What Is the Evidence?

Abstract

ProblemA 4-year-old male German Shepherd Dog weighing 33.2 kg (73 lb) was evaluated at the University of Missouri Veterinary Medical Teaching Hospital for a 3-month history of decreased ability to perform athletically. The dog trained for and competed in agility events, and the owner had observed that the dog would refuse or not successfully complete jumps and A-frames during training and competition. According to the owner, the dog also had signs of mild, intermittent lameness of the right hind limb. When the owner first noticed the problem, the dog was evaluated by a veterinarian who diagnosed a possible hamstring (semimembranosus, semitendinosus, and biceps femoris muscles) injury and recommended physical rehabilitation and NSAID medications. The owner also sought treatment from a veterinarian practicing chiropractic manipulations. This treatment regimen was undertaken for 6 weeks with no improvement observed.At the hospital, physical and orthopedic examinations revealed the dog was in good body condition (score of 5 on a 9-point scale) but had apparent atrophy of the gluteal and thigh musculature bilaterally. The dog had a consistent shortening of the stride in the right hind limb. No evidence of pain or musculoskeletal abnormality was detected during palpation and manipulation of either forelimb and the hip, stifle, and tibiotarsal joints. Marked signs of pain in the dog were observed to be associated with pelvic lordosis and direct palpation over the lumbosacral joint. Neurologic examination revealed normal cranial nerve and thoracic limb neurologic function. Slightly delayed conscious proprioception responses were evident in the hind limbs. A slightly exaggerated patellar reflex with slightly depressed sciatic and cranial tibial reflexes was detected in the right hind limb. The neurologic abnormalities were localized to the L4 through S3 spinal cord segments.The dog was sedated with medetomidine to allow for palpation and radiography. While the dog was sedated, palpation and radiography of the hip and stifle regions as well as palpation of the tarsal joints revealed no abnormalities. Radiographic views of the lumbosacral vertebral column were obtained, including a ventrodorsal view and lateral views with the vertebral column in a neutral position, flexed at the lumbosacral joint, and extended at the lumbosacral joint. Assessment of the radiographs revealed sclerosis of the endplate of S1, bony remodeling of the caudal articular In cooperation with facets of L7 as well as the cranial articular facets of S1, and subluxation of the facet joints at L7-S1 and stairstepping of the L7 and S1 vertebral bodies and lamina in the flexed and extended views. A presumptive diagnosis of dynamic lumbosacral stenosis and lumbosacral instability (LSI) was made, and computed tomography (CT) with the possibility for subsequent surgery was recommended to the owner.The following day, the dog was anesthetized and CT imaging was performed with the vertebral column in a neutral position, flexed at the lumbosacral joint, and extend...