An 11-year-old (44.5-kg [97.9-lb]) sexually intact male Weimaraner was evaluated at the Veterinary Teaching Hospital of the University of Georgia because of a 2-day history of weakness and difficulty rising from a lying position associated with all 4 limbs. Several years earlier, the dog had bilateral cranial cruciate ligament disease and tibial plateau leveling osteotomies were performed bilaterally. Three months prior to evaluation at the hospital, the right tibial plateau leveling osteotomy plate was removed because of lameness and suspected infection. Electrocardiographic abnormalities were not detected during any of the dog's previous anesthetic episodes. The dog had no other pertinent medical history.
Initial physical examination findings were unremarkable, and the dog's heart rate was 112 beats/min. During auscultation of the thoracic cavity, no murmur or arrhythmia was detected and lung sounds were apparently normal bilaterally. Results of a neurologic examination were consistent with a lesion affecting C6 through T2 spinal cord segments. Abnormalities detected via a CBC and serum biochemical analyses included mild leukocytosis characterized by a mature neutrophilia (12.5 × 103 cells/μL; reference range, 2.9 × 103 cells/μL to 12 × 103 cells/μL), monocytosis (2.0 × 103 cells/μL; reference range, 0.1 × 103 cells/μL to 1.4 × 103 cells/μL), and mild hyperglycemia (124 mg/dL; reference range, 77 to 120 mg/dL). Results of a urinalysis were also within reference limits. Radiography of the thorax and cervical portion of the vertebral column revealed no abnormalities, with the exception of a narrow intervertebral disk space at C6-7.
To perform magnetic resonance imaging of the cervical portion of the vertebral column, the dog was anesthetized. After administration of glycopyrrolate (0.005 mg/kg [0.002 mg/lb], IV), butorphanol (0.2 mg/kg [0.09 mg/lb], IV), and midazolam (0.2 mg/kg, IV), anesthesia was induced with propofol (4 mg/kg [1.8 mg/lb], IV) and maintained via inhalation of isoflurane and oxygen. During anesthesia, pulse oxymetry, assessment of endtidal carbon dioxide tension, and noninvasive blood pressure monitoring were performed. Throughout the anesthetic episode, the dog's heart rate was 120 to 130 beats/min with a regular rhythm (determined from the pulse wave provided by the pulse oxymeter). End-tidal carbon dioxide tension was 25 to 40 mm Hg. Systolic blood pressure ranged from 60 mm Hg at induction of anesthesia to 110 mm Hg throughout the remainder of the anesthetic episode. Magnetic resonance imaging revealed herniated intervertebral disks at the C5-6 and C6-7 disk spaces, which had resulted in compression of the spinal cord. The lesions were dynamic with traction. On extubation, the dog's rectal temperature was 32.2°C (93.7°F). The dog was transferred to the intensive care unit of the hospital for monitoring and active warming by use of a forced-air patient warming unit. Cardiac auscultation performed during the dog's recovery from anesthesia revealed tachycardia and an abnormal cardiac rhythm. Electrocardiography was performed to evaluate the tachyarrhythmia.
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