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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


Objective—To evaluate effects of injection with a nonsteroidal anti-inflammatory drug (NSAID) followed by oral administration of an NSAID on the gastrointestinal tract (GIT) of healthy dogs.

Animals—6 healthy Walker Hounds.

Procedures—In a randomized, crossover design, dogs were administered 4 treatments consisting of an SC injection of an NSAID or control solution (day 0), followed by oral administration of an NSAID or inert substance for 4 days (days 1 through 4). Treatment regimens included carprofen (4 mg/kg) followed by inert substance; saline (0.9% NaCl) solution followed by deracoxib (4 mg/kg); carprofen (4 mg/kg) followed by carprofen (4 mg/kg); and carprofen (4 mg/kg) followed by deracoxib (4 mg/kg). Hematologic, serum biochemical, and fecal evaluations were conducted weekly, and clinical scores were obtained daily. Endoscopy of the GIT was performed before and on days 1, 2, and 5 for each treatment. Lesions were scored by use of a 6-point scale.

Results—No significant differences existed for clinical data, clinicopathologic data, or lesion scores in the esophagus, cardia, or duodenum. For the gastric fundus, antrum, and lesser curvature, an effect of time was observed for all treatments, with lesions worsening from before to day 2 of treatments but improving by day 5.

Conclusions and Clinical Relevance—Sequential administration of NSAIDs in this experiment did not result in clinically important gastroduodenal ulcers. A larger study to investigate the effect of sequential administration of NSAIDs for longer durations and in dogs with signs of acute and chronic pain is essential to substantiate these findings.

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in American Journal of Veterinary Research