Laminitis is an incredibly painful hoof disease in the horse. We should all be very aware of this since despite top-notch care, 2006 Kentucky Derby winner Barbaro was humanely euthanatized due to unresolvable pain from laminitis.

Laminitis strikes with varying severity, causing disparate levels of pain in individual horses; pain management is an important humane aspect of caring for these horses. But many veterinarians say that focusing solely on managing pain is the wrong approach–that the goal should be to provide mechanical support to help the horse’s feet heal, reducing pain with healing instead of just relying on drugs.

Andrea Floyd, DVM, owner of Serenity Equine in Evington, Va., and an equine veterinary podiatrist for the last 23 years, says that the most effective thing an owner can do to reduce pain in a laminitic horse is to seek the help of an equine veterinary podiatrist. Combining a podiatrist’s expertise in mechanical and medical treatment (emphasis on the mechanical) with proper owner care provides the best pain relief and chance for future soundness.

What Causes the Pain?

To understand how to heal the pain of laminitis, we first have to understand just what causes it. Rustin Moore, DVM, PhD, Dipl. ACVS, professor and chair of the Department of Veterinary Clinical Sciences at The Ohio State University, says at least three things likely contribute to pain:

Inflammation­­ sensitizes nerve endings to pain (think of how touchy your finger gets when it has an inflamed cut).

Edema (fluid swelling) forms between the hoof wall and third phalanx (coffin bone) in the foot with laminitis. “Imagine that if you smash your finger, there is swelling under your fingernail, and that physical swelling stretches the tissues and causes mechanical pain,” he explains. “It’s considered a compartmentlike syndrome, causing pain because the swelling is trapped in a compartment (between the hoof wall and the third phalanx).” Accumulation of fluid, serum, blood, or pus can also occur between the hoof and bone, all causing increased pressure and, thus, pain.

Mechanical stretching and tearing of the laminae that attach the hoof capsule to the third phalanx bone in the foot also cause pain. “I use the analogy of tearing your fingernail partly loose, then trying to walk on that,” he says. “Once you get disruption of that laminar interface, that instability leads to pain just from the mechanical stretching, tearing, and pulling on the damaged laminae, particularly as the horse bears weight on the affected foot/feet.”

Inflammation and swelling contribute significantly to pain in the early stages of the disease, he says, while the mechanical stress likely becomes more of a problem a little later in the process.

Quick Action Reduces Damage and Pain

“Anytime you see a horse lying down more than he should, walking stilted, and/or rocking back on his back feet, call your veterinarian immediately,” recommends Moore. “Sometimes it’s difficult to ascertain if the horse is tying-up, has neurologic disease or other problems, is foundering, or is colicking, as all of these can have similar signs.

“Also, any time you discover your horse has gotten into the feed room and eaten excessive amounts of grain, or has gotten out and eaten lush pasture when not used to this diet, you should immediately call your veterinarian to try to prevent the onset or reduce the severity of the impending starch-induced laminitis,” he advises.

While waiting for the veterinarian to arrive and diagnose the problem, he says to keep an affected horse from eating anything and keep him calm in a stall deeply bedded with sand or shavings. Some researchers recommend standing the horse in ice cold water to prevent the onset of laminitis.

Emergency treatment (such as providing soft frog support with Styrofoam blocks, polyvinyl silicone, or other moldable materials) can be helpful in acute cases such as these, Moore adds. Applied appropriately, cryotherapy (cold therapy) can also be helpful in the early stages before a horse becomes lame; he says it provides analgesia and has been shown to prevent laminitis in laboratory situations. There is evidence that prolonged cold/ice therapy for 48 hours will prevent experimental starch-induced laminitis.

Anti-inflammatory medication (such as phenylbutazone or Bute) can help control inflammation, pain, and edema, he adds. “However, it would be best if medications were not given prior to veterinary examination so that an accurate assessment can be made. If your veterinarian cannot examine your horse for a short period, he or she might recommend you medicate the horse; however, you should always check first with your veterinarian before proceeding.”

Mechanical Pain Management

To combat mechanical stretching and tearing of the laminae, one must reduce the forces pulling the coffin bone away from the hoof wall at the toe. This means changing the position of the hoof/coffin bone so the rearward pull of the deep digital flexor tendon is reduced. Another important consideration is to load the healthiest areas of the foot (usually the rear half) to reduce pressure on the damaged areas, giving them a chance to heal.

“You have to remove the obstacles in that foot (i.e., poor digital alignment that stresses the laminae and compromises blood flow) so that Mother Nature can get in there and heal it,” says Ric Redden, DVM, founder of the International Equine Podiatry Center in Versailles, Ky. “We can’t fix the foot, but we can provide a proper healing environment so it can fix itself. My first goal is to recognize the seat of pain and quickly devise a mechanical plan to reverse the forces at play that are contributing to the intense pain.”

Redden uses radiographs (X rays) and venograms to help him assess the damage in a foot and devise his shoeing plan. The venogram procedure involves isolating the foot’s blood supply with a tourniquet, injecting contrast media into the palmar digital vein, then taking a radiograph to see the blood flow within the foot. Areas where blood flow is compromised indicate damage that needs mechanical support to heal. (For more information on venograms, see page 30.)

In nearly all laminitis cases, the toe area of the foot is most affected because the laminae there bear the most direct pull of the deep digital flexor tendon. “Unloading the deep digital flexor tendon in the earliest stage of laminitis is paramount for my cases,” Redden says. “You need to be able to reduce the tension in that tendon so much that you can move it back and forth with your fingers. Simply establishing an 18-20° self-adjusting palmar angle (so the bottom of the coffin bone is at an 18-20° angle with the ground, with the heels higher than the toe) can do this, and usually offers dramatic (pain relief) results within minutes.

“In advanced cases with circumflex prolapse (rotation or sinking of the coffin bone past the circumflex blood vessels that normally run beneath it, following the arc of the bone) or a progressively deteriorating venogram picture, a deep digital flexor tenotomy (cutting the tendon) following proper realignment and decompression shoeing provides pain control, as these methods all enhance the healing environment,” he states. “The same is true for pin casts and wall stripping (taking off partly detached hoof wall and supporting the horse’s weight on a cast built around pins through the cannon bone, ‘floating’ the foot). They are highly effective in pain control situations when indicated. When the mechanics are right, and I have effectively moved the load to more healthy areas of the foot, my cases have an acceptable clinical picture.”

Floyd adds, that, “Trimming and shoeing must correct the digital alignment and restore the blood supply. Most shoeing modalities do not address this.”

Medical/Surgical Pain Management

Phenylbutazone and other painkillers are part of most laminitis treatment regimens, but Floyd notes that they “are used for their anti-inflammatory and analgesic effects–they are simply an adjunct to controlling pain during the recuperative process. They are not the cure in themselves.”

“Probably the most effective painkillers are anti-inflammatories, especially the non-steroidals like Bute, Banamine, ketoprofen, etc.,” says Moore. “Part of the pain probably has to do with different enzymes involved in inflammation– cyclooxygenase (pronounced cyclo-oxygenase, COX)-1 and COX-2. In laminitis, we know there’s an increase in COX-2 very early in black walnut extract- and carbohydrate-induced laminitis. So probably drugs that target COX-2 would be more effective for that. Pharmaceutical companies are developing the types of drugs that would be effective and useful in horses, much like the ones that have entered the human market in recent years.

“Some people use lidocaine systemically (as a continuous 48-hour intravenous infusion, in a hospital setting),” Moore says. “It is a local anesthetic that we use for nerve blocks, but it also has anti-inflammatory activity–it decreases activity of neutrophils (a type of inflammatory cell), so by giving that, you may be decreasing inflammation along with decreasing pain. That’s used more for systemic inflammatory conditions such as endotoxemia, colic, retained placenta, or pleuropneumonia.” In addition to the anti-inflammatory effect, lidocaine does impart some analgesic/pain-relieving effects when administered as an intravenous infusion.

Redden warns that, “Regional blocks and nerving are out of the question for a laminitic horse, as they invariably cause further damage (from the horse becoming overactive on his injured, numb feet) and can offer disastrous results.” In other words, if you completely kill the pain (without healing the feet), you will often kill the horse because he’ll damage his already- compromised feet beyond repair.

Strong medications, including morphinelike drugs, butorphanol, fentanyl patches, and epidurals (spinal cord anesthesia) are most often used for cases when nothing else works, and often as a last resort, says Moore. “Epidurals are only useful for cases of laminitis in the rear feet, and often are used for overload laminitis in a limb opposite a severe lameness, such as was the case with Barbaro,” he comments.

Redden says, “I have used (fentanyl) patches a few times and find them to be helpful, but if I continue needing them, that means things are not going very well. For the same reason, I have never used epidural anesthesia for hind limb lameness. Masking pain without enhancing the healing environment is not compatible with longevity with foot problems. I want mechanics to be the source of my pain control.”

Adjunct Therapies

Mechanics and medicine provide most of the treatment and pain management for a laminitic horse, but a few other things can help these horses become more comfortable.

Deep, soft bedding in a large stall “Bedding and stall size are very important,” states Redden. “Horses don’t like to lie down and get up in a small stall if they are quite lame. My stalls are 17 by 16½ feet, with a rubber floor and 8-10 inches of shavings. I line the walls with straw bales, bank shavings up over the bales, and cover the shavings with another six to eight inches of straw. This has been very helpful, as the 4-foot bank lets the horse ease down without having to drop flat, and it helps him get up.”

Proper diet/weight loss “Some horses that are very overweight and/or have metabolic syndrome or insulin resistance are highly predisposed to laminitis,” says Moore. “In those horses, it’s amazing how much dietary changes and weight loss can decrease recurrent bouts of laminitis. The weight loss helps reduce mechanical forces and pain, and a proper diet will also help control the metabolic problems that lead to a recurrent episode.” (For more information on feeding horses prone to laminitis, see page 51.)

Massage “When a horse has laminitis, they have pelvic tilt and a pronounced lumbosacral ridge on their spines (caused by altered weight carriage as they try to unload their painful forefeet by placing their hind feet nearer to their forefeet) that affect all the muscles of the rear end and lower back,” says Floyd. “They also distort their neck carriage and their shoulders are used stiffly. Massage won’t help the feet, but it will definitely help these other regions.”

Take-Home Message

Managing pain in the laminitic horse means quick, thorough mechanical and medical treatment. The disease must be caught early and aggressive treatment provided to minimize damage and maximize the horse’s chance at a sound, pain-free future. 

Further Reading

See our Laminitis article category at www.TheHorse.com.   

PREVENT LAMINITIS DAMAGE

What’s the easiest way to treat laminitis and the pain it causes? Avoid it at all costs. One of the keys is knowing what situations increase a horse’s risk of contracting the disease and avoiding or managing them.

Rustin Moore, DVM, PhD, Dipl. ACVS, professor and chair of the Department of Veterinary Clinical Sciences at The Ohio State University, describes the following categories of horses at high risk for laminitis:

Systemic illness “Any horse that’s had an inflammatory type of systemic illness such as pneumonia, pleuropneumonia, colic, diarrhea, retained placenta, any of those major inflammatory diseases, those horses are at risk,” he said. “Your vet should be doing things to help support and protect the feet.”

Carbohydrate overload There might also be a time when you catch a horse chowing down in the feed room or mowing down a rich pasture he’s normally not allowed to graze. This means he’s likely consumed an overdose of carbohydrates, which can easily trigger laminitis. “Call the veterinarian immediately, before the horse gets lame,” urges Moore. “A horse that gets laminitis like this will initially seem okay, but 36-48 hours later he’ll founder.”

Overweight/metabolic problems “With horses that are overweight, prone to obesity, and/or have metabolic diseases such as Cushing’s disease or insulin resistance, there’s a lot owners can do to prevent laminitis, such as feeding an appropriate diet, exercising the horse to lose weight, and potentially administering medications like pergolide,” he added. (For more information on feeding horses prone to laminitis, see page 51.)

Black walnut shavings “Obviously, keep them off black walnut shavings,” he notes, as it’s a well-known laminitis trigger–in fact, black walnut extract is often used to induce laminitis in some laboratories. “You can’t really tell just by looking at shavings if they’re black walnut, so get a reputable source for your shavings so they can ensure there’s none in there.”

What’s the common thread here? “Take more of a proactive than a reactive approach,” advises Moore. “You would much rather prevent this disease than treat it