Applying Laminitis Research to Clinical Practice

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Originally published on TheHorse.com

Seeing the forest for the trees with regards to laminitis can be difficult because researchers are approaching the problem from many different angles, often at the molecular level. At the Sept. 17-18 Laminitis West Conference in Monterey, Calif., Thomas J. Divers, DVM, Dipl. ACVIM, Dipl. ACVECC, professor and Chief of Large Animal Medicine at Cornell University spoke about how veterinarians are putting the whole picture together to help treat and prevent laminitis cases.

Divers explained three reasons why applying results of laminitis research to actual cases is difficult:

• Laminitis has several different causes, including equine metabolic syndrome, systemic inflammatory disease (SID), equine Cushing's disease, corticosteroid use, and uneven weight-bearing as a result of injury (opposite-limb laminitis).
• With SID, two different models are used in research to induce laminitis--carbohydrate overload and black walnut extract. There are some differences in the pathophysiology of the disease in each model.
• There are different stages of laminitis, all with different pathophysiologic findings, making it more difficult to study disease mechanisms and target treatment.

In treating horses with conditions that could lead to laminitis, Divers has two goals--treating the primary disease and inhibiting the laminitis disease process in the hoof. He begins by treating the whole horse to (control sepsis), often using fluid and anti-inflammatory treatments in addition to toxin drainage or neutralization when possible. He then works on the foot to prevent laminitis or provide treatment during the earliest stages.

The use of non-steroidal anti-inflammatory drugs [NSAIDs, such as phenylbutazone (Bute) or flunixin meglumine (Banamine)] is well documented in alleviating many clinical signs associated with SID, but Divers said NSAID use is not as well-documented for efficacy in directly preventing laminitis. He added that the type and dose of NSAID prescribed depends on the primary disease causing the laminitis and the stage of the laminitis.

Divers outlined several other commonly used treatments: vasomotor-modifying drugs (which act to dilate or contract blood vessels in the hoof, enzyme inhibitors (which can slow certain chemical reactions in the tissues), inhibitors of neutrophils and platelets (mediators of endothelial inflammation), and antioxidants. More research into the efficacy of these is required, he noted.

One treatment that has been shown to work well to prevent laminitis in at-risk horses is cryotherapy (cold therapy). Lowering the temperature of the foot might decrease laminar inflammation by inhibiting destructive enzyme activity and oxidative reactions. It also decreases laminar metabolism, thus decreasing oxygen and nutrient requirements. Lastly, it might also decrease the delivery of blood-borne toxins that can trigger enzymatic destruction of the laminae.

"The problem is, by what practical method can cryotherapy be applied," said Divers, "and how long do we do continue it during a systemic disease?"

Cornell practitioners have successfully experimented with devices filled with crushed ice, which makes better contact with the foot than ice cubes. Divers recommends that in conjunction with other therapies, veterinarians should employ cryotherapy to ice the feet of horses with systemic inflammation and endotoxemia for 24 hours past the point where the horse shows a normal heart rate, digital pulses, rectal temperature, and normal neutrophil morphology.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.

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