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Objective—To determine whether IV administration of a combination of medetomidine and ketamine depresses cardiopulmonary function in healthy adult gopher tortoises.

Design—Prospective study.

Animals—3 adult male and 3 adult female nonreleasable gopher tortoises.

Procedure—Prior to the study, carotid and jugular catheters were surgically placed in each tortoise for blood collection, direct arterial blood pressure monitoring, and drug administration. Heart rate, direct carotid arterial blood pressure, and body temperature were measured before and every 5 minutes for 45 minutes after IV injection of medetomidine (100 µg/kg [45.5 µg/lb]) and ketamine (5 mg/kg [2.3 mg/lb]). Carotid arterial blood samples were collected before and 5, 15, 30, and 45 minutes after medetomidineketamine administration to determine pH, PO2, and PCO2. Atipamezole (500 mg/kg [227 µg/lb], IV) was administered 30 minutes after administration of medetomidine-ketamine.

Results—The medetomidine-ketamine combination caused a moderate increase in arterial blood pressure, and moderate hypercapnia and hypoxemia. There were no significant changes in heart rate or body temperature. Intravenous administration of atipamezole rapidly induced severe hypotension.

Conclusions and Clinical Relevance—The combination of medetomidine and ketamine administered IV resulted in effective short-term immobilization adequate for minor diagnostic procedures in gopher tortoises. This combination also caused moderate hypoventilation, and it is recommended that a supplemental source of oxygen or assisted ventilation be provided. Atipamezole administration hastens recovery from chemical immobilization but induces severe hypotension. It is recommended that atipamezole not be administered IV for reversal of medetomidine in tortoises and turtles. (J Am Vet Med Assoc 2002;220: 1516–1519)

Full access
in Journal of the American Veterinary Medical Association



To determine comparative cardiopulmonary effects of IM administered etorphine and carfentanil in goats.


Seven clinically normal adult female goats.


Each goat received at least 9 drug treatments (etorphine HCI, 5 (twice], 10, 20, and 40 and carfentanil citrate, 5, 10, 20, and 40 μg/kg of body weight), with a minimal 2-day interval between trials. Although drug dosages were randomized, etorphine and carfentanil treatments were alternated. To assess for drug tolerance, the first and last treatments always were etorphine (5 μg/kg).


All goats were instrumented for long-term cardiopulmonary variable data collection.


Both drugs induced rapid catatonic immobilization, characterized by limb and neck hyperextension, with occasional vocalization and bruxation. Etorphine elicited transient violent struggling and vocalization immediately. Time to immobilization appeared dose-dependent, and was more rapid with carfentanil (≤ 5 minutes) than etorphine (5 to 10 minutes) at all dosages. Recovery to standing occurred earlier for etorphine (1 to 2 hours) than carfentanil (> 2 hours) at all dosages.

Both drugs at all dosages significantly (P ≤ 0.05) increased systemic and left ventricular (LV) end-diastolic pressures, LV peak negative dP/dt, total peripheral resistance (TPR), hemoglobin concentration, and left atrial (LA) and pulmonary O2 contents. They also significantly decreased heart and respiration rates, and TPR. A significant increase was observed at some dosages for LV stroke volume and index, LV peak positive dP/dt, mean pulmonary artery pressure, PaO2 , pulmonary artery oxygen partial pressure, PaCO2 , pulmonary mixed venous carbon dioxide partial pressure, LA hemoglobin saturation, LA transport index, and body temperature. Pulmonary and systemic mixed venous carbon dioxide and oxygen contents were significantly decreased at some dosages.


Intramuscularly administered etorphine and carfentanil induce hypertension, bradycardia, and bradypnea in goats. The hypertension appears attributable to an increase in TPR.

Clinical Relevance

Although the cardiopulmonary effects of carfentanil occurred more rapidly, these effects were similar in magnitude for etorphine and carfentanil over the evaluated dosage range. (Am J Vet Res 1996;57:87-96)

Free access
in American Journal of Veterinary Research


Effects of thyroid-stimulating hormone (tsh) and thyrotropin-releasing hormone (trh) on plasma concentrations of thyroid hormones, and effects of acth and dexamethasone on plasma concentrations of cortisol, were studied in adult male ferrets. Thirteen ferrets were randomly assigned to test or control groups of eight and five animals, respectively. Combined (test + control groups) mean basal plasma thyroxine (T4) values were different between the trh (1.81 ± 0.41 μg/dl, mean + SD) and tsh (2.69 ± 0.87 μg/dl) experiments, which were performed 2 months apart. Plasma T4 values significantly (P < 0.05) increased as early as 2 hours (3.37 ± 1.10 μg/dl) and remained high until 6 hours (3,45 ± 0.86 μg/dl) after iv injection of 1 IU of tsh/ferret. In contrast, iv injection of 500 μg of trh/ferret did not induce a significant increase until 6 hours (2.75 ± 0.79) after injection, and induced side effects of hyperventilation, salivation, vomiting, and sedation. There was no significant increase in triiodothyronine (T3) values following tsh or trh administration.

Combined mean basal plasma cortisol values were not significantly different between acth stimulation (1.29 ± 0.84 μg/dl) and dexamethasone suppression test (0.74 ± 0.56 μg/dl) experiments. Intravenous injection of 0.5 IU of acth/ferret induced a significant increase in plasma cortisol concentrations by 30 minutes (5.26 ± 1.21 μg/ dl), which persisted until 60 minutes (5.17 ± 1.99 μg/dl) after injection. Plasma cortisol values significantly decreased as early as 1 hour (0.41 ± 0.13 μg/dl), and had further decreased by 5 hours (0.26 ± 0.15 μg/dl) following iv injection of 0.2 mg of dexamethasone/ferret. These results indicate that iv injection of 1 IU of tsh/ferret is preferable to iv injection of 500 μg of trh/ferret for thyroid function testing in adult male ferrets. Results of this study also indicated that when trh or tsh is used for the thyroid-stimulation test in male ferrets, plasma T4 concentrations, instead of T3, should be used as the indicator of thyroid response. Additionally, iv injection of 0.5 IU of acth and 0.2 mg of dexamethasone may be used in ferrets for the acth stimulation and dexamethasone-suppression tests, respectively.

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