“My horse has laminitis. What do I do?” Even though we might know the fundamentals—cool the feet, provide support, address pain—it can be helpful to ask veterinarians researching the painful hoof disease for updated advice on how to manage cases. Recommendations do change as researchers learn more about laminitis.
Andrew van Eps, BVSc, PhD, MACVSc, Dipl. ACVIM, is associate professor of equine musculoskeletal research at the University of Pennsylvania School of Veterinary Medicine’s (Penn Vet) New Bolton Center, in Kennett Square. He and his colleagues focus on laminitis in the van Eps Laboratory at Penn Vet, working to understand why it occurs in different clinical situations. Along the way they’ve found or confirmed the efficacy of mechanical methods to help both acutely and chronically laminitic horses.
Van Eps reviewed these approaches for veterinarians and farriers during the 11th annual Northeast Association of Equine Practitioners (NEAEP) symposium, held Sept. 25-28, 2019, in Saratoga Springs, New York.
Laminitis occurs when the interlocking laminae, which suspend the coffin bone within the hoof capsule, are damaged or inflamed. In severe cases the laminae pull apart, and the coffin bone rotates downward or sinks. A variety of scenarios, from sepsis (infection of the blood) and endocrine problems to excessive weight-bearing on a limb can cause laminitis. (Learn more about why and how it happens here.) Many horses with the acute or chronic forms of the condition suffer tremendous pain, enough so that veterinarians elect to euthanize them.
Managing Acute and Chronic Cases Mechanically
With laminar inflammation and failure comes a need to unload the hoof wall and reduce the lever arm of the foot. Think of the bones in the limb and hoof as levers; if the toe is quite long, then the load on it is increased as the foot breaks over during movement, which is painful for the animal with laminar inflammation. Van Eps has several ways he supports the horse and attempts to reduce that lever arm.
- He uses solar impression material as a first line to unload the hoof wall: “There are some fantastic boots out there that you can build custom impression material inserts into,” he said.
- He recommends standing horses with acute severe laminitis on sand. “It conforms to the frog and sole,” he said. “It transfers load from the hoof wall to the frog and sole, it allows ease of pivoting so it will give underfoot and reduces that torsional stress on the wall, and it enables the foot to find its own comfort zone a bit. It reduces that moment arm lever on the toe during breakover.”
He acknowledged sand is difficult to manage in the barn; it’s heavy and is difficult to keep dry, and it must stay dry to be useful for these cases (it gets hard if it’s allowed to get wet/soiled). Some horses do not like to lie down in sand, so he recommends putting it where the horse is most likely to stand and then bedding the rest of the stall. Despite the inconvenience, “I don’t think you can beat it for an acute case.”
In fact, he said, standing on sand and soaking in ice water are the two things that help severe acute laminitis the most.
There aren’t many new mechanical ways to manage the severe acute laminitis case, said van Eps, but he referred to an in vitro (in the lab) study in which researchers assessed how trimming the hoof wall affected laminar tissue damage in cadaver limbs. When they thinned the hoof wall by 25%, it translated to a more deformable hoof that sustained less lamellar damage when it was loaded. “I’m not advocating people do this now,” he said, noting that increasing water content in the foot is another way to make a foot more deformable, “but it’s definitely food for thought.”
Van Eps considers chronic cases due to underlying endocrine disease (PPID or EMS) “our nemesis,” because signs can be very mild and easily missed by veterinarians, and these cases can be difficult to treat. “Look for (hoof growth) rings that are further apart at the heel than they are at the toe,” he said.
He encouraged veterinarians to use radiographs as a screening tool, looking for mild changes including increases in the measured thickness of the dorsal hoof wall and remodeling of the dorsal surface of the coffin bone that might indicate subtle early laminitic change. “I think we probably need to do a little bit better in interpreting mild signs,” he said.
As laminitis progresses a lamellar wedge forms between the coffin bone and the hoof wall and this is largely irreversible, he explained. “This wedge of tissue is associated with stretching and mechanical failure of the lamellar tissue, which normally suspends the bone within the hoof capsule,” he said. “The bottom surface of the coffin bone and the sole beneath is not designed to bear the load of the horse.
“Once we lose that suspensory function that the lamellae normally provide, this is where we get compression of the sole and where we get … the pain,” he said, along with vascular compromise of the region. In severe cases the coffin bone might penetrate the sole, which complicates management further.
Controlling Laminitis Pain
The pain in acute laminitis comes largely from the inflamed lamellae, said van Eps, but he believes a lot of the pain in chronic cases comes from that sole compression under the tip of the coffin bone. “However the pain of chronic laminitis is multifactorial and also involves an element of neuropathic pain,” he said, meaning that changes in the nerves in the limb and the spinal cord can actually contribute to a heightened perception of pain.
“Our ability to control pain will determine the outcome in most of these cases,” he said.
Recognizing and accurately monitoring pain in horses can be difficult, he said, though behavioral responses are probably the best ways.
He reviewed approaches to evaluate pain level in the laminitic horse:
- Systemic parameters: increased heart rate, respiratory rate, and blood pressure.
- Other measurable parameters: force plates and other means of objectively measuring weight distribution, pedometers/accelerometers to measure weight-shifting behaviors.
- Behavioral signs:
- Low head carriage
- Unusual posture
- Facing away from you in the stall, not coming to you.
Some people see a horse eating and assume that the horse isn’t in pain, he said, but that assumption is incorrect.
“Horses will eat to the bitter end,” he said. “They’ll eat for comfort; it’s not an indicator of happiness.”
Van Eps advocates serial monitoring of multiple pain parameters—checking on the horse regularly and recording findings serially on paper to track progress. “I think you should always challenge yourself on how (your pain control methods are) working or not,” he said. “The only way of doing that is objective measures.
For laminitic horses van Eps uses several systemic pain control methods:
- Systemic and regional analgesia (delivered intravenously or straight to the lower limb, respectively). “We probably are not proactive enough,” he said, “but we also have to remember that pain can be protective.”
In other words, by eliminating pain entirely, particularly in acute laminitis cases, we risk the horse injuring his foot tissues further, especially if the horse is not properly confined.
- Although NSAIDs (phenylbutazone, flunixin meglumine) are the most effective first-line analgesics for laminitis, he said veterinarians must also keep colonic ulceration and renal damage in mind when they’re using these drugs in laminitic horses. Firocoxib and meloxicam might be useful in chronic cases to minimize the risk of these complications.
- Gabapentin is effective against neuropathic pain in people and is now commonly used in horses with acute and chronic laminitis. Early use of gabapentin, even in acute cases, might help control this aspect of laminitis pain.
- Other analgesics are emerging. One is acetaminophen, which offers some analgesic benefit and is reasonably cost-effective and appears to be safe to use in horses, he said.
“I am interested in regional techniques to improve analgesia in horses, particularly when one limb is worse than another or they need some adjunct pain relief on top of the systemic meds,” he said.
Examples of regional approaches include:
- Epidurals for hind-limb lameness, and even the forelimb with certain adjustments to the treatment approach, can be useful in the short term.
- A continuous peripheral nerve block (CPNB) numbs the lower extremity in the desired limb. Basically, he uses a small pump to continuously deliver local anesthetic to the palmar nerves in cases where supporting limb laminitis is a threat, such as surgeries to one limb: “I think we are sometimes not proactive enough in these cases,” he said.
- With cold therapy, pain relief at the surface of the skin begins to happen once surface tissue temperature gets below about 7 degrees Celsius (44.6 degrees Fahrenheit), he said.
Van Eps has found remarkable bone pathology (damage) in many chronic laminitis cases that are resistant to analgesic treatment.
“This has some parallels with human cancer-induced bone pain, where there’s bone loss and intractable pain,” he said, “and complex regional pain syndrome (damage to, or malfunction of, the peripheral and central nervous systems, often seen in one limb after injury) where they also lose bone … and have severe pain. In those cases, interestingly, bisphosphonates are the most effective means of controlling pain.
“So, I do think it may be worth—in cases where pain is not being controlled with traditional means and there is evidence of a lot of bone loss—considering trying bisphosphonates,” he added.
Foot Care for Chronic Laminitis
To help laminitis horses be more comfortable on their feet, van Eps:
- Uses clogs to help chronic laminitic horses in which there has been rotation/sinking of the coffin bone. “I am a clog convert,” he said. “I really like clogs and it’s not just my Dutch heritage coming through. They are pretty easy to put on, they offer you so much depth that you can work with in terms of moving the breakover back where you want it or adjusting it laterally to medially. The big benefit, I think, is being able to actively relieve load under the tip of the coffin bone where it is crushing the sole. I think you see some remarkable improvement even straight away in chronic cases.”
- Uses heart-bar shoes in many cases with mild-moderate chronic laminitis.
- Resects the hoof wall (removes sections of it) in some cases.
- Uses sterile maggots when there’s evidence of coffin bone osteomyelitis (bone infection) to clear away the necrotic tissue.
- Aggressively targets the root cause of the laminitis, which in many chronic cases is endocrine issues; in these horses van Eps performs dynamic endocrine testing for PPID and EMS, and retests regularly: “Even if they’re on pergolide, re-measure their ACTH regularly and make sure it’s controlled.”
Finally, van Eps said, good communication between the veterinarian and farrier can really help when managing both acute and chronic laminitis cases.
“Overall it is important to recognize that treatment of chronic laminitis is always going to be very difficult and there will never be a ‘cure,’” he said, “therefore prevention is the key. Screening tests for underlying endocrine disease (PPID and EMS), early diagnosis of laminitis (detecting early change on radiographs) and institution of appropriate management before the laminitis progresses are the keys to successfully beating this disease.”