Traumatic Lumbar Instability in a Red Fox (Vulpes vulpes): Evaluation of Pedicle Screw-Rod Fixation

FIXAÇÃO POR PARAFUSO-HASTE PEDICULAR EM RAPOSA VERMELHA (VULPES VULPES)

Abstract

Background: Fox injuries can occur throughout the year. The primary causes of injuries include traffic accidents, entanglement in fences or wire mesh, trapping incidents, poisoning, self-inflicted injuries from mange irritation, and attacks by domestic animals or other foxes, particularly when weakened and partially helpless due to other circumstances. This case presentation delves into the clinical and radiographic findings, anesthesia applications, surgical procedures, and prognosis of a red fox (Vulpes vulpes) that suffered a lumbar vertebral fracture due to trauma. It stands as a pioneering study in the literature on this specific topic.

Case: An approximately 1-year-old female Red Fox (Vulpes vulpes) weighing 3.7 kg, presenting with hind limb paralysis. Clinical and neurological examination was conducted. Radiography and Computer Tomography imaging were performed. The neurological examination, radiological and computed tomography images confirmed a fracture in the corpus vertebra of L6. Pedicle screw-rod fixation was used to achieve stabilisation. Postoperative examinations revealed no complications. Remarkably, the fox was able to stand up on the first day post-operation and exhibited swift walking abilities. Improvement in the use of the right hind limb was noted, with the ability to exert pressure on the left hind limb. In conclusion, we posit that incorporating new data on Fox and similar species into the literature would prove advantageous for clinicians specializing in exotic animals. Furthermore, evaluating the outcomes of the pioneering Pedicle screw-rod fixation application in a fox and similar species contributes valuable insights to the existing knowledge in this field.

Discussion: As this case marks the inaugural investigation into lumbar vertebral fractures in the fox, a comprehensive analysis was undertaken, drawing references from existing canine and feline literature while there are existing studies in wolves. In the observed case, a fracture of the corpus of L6 was identified. L6 fractures can cause severe low back pain, hindering standing, and surgical stabilization is often indicated. Based on the literature review, although there are many techniques, but, a specific surgical technique for treating L6 fractures in dogs remains unclear.  In this case, pedicle screw-rod fixation was employed, and good fixation was observed in the postoperative period. The biomechanical advantage of these dorsally applied fixation devices lies in their resistance to ventral bending forces associated with thoracolumbar sacrocaudal luxation since the implant is positioned on the tension side of the vertebral column, limiting flexion or extension. As far as we are aware, this study represents the first documentation of traumatic spinal injuries in foxes. Introducing new data on foxes and similar species to the literature can be valuable for clinicians working with exotic animals. Additionally, the assessment of results from the application of pedicle screw-rod fixation, a procedure performed for the 1st time in a fox and similar species, would contribute to the existing knowledge in this field. The use of pedicle screw-rod application is considered to be straightforward, less invasive, and has shown favorable outcomes in the postoperative period. It has the potential to promote neurological and motor function recovery following surgery.

Keywords: Patellar reflexes, pain test, sciatic reflexes, spinal fracture, luxation.