Effects of epidural xylazine on EEG responses to surgical stimulation during isoflurane anaesthesia in dogs

The effects of epidural administration of 250 μg/kg xylazine on EEG responses to surgical stimulation of 5 different intensities were evaluated during isoflurane anaesthesia for an experimental orthopaedic procedure in dogs. The dogs were assigned randomly to one of 2 treatment groups receiving either xylazine (n = 4) or equal volumes of sterile water (n = 4) (control group) epidurally. Intense surgical stimulation during removal of a bone graft from the dorsoiliac spine of the ileum was associated with a significantly (P = 0.0339) higher increase in EEG alpha/delta ratio after epidural administration of sterile water than after epidural injection of 250 μg/kg of xylazine. In addition, the preincision baseline values for 80% spectral edge frequency were significantly (P = 0.0339) lower in the xylazine group compared to control dogs. Our results suggest that epidural administration of 250 μg/kg of xylazine during orthopaedic procedures in dogs exerts antinociceptive effects which may be in part mediated by a supraspinal effect of xylazine.     

Utilization of free and protein-bound lysine in the Japanese quail

The utilization of dietary lysine for protein synthesis is affected by the digestibility of protein-bound lysine, by its intestinal resorption and by its oxidative catabolism. The approach chosen in this paper enables a comparison of the cumulative effect of these processes on the utilization of free and protein-bound lysine, respectively. The principle of the approach is based on a quantification of the expiration of 14C-labelled carbon dioxide after an oral administration of a diet, which contains L-(U-14C)-lysine either as a free amino acid or bound to yeast proteins. During an adaptation phase cockerels of the Japanese quail received a diet based mainly on ground wheat and wheat gluten. This diet was supplemented either with yeast proteins or with a mixture of L-amino acids which simulates the composition of the yeast proteins. In the main experiment the expiration of labelled carbon dioxide was measured during 240 minutes after the administration of the corresponding labelled diets. Just before treatment the animals were either in the postprandial phase or in a state of slight hunger. The maximum of expiration of labelled carbon dioxide occurred around the 60th minute after administration of the corresponding labelled diets. The cumulative expiration of labelled carbon dioxide, expressed in per cent of the radioactive dose used, amounts to 15.5% and 14.3% for free and protein-bound lysine, respectively. The utilization of both forms of lysine in the Japanese quail is lower than in broilers.     

Determination of plasma lysosomal enzyme activity and its relationship to severity of injury following blunt vehicular trauma in dogs

Objective: To determine plasma β‐d ‐glucuronidase (βG) activity in the first 4 hours following injury in dogs struck by a motor vehicle, and to evaluate whether the degree of enzyme activity is correlated with the severity of injury. Design: A prospective clinical study. Setting: Veterinary Medical Teaching Hospital. Animals: Thirteen client‐owned dogs that were presented to the Veterinary Hospital of the University of Pennsylvania between June and August 1999 for blunt vehicular trauma. Ten healthy student and staff‐owned dogs served as controls. Interventions: None. Measurements: Plasma was analyzed for βG enzyme activity at the time of presentation (n=13), and 1 and 4 hours (n=7) following presentation to the Emergency Service for blunt vehicular trauma. The results were compared with enzyme activity from healthy controls evaluated serially over 4 hours. Fluorometric analysis using 96‐well microtiter plates was used to perform the enzyme assays. The relationships between presentation (n=13) and 4 hours (n=7) of enzyme activity and 3 indices of metabolic and physical disturbance (serum pH, serum lactate and Animal Trauma Triage (ATT) score) at the time of presentation were also investigated. Main results: Of the 13 dogs, 7 fulfilled the inclusion criteria for comparison of enzyme activity of the trauma over time. A statistically significant difference in βG activity was found in the trauma group (mean 75.6±10.4 U) at 4 hours following presentation compared with controls (mean 48.0±6.4 U). This difference was suggested by 1 hour following presentation (trauma group, mean 70.4±10.9 U; control group, mean 49.8±5.5 U), although it did not reach statistical significance. Thirteen dogs fulfilled the inclusion criteria for comparison of only presentation enzyme activity with trauma severity score, serum lactate, and serum pH. No statistically significant relationship was found between the βd ‐glucuronidase activity and the presenting ATT score, serum lactate concentration, or serum pH at either presentation or 4 hours, although the power of these analyses was low. Conclusions: These results demonstrate that the activity of βG, a lysosomal enzyme, increases significantly in the systemic circulation in dogs 4 hours following blunt trauma. Additional research to include more severely injured dogs, a larger number of dogs, and to follow the course of injury for a longer period of time would be beneficial to further characterize βG activity following blunt trauma.     

Computed tomographic anatomy of the canine cervical vertebral venous system

Computed tomographic (CT) venography of the cervical vertebral canal was performed in six, clinically normal, adult mixed-breed dogs from 14 to 23 kg. After dogs were euthanized and saline perfused, a gelatin and iothalamate mixture was injected into the right external jugular vein. Contiguous, 4-mm-thick CT images were obtained with dogs in sternal recumbency. Dogs were kept in the same position as for the CT scan and frozen to approximately -8 degrees C. All post-contrast CT images were analyzed using similar bone window and level settings. Additional multiplanar reformatted dorsal images were obtained in all dogs. The frozen cadavers were sectioned through the cervical region extending from the occiput to T1 at approximately 8-mm intervals. The frozen sections were then compared with the CT images. The CT appearance of the normal cervical vertebral venous system was described and illustrated. Components such as the internal vertebral venous plexus, interarcuate veins, intervertebral veins, and vertebral veins were clearly identified on the CT images.