Objective—To determine the change in stiffness as evaluated by the dorsal bending moment of cervical vertebral specimens obtained from canine cadavers after internally stabilizing the vertebral motion unit (VMU) of C4 and C5 with a traditional pin-polymethylmethacrylate (PMMA) fixation implant or a novel screw-bar–PMMA fixation implant.
Sample Population—12 vertebral column specimens (C3 through C6) obtained from canine cadavers.
Procedures—A dorsal bending moment was applied to the vertebral specimens before and after fixation of the VMU of C4 and C5 by use of a traditional pin-PMMA implant or a novel screw-bar–PMMA implant. Biomechanical data were collected and compared within a specimen (unaltered vs treated) and between treatment groups. Additionally, implant placement was evaluated after biomechanical testing to screen for penetration of the transverse foramen or vertebral canal by the pins or screws.
Results—Treated vertebral specimens were significantly stiffer than unaltered specimens. There was no significant difference in stiffness between vertebral specimen groups after treatment. None of the screws in the novel screw-bar–PMMA implant group penetrated the transverse foramen or vertebral canal, whereas there was mild to severe penetration for 22 of 24 (92%) pins in the traditional pin-PMMA implant group.
Conclusions and Clinical Relevance—Both fixation treatments altered the biomechanical properties of the cervical vertebral specimens as evaluated by the dorsal bending moment. There was reduced incidence of penetration of the transverse foramen or vertebral canal with the novel screw-bar–PMMA implant, compared with the incidence for the traditional pin-PMMA implant.
Objective—To compare effects of isoflurane and sevoflurane on intracranial pressure and cardiovascular variables at 1.0, 1.5, and 2.0 times the minimum alveolar concentration (MAC) in mechanically ventilated normocapnic dogs.
Animals—6 healthy male Beagles.
Procedures—The individual MAC was determined for each agent with an electrical stimulus. After a minimum of 1 week, anesthetic induction by use of a mask with one of the inhalation anesthetics selected randomly was followed by mechanical ventilation and instrumentation for measurement of intracranial pressure and cardiovascular variables. Heart rate; systolic, mean, and diastolic arterial blood pressures; central venous pressure; mean pulmonary arterial pressure; pulmonary artery occlusion pressure; cardiac output; intracranial pressure (ICP); core body temperature; end-tidal inhalation anesthetic and carbon dioxide concentration; and arterial blood gas values were measured after attaining equilibrium at 1.0, 1.5, and 2.0 MAC of each inhalation anesthetic. Cardiac index, systemic vascular resistance, pulmonary vascular resistance, and cerebral perfusion pressure (CPP) were calculated.
Results—Mean ICP did not differ within and between anesthetics at any MAC. Compared with equipotent concentrations of isoflurane, the CPP and mean values for systolic, mean, and diastolic arterial blood pressures were increased at 2.0 MAC for sevoflurane, whereas mean values for mean and diastolic arterial blood pressures and systemic vascular resistance were increased at 1.5 MAC for sevoflurane.
Conclusions and Clinical Relevance—Although ICP was similar in healthy normocapnic dogs, CPP was better maintained during 2.0 MAC for sevoflurane, compared with isoflurane.
Objective—To describe the signalment, clinical features, and most common MRI characteristics in dogs with diskospondylitis and investigate whether a correlation exists between the degree of spinal cord compression and neurologic status of the patient.
Design—Retrospective case series.
Procedures—The medical records and imaging database of the Veterinary Teaching Hospital at Washington State University were retrospectively cross-referenced for cases of diskospondylitis in dogs from 1997 through 2010. Signalment, clinical signs, MRI characteristics, and results of bacteriologic cultures of urine, blood, CSF, or intervertebral disk material were reviewed.
Results—On T2-weighted sequences, vertebral endplates were most often of mixed signal intensity, whereas the vertebral body was hypointense. The intervertebral disk space was most often hyperintense on T2-weighted and short tau inversion recovery sequences and of mixed signal intensity on T1-weighted sequences. Paravertebral soft tissue hyperintensities were noted commonly on T2-weighted and short tau inversion recovery sequences. Heterogenous contrast enhancement of endplates and intervertebral disk spaces also occurred commonly, whereas contrast enhancement of vertebral bodies and paravertebral soft tissues was uncommon. Intramedullary spinal cord intensity was noted at 10 of 27 sites on T2-weighted sequences. Static spinal cord compression occurred in 17 of 23 dogs, and a significant direct correlation was found between the percentage of spinal cord compression and the patient neurologic score.
Conclusions and Clinical Relevance—Results suggested that diskospondylitis in dogs has a characteristic MRI appearance, and in some patients, MRI may aid in the identification of severe spinal cord compression, which could warrant surgical intervention.