Changes in blood glucose and insulin responses to intravenous glucose tolerance tests and blood biochemical values in adult female Japanese black bears (Ursus thibetanus japonicus)

The metabolic mechanisms to circannual changes in body mass of bears have yet to be elucidated. We hypothesized that the Japanese black bear (Ursus thibetanus japonicus) has a metabolic mechanism that efficiently converts carbohydrates into body fat by altering insulin sensitivity during the hyperphagic stage before hibernation. To test this hypothesis, we investigated the changes in blood biochemical values and glucose and insulin responses to intravenous glucose tolerance tests (IVGTT) during the active season (August, early and late November). Four, adult, female bears (5-17 years old) were anesthetized with 6 mg/kg TZ (tiletamine HCl and zolazepam HCl) in combination with 0.1 mg/kg acepromazine maleate. The bears were injected intravenously with glucose (0.5 g/kg of body mass), and blood samples were obtained before, at, and intermittently after glucose injection. The basal triglycerides concentration decreased significantly with increase in body mass from August to November. Basal levels of plasma glucose and serum insulin concentrations were not significantly different among groups. The results of IVGTT demonstrated the increased peripheral insulin sensitivity and glucose tolerance in early November. In contrast, peripheral insulin resistance was indicated by the exaggerated insulin response in late November. Our findings suggest that bears shift their glucose and lipid metabolism from the stage of normal activity to the hyperphagic stage in which they show lipogenic-predominant metabolism and accelerate glucose uptake by increasing the peripheral insulin sensitivity.     

Immobilization of Japanese black bears (Ursus thibetanus japonicus) with tiletamine hydrochloride and zolazepam hydrochloride

The effect of anesthetizing with a 1:1 combination of tiletamine hydrochloride and zolazepam hydrochloride (TZ) was evaluated in 75 Japanese black bears. TZ was administered to 43 captive and 11 wild, 8 captives and 13 hibernating captive bears at the doses of approximately 9.0 mg/kg (usual dosage), 18.0 mg/kg (high dosage) and 5.0 mg/kg (low dosage), respectively. Sufficient anesthetic effects were achieved in all bears, and rectal temperatures, heart rates and respiratory rates did not change significantly during an hour handling. Complete blood cell examinations showed no abnormal data. A combination of TZ would be an efficient and safe drug for chemical immobilization of Japanese black bears.     

Influence of medetomidine on stress-related neurohormonal and metabolic effects caused by butorphanol, fentanyl, and ketamine administration in dogs

OBJECTIVE: To examine stress-related neurohormonal and metabolic effects of butorphanol, fentanyl, and ketamine administration alone and in combination with medetomidine in dogs. ANIMALS: 10 Beagles. PROCEDURE: 5 dogs received either butorphanol (0.1 mg/kg), fentanyl (0.01 mg/kg), or ketamine (10 mg/kg) IM in a crossover design. Another 5 dogs received either medetomidine (0.02 mg/kg) and butorphanol (0.1 mg/kg), medetomidine and fentanyl (0.01 mg/kg), medetomidine and ketamine (10 mg/kg), or medetomidine and saline (0.9% NaCI) solution (0.1 mL/kg) in a similar design. Blood samples were obtained for 6 hours following the treatments. Norepinephrine, epinephrine, cortisol, glucose, insulin, and nonesterified fatty acid concentrations were determined in plasma. RESULTS: Administration of butorphanol, fentanyl, and ketamine caused neurohormonal and metabolic changes similar to stress, including increased plasma epinephrine, cortisol, and glucose concentrations. The hyperglycemic effect of butorphanol was not significant. Ketamine caused increased norepinephrine concentration. Epinephrine concentration was correlated with glucose concentration in the butorphanol and fentanyl groups but not in the ketamine groups, suggesting an important difference between the mechanisms of the hyperglycemic effects of these drugs. Medetomidine prevented most of these effects except for hyperglycemia. Plasma glucose concentrations were lower in the combined sedation groups than in the medetomidine-saline solution group. CONCLUSIONS AND CLINICAL RELEVANCE: Opioids or ketamine used alone may cause changes in stress-related biochemical variables in plasma. Medetomidine prevented or blunted these changes. Combined sedation provided better hormonal and metabolic stability than either component alone. We recommend using medetomidine-butorphanol or medetomidine-ketamine combinations for sedation or anesthesia of systemically healthy dogs.     

Effects of acepromazine and butorphanol on tiletamine-zolazepam anesthesia in llamas

OBJECTIVE: To evaluate sedative, antinociceptive, and physiologic effects of acepromazine and butorphanol during tiletamine-zolazepam (TZ) anesthesia in llamas. ANIMALS: 5 young adult llamas. PROCEDURES: Llamas received each of 5 treatments IM (1-week intervals): A (acepromazine, 0.05 mg/kg), B1 (butorphanol, 0.1 mg/kg), AB (acepromazine, 0.05 mg/kg, and butorphanol, 0.1 mg/kg), B2 (butorphanol, 0.2 mg/kg), or C (saline [0.9% NaCl] solution). Sedation was evaluated during a 30-minute period prior to anesthesia with TZ (2 mg/kg, IM). Anesthesia and recovery characteristics and selected cardiorespiratory variables were recorded at intervals. Antinociception was assessed via a toe-clamp technique. RESULTS: Sedation was not evident following any treatment. Times to sternal and lateral recumbency did not differ among treatments. Duration of lateral recumbency was significantly longer for treatment AB than for treatment C. Duration of antinociception was significantly longer for treatments A and AB, compared with treatment C, and longer for treatment AB, compared with treatment B2. Treatment B1 resulted in a significant decrease in respiratory rate, compared with treatment C. Compared with treatment C, diastolic and mean blood pressures were lower after treatment A. Heart rate was increased with treatment A, compared with treatment B1 or treatment C. Although severe hypoxemia developed in llamas anesthetized with TZ alone and with each treatment-TZ combination, hemoglobin saturation remained high and the hypoxemia was not considered clinically important. CONCLUSIONS AND CLINICAL RELEVANCE: Sedation or changes in heart and respiratory rates were not detected with any treatment before administration of TZ. Acepromazine alone and acepromazine with butorphanol (0.1 mg/kg) prolonged the duration of antinociception in TZ-treated llamas.     

A comparison of anesthetic and cardiorespiratory effects of tiletamine-zolazepam-butorphanol and tiletamine-zolazepam-butorphanol- medetomidine in cats

Using a randomized crossover design, this study compared the anesthetic and cardiorespiratory effects of three intramuscular anesthetic combinations in seven 2-year-old cats: tiletamine-zolazepam (8 mg/kg) and butorphanol (0.2 mg/kg) (TT); tiletamine-zolazepam (3 mg/kg), butorphanol (0.15 mg/kg), and medetomidine (15 microg/kg) (TTD); or the TTD protocol plus atipamezole (75 microg/kg IM) given 20 minutes later to reverse medetomidine. Analgesia was assessed using algometry and needle pricking. All three combinations effectively induced anesthesia suitable for orotracheal intubation within 5 minutes after injection. Hemoglobin oxygen saturation was lower than 90% at least once in all three groups between 5 and 15 minutes after drug administration. Blood pressure and heart and respiratory rates were within normal ranges. Both TT and TTD appeared to be effective injectable anesthetic combinations. TTD provided significantly better analgesia with a longer duration than did TT. Atipamezole administration shortened the duration of analgesia and decreased blood pressure but did not shorten total recovery time.     

Evaluation of the perioperative stress response in dogs administered medetomidine or acepromazine as part of the preanesthetic medication

OBJECTIVE: To compare the perioperative stress response in dogs administered medetomidine or acepromazine as part of the preanesthetic medication. ANIMALS: 42 client-owned dogs that underwent elective ovariohysterectomy. PROCEDURE: Each dog was randomly allocated to receive medetomidine and butorphanol tartrate (20 microgram/kg and 0.2 mg/kg, respectively, IM) or acepromazine maleate and butorphanol (0.05 and 0.2 mg/kg, respectively, IM) for preanesthetic medication. Approximately 80 minutes later, anesthesia was induced by administration of propofol and maintained by use of isoflurane in oxygen. Each dog was also given carprofen before surgery and buprenorphine after surgery. Plasma concentrations of epinephrine, norepinephrine, cortisol, and beta-endorphin were measured at various stages during the perioperative period. In addition, cardiovascular and clinical variables were monitored. RESULTS: Concentrations of epinephrine, norepinephrine, and cortisol were significantly lower for dogs administered medetomidine. Concentrations of beta-endorphin did not differ between the 2 groups. Heart rate was significantly lower and mean arterial blood pressure significantly higher in dogs administered medetomidine, compared with values for dogs administered acepromazine. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that for preanesthetic medications, medetomidine may offer some advantages over acepromazine with respect to the ability to decrease perioperative concentrations of stress-related hormones. In particular, the ability to provide stable plasma catecholamine concentrations may help to attenuate perioperative activation of the sympathetic nervous system.     

The effect of four anesthetic protocols on splenic size in dogs

Objective To characterize the effects of four anesthetic protocols on the size of the spleen during surgery in dogs. Study design Prospective experimental trial. Animals Twenty‐four beagle dogs, 1.1 ± 0.3 years of age and weighing 10.9 ± 2.7 kg. Methods Dogs were allocated to receive one of four anesthetic protocols: 1 – pre‐medication with acepromazine and butorphanol, induction with thiopental; 2 – pre‐medication with acepromazine and butorphanol, induction with propofol; 3 – pre‐medication with medetomidine and butorphanol, induction with propofol; and 4 – pre‐medication with medetomidine and butorphanol, induction with ketamine and diazepam. Anesthesia was then maintained with halothane. At laparotomy, the spleen length, width, and height were measured, these were measured again just prior to closure of the abdomen. Splenic area and volume were calculated. Hematocrit and total serum protein (TSP) were measured before and after induction and during laparotomy. Results Splenic volume was greatest after protocol 4 (161.2 ± 40.2 cm³; p < 0.05) and was least after protocol 2. The differences in volume were because of differences in length, width, and height between groups. There was no significant change in area, length, or width over the study period. Hematocrit decreased significantly in all dogs but at different times. The decrease occurred after pre‐medication if acepromazine was administered, at induction following protocol 3 and during surgery following protocol 4. Conclusions If splenic volume is to be minimized during surgery, then acepromazine and propofol should be used in the anesthetic protocol. The administration of medetomidine, diazepam, and ketamine will produce a greater splenic volume. Lack of correlation between hematocrit and spleen size following the anesthetic protocols studied suggests sequestration of red blood cells in nonsplenic sites.     

Medetomidine-ketamine-butorphanol anesthetic combinations in binturongs (Arctictis binturong).

The efficacy, safety, and reliability of two ketamine-medetomidine-butorphanol anesthetic combinations were evaluated in 34 adult binturongs (Arctictis binturong). The animals were randomly assigned to one of the two groups. On the basis of estimated body weights, group high ketamine (HK) received ketamine (8 mg/kg, i.m.), medetomidine (0.02 mg/kg, i.m.), and butorphanol (0.2 mg/kg, i.m.) combined in a single injection, and group low ketamine (LK) received ketamine (2 mg/kg, i.m.), medetomidine (0.04 mg/kg, i.m.), and butorphanol (0.2 mg/kg, i.m.). Cardiopulmonary parameters were measured for approximately 45 min; the animals were then administered atipamezole (5 mg/mg medetomidine, i.m.). Individual responses varied greatly to the anesthetic combinations, but similar numbers of animals in each group needed supplemental anesthetic agents (seven in group HK and six in group LK). Mean heart rates were higher in the LK group throughout anesthesia. Animals in both groups were mildly to moderately hypoxemic, but oxygenation improved in both groups following supplemental oxygen administration. Respiratory rates, arterial blood pressures, body temperatures, and end-tidal CO2 values were similar in both groups. Both protocols were effective; however, the LK combination is preferable because the mean recovery time was shorter.     

Duration of nonresponse to noxious stimulation after intramuscular administration of butorphanol, medetomidine, or a butorphanol-medetomidine combination during isoflurane administration in dogs

OBJECTIVE: To assess duration of actions of butorphanol, medetomidine, and a butorphanol-medetomidine combination in dogs given subanesthetic doses of isoflurane (ISO). ANIMALS: 6 healthy dogs. PROCEDURE: Minimum alveolar concentration (MAC) values for ISO were determined. for each dog. Subsequently, 4 treatments were administered to each dog (saline [0.9% NaCl] solution, butorphanol [0.2 mg/kg of body weight], medetomidine [5.0 microg/kg], and a combination of butorphanol [0.2 mg/kg] and medetomidine [5.0 microg/kg]). All treatments were administered IM to dogs concurrent with isoflurane; treatment order was determined, using a randomized crossover design. Treatments were given at 7-day intervals. After mask induction with ISO and instrumentation with a rectal temperature probe, end-tidal CO2 and anesthetic gas concentrations were analyzed. End-tidal ISO concentration was reduced to 90% MAC for each dog. A tail clamp was applied 15 minutes later. After a positive response, 1 of the treatments was administered. Response to application of the tail clamp was assessed at 15-minute intervals until a positive response again was detected. RESULTS: Duration of nonresponse after administration of saline solution, butorphanol, medetomidine, and butorphanol-medetomidine (mean +/- SD) was 0.0+/-0.0, 1.5+/-1.5, 2.63+/-0.49, and 5.58+/-2.28 hours, respectively. Medetomidine effects were evident significantly longer than those for saline solution, whereas effects for butorphanol-medetomidine were evident significantly longer than for each agent administered alone. CONCLUSION AND CLINICAL RELEVANCE: During ISO-induced anesthesia, administration of medetomidine, but not butorphanol, provides longer and more consistent analgesia than does saline solution, and the combination of butorphanol-medetomidine appears superior to the use of medetomidine or butorphanol alone.     

Effects of sedation on echocardiographic variables of left atrial and left ventricular function in healthy cats

Although sedation is frequently used to facilitate patient compliance in feline echocardiography, the effects of sedative drugs on echocardiographic variables have been poorly documented. This study investigated the effects of two sedation protocols on echocardiographic indices in healthy cats, with special emphasis on the assessment of left atrial size and function, as well as left ventricular diastolic performance. Seven cats underwent echocardiography (transthoracic two-dimensional, spectral Doppler, color flow Doppler and tissue Doppler imaging) before and after sedation with both acepromazine (0.1 mg/kg IM) and butorphanol (0.25 mg/kg IM), or acepromazine (0.1 mg/kg IM), butorphanol (0.25 mg/kg IM) and ketamine (1.5 mg/kg IV). Heart rate increased significantly following acepromazine/butorphanol/ketamine (mean ± SD of increase, 40 ± 26 beats/min) and non-invasive systolic blood pressure decreased significantly following acepromazine/butorphanol (mean ± SD of decrease, 12 ± 19 mmHg). The majority of echocardiographic variables were not significantly different after sedation compared with baseline values. Both sedation protocols resulted in mildly decreased left ventricular end-diastolic dimension and mildly increased left ventricular end-diastolic wall thickness. This study therefore failed to demonstrate clinically meaningful effects of these sedation protocols on echocardiographic measurements, suggesting that sedation with acepromazine, butorphanol and/or ketamine can be used to facilitate echocardiography in healthy cats.     

Investigation of the effect of acepromazine on intravenous glucose tolerance tests in dogs

OBJECTIVE: To investigate the effects of administration of acepromazine on IV glucose tolerance tests (IVGTTs) in dogs. ANIMALS: 8 male mixed-breed dogs. PROCEDURE: With a 1-week interval between tests, each dog underwent (in random order) an IVGTT with or without pretest administration of acepromazine maleate (0.1 mg/kg, SC, 30 minutes prior to the start of the IVGTT). Food was withheld from the dogs for 14 hours prior to each test. Blood samples were obtained at 20, 10, and 1 minute prior to and at 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 19, 22, 25, 30, 40, 50, 60, 70, 80, 90, 100, 120, 140, 160, and 180 minutes after administration of glucose. RESULTS: There were no significant differences in the baseline (ie, after food was withheld) plasma glucose, lactate, and insulin concentrations between dogs undergoing the IVGTT and acepromazine-IVGTT; however, lower baseline free fatty acid concentration was observed in acepromazine-treated dogs. Analysis of data via the application of Bergman's minimal model of glucose kinetics revealed no differences in insulin sensitivity, acute insulin response to glucose, disposition index, or glucose effectiveness between dogs treated or not treated with acepromazine before testing. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that in dogs undergoing IV glucose tolerance testing, pretest administration of small doses of acepromazine can be used as a means of chemical restraint without interfering with results of the glucose metabolism assessment.     

Comparison of the cardiorespiratory effects of medetomidine-butorphanol-ketamine and medetomidine-butorphanol-midazolam in patas monkeys (Erythrocebus patas).

The cardiorespiratory effects, effectiveness, and reversibility of two injectable anesthetic combinations were compared in captive patas monkeys (Erythrocebus patas). Seven patas monkeys were hand-injected with medetomidine (40 microg/kg, i.m.), butorphanol (0.4 mg/kg. i.m.), and ketamine (3.0 mg/kg. i.m.), and seven were injected with the same dosages of medetomidine and butorphanol plus midazolam (0.3 mg/kg, i.m.). Heart rates decreased in monkeys in both treatment groups and were lower than those previously recorded in patas monkeys anesthetized with either ketamine or ketamine and isoflurane. Mean arterial pressures were highest in ketamine-treated monkeys but remained within normal limits for both groups. End tidal CO2 values increased gradually over time in both groups and were above physiologic norms after 20 min. Respiratory rates were similar between groups and remained constant throughout the procedures. Despite adequate ventilation parameters, initial low percent oxygen-hemoglobin saturation (SpO2) values were suggestive of severe hypoxemia. It was not clear whether these were accurate readings or an artifact of medetomidine-induced peripheral vasoconstriction. Oxygen supplementation restored SpO2 values to normal (>94%) in both groups. Both combinations effectively produced a state of light anesthesia, although spontaneous recoveries occurred after 30 min in three ketamine-treated monkeys. All monkeys were given i.m. atipamezole (0.2 mg/kg) and naloxone (0.02 mg/kg), whereas midazolam-treated monkeys also received flumazenil (0.02 mg/kg, i.v.), which resulted in faster (median recovery time = 5 min) and more complete recoveries in this group. Both combinations are safe to use when supplemented with oxygen, although the midazolam combination provided a longer anesthetic period and was more fully reversible.     

Comparison of intraoperative cardiorespiratory and behavioral responses to medetomidine combined with tramadol or butorphanol during standing laparoscopic ovariectomy in horses

The purpose of this study was to assess the cardiorespiratory and behavioral responses to the combination of medetomidine and tramadol (M-T) or butorphanol (M-B) in standing laparoscopic ovariectomy in horses. One ovary was removed under M-T and the contralateral ovary was removed under M-B with at least 4 weeks between operations at random. Horses were sedated using intravenous medetomidine (5 µg/kg) followed by tramadol (1 mg/kg) or butorphanol (10 µg/kg) after 5 min. Sedation was maintained through the repeated injection of medetomidine (1 µg/kg) and tramadol (0.4 mg/kg) or medetomidine (1 µg/kg) and butorphanol (4 µg/kg) every 15 min. Cardiorespiratory function and behavioral responses, including, sedation, ataxia, and analgesia, were assessed during the surgery. There were no significant differences in cardiorespiratory values and sedation and analgesia scores between M-T and M-B. Ataxia scores were significantly lower in M-T than in M-B. This result suggests that M-T could maintain smooth and stable standing surgery with minimal cardiorespiratory changes in horses.     

The effect of opioid and acepromazine premedication on the anesthetic induction dose of propofol in cats

The median effective dosage (ED50) for induction of anesthesia with propofol was determined by using the up-and-down method in 31 unpremedicated cats, in 30 cats premedicated with butorphanol, 0.4 mg/kg body weight (BW), and acepromazine, 0.1 mg/kg BW, intramuscularly, and in 30 cats premedicated with morphine, 0.2 mg/kg BW, and acepromazine, 0.1 mg/kg BW, intramuscularly. The dose required for a satisfactory anesthetic induction in 50% of unpremedicated cats (ED50) was 7.22 mg/kg BW and of premedicated cats was 5.00 mg/kg BW. The reduction in dose was statistically significant in both premedicated groups compared with no premedication. There was no significant difference in ED50 between premedication regimes. Cyanosis was the most common adverse effect observed in all groups following anesthetic induction with propofol.     

Sedative and cardiorespiratory effects of medetomidine, medetomidine-butorphanol, and medetomidine-ketamine in dogs

OBJECTIVE: To determine sedative and cardiorespiratory effects of i.m. administration of medetomidine alone and in combination with butorphanol or ketamine in dogs. DESIGN: Randomized, crossover study. ANIMALS: 6 healthy adult dogs. PROCEDURES: Dogs were given medetomidine alone (30 micrograms/kg [13.6 micrograms/lb] of body weight, i.m.), a combination of medetomidine (30 micrograms/kg, i.m.) and butorphanol (0.2 mg/kg [0.09 mg/lb], i.m.), or a combination of medetomidine (30 micrograms/kg, i.m.) and ketamine (3 mg/kg [1.36 mg/lb], i.m.). Treatments were administered in random order with a minimum of 1 week between treatments. Glycopyrrolate was given at the same time. Atipamezole (150 micrograms/kg [68 micrograms/lb], i.m.) was given 40 minutes after administration of medetomidine. RESULTS: All but 1 dog (given medetomidine alone) assumed lateral recumbency within 6 minutes after drug administration. Endotracheal intubation was significantly more difficult when dogs were given medetomidine alone than when given medetomidine and butorphanol. At all evaluation times, percentages of dogs with positive responses to tail clamping or to needle pricks in the cervical region, shoulder region, abdominal region, or hindquarters were not significantly different among drug treatments. The Paco2 was significantly higher and the arterial pH and Pao2 were significantly lower when dogs were given medetomidine and butorphanol or medetomidine and ketamine than when they were given medetomidine alone. Recovery quality following atipamezole administration was unsatisfactory in 1 dog when given medetomidine and ketamine. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that a combination of medetomidine with butorphanol or ketamine resulted in more reliable and uniform sedation in dogs than did medetomidine alone.     

Cardiorespiratory effects of a combination of medetomidine, midazolam, and butorphanol in dogs.

OBJECTIVE: To characterize cardiorespiratory effects for a combination of medetomidine, butorphanol, and midazolam and to compare magnitude of cardiorespiratory depression with that induced by a commonly used inhalation anesthetic regimen (acepromazine-butorphanol-thiopental-halothane). ANIMALS: 10 clinically normal dogs (2 groups of 5). PROCEDURE: In treated dogs, medetomidine was administered (time, 0 minutes); midazolam and butorphanol were administered when effects of medetomidine were maximal (time, 20), and atipamezole was administered subsequently (time 60). In control dogs, drugs were administered after allowing effects of each agent to be achieved: acepromazine was given at time 0, butorphanol and thiopental were administered at time 35, and halothane was administered from time 45 until 110. Various cardiorespiratory and hematologic variables were measured or calculated. RESULTS: Respiratory rate, arterial and venous pH, venous oxygen content, oxygen consumption, and oxygen delivery decreased significantly below baseline values for treated dogs; end-tidal CO2, arterial and venous P(CO)2, and O2 extraction increased significantly above baseline values. Compared with data obtained after anesthesia, arterial HCO3- concentration, venous P(O2) and S(O2), cardiac output, oxygen extraction, and oxygen delivery appeared more modified in treated dogs. Oxygen consumption and physiologic shunt fraction were less modified in treated dogs than control dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Medetomidine-butorphanol-midazolam combination induced respiratory depression, comparable in magnitude to that induced by a widely used inhalation anesthetic regimen. Respiratory variables remained within acceptable limits during anesthesia; however, those associated with cardiovascular function were more severely affected.     

Effects of intramuscular administration of low doses of medetomidine and medetomidine-butorphanol in middle-aged and old dogs.

OBJECTIVE: To determine effects of low doses of medetomidine administered with and without butorphanol and glycopyrrolate to middle-aged and old dogs. DESIGN: Prospective randomized clinical trial. ANIMALS: 88 healthy dogs > or = 5 years old. PROCEDURE: Dogs were assigned randomly to receive medetomidine (2, 5, or 10 micrograms/kg [0.9, 2.3, or 4.6 micrograms/lb] of body weight, i.m.) alone or with glycopyrrolate (0.01 mg/kg [0.005 mg/lb], s.c.), medetomidine (10 micrograms/kg) and butorphanol (0.2 mg/kg [0.1 mg/lb], i.m.), or medetomidine (10 micrograms/kg), butorphanol (0.2 mg/kg), and glycopyrrolate (0.01 mg/kg). Anesthesia was induced with thiopental sodium and maintained with isoflurane. Degree of sedation and analgesia were determined before and after medetomidine administration. Respiratory rate, heart rate, and mean arterial blood pressure were determined 10 and 30 minutes after medetomidine administration. Adverse effects and amounts of thiopental and isoflurane used were recorded. RESULTS: Sedation increased after medetomidine administration in 79 of 88 dogs, but decreased in 7 dogs that received 2 or 5 micrograms of medetomidine/kg. Mean postsedation analgesia score and amounts of thiopental and isoflurane used were less in dogs that received medetomidine and butorphanol, compared with other groups. Respiratory rate, heart rate, and blood pressure were not different among groups. Significantly more adverse effects developed in dogs that did not receive glycopyrrolate. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of medetomidine (10 micrograms/kg, i.m.) and butorphanol (0.2 mg/kg, i.m.) induced sedation and analgesia and reduced amounts of thiopental and isoflurane required for anesthesia in middle-aged and old dogs. Glycopyrrolate decreased frequency of medetomidine-associated adverse effects.     

Cardiopulmonary assessment of medetomidine, ketamine, and butorphanol anesthesia in captive Thomson's gazelles (Gazella thomsoni).

This investigation evaluated the cardiopulmonary effects of medetomidine, ketamine, and butorphanol anesthesia in captive juvenile Thomson's gazelles (Gazella thomsoni). Butorphanol was incorporated to reduce the dose of medetomidine necessary for immobilization and minimize medetomidine-induced adverse cardiovascular side effects. Medetomidine 40.1 +/- 3.6 microg/kg, ketamine 4.9 +/- 0.6 mg/kg, and butorphanol 0.40 +/- 0.04 mg/kg were administered intramuscularly by hand injection to nine gazelles. Times to initial effect and recumbency were within 8 min postinjection. Cardiopulmonary status was monitored every 5 min by measuring heart rate, respiratory rate, indirect blood pressure, end-tidal CO2, and indirect oxygen-hemoglobin saturation by pulse oximetry. Venous blood gases were collected every 15 min postinjection. Oxygen saturations less than 90% in three gazelles suggested hypoxemia. Subsequent immobilized gazelles were supplemented with intranasal oxygen throughout the anesthetic period. Sustained bradycardia (<60 beats per minute, as compared with anesthetized domestic calves, sheep, and goats) was noted in eight of nine gazelles. Heart and respiratory rates and rectal temperatures decreased slightly, whereas systolic, mean, and diastolic blood pressure values were consistent over the anesthetic period. Mild elevations in end tidal CO2 and PCO2 suggested hypoventilation. Local lidocaine blocks were necessary to perform castrations in all seven of the gazelles undergoing the procedure. Return to sternal recumbency occurred within 7 min and return to standing occurred within 12 min after reversal with atipamezole (0.2 +/- 0.03 mg/kg) and naloxone (0.02 +/- 0.001 mg/kg). Medetomidine, ketamine, and butorphanol can be used to safely anesthetize Thomson's gazelles for routine, noninvasive procedures. More invasive procedures, such as castration, can be readily performed with the additional use of local anesthetics.     

The use of propofol for induction of anaesthesia in dogs premedicated with acepromazine, butorphanol and acepromazine-butorphanol

Cardiovascular, pulmonary and anaesthetic-analgesic responses were evaluated in 18 male and female dogs to determine the effect of the injectable anaesthetic propofol used in conjuction with acepromazine and butorphanol. The dogs were randomly divided into three groups. Dogs in Group A were premeditated with 0.1 mg/kg of intramuscular acepromazine followed by an induction dose of 4.4 mg/kg of intravenous propofol; Group B received 0.2 mg/kg of intramuscular butorphanol and 4.4 mg/kg of intravenous propofol; dogs in Group AB were administered a premeditation combination of 0.1 mg/kg of intramuscular acepromazine and 0.2 mg/kg of intramuscular butorphanol, followed by induction with 3.3 mg/kg of intravenous propofol. The induction dose of propofol was given over a period of 30-60 seconds to determine responses and duration of anaesthesia. Observations recorded in the dogs included heart and respiratory rates, indirect arterial blood pressures (systolic, diastolic and mean), cardiac rhythm, end-tidal CO, tension, oxygen saturation, induction time, duration of anaesthesia, recovery time and adverse reactions. The depth of anaesthesia was assessed by the response to mechanical noxious stimuli (tail clamping), the degree of muscle relaxation and the strength of reflexes. Significant respiratory depression was seen after propofol induction in both groups receiving butorphanol with or without acepromazine. The incidence of apnea was 4/6 dogs in Group B, and 5/6 dogs in Group AB. The incidence of apnea was also correlated to the rate of propofol administration. Propofol-mediated decreases in arterial blood pressure were observed in all three groups. Moderate bradycardia (minimum value > 55 beats/min) was observed in both Groups B and AB. There were no cardiac dysrhythmias noted in any of the 18 dogs. The anaesthetic duration and recovery times were longer in dogs premeditated with acepromazine/butorphanol.     

Comparison of the efficacy and cardiorespiratory effects of medetomidine-based anesthetic protocols in ring-tailed lemurs (Lemur catta).

The relative efficacies and cardiorespiratory effects of three injectable anesthetic combinations containing medetomidine were evaluated in ring-tailed lemurs (Lemur catta). In addition, the direct effects of medetomidine on heart rate and blood pressure were evaluated in lemurs anesthetized with isoflurane. For injectable anesthesia, captive adult ring-tailed lemurs were anesthetized with medetomidine and ketamine (0.04-0.06 mg/kg, i.m. and 3 mg/kg, i.m., respectively), medetomidine, butorphanol, and ketamine (0.04 mg/kg, i.m., 0.4 mg/kg, i.m., and 3 mg/kg, i.m., respectively), or medetomidine, butorphanol, and midazolam (0.04 mg/kg, i.m., 0.4 mg/kg, i.m., and 0.3 mg/kg, i.m., respectively). For inhalation anesthesia, lemurs were mask-induced and maintained with isoflurane for 30 min before receiving medetomidine (0.04 mg/kg, i.m.). Sedation produced by medetomidine-ketamine was unpredictable and of short duration. Both medetomidine-butorphanol-ketamine (MBK) and medetomidine-butorphanol-midazolam (MBMz) provided adequate anesthesia for routine physical exams; however, the effects of MBMz lasted longer than those of MBK. Heart rates and respiratory rates were within clinically normal ranges for all groups, and lemurs remained normotensive throughout the study. Common side effects such as hypertension and bradycardia associated with the use of alpha2-adrenergic receptor agonist combinations in other species were not observed. Likewise, medetomidine administration had no effect on HR in lemurs receiving isoflurane. Lemurs in all groups were well ventilated and remained well oxygenated throughout the procedures, though arterial partial pressure of O2 was lowest in the MBMz group. All three injectable medetomidine combinations were effective in ring-tailed lemurs but only MBK and MBMz provided adequate depth and duration of anesthesia for use as sole regimes. For many clinical procedures in lemurs, MBMz offers advantages over MBK because of its longer duration of action and its rapid and more complete reversibility with specific antagonists.