The word "laminitis" can send a jolt of fear through any horse owner. Certainly, you need a healthy respect for the disease. But you can get control of laminitis by following?a three-prong approach-diagnosis, diet and medications, and trim.
Laminitis can have many causes. The one we usually think of is when a horse overeats grain or large amounts of lush, green pasture grass. Other causes include severe colic, some drugs (corticosteroids), serious infections (such as salmonella), Potomac Horse Fever, systemic strangles, Lyme disease, retained placenta, and exposure to black walnut or other toxins.
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When laminitis stems from one of the above, it's usually not difficult to identify the cause. However, a growing number of horses develop laminitis without any of these triggers, and the underlying cause for these cases is hormonal or metabolic. Recurrent problems are the rule rather than the exception, and the laminitis can get to the point that the horse is in pain more often than not.
The future of these horses has often been dim, with traditional treatments having low success rates. As we come to understand better what's going on, though, it's been possible to put together a plan for identifying the causes and bringing them under control at the same time as the feet are receiving correct care so that they can heal.
Limit the Impact
- Find the cause of the laminitis, so the culprit(s) can be eliminated or controlled.
- Feed the horse a proper balance of protein, vitamins and minerals to help repair his feet.
- Adjust his daily diet to achieve and maintain the ideal body weight.
- Discontinue use of anti-inflammatory drugs after the acute phase has passed.
- Get and maintain a correct trim to make the horse comfortable and to lower the risk of further damage.
Unless the cause of the laminitis is removed or controlled, it's unrealistic to expect long-term improvement. If the cause is unknown, your vet will need to do blood work to check for any signs of infection, a blood chemistry analysis for organ function, and a blood insulin level test (which means your horse gets nothing to eat except hay for at least four hours before having his blood drawn).
Middle-aged to older horses should also be screened for Cushing's disease, which is caused by a pituitary tumor. A serum ACTH level is the safest Cushing's test to perform in horses with a history of laminitis.
This detective phase is very important because the results will dictate what the horse needs for treatment, and if there are special dietary concerns.
Meals and Medications
Regardless of the cause of the laminitis, the horse will need a diet with adequate protein, vitamins and minerals to repair the feet. Because the horse won't be exercising until the repair process is completed, you'll need to carefully match how much the horse is fed to his body condition so that he doesn't become overweight, which mechanically stresses the feet.
Free-choice hay is usually the best place to start, along with a vitamin, mineral and protein supplement that matches your hay. If the horse is overweight, but developed laminitis from a cause other than insulin resistance, you can still use the insulin-resistance diet guidelines below or implement the tips in our "Lean Cuisine" article. (See the April 2006 issue of Perfect Horse.)
If your horse is laminitic because of insulin resistance, diet is absolutely critical. Even if the horse is insulin resistant because of Cushing's disease, odds are that medication may not be enough to completely control the insulin resistance and avoid laminitis.
The most critical point is to reduce your horse's level of sugar and starch. Both sugars and starch cause blood glucose levels to rise, and insulin along with them. Items on the forbidden list include:
Grain in any amount, including in treats or as an ingredient in complete or senior feeds
- Apples or other fruits
- Fresh grass
- Oat hay or other grain haysFor reasons that aren't clear, alfalfa hay can cause problems for some laminitic horses. Others are okay with it, and the sugar and starch level in alfalfa is often lower than in many grass hays.
Horses with insulin resistance may vary quite a bit in how sensitive they are to the sugar and starch levels in their diets, but for many, even the levels found in grass hays may be too high. Most do okay with a combined sugar and starch level of 10%.
The only way to know for sure how high your hay's level of sugar and starch reads is to have it tested. This can be done at Litchfield Laboratories, www.litchlab.com, or Dairy One, www.dairyone.com. These labs can also test mineral levels in the hay.
Laminitic horses do well with minerals balanced to the following ratios:
- Calcium:magnesium:phosphorus: 2:1:1
- Copper:Zinc:Manganese: 1:3:3
- Iron:Copper: no greater than 10:1
Insulin Resistance is the Enemy
We've long known that overweight horses, many ponies, pregnant mares, and older horses with pituitary tumors (Cushing's disease) are at high risk for laminitis. But a connection between them wasn't obvious. Heavy body weights stressing the feet, hypothyroidism, and "rich" pastures were often blamed. But not all cases fit neatly into these boxes. Worse yet, treatments aimed at what was thought to be the cause, like drastic cuts in rations or thyroid supplementation, didn't correct or prevent the problem.
Ponies are often less sensitive to insulin (i.e., insulin resistant) than full-sized horses. Horses with pituitary tumors commonly develop insulin resistance as a consequence of high circulating levels of naturally occurring corticosteroids. In 2002, Dr. Phillip Johnson at the University of Missouri coined the term "equine metabolic syndrome" to describe horses that had insulin resistance but not pituitary tumors, associated usually with being overweight and being at risk for laminitis.
Back in 2001, I had done a field trial of magnesium supplementation of cresty, overweight, laminitic horses and ponies, which is an old European "folk remedy" for grass laminitis. Magnesium also happens to be a common deficiency with insulin resistance. A pretty clear pattern suggesting insulin resistance as the common denominator in these different laminitis scenarios was emerging.
Although many researchers were at first skeptical of the idea that insulin resistance could exist in horses that didn't have a pituitary tumor, testing has shown beyond a doubt that it does. Most recently, a group of researchers from Virginia Polytechnic studied a large herd of Dartmoor and Welsh ponies, confirming that the risk of developing laminitis on pasture was tied to insulin resistance. The study showed that all ponies studied with a history of pasture laminitis had insulin resistance while none of the non-laminitic ponies did. In addition, the study found that the insulin resistance and tendency for pasture laminitis were likely hereditary in this group of ponies, showing a pattern of dominant genetics.
If you can't test your hay because you are constantly changing it, the next best option is to soak it before feeding to draw out some of the sugar. The more water used and the longer it is soaked, the better the results will be, although some hays do not show a drop in sugar with soaking. Hay should be soaked a minimum of half an hour in hot water, or an hour in cold water.
If you will be feeding soaked hay with unknown mineral profiles, or that changes all the time, at least check with the state university of the area where the hay was grown to find out what mineral deficiencies and imbalances are common, and to get advice on supplementation.
Beet pulp is also very safe to feed these horses. Rinse it well before soaking so that any molasses is rinsed off.
The diet is rounded off with 2,000 IU of vitamin E per day for a full-sized horse, 4 ounces of flaxseed (whole, freshly ground, or ground stabilized), and an ounce per day (2 tablespoons) of iodized table salt in winter, 2+ oz./day in summer.
If the horse needs to lose weight, limit hay to either 1.5% of current bodyweight or 2% of ideal bodyweight, whichever is greater, to start. Do not put an insulin-resistant horse on severely limited quantities of hay because that will only make it worse. Limit how much beet pulp you feed since that has about twice as many calories as hay.
Currently, no medications are available to treat insulin resistance. Even in people, where several drugs are available, none works better than diet.
If your horse has Cushing's disease, pergolide is the drug of choice and will be needed in addition to the diet changes to keep insulin resistance under control. Some horses do well on the herbal alternative, Vitex agnus-castus, or "Chastetree berry." However, this herb is still being studied to determine best dosages, best candidates, etc.
In acute stages of laminitis, phenylbutazone or Banamine will be used to get control of the active inflammation. Once the acute phase is over, it's best to limit or discontinue anti-inflammatory drugs, even if your horse still has pain. Long-term use may produce side effects such as stomach or colonic ulcers and/or kidney damage. They may slow healing or the exiting of abscesses and fluid collections from the laminitis. Plus a horse may move around too much on weakened feet if he does not have pain to guide him, causing more damage.
Acepromazine is often used to encourage dilation of the blood vessels in the feet and keep blood flowing. Another drug sometimes used for this is isoxuprine, although its effectiveness is questionable.
Last on our three-point checklist, but absolutely essential, is correct foot care. Unfortunately, this is often where most owners have trouble getting competent help for their horses.
Many opinions exist regarding what should be done with a laminitic horse's feet, and the topic is far too involved to go into here. It's also true that what makes one horse more comfortable won't necessarily help the next. Each case must be approached individually, but a few general truths apply to all horses.
Step I: Get your vet to take radiographs of the feet, pull the horse's shoes, and apply Styrofoam to the feet. A good protocol to follow can be found at the Northern Virginia Equine website (http://www.equipodiatry.com/hoofsupt.htm). If you have, or get, hoof boots, the two pieces of Styrofoam used with this method can be taped together and placed inside the boots.
- ACTH-a hormone produced by the pituitary gland that causes the adrenal gland to produce cortisol. ACTH is increased in horses with Cushing's disease.
- Cortisol-a hormone produced by the adrenal gland. Too much cortisol interferes with the action of insulin.
- Insulin-hormone produced by the pancreas, needed to get glucose from the bloodstream into the muscles and other tissues.
- Insulin resistance-a pre-diabetic state where the cells are not as sensitive to insulin as normal, with the result that higher levels of insulin are required to keep blood glucose normal and get the glucose into the cells. This may simply be the horse's normal metabolism, or may be the result of high cortisol output in Cushing's disease.
- Laminitis-inflammation of the tissues (laminae) that secure the coffin bone to the inside of the hoof wall
Step II: As soon as the x-rays are available, get your farrier/trimmer out to trim the horse according to the x-rays. The goal is to shape the hoof wall to conform as closely as possible to the position of the coffin bone. This will involve removing any excess toe and lowering the heels so that the cartilage wings on the coffin bone are parallel with the ground. The bottom of the bone itself will then be sitting about 4 to 5 degrees higher than ground parallel. Once the horse is correctly trimmed, reapply the Styrofoam supports.
Step III: Apply a dot of nail polish to the very top of the hoof capsule under the bulbs of the heels and another dot directly in the center of the toe under the coronary band. Check the position of these dots every five days. If you see the dots at the heels growing down faster than the one at the toe, get your horse trimmed again immediately, and get a trim as soon as the dots have grown down a quarter-inch. The reason for the dots is that horses with laminitis often grow their hooves quickly but unevenly. This rapidly destroys the benefits of the initial trim.
Failure to get and maintain a correct trim puts the horse at risk of further damage to his feet. Staying on top of the trim is essential to making the horse comfortable.
The Styrofoam does more than just cushion the feet, although that's a big plus. It also distributes weight bearing over the entire bottom of the foot, rather than just along the hoof wall. This helps protect from further tearing of the weakened laminae because every time the horse's foot contacts the ground, the hoof wall naturally tends to spread out, which pulls on the laminae.
The Styrofoam should stay in place for as long as the horse is more comfortable with it on than he is with it off. This may be a week, or it may be months. Every case is different.
A variety of shoeing suggestions are also available, some extremely intricate. When used by someone highly experienced with the technique, they can be very effective. Unfortunately, it's often difficult to find someone who sees a large number of laminitis cases on a regular basis.
The major drawback to shoes, especially early in treatment, is that you can't get to the feet to trim them frequently enough. No shoe can ever take the place of a correct trim, and every bona fide shoeing method has the correct trim as a starting point.
Far too often shoes are applied without a correct trim first, or they are left on longer than they should be without a trim. This is like putting a broken bone into a cast without realigning the fracture.
Laminitis isn't simple. Caring for a horse that's afflicted takes effort to get all three components-diet, medication and trims-right. However, realizing that there's no magical drug, supplement, diet, trim or shoe that can fix this problem on its own is half the battle. If you keep the big picture in mind, you can beat it.