Hemi-tongue Allograft Transplantation in Dogs

Background: When complete recovery of tongue function following tumor excision is desired, reestablishment of the complex movements of the tongue is necessary. However, currently available methods for recovery of tongue function, such as flap surgery or prosthesis insertion, are inadequate. In the current study, we investigated the effects of transplantations of tongue allografts. Methods: Hemi-tongue allotransplantation procedures were performed with 8 pairs of sex-blind and unrelated beagle dogs. In each donor, the right side of the tongue, including the lingual and hypoglossal nerves, extrinsic muscles of the tongue, mucous membrane of the oral floor, lingual artery, and vein were exposed. A vascularized transplantation method was used with manual anastomosis of the blood vessels and nerves. Results: Survival of the grafted tongue was only noted in 1 dog that died 5 days after transplantation. We suspected that the death was due to nutritional deficiency or dehydration, rather than hyperacute rejection of the transplant or technical failure of the microsurgical anastomosis. The grafted tongue was partially connected to the side of the recipient tongue, and lymphocyte infiltration was observed in this dog. Conclusions: Postoperative management is difficult in dogs. Even if tongue allograft including nerves and extrinsic muscles is performed, it seems to take a long time before the tongue recovers its functions. Furthermore, expansive tongue allograft was too invasive a treatment for animals. If we want to adapt this procedure to humans, the first trial in a human will be done without animal experiments, as was the case with face transplantations.