Neuroanesthesia: A Review of the Effects of Anesthetic Agents on Cerebral Blood Flow and Intracranial Pressure in the Dog

Successful anesthetic management of dogs with reduced intracranial compliance requires a knowledge of the effects of various anesthetic agents on cerebral blood flow and intracranial pressure. The major physiologic factors that influence cerebral blood flow and intracranial pressure (ICP) include the cerebrovascular autoregulatory mechanism, intracranial compliance, blood pressure, and the partial pressure of carbon dioxide. Intravenous and inhalation anesthetic agents alter cerebral blood flow and intracranial pressure in the dog. These alterations can have profound effects in dogs with reduced intracranial compliance, necessitating proper anesthetic management. Suggested guidelines for neuroleptanesthetic and inhalation anesthesia regimens in dogs with reduced intracranial compliance include thorough presurgical evaluation, minimal patient stress during induction, use of an anesthetic protocol that minimizes ICP effects, and hyperventilation to maintain a Pco₂ within a range of 25 to 35 mm Hg.     

Cultural Commodity Chains,Cultural Clusters,or Cultural Production Chains?

ABSTRACT The paper begins with a discussion of the definition of cultural industries. The paper's three main themes are concerned with, first: 1) a contestation of the generic application of the global commodity chain concept, 2) the need for a unique focus on cultural industries associated with the particular nature of its production process, and 3) the role of embedded judgments of quality is an integral part of this process. Second, the paper suggests that a restyled focus on production chains (involving the full cycle of production to use) might be more appropriate than “commodity chains” for this application. Finally, issues of spatiality and scale are discussed: it is argued that although global commodity chain debates explore linkages at a regional and national scale, they downplay linkages at the local level.     

Meningeal sarcoma mimicking a sciatic neuropathy in a dog

A 5-year-old Golden Retriever presented for lameness evaluation and removal of a dynamic compression plate on the left femur exhibited neurologic signs compatible with a left sciatic peripheral neuropathy. Radiographs revealed a healed fracture of the left femur and a slightly narrowed intervertebral disc space with ventral spondylosis at T_12–13. An EMG demonstrated fibrillation potentials and positive sharp waves in the left hind limb muscles innervated by the peroneal nerve. Surgery was performed to remove the bone plate and explore the left sciatic nerve. The proximal 3 cm of the left peroneal nerve was surrounded by thick fibrous connective tissue and its diameter was smaller than the more distal segment. The dog's condition remained static for 4 weeks and then gradually progressed to paraparesis in 2 weeks. A neurologic examination at that time indicated a caudal lumbar spinal cord lesion and a myelogram confirmed an intradural mass at the level of the 4th lumbar vertebra. The dog was destroyed and a necropsy performed. The histologic diagnosis was meningeal sarcoma.     

Structural Changes in Thoracolumbar Disks Following Lateral Fenestration A Study of the Radiographic, Histologic, and Histochemical Changes in the Chondrodystrophoid Dog

Lateral fenestrations of intervertebral disks T12–13 through L2–3 were performed on 16 1-year-old chondrodystrophoid dogs. The disks of five dogs were fenestrated by removing the core of disk material with a 20 gauge spinal needle, six were fenestrated in the same manner with a 14 gauge spinal needle, and five were fenestrated with a 14 gauge spinal needle and a tartar scraper. Forty-two of 48 disks had radiographic evidence of narrowing following surgery. Microscopic examination of the disks indicated that the nucleus pulposus was nonreactive tissue and that fenestration did not incite an inflammatory response that resulted in dissolution of the nucleus pulposus. Results of histochemical analyses of the fenestrated disks were not different from those of control disks. The only effects observed during a 24 week period following fenestration were disruption of the annulus fibrosus and nucleus pulposus by the fenestration device, removal of varying amounts of the nucleus pulposus, and vascular and fibrous tissue invasion of the lateral annulus fibrosus. These findings suggest that the effectiveness of fenestration is governed by the amount of nucleus pulposus removed.