Dr. James Orsini

Laminitis is one of the most dreaded equine diseases. Many horses affected by it eventually develop severe or chronic lameness.

Dr. James Orsini, former director of the Laminitis Institute at the University of Pennsylvania School of Veterinary Medicine’s New Bolton Center, is well-acquainted with the disease. He has seen many laminitic cases as a complication relative to a number of problems. Although laminitis can be successfully treated, it is often a lifelong process that requires considerable time, expense and energy.

Orsini shared his insight about the disease in an American Farriers Journal Online Hoof-Care Classroom webinar “Laminitis: Research and Recommendations on Management for Horse Owners and Horse Care Professionals,” sponsored by Ice Horse.

Understanding the causes of laminitis, Orsini says, helps farriers to prevent and detect early signs to keep the disease from escalating.

Identify the Underlying Problem

The causes of laminitis usually can be broken down into three major etiologies, Orsini says. The one that creates the most devastation to the foot is systemic inflammatory response system (SIRS). The second cause is equine metabolic syndrome, in which the horse becomes insulin resistant. The third is support limb laminitis, in which one limb is injured and the other limb is overloaded while the injured limb heals.

“There’s a fourth, too, that sometimes you’ll hear about called ‘road founder,’ or repetitive injury,” Orsini says. “Those are horses that run on hard surfaces and constantly have concussion to the footfall.”

Each of the three primary causes, at some point, result in inflammation of the lamellar tissue, which acts like a glue that bonds the hoof wall and the coffin bone. When the tissue becomes inflamed, that tight bond and the basal cells and basement membrane start to fail, Orsini says. That’s when the coffin bone starts to rotate.

“When we see the rotation radiographically, you’ll hear the term ‘founder.’ Founder really designates a radiographic change where the coffin bone is actually rotated or dropped, and is no longer fully attached to the hoof wall. That’s important. What we hope to do is try to recognize the disease before we get that failure that occurs,” Orsini says.

Systemic Inflammatory Response System (SIRS)

Several types of conditions can cause SIRS including colic or a twisted intestine, a retained placenta, pneumonia or pleuritis, endotoxemia, trauma, ischemia, immune-mediated diseases, surgery, hypo- or hyperthermia, profound hypoxia and hemorrhagic shock. The resulting systemic inflammation targets specific organs, Orsini says.

“In people, inflammatory mediators target the lungs or the liver,” Orsini says. “In horses it’s the foot, lung or liver. The foot, in particular, is the one that fails.”

Horses succumbing to a SIRS exhibit very specific signs including:

• Elevated temperatures on the high and low end of the spectrum (101.5 degrees Fahrenheit or higher, or 98 degrees Fahrenheit or lower).
• Elevated heart rate (in excess of 60 beats per minute.)
• Fast breathing (tachypnea) or hyperventilating
• Abnormal white cell count (very high or very low)

“These are signals to us that these horses are at risk for SIRS and need to have something done to protect their feet,” Orsini says. “It’s a very acute, very rapid occurring disease, that can target the foot and result in failure of the foot at a very rapid rate. These horses need to be treated aggressively to prevent the disease.”

Equine Metabolic Syndrome (EMS)

EMS is something that has become much more commonplace, for a couple reasons, Orsini says. First, health care has gotten better over the last 20 or 30 years — this is true for humans and horses, too.

“What we now have is an older population of horses that are maybe less active but they’re still being fed the same way, and they start to put weight on. What happens is, like in people, they become insulin resistant. In other words, their ability to manage sugar becomes dysfunctional.”

Unlike SIRS, EMS is insidious and signs are not as easy to detect. Horses may have sore feet, but it’s not as though they become crippled, Orsini says. Some may look like they are in great shape, but can still be at risk. Monitoring diet, weight and activity are all important parts of prevention.

“Think about the older horse, the horse that’s less active, the horse that may be a little bit overweight,” Orsini says. “Think about testing insulin levels in advance as part of annual health care in order to try to be proactive, rather than reactive.”

Supporting Limb Laminitis

The classic case of supporting limb laminitis that most people remember is Barbaro, Orsini says, who had a severe injury in one of his hind limbs—a fracture—and developed laminitis in his supporting limb, and then ultimately in his front limbs.

“This is a little bit of a different variation from the other two causes,” Orsini says. “We think that actually, there’s a vascular problem where the foot is being starved of oxygen and glucose; the things that it needs to survive. What happens is that over a period of time, three weeks seems to be about the average, the foot starts to fail.”

Orsini advises nurturing the “good” foot and treating the “bad.” Provide stability, he says, but also take good care of that other foot by trimming and using support wraps.

“One of the things that we notice in some of these horses, is that they develop an overgrown or unbalanced hoof,” Orsini says. “What this does, it just increases the stress and the strain on the lamellar tissue that supports the coffin bone. The horse with a long toe and low heel increases the pull on the coffin bone and then, over time, if they have a support limb problem, it eventually starts to fail.”

Early Warning Signs

Horses, in two out of the three laminitic etiologies, will offer signs that something isn’t right. Orsini offers a couple of clues to look for:

Bounding pulses. If you look at the foot itself, one of the things you’ll find is that with inflammation, you get these pulses that are very easy to feel on the back of the pastern, and at the level of the fetlock.

Change in temperature. The foot will change in temperature, but for a horse that has a laminitic episode, the foot will remain warm. It actually is almost hot to touch, because of the inflammation.

Constant shifting. Normally, horses will shift their weight on occasion, but a constant shifting tells you that they’re uncomfortable, and that they are trying to get off the foot that hurt the most at that time.

Age and weight. Check the insulin level in the older horse that’s obese, and if they have any inflammatory diseases such as diarrhea, some other infection, pneumonia, or some other inflammatory disease, these are warning signs that those horses could be at risk for laminitis.

Increased heart rate. Take the pulse of the horse and establish a baseline. A healthy horse has a heart rate of 28 to 40 beats per minute.

Thin-soles. In general, thin-soled horses are at a greater risk of developing laminitis, Orsini says, because of the lack of depth between the bottom of the bone and the bottom of the hoof itself.

Hoof Care Treatment at Different Stages

One of the evidence-based treatments that Orsini has found to aid in laminitis treatment and prevention is cryotherapy or “cold” therapy. At-risk horses should undergo cryotherapy for 72 hours. Although it may sound extreme, the horse’s foot actually responds very well to cold temperatures, even those just above freezing. Maintaining temperatures of 10 degrees centigrade (50 degrees Fahrenheit) or less seems to be protective, Orsini says.

“We’ve had, in our experimental studies, temperatures down to three degrees centigrade, just above freezing, and the horse’s hoof never develops frostbite,” he says. “It’s well-tolerated and very effective.”

Orsini uses Ice Horse, but there are a variety of cooling systems available. The key is providing continuous cooling. Ice packs need to fit to the hoof and the pastern to be effective in preventing and managing laminitis.

The importance of a partnership between farriers and veterinarians cannot be overstated when it comes to caring for the foot of the laminitic horse.

“Much of what I think the farrier does mechanically is dependent on what the veterinarian sees radiographically,” Orsini says, who works with farrier Pat Reilly at the New Bolton Center. “We use our radiographs as an important means of trying to determine what this horse needs for mechanical support. Radiographs help guide us, so we know where the breakover is. We know how much of an angle or how much heel we may be able to remove without creating too much stress on the lamellar tissue along the front of the foot, especially knowing that it takes virtually weeks to months for that lamellar tissue to actually heal once there’s been a laminitic episode.”

The challenge, Orsini says, is even with the science, there’s still a lot of art that’s involved, and that is really where experience comes into play.

“Because we’ve all seen what looks to be the perfect shoe to apply to a foot, and yet the patient, the horse, is not any more comfortable,” Orsini says. “You can’t always rely on what looks to be scientifically sound, if the horse is not any happier. This is where I think making those adjustments and, sometimes, it may mean changing the angle by one or two degrees, can make the difference.”

Orsini says looking at the radiographs is just the first step for the veterinarian and farrier. Next, they observe how the horse walks and loads the foot. Information from both steps is part of the equation in determining the appropriate appliance to use.

Initially, a farrier may provide some interim mechanical support, whether that be a boot or a glue-on shoe, Orsini says. He finds many farriers opt for an application to minimize the pounding of nails. However, a correctly applied nailed support system, such as a heart bar remains effective in many situations.

Mechanical support of the foot is a critical part of the treatment, even early on, Orsini says. In the acute stage, the goal is just to provide some cushioning while addressing the underlying cause of the laminitis.

“One of the things that we want to do is protect the foot as much as possible. We may use one of the commercial boots that are out there. We’ll try different soft elastomers. I think one of the things you want to try to do is distribute the weight bearing over as large a surface area as possible, because we know that the hoof wall itself is tenuous, at best.”

If the foot is stable, however, farriers could consider a glue-on shoe with different putty elastomers or even a hospital plate — something along the bottom — so that when the horse is bearing weight, it’s not loading the hoof wall specifically, but trying to use as large a surface area as possible. Radiographs taken at regular intervals along with other clinical signs will help the veterinarian determine when that is achieved. “Generally, when their comfort level stabilizes and they’re on routine medication such as Phenylbutazone or other NSAIDs, their heart rate goes down, their respiratory rate goes down, their vital signs start to improve; those are all clinical signs to me that they are becoming more stable,” Orsini says. “Once they’re stable and the foot itself is not continuing to deteriorate, then something more permanent in the way of a shoeing can be devised or developed. You’re going to find that if they’ve had rotation or sinking, that there’s going to be some change in how they’re shod from that point going forward.”

Learn More

Cryotherapy’s Role in Helping Lame Horses
Researchers examine cryotherapy’s analgesic effects with study of horses with induced lameness.

September/October 2019