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Abstract

Objective—To determine effects of selegiline hydrochloride, phenylpropanolamine (PPA), or a combination of both on physiologic and behavioral variables in dogs.

Animals—40 adult hound-type dogs.

Procedure—Dogs were assigned to 4 groups. One group received selegiline (1 mg/kg, PO, q 24 h) and PPA (1.1 mg/kg, PO, q 8 h), a second group received selegiline alone, a third group received PPA alone, and a fourth group received neither drug. Dogs were observed 3 times/d throughout the 30-day study (daily during the first week, on alternate days during the next 2 weeks, and again daily during the final week). Observers recorded rectal temperature, pulse, respiratory rate, oscillometric blood pressure, and lead-II ECG and assessed 4 behaviors, using an analogue scale. Variables were compared among treatment groups by use of a 2-factor ANOVA with data categorized into three 10-day treatment periods. A similar comparison was made among treatment groups with data categorized by time of observation (morning, afternoon, or evening) for all study days.

Results—Variables did not differ among groups at study initiation. Pulse rate was the only variable that differed significantly among treatment groups during the study. During the first 10 days of treatment, dogs receiving PPA had a lower pulse rate than dogs that did not. Although signs of illness were apparent in a few dogs, illness did not appear to be related to treatment.

Conclusion and Clinical Relevance—Adverse effects were not detected after administration of selegiline, PPA, or a combination of the drugs in healthy dogs. (Am J Vet Res 2002;63:827–832)

Full access
in American Journal of Veterinary Research

Summary

Plasma cortisol concentrations were compared in canine surgical patients given etomidate (2 mg/kg of body weight, iv) or thiopental sodium (12 mg/kg, iv) for anesthetic induction. Blood samples to determine plasma concentrations of etomidate were obtained at 0, 5, 10, 15, and 30 minutes and 1, 2, 3, 4, 5, 6, 8, 12, and 24 hours after induction. Adrenocortical function was evaluated before surgery by use of adrenocorticotropic hormone stimulation tests. Dogs in both induction groups had high plasma cortisol concentrations after induction. Dogs given thiopental had a significant increase (P < 0.05) in plasma cortisol concentration from baseline at 2, 3, 4, 5, 6, 8, and 12 hours after induction. Dogs given etomidate had a significant increase (P < 0.05) in plasma cortisol concentration from baseline at 5, 6, and 8 hours after induction. A comparison of plasma cortisol concentrations determined at 2, 3, 4, 5, and 6 hours after induction with thiopental or etomidate revealed a higher (P < 0.05) concentration in dogs given thiopental.

The disposition of etomidate was best described by a 2-compartment model, with a redistribution half-life of 0.12 ± 0.04 minute and a terminal half-life of 1.70 ± 0.27 minute. Plasma cortisol concentrations did not correlate with plasma etomidate concentrations.

We conclude that, compared with thiopental, a single bolus injection of etomidate reduces the adrenocortical response to anesthesia and surgery from 2 to 6 hours after induction. Because cortisol concentrations were significantly higher than baseline, and because cardiopulmonary function is maintained after a single bolus injection of etomidate, it can be considered a safe induction agent in dogs.

Free access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Abstract

Objective

To describe alterations in respiratory and cardiovascular variables during diagnostic thoracoscopy, using bilateral hemithorax ventilation with sustained pneumothorax.

Animals

7 adult dogs.

Procedure

Each dog was anesthetized and instrumented for 2 episodes of cardiopulmonary monitoring that were performed at an interval of more than 14 days. The first anesthetic episode served as a control procedure for the thoracoscopy treatment performed during the second anesthetic episode. Multiple cardiopulmonary variables were evaluated by comparing changes from baseline values within treatments and between treatments.

Results

Arterial oxygen tension decreased significantly from baseline values during thoracoscopy but was unchanged during sham treatment. Arterial carbon dioxide tension, clinical shunt fraction, and systemic mean arterial pressure increased during thoracoscopy. In contrast, these variables were unaffected by the sham treatment. Heart rate and cardiac index increased during sham and thoracoscopy treatments; however, the increase was significantly greater during thoracoscopy. Total peripheral vascular resistance significantly decreased from baseline values for both treatments, but the decrease was greater during thoracoscopy. Significant changes were not observed for oxyhemoglobin saturation or pulmonary vascular resistance during either treatment. Dogs recovered without major clinical complications.

Conclusions

Significant changes were found for several cardiopulmonary variables during bilateral hemithorax ventilation with sustained pneumothorax for diagnostic thoracoscopy of clinically normal dogs.

Clinical Relevance

Diagnostic thoracoscopy with bilateral hemithorax ventilation and sustained pneumothorax is well tolerated in clinically normal dogs and may provide a diagnostic modality enabling intrathoracic procedures with less morbidity than thoracotomy for dogs with intrathoracic disease. (Am J Vet Res 1998;59:1494–1498)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine effects of dietary supplementation with chromium (Cr) picolinate on health and response to IV glucose tolerance testing (IVGTT) in obese and nonobese cats.

Animals

7 obese and 12 nonobese cats.

Procedure

6 nonobese cats were untreated controls, whereas 6 different nonobese cats and 7 obese cats received oral administration of 100 μg Cr/d for 6 weeks. All cats were evaluated before and immediately after the treatment period by use of physical examination, CBC, serum biochemical analyses, and IVGTT. Calculated values included glucose half-life, coefficient of glucose disappearance, insulin peak response, insulinogenic index, and insulin secretion rate determined at various times after start of IVGTT.

Results

Adverse effects on cats’ health were not observed during or after treatment, and significant changes in body weight, hematologic values, or most serum biochemical values were not detected. Serum potassium concentration decreased significantly after treatment in obese cats but was within reference range. Compared with nonobese cats, obese cats had significantly higher insulin peak response, insulinogenic index, and insulin secretion rate before and after treatment. Chromium supplementation did not alter responses to IVGTT in either treatment group.

Conclusions and Clinical Relevance

Dietary supplementation with 100 μg of Cr/d for 6 weeks is safe but does not affect glucose tolerance in obese or nonobese cats. (Am J Vet Res 1999;60:1360–1363)

Free access
in American Journal of Veterinary Research

SUMMARY

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.

Free access
in American Journal of Veterinary Research

SUMMARY

Dynamic baroreflex sensitivity for increasing arterial pressure (dbsi) was used to quantitatively assess the effects of anesthesia on the heart rate/arterial pressure relationship during rapid (≤ 2 minutes) pressure changes in the horse. Anesthesia was induced with iv administration of xylazine and ketamine and maintained with halothane at a constant end-tidal concentration of 1.1 to 1.2% (1.25 to 1.3 minimal alveolar concentration). Systolic arterial pressure (sap) was increased a minimum of 30 mm of Hg in response to an iv bolus injection of phenylephrine HCl. Linear regression was used to determine the slope of the r-r interval/sap relationship. During dynamic increases in sap, a significant correlation between r-r interval and sap was observed in 8 of 8 halothane-anesthetized horses. Correlation coefficients between r-r interval and sap were > 0.80 in 5 of 8 horses. Mean (± sd) dbsi was 4.8 ± 3.4 ms/mm of Hg in anesthetized horses. A significant correlation between r-r interval and sap was observed in only 3 of 6 awake horses during dynamic increases in sap. Lack of correlation between r-r interval and sap in 3 of 6 awake horses indicated that rapidly increasing sap with an iv phenylephrine bolus is a poor method to evaluate baroreceptor-mediated heart rate changes in awake horses. Reflex slowing of heart rate in response to a rising arterial pressure appeared to have been overridden by the effects of excitement. Mean (± sd) dbsi (3 horses) was 7.3 ± 3.3 ms/mm of Hg in awake horses.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether anesthesia of the infraorbital and inferior alveolar nerves abolishes reflex-evoked muscle action potentials (REMP) during tooth-pulp stimulation in halothane-anesthetized cats.

Animals—8 healthy adult cats.

Procedure—In halothane-anesthetized cats, an anodal electrode was attached to the tooth to be stimulated and a platinum needle cathodal electrode was inserted in adjacent gingival mucosa. Cathodal and anodal electrodes were moved to the upper and lower canine, upper fourth premolar, and lower first molar teeth for stimulation; baseline REMP was recorded. A 25-gauge 1-cm needle was inserted 0.5 cm into the infraorbital canal. A 25-gauge 1-cm needle was inserted 1 cm rostral to the angular process of the ramus, and advanced 0.5 cm along the medial aspect. Chloroprocaine was injected at each site. Each tooth was stimulated every 10 minutes for 90 minutes.

Results—REMP was abolished within 10 minutes for all upper teeth, except for the upper canine tooth in 1 cat, and abolished within 10 minutes for lower teeth in 4 cats. In 1 cat, REMP was not abolished in the lower first molar tooth. In 3 cats, REMP was not abolished in the lower canine and first molar teeth. At 90 minutes, REMP was restored for all teeth except the lower canine tooth in 1 cat, for which REMP was restored at 120 minutes.

Conclusions and Clinical Relevance—Regional anesthesia of the infraorbital and inferior alveolar nerves may provide dental analgesia in cats. (Am J Vet Res 2000;61:1245–1247)

Full access
in American Journal of Veterinary Research