Prognostic factors and complications associated with surgery for oral tumors

Tumor location and completeness of excision are significantly associated with survival time in dogs with oral tumors treated surgically, regardless of histologic type. Dogs with tumors occurring between the canine and third premolar are 4.6 times more likely to die of their disease than are dogs with tumors rostral to the canine teeth, and those with tumors occurring caudal to the fourth premolar are 5.1 times more likely to die of their disease.1 Complete surgical removal of the tumor is also associated with a significantly longer survival time compared with incomplete removal.1

The most common complications noted with surgery are hemorrhage and dehiscence. Both of these complications increase with the aggressiveness of the surgical procedure. In one study of 69 dogs treated with hemimaxillectomies, six experienced anemia secondary to blood loss during surgery, and one dog died of hemorrhage and hypovolemic shock.2 If extensive hemorrhage is expected, the ipsilateral carotid artery can be ligated.2 Dehiscence is more common if the incision is caudal to the premolars because of wound closure tension.1,2 Eighty percent of patients that experienced dehiscence had resections of the maxilla caudal to the canine tooth.1 In dogs treated with partial maxillary resection, 20 of 61 (33%) experienced a partial dehiscence of their surgical site.1 Just over half of the dogs with partial dehiscence had radiation therapy postoperatively. This additional therapy may have contributed to the breakdown at the surgical site.1

Mandibulectomies are not without postoperative complications. Eighteen of 81 (22%) dogs in one study had complications after mandibulectomy, including dehiscence (seven dogs), prehension dysfunction (four dogs), as well as medial drift, tongue lag, and excessive drooling.3 A second study of 142 dogs treated with partial mandibulectomies stated that most of the dogs experienced varying degrees of mandibular instability and malocclusion, but only three required canine tooth extraction to treat palate ulceration caused by malocclusion.4 Of 21 dogs treated with a modified hemimandibulectomy technique, five (24%) experienced skin suture dehiscence.5 Collectively, these studies show a lower complication rate than for maxillectomies, with dehiscence and mandibular drift occurring most commonly.

Virginia J. Coyle, DVM

Laura D. Garrett, DVM, DACVIM (oncology)

Department of Veterinary Clinical Medicine

College of Veterinary Medicine

University of Illinois

Urbana, IL 61802

REFERENCES

1. Schwarz PD, Withrow SJ, Curtis CR, et al. Partial maxillary resection as a treatment for oral cancer in 61 dogs. J Am Anim Hosp Assoc 1991;27(6):617-624.

2. Wallace J, Matthiesen DT, Patnaik AK. Hemimaxillectomy for the treatment of oral tumors in 69 dogs. Vet Surg 1992;21(5):337-341.

3. Schwarz PD, Withrow SJ, Curtis CR, et al. Mandibular resection as a treatment for oral cancer in 81 dogs. J Am Anim Hosp Assoc 1991;27(6):601-610.

4. Kosovsky JK, Matthiesen DT, Marretta SM, et al. Results of partial mandibulectomy for the treatment of oral tumors in 142 dogs. Vet Surg 1991;20(6):397-401.

5. Felizzola CR, Stopiglia AJ, de Araújo VC, et al. Evaluation of a modified hemimandibulectomy for treatment of oral neoplasms in dogs. J Vet Dent 2002;19(3):127-135.