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Chickens (n = 18), ranging in age from 30 to 50 weeks and in body weight from 1.1 to 2.1 kg, were anesthetized with isoflurane. Ventilation was controlled, and temperature was maintained at 40.1 ± 1.0 C. The minimal anesthetic concentration (mac) of isoflurane was determined by use of a bracketing technique based on purposeful movement in response to a toe clamp. After determining isoflurane mac in triplicate, birds were given a mu-opioid agonist (morphine, n = 9) or a kappa-opioid agonist (U50488H, n = 9). Determination of mac was repeated after each IV administration of agonist in progressive doses of 0.1, 1.0, and 3.0 mg/kg of body weight. Heart rate and mean arterial blood pressure (MAP) were recorded immediately before and after each injection. Control mac (mean ± SEM) was 1.24 ± 0.05% and 1.05 ± 0.03% for the mu- and kappaopioid agonist groups, respectively. Morphine and U50488H caused a dose-dependent decrease in isoflurane mac in all birds. Reduction of mac from control (mean ± SEM) was 15.1 ± 2.7, 39.7 ± 3.1, and 52.4 ± 4.0% after the 3 successive doses of morphine and was 13.3 ± 3.0, 27.6 ± 3.3, and 40.8 ± 3.8% after U50488H was given. Each opioid injection resulted in significant (P ≤ 0.05, repeated measures anova) lowering of mac. Heart rate and MAP did not change significantly (P ≤ 0.05, paired Student’s t- test) after any dose of opioid. In conclusion, morphine or U50488H decreased isoflurane mac in dose-dependent manner without significant effect on heart rate and MAP.

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in American Journal of Veterinary Research


We investigated changes in hemostatic function after infusion of 6% dextran 70 (high molecular weight dextran) at 2 rates. Six healthy dogs underwent 3 regimens: 20 ml of dextran/kg of body weight administered in 1 hour (trial A), 20 ml of dextran/kg administered in 30 minutes (trial B) and 0.9% sodium chloride solution as a control administered over 1 hour to achieve hemodilution equivalent to that for 20 ml of dextran/kg (trial C). Before and at 2, 4, 8, and 24 hours after the start of trials A and B, we measured pcv, total solids (ts) concentration, amount of von Willebrand factor antigen (vWf:Ag), factor VIII coagulant activity (VIII:C), prothrombin time, activated partial thromboplastin time (aptt), platelet retention in a glass bead column, and buccal mucosa bleeding time (bmbt). Values were not obtained at 8 and 24 hours for trial C. Saline-induced changes in hemostasis were significant (P < 0.05) from baseline throughout the sample collection period. Significant differences (P < 0.05) between trial A and control were observed for vWf:Ag, VIII:C, bmbt, aptt, ts, and pcv values at 2 hours, and for VIII:C at 4 hours. Significant differences (P < 0.05) between trial B and control were observed for aptt, ts, and pcv values at 2 hours, and for vWf:Ag, VIII:C, bmbt, aptt, ts, and pcv values at 4 hours. During trials A and B, mean values of analytes infrequently deviated from reference intervals, and clinical signs of bleeding were not observed in any dog. Data for the dextran infusions paralleled each other and had a tendency to normalize, infrequently reaching baseline by 24 hours. Differences in overall hemostatic function were not detected between dextran infusions. Dextran 70 at a dosage of 20 ml/kg induces minimal hemostatic abnormalities when infused over 30 or 60 minutes to clinically normal dogs, but may precipitate bleeding in dogs with marginal hemostatic function.

Free access
in American Journal of Veterinary Research