Mandibular Symphysis Stabilization after Traumatic Disjunction in a Crab-Eating Fox (Cerdocyon thous)
Authors: Zafalon-Silva Bruna , Silva Laurenn Bittencourt , Da Costa Priscila Medina , Goulart Miúrel De Aquino , Schmidt Victória Regina Queiroz , Do Santos Eduardo Almeida Ruivo , Exterckötter Breno Tiago Vargas , Alievi Marcelo Meller 
Published: May 2019

Background: Fractures and dislocations are common orthopedic conditions arising from traumas from anthropic interaction on wild species, such as those caused by road trampling, being the mandibular separation with great frequency of occurrence in dogs and cats. The procedures for mandibular symphysis stabilization are described as of low complexity in the literature, however no reports of this procedure in wild canids were found. The purpose of this study is to report a surgical procedure of mandibular symphysis disjunction stabilization in an individual of the species Cerdocyon thous (crab-eating fox) through the technique of cerclage fixation using stainless steel wire.Case: An adult male individual of the free-living specie weighing 5.6 kg was referred to veterinary care after having been run-over. General physical examination showed abrasions in the ventral region of the jaw, discreet bleeding in the oral cavity, and mandibular instability. Subsequently, the patient underwent radiographic examination that revealed mandibular disjunction. The patient was therefore referred to the surgical unit for stabilization. During surgical anesthesia, two 12-gauge hypodermic needles (40x12 mm) were inserted percutaneously through the ventral region of the mandible, protruding into the oral cavity immediately caudal to the canine teeth. Next, both extremities of a 0.5 mm stainless steel wire were introduced into the interior of the needles and, when both ends extruded through the other end of the needles, the latter were removed, leaving only the steel wire uniting both rostral rami of the mandible. Using a twisting apparatus, the steel wire was twisted until the disjunction was completely stabilized and mandibular occlusion was deemed appropriate. Lastly, the surplus steel wire was sectioned, leaving a small segment that remained exposed to surface in the ventral region of the mandible. During the patient’s recovery period no complications or recurrence were observed, signifying a successful stabilization procedure by the chosen technique. Thirty-four days postoperatively, the metallic implant was removed under radiographic guidance, and the patient discharged after confirming adequate oral occlusion. After recuperation, the animal was referred to the responsible environmental agencies to be released back into the wild, 55 days postoperatively.Discussion: Among the several techniques described for mandibular symphysis stabilization, success was obtained in this case using the technique of cerclage fixation using stainless steel wire. The procedure in question was chosen for its easy implantation, low cost, and short time of permanence of the implant, which led to a reduction in the patient’s stay in captivity, favoring his rehabilitation and aiming at an early return of the individual to its habitat. There is no consensus of mean healing time of the mandibular symphysis or the period the implant should stay in situ, with reported periods varying from three to four weeks to six to eight weeks. Several factors may influence the formation of the bone callus, including proper stabilization of the hemimandible, occlusal alignment, preservation of hard and soft tissues, and preservation of the dentition, which can lead to quicker return of mandibular function. During the hospitalization period, no surgical complications were observed on periodic clinical evaluations. Thus, we conclude that this stabilization of mandibular symphysis in an individual of the species Cerdocyon thous with cerclage using steel wire, with adequate preoperative and postoperative management, was successful in the treatment of traumatic disjunction.