A group of scientists from Australia and the United States investigated the perfusion of the laminae when a horse stands with increased loading of one front limb such as occurs following a fracture repair that can lead to supporting limb laminitis in the opposite limb.

Tiny fluid probes were implanted in the laminae of one forelimb in 13 normal Standardbreds. Half the horses were shod with a platform shoe to overload the opposite hoof while half served as unshod controls. Tissue fluid samples from the laminae were collected every 4 hours for 92 hours and tested for glucose, lactate and pyruvate to estimate lamellar perfusion while loading of the hoof was measured using a force plate platform.

The experimentally overloaded limbs were measured as bearing 39% of body weight while the “rested” limbs were bearing 27% of body weight, and as expected the shod horses rested the overloaded limbs less frequently compared with the controls. Glucose levels and lactate-to-pyruvate ratios indicated that the overloaded limbs were experiencing lamellar ischemia as expected, while the controls remained normal.

The authors concluded that increased mechanical loading of the supporting limb (which would be opposite the limb with a fracture in a clinical case) causes lamellar ischemia, and this likely contributes to the supporting limb laminitis that sometimes occurs as a complication following fracture repair.

— van Eps AW, Belknap JK, Schneider X, et al. Lamellar perfusion and energy metabolism in a preferential weight bearing model. Equine Vet J. 2020; 00: 1– 11. …