching microscopic fingers of live tissue between the coffin bone and outer hoof wall. The millions of live cells making up these
fingers of attachment are under precise control by signals from the body and local signals from the foot tissues.

 I like to use Velcro as a model to illustrate the laminar layers. Imagine the coffin bone glued to the soft Velcro layer. Now imagine the outer hoof wall glued to the rough Velcro layer. The Velcro surfaces come together at the white line. Now imagine that there is precise control of this attachment which allows limited sliding of the hoof wall over the coffin bone. Tiny releases and reattachments constantly occur to allow the hoof wall to grow down from the coronet band (the hairline of the hoof).

Protruding into and between these laminar layers is a fine web of tiny blood vessels that bring oxygen and other essential nutrients to the cells.

 At any one time, the cells making up these fingers are mainly adhered to one another. Precise control of the laminar cells allows movement of the hoof wall along the coffin bone while never completely releasing it and thus never allowing it to alter its position within the foot.

The Mechanism of Laminitis
The word “laminitis” means “inflammation of the laminae”. It is a disease that involves dysfunction of this unique system of attachment. It can progress to allow complete breakdown of the structure of the foot.

 The old mechanism for laminitis that I learned as a vet student involves blockage of the circulation to the laminae, leading to cell injury and stretching of the laminar attachments. New research has shown that certain biochemical “laminitis triggers” can cause over-activation of this release mechanism, allowing the coffin bone
freedom to move within the hoof. Horses undergoing undergoing this "over-release" show the signs of laminitis.

To what degree the coffin bone moves is dependent on many factors but, in general, the more movement of the coffin bone, the more severe the damage, and the less likely the horse is to make a complete recovery. Understanding
the new concept of laminitis triggers is important. Any substance that can function as a trigger can cause the mechanism of laminitis. The blockage of blood supply to the laminae is likely a later contributor, but the main event in initiating laminitis is this over-release of the laminae caused by the laminitis trigger.

 Where do these laminitis triggers come from? Classically, founder has been thought of as a disease resulting from grain overload. Unlike cattle, which ferment feed in a rumen “foregut,” horses are known as hindgut fermenters. This is because the large, specialized “hindgut,” or large colon is the place where the tough structural components of grass are broken down by the action of bacteria. Ordinarily, simple sugars and starch are absorbed upstream of this by the small
intestine before many reach the colon. An overload of this system with sugar or starch (from a sudden load of grain or other high starch feed) allows increased starch or simple sugar to reach the colon. This can result in a die-off of the normal bacteria here and a shift to new types and numbers of bacteria. Some of these new bacterial types may produce substances that act as triggers, and result in the signs of laminitis.

 There are many other laminitis triggers. Bacterial toxins coming from retained placenta, abdominal infection, or from intestine damaged by a colic episode, are examples of triggers. There are specific toxins found in nature which are known to be direct triggers. An example of this is a toxin found within Black Walnut wood shavings.

Predisposing Causes
 Anything that makes the laminar cells more susceptible to a trigger will increase the chances of a horse developing laminitis. Genetics plays a role in the sensitivity of a given horse to laminitis triggers. Some breeds are more sensitive than others. Endocrine disorders (hormonal problems such as Equine Cushings disease or “Equine Metabolic Syndrome”) can predispose horses to laminitis by increasing sensitivity to triggers. A horse that has had prior laminitis episodes is more sensitive as well.

 For a variety of reasons, horses that are abnormally fat are more predisposed to developing laminitis than a horse in normal body condition.
Obesity may cause specific problems with the circulation in the foot. This in turn may interfere with delivery of oxygen and nutrients to the live cells of the laminae. Because of this, these laminar cells may be more sensitive to the action of a trigger.

 Reaction to any trigger causes the same end resulT either over-activation of the releasing mechanism, or damage to the live cells themselves. Either alone or together, these two factors allow movement of the coffin bone within the hoof. Once the coffin bone rotates or moves within the hoof, the live layers of the sole may be crushed and the blood supply to the laminae damaged. This further contributes to a cycle of destructive events in the hoof which ultimately can break down the entire structure.

 In the next part of this article, we will look at ways to prevent and treat laminitis in its acute and chronic forms. We will pay special attention to some new research regarding feeding and grazing management to avoid this serious problem.

Doug Thal, DVM is a veterinarian at Thal Equine in Taos,
New Mexico. Contact Dr. Thal at info@thalequine.com or
visit their website at www.thalequine.com

Hard-Mouthed Mule Part two


In the last issue we began to discuss retraining a mule that is unresponsive to the bit. Ground work is where training starts, and it is often the best place to regain control of a misbehaving mule. However, not everyone likes to ground drive or has the experience to do it. Many good horsemen and muleteers break a riding equine to ride and never ground drive them at all. If you prefer to omit ground driving, you should still work with the mule “in-hand” (halter sessions). You should also work with your mule on the lunge line, teaching it to be completely obedient to voice, whip and line commands. Then you will have a good foundation for under-saddle work.

 When I start riding a hard-mouthed mule I use a snaffle bit and work the mule in a small corral or an arena where I am certain the mule will not bolt or get upset. A trainer should always try to set themselves up for success by “manipulating the environment”. For instance, I don’t take a hardmouthed mule out in a big open field—or in an arena next to other horses that are turned out and may run, play or otherwise disturb your mule. I work the mule where I know I will not be distracted, have a reasonable assurance of control, and where I can maintain the upper-hand. As a result, the training session is likely to be much more successful.

 If the mule is difficult to handle under-saddle with a smooth snaffle, I will try a mild-twisted one. If the mule will not work easily with a mild-twisted snaffle, then I will use draw-reins and a smooth, gentle snaffle—usually a full cheek or “D” bit. If you use draw reins under-saddle, attach the ends of the reins to the billets (English saddle) or dees/rigging rings (Western) on the side of the saddle about the level of the mule’s head. Never put the drawreins between the mule’s legs and attach the ends to the girth/cinch. This configuration is sometimes used by horsemen, but with mules, this method of attaching the draw-reins is not recommended. With the draw-reins leverage point low and between the mule’s legs, the mule can “curl up in a ball” and buck like a first class rodeo star. In addition, the mule can be better at avoiding contact, get behind your aids, and usurp your efforts to maintain
control.

 If I work a mule in draw-reins and a smooth bit, then I will use regular
reins and a twisted bit in alternate training sessions. It is important to keep
the mule interested in its work and avoid resorting to pulling and heavy-handedness.
Work the mule where you are confident that you will be able to maintain control.



Next Month: Hard-Mouth Mule Part Three


Sophia Sarember is a trainer, writer, and “muleteer” living in Edgewood, NM. She can be reached at Mulegal@aol.com.