Supporting Limb Laminitis (AAEP 2008)

The publicity given to supporting limb laminitis by horses such as Barbaro showed that success with these tough cases often remains elusive. At the 2008 American Association of Equine Practitioners convention, held Dec. 6-10 in San Diego, Calif., Gary Baxter, VMD, MS, professor of equine clinical sciences at Colorado State University, presented a review of what we know about this devastating disease.

"In many of these horses, the lack of a 'good foot to stand on' creates a very difficult management situation."
--Dr. Gary Baxter

Supporting (also called contralateral) limb laminitis strikes a previously healthy hoof when it bears excessive weight for long periods because the other front or hind foot is extremely painful (such as from a fracture, surgery, severe infection, etc.). It is "the most common and significant complication of excessive unilateral (on one front or hind foot) weight bearing in adult horses," said Baxter. "In many of these horses, the lack of a 'good foot to stand on' creates a very difficult management situation."

He noted that unlike with most other forms of laminitis, there is usually no systemic disease present (such as Cushing's disease, colitis, or carbohydrate overload), which points to mechanical overload and possibly the resulting reduction in blood flow as the cause. Additionally, constant deep digital flexor tendon tension might contribute to pulling the foot apart in these painful cases.

Risk Factors

Baxter noted the two consistent research-supported risk factors for supporting limb laminitis are the length of time a horse spends standing on one front or hind foot (resting the painful one) and the severity of the lameness. "Horses that are unwilling to bear any weight on the diseased limb for even small periods of time seem to be more prone to develop support limb laminitis than horses that can shuffle or hobble around to periodically relieve ... the contralateral limb," he explained.

He said several other factors might increase a horse's risk, based on his and others' experience, such as increased body weight and poor foot quality (i.e., thin walls/soles, low heels, hoof wall defects) before the lameness/injury.

Detecting Supporting Limb Laminitis

"Any horse with unilateral weight bearing should be monitored closely for signs of laminitis in the contralateral limb," Baxter advised. Lameness might not be a good indicator, as the horse will stand on the previously healthy foot, perhaps with only momentary rests on the injured limb, until progressive laminitis makes it the more painful one. "If you look at the horse and think, 'Wow, we're doing really good on that surgical limb,' a bell should go off and tell you to pay attention to the opposite leg."

He suggested monitoring digital pulses and heat in the foot and palpating the coronary band to check for sinking of the bony column. Radiographs can also help diagnose this condition; he noted that baseline films (taken as early as possible in the disease process) are important for detecting subsequent changes in the foot. Here's what he said one should look for on repeated films (he takes them weekly on at-risk cases).

  • A horn-lamellar (HL) zone that's abnormally thick (more than 15-18 mm for light-breed horses) or thickened as compared to previous measurements.
  • One study reported that an HL zone greater than 29% of the palmar (lower) surface length of the coffin bone was suggestive of contralateral laminitis.
  • Rotation of the coffin bone within the hoof (evidenced by an increasing angle with the outer hoof wall marker).
  • Increased coronary band-extensor process distance compared to previous measurements.
  • Decreased sole depth.

However, "If you wait to treat the horse until you see radiographic changes, you're well behind the curve," he commented. He noted that veterinarians can apply several treatment options preventively and/or once the disease is detected to make the horse more comfortable and, ultimately, try to save his life.

Prevention/Treatment

Baxter reported that while there's no "magic bullet" for preventing or treating supporting limb laminitis, several options might help reduce load on the laminitic foot and minimize the disease's effects.

  • Reduce the horse's body weight if possible.
  • Try to get the horse comfortable bearing weight on the initially injured limb as soon as possible to unload the laminitic or at-risk one.
  • Evenly distribute the horse's weight between the lame and sound foot. Often the injured limb will be casted and effectively "longer" than the sound limb, so the horse leans into the "shorter," sound limb. Adding a block or thick shoe to the sound foot to even up the horse's knees can be helpful.
  • Encourage the horse to lie down with soft, deep stall bedding. Sedation might help.
  • Slings can help reduce weight on the sound foot. The horse doesn't need to be lifted off the floor, he just needs to be able to rest weight into the sling.
  • Shoeing should redistribute weight bearing to the rear half of the foot (impression material can be helpful). Reducing breakover forces by beveling the toe can also help, as can elevating the heels up to 10� to reduce deep digital flexor tendon tension.
  • Anti-inflammatory medication and cryotherapy (cold therapy) can help reduce inflammation, particularly early in the case.
  • Some practitioners have found foot casts help stabilize the foot.
  • Pain management with non-steroidal anti-inflammatory drugs (NSAIDs, such as phenylbutazone) or more aggressive measures will help improve the horse's comfort level.

Regardless of the treatments applied, they should be initiated early and aggressively. "Time is important; you can't just wait and see how he is next week if he has significant lameness," Baxter said.

About the Author

Christy M. West

Christy West has a BS in Equine Science from the University of Kentucky, and an MS in Agricultural Journalism from the University of Wisconsin-Madison.

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