Mucocutaneous subdermal plexus flap from the lip for lower eyelid restoration in the dog

A mucocutaneous subdermal plexus flap from the lip was transplanted into a defect created by removing the lower eyelid in 17 dogs. The grafts were evaluated from 10 days to 6 months later to assess their survivability, function, and cosmetic appearance. Histology was used in selected cases to examine changes in the grafted tissue. In addition, electromyograms were obtained for 2 grafts at 2 weeks and for 2 grafts at 24 weeks to assess reinnervation of transplanted segments of the orbicularis oris and buccinator muscles. Minor necrosis of the outer flap margin occurred in 4 dogs, but healing by second intention was satisfactory. Results from the histologic and electromyographic analyses suggested reinnervation of the orbicularis oris and buccinator muscle segments occurred from portions of the auriculopalpebral nerve in 2 grafts. The cosmetic and functional results in this procedure were satisfactory. It was concluded that the lip flap is a suitable substitute for the lower eyelid in the dog and can be effectively used for single-stage replacement of major lower eyelid losses, but that an elective second-stage procedure can be done to improve the cosmetic results in selected cases.