FREE SEGMENTAL PAW PAD GRAFTS IN DOGS

After removal of 1 metatarsal pad and formation of a granulation tissu e bed, free segmental 6- x 8-mm grafts from digital pads were sutured into recessed same-size recipient sites in the granulation tissue. In 5 dogs, the grafted area had been denervated by excision of a segment of the tibial nerve at the level of the tarsus. The grafted area was n ot denervated in the remaining 5 dogs. In both groups of dogs, the gra fts placed around the periphery of the wound healed, blocked ingrowth of delicate epithelium from the surrounding skin, and provided a tough keratinized epithelium that covered the wound's center. As healing pr ogressed, the grafts coalesced as the wounds contracted. Weight bearin g resulted in graft expansion to provide functional weight-bearing tis sue. Dogs of the denervated group had clinical and histologic evidence of collateral sensory reinnervation of the denervated area. However, with the exception of 1 dog, results of sensory nerve action potential tests indicated that reinnervation may not have been by way of regene ration across the excisional gap in the nerve. Evaluation of reinnerva tion of the tibial autonomous zone in 2 additional dogs revealed clini cal evidence that collateral reinnervation began between 19 and 28 day s after nerve excision and progressed proximad to distad. Results of s ensory nerve action potential tests indicated that reinnervation may n ot have been via regeneration across the excision site. Results of flu orescent tracer studies did not have positive findings regarding the r oute of collateral reinnervation. Segmental paw pad grafts can be used effectively to provide weight-bearing tissue on a dog's limb. With lo cal nerve damage on the distal portion of the limb, collateral innerva tion can grow into the area to reinnervate tissues, including pad graf ts.