Anesthetic Management of an Orange-Spined-Hairy-Dwarf-Porcupine (Sphiggurus villosus) Undergoing Myelography

Abstract

Background: The orange-spined hairy dwarf porcupine (Sphiggurus villosus) is a mammal that belongs to the rodentia order. Accidents involving this porcupine and dogs have become usual in some cities of Brazil. Dog bites may eventually result in spinal injuries. When there is clinical evidence of spinal cord injury, a myelography under general anesthesia may be required to allow identification of the exact location of the injury. To the authors’ knowledge, there is only one case report about anesthesia in Sphiggurus villosus where dissociative anesthesia was employed. This paper describes one case report of inhalation anesthesia with isoflurane in a Sphiggurus villosus undergoing myelography.Case: A 1.6 kg orange-spined hairy dwarf porcupine, with a history of dog bite was referred to the Veterinary Hospital of the University. On clinical examination, the patient was in good physical condition, alert, with an approximately 1-cm injury near the 10th and 11th thoracic vertebrae. Nociception in pelvic limbs was present whereas proprioception was absent. Radiographic examinations were suggestive of vertebral dislocation and fracture between the 10th and 11th thoracic verte­brae. A myelography was then requested by the responsible veterinarian. The porcupine received intramuscular midazolam (0.5 mg/kg) in combination with meperidine (10 mg/kg) as premedication. Anesthesia was induced and maintained with isoflurane in 100% oxygen via a face mask connected to a non-rebreathing circuit. Monitored variables at 5-min intervals included: pulse rate (PR) and systolic arterial blood pressure (SAP) measured by a Doppler ultrasound with its probe positioned at the palmar metacarpal artery; pulse oximetry (SpO2) measured by a sensor positioned at the tarsus; rectal temperature; and respiratory rate (RR). During the myelography, the range of values for the above mentioned variables were: PR, 189-206 beats/min; SAP, 90-130 mmHg; SpO2, 94-96%; RR, 32-40 breaths/min; and rectal temperature decreased by 0.5oC. Anesthetic recovery was uneventful. Postoperative pain relief was achieved with intramuscular tramadol (5 mg/kg).Discussion: To the authors’ knowledge, this is the first case report of inhalation anesthesia in a Sphiggurus villosus speci­men. In a previous case report, other authors described anesthesia for myelography in a porcupine with IM tiletamine/ zolazepam (5 mg/kg). In the case reported here, dissociative anesthetics, such as tiletamine, were avoided because these agents may increase intracranial pressure, cerebral blood flow and cerebrospinal fluid pressure, which are undesirable in patients with spinal trauma. Although physiologic variables were considered to be stable during anesthesia with isoflurane in this report, these findings have to be interpreted carefully. First, normal range of values for physiologic variables has not been reported for porcupines. Second, accuracy of the measurement techniques used (e.g. noninvasive measurement of SAP) has not been validated. Under the conditions reported in this case report, premedication with meperidine and mid­azolam was effective to induce good muscle relaxation and allowed anesthetic induction with isoflurane via a face mask. This anesthetic protocol provided adequate conditions for performing the myelography in a porcupine and physiologic variables remained stable throughout the procedure.Keywords: rodents, anesthesia, spinal trauma.