• Journal of Veterinary Clinics
• /
• v.18 no.3
• /
• pp.226-231
• /
• 2001

We investigated the effects of interactions of medetomidine and atipamezole on electroencephalography (EEG) in seven dogs. The dogs were sedated with medetomidine at dose of 30$\mu\textrm{g}$/kg, IM. Atipamezole was injected 15 min later at dose of 30$\mu\textrm{g}$/kg, IV. Recording electrode was positioned at Cz, which was applied to International 10-20 system. Heart rates, arterial blood pressures and behavioral changes were also measured. EEG was recorded in 6 stages(S1: before medetomidine injection, S2: prior to head-down movement after medetomidine injection, S3: 5 minutes after medetomidine injection, S4: 10 minutes after medetomidine injection, S5: 15 minutes after medetomidine injection, S6: prior to head-up movement after atipamezole injection), and heart rates and arterial pressures were recorded at S1, S5 and S6. All results were compared with those of control(S1). After medetomidine injection, the power spectra of EEG were gradually decreased and those of the frequency over 13 Hz were significantly decreased(p<0.05), which were still in the significantly decreased state after atipamezole injection. In the band powers (Band1; 1-2.5 Hz, Band2; 2.5-4.5 Hz, Band3; 4-8Hz, Band4; 8-13 Hz, Band5; 13-20 Hz, Band6; 20-30 Hz, Band7; 30-50 Hz, Band8; 1-50 Hz), band 1, 2, 3, 4, 8 were not significantly changed in any stages. Band 5, 6, 7 were significantly decreased in S 3, 4, 5, 6. That is, medetomidine affects the frequency band over 13 Hz on EEG, and atipamezole does not restored the decreased band powers until dogs showed head-up movement.

• Journal of Veterinary Clinics
• /
• v.28 no.3
• /
• pp.291-296
• /
• 2011

The aims of the present study were to investigate the anesthetic and hemodynamic effects of medetomidine-ketamine combination and to compare antagonistic effects of atipamezole and yohimbine on the recovery of pig from anesthesia induced by medetomidine-ketamine combination. Landrace and Yorkshire cross-bred pigs were evaluated in the present study. Pigs (n = 8) received three different treatments (one treatment per 14 days in a random order). All pigs were injected intramuscularly with medetomidine, and ketamine in a single syringe. Intravenous injections of atipamezole (MKA), yohimbine (MKY), or a control saline solution (MK) were administered 20 minutes after the medetomidine-ketamine combination injection. The intravenous antagonist injections quickly reversed the medetomidine-ketamine induced sedation in the pigs, resulting in a significantly shorter duration of anesthesia in the MKA and MKY groups compared to the MK group. Mean arterial pressure (MAP) levels were significantly lower in the MKA and MKY groups compared to the MK group. Scores for posture and responses to noxious stimuli after atipamezole and yohimbine administration were significantly lower in the MKA and MKY groups than in the MK. In conclusion, the sedative effects and increases in blood pressure induced by a medetomidine-ketamine combination were quickly and smoothly reversed by atipamezole or yohimbine.

• Journal of Veterinary Clinics
• /
• v.27 no.6
• /
• pp.668-673
• /
• 2010

This study was to evaluate the effects of tramadol and medetomidine administration on minimum alveolar concentration (MAC) of isoflurane in dogs. MAC of isoflurane was determined in four occasions; 1 ml saline (Control), $2{\mu}g$/kg medetomidine (M2), 4 mg/kg tramadol (T4), $2{\mu}g$/kg medetomidine-4 mg/kg tramadol combination (M2T4). Heart rate, blood pressure, respiratory rate, end-tidal carbon dioxide concentration, saturation of hemoglobin with oxygen and body temperature were recorded. After administration of M2 ($0.81{\times}0.18%$), T4 ($0.81{\times}0.14%$) and M2T4 ($0.62{\times}0.12%$), less isoflurane was required than the control value ($1.13{\times}0.19%$). Significantly lower heart rate than the control value was detected after treatment of M2, T4, and M2T4. When only M2T4 was administered, blood pressure was significantly higher than the control value. In conclusion, administrations of tramadol, medetomidine and medetomidine-tramadol combination decreased the MAC of isoflurane in dogs. Especially, medetomidine-tramadol combinations could be useful as a premedication because of the anesthetic sparing effect and moderate changes in cardiovascular system.

• Journal of Veterinary Clinics
• /
• v.9 no.2
• /
• pp.391-399
• /
• 1992

This study was carried out to evaluate the effects of doxapram after medetomidine treatment. Twenty dogs were sedated with medetomidine(0.04mg/kg IM) Ten dogs were injected doxapram(2mg/kg IV) as a experimental group and ten dogs were injected with saline(5$m\ell$ IV) as a control group in twenty minutes after the injection of medetomidine. Recovery time, heart rate, respiratory rate, body temperature. blood chemistry, electrocardiogram findings (ECG) were recorded. The results obtained were as follows ; 1. Medetomidine revealed fast and excellent sedative effect. 2. Recovery time was shorted by doxapram(p<0.01) 3. Respiratory rates were decreased significantly by medetommidine, but increased remarkably after the injection of doxapram and them decreased gradually and revealed normal levels(p<0.01). 4. Herts rates were decreased significantly by medetomidine but increased remarkably after the injection of doxapram and then decreased gradually and revealed normal levels(p<0.01). 5. Body temperature were increased slightly and then decreased by medetomldine and in experimental group revealed with higher levels than those of control group(p<0.01) 6. Arrhythmias were observed after the injection of medetomidine, but relieved after the injection of doxapram . There was no another change on electrocardiograms.

• Journal of Veterinary Clinics
• /
• v.30 no.6
• /
• pp.415-420
• /
• 2013

This study was performed to examine the anesthetic and cardiopulmonary effects of medetomidine, midazolam and ketamine (MMK) combination in ten beagle dogs. Dogs were randomly allocated to two groups. Treatment group MMK-L received 0.015 mg/kg medetomidine followed by 0.3 mg/kg midazolam and 5 mg/kg ketamine by intramuscular injection. Treatment group MMK-H received 0.02 mg/kg medetomidine followed by 0.3 mg/kg midazolam and 5 mg/kg ketamine by intramuscular injection. Induction, anesthesia, sternal recumbency, standing, walking time, heart rate, arterial blood pressure, rectal temperature, respiratory rate and arterial blood gases were measured. Mean anesthesia time was significantly different between MMK-L group ($52.4{\pm}11.08$ minutes) and MMK-H group ($78.2{\pm}20.72$ minutes). Sedative scores and noxious stimuli were raised to the maximum value at 5 minutes after administration of the test dose and maintained until 40 minutes in both groups. In both groups, the heart rate significantly decreased after MMK administration. The blood pressures (MAP, SAP and DAP) increased after MMK administration but there were no significant differences in blood pressures between two groups. In conclusion, intramuscular administration of medetomidine followed by intramuscular injection of midazolam and ketamine in beagle dogs, leads immediate and sufficient anesthesia and proper doses of medetomidine for minimal adverse effects in intramuscular MMK combination will be 0.015 mg/kg in dogs.

• Journal of Veterinary Clinics
• /
• v.32 no.5
• /
• pp.422-425
• /
• 2015

This study evaluated the myocardial performance on echocardiography after the sedation/anesthesia of medetomidine (D), the combination of medetomidine and tiletamine/zolazepam (DZ), and the combination of medetomidine, tiletamine/zolazepam and tramadol (DZT) in Beagle dogs. Ten healthy adult Beagle dogs (weighing $8.6{\pm}1.0kg$) were enrolled in this study. Heart rate (HR), fractional shortening (%FS), left ventricular ejection fraction (%LVEF), stroke volume (SV), cardiac output (CO), left ventricular internal diameter in systole (LVIDs) and left ventricular internal diameter in diastole (LVIDd) using M-mode echocardiography were measured prior to anesthesia, then every 10 min for 60 min. The HR, %FS, %LVEF, SV and CO were significantly decreased during sedation/anesthesia with D, DZ and DZT combination of anesthesia. Although those anesthetic protocols provided acceptable quality of sedation/anesthesia, levels of cardiovascular suppression were substantial and persistent and thus the continuous monitoring on vital signs should be accompanied in any situation. Close attention is required for dogs with pre-existing heart diseases, when those anesthetic protocols were applied.

• Korean Journal of Veterinary Research
• /
• v.47 no.1
• /
• pp.103-115
• /
• 2007

The aim of this study was to compare the reaction of the cardiovascular system, and the anesthetic effect among 3 experimental groups, epidural administration of medetomidine as a single agent, the combination of buprenorphine and medetomidine, and the combination of fentanyl and medetomidine. Twenty one dogs were anesthetized with isoflurane and allowed to breathe spontaneously. Epidural, arterial, and venous catheters were inserted. The tip of epidural catheter was positioned at the level of the space between the sixth and seventh lumbar vertebra. After a stable plane of anesthesia was achieved, these dogs were each administered one of the following treatments epidurally : medetomidine $10{\mu}g/kg$ (Group M), a combination of medetomidine $5{\mu}g/kg$ and buprenorphine $10{\mu}g/kg$ (Group M/B), and a combination of medetomidine $5{\mu}g/kg$ and fentanyl $10{\mu}g/kg$ (Group M/F). Heart rate (HR), Respiratory rate (RR), End-tidal carbon dioxide (EtCO2), and arterial blood pressure were measured before drug administration (base line) and 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 min postinjection. Blood gas analysis was performed before injection and 5, 15, 25, 35, 45, 60 min postinjection. Isoflurane was discontinued 80 min postinjection and pain/motor function were evaluated up to 260 min postinjection every 15 min. At the early stage of drug introduction (until 5 min), the HR was decreased significantly in all 3 groups compared with base line. In Group M, HR was significantly decreased compared with the other 2 groups. With time (starting 20 min after drug introduction), the HR was decreased significantly in Group M/B in respect to base line. However, no significant difference was seen number-wise in all 3 groups. During 60 min after drug introduction, the systolic, diastolic and mean arterial pressures were highest in Group M and lowest in Group M/F. Among 3 groups, drug action and motor loss duration were longest in Group M/F. Analgesic effect observed in the M/F group was the most prominent and long-lasting, compared to those seen in the other 2 groups. Given the fact that the recovery of motor function takes place in a short period of time after analgesic effects disappeared, additional use of M/F depending on the patient's condition would be a good way to achieve effective pain management. However, proper care should be taken to ensure the function of cardiovascular system in the patient because the administration of M/F under isoflurane anesthesia results in a significant decline in arterial blood pressure ($65{\pm}10mmHg$).

• Journal of Veterinary Clinics
• /
• v.27 no.4
• /
• pp.343-347
• /
• 2010

The purpose of this study was to determine the antagonistic effects of yohimbine on sedation induced in dogs with medetomidine. Six mixed breed dogs were repeatedly used at a 2 weeks withdrawal time in this study. The dogs received $40\;{\mu}g/kg$ of medetomidine followed 15 minutes later by 0.2 ml/kg saline solution (group M) or 0.11 mg/kg yohimbine (group MY). All the dogs were examined before and 5, 15, 30, 45, 60, 75, 90, 120 and 150 minutes after the injection of medetomidine, and the induction and recovery times, vital signs, blood biochemistry and anesthetic quality were recorded. There were significant differences in the recovery of anesthesia between the groups. In both groups the heart rate decreased rapidly down to five minutes after the administration of medetomidine. The activity of ALT, AST and the protein concentration did not change significantly in either group and there was no significant difference between them at any time. Response to noise, muscle tone and analgesic score in the MY group at 30 minutes were significantly lower than those of the M group. When recovering from anesthesia, the dogs treated with yohimbine took less time to achieve sternal recumbency and less time to be able to stand and walk. It was concluded that yohimbine reversed effectively medetomidine sedation in dogs.

• Journal of Veterinary Clinics
• /
• v.24 no.2
• /
• pp.104-108
• /
• 2007

The purpose of the study is to evaluate the clinical antagonistic effect of atipamezole(0.25 mg/kg, IM) in cats anesthetized with tiletamine-zolazepam ($Zoletil^{(R)}$, 10 mg/kg, IM) and medetomidine (0.05 mg/kg, IM). Twelve healthy 1 year old Korean mixed breed cats were used for this study. They were 4 males and 8 females. These cats were randomly assigned to two groups. One was control group ($Zoletil^{(R)}$ + medetomidine, ZM), and the other was treatment group ($Zoletil^{(R)}$ + medetomidine and antagonism by atipamezole, ZMA). All cats were examined 15 minutes before, 5, 25, 65 and 105 minutes after administration of tiletamine-zolazepam and medetomidine. Atipamezole was injected intramuscularly 20 minutes after ZM administation. Recovery time, heart rate, respiratory rate, total plasma protein and blood glucose were significantly different between ZM group and ZMA group (P<0.05). However, rectal temperature was not significantly different between ZM group and ZMA group. Two groups were able to induce sternal recumbency within 2 minutes and lateral recumbency within 4 minutes after the anesthetics injection. Mean sternal position time ($mean{\pm}SD$) was $174.0{\pm}44.6\;and\;116.2{\pm}27.3$ minutes, and mean standing position time was $210.8{\pm}45.6\;and\;154.2{\pm}21.1$ minutes in ZM and ZMA group, respectively. In these two groups, adverse effects during recovery time from anesthesia were not seen. As a result, the ZMA group had a faster recovery than the ZM group. Thus it was concluded that atipamezole could exert a useful reversal effect in cats anesthetized with medetomidine-tiletamine/zolazepam combination.

• Journal of Veterinary Clinics
• /
• v.26 no.6
• /
• pp.534-538
• /
• 2009

Antiemetic effect of dexamethasone in dogs sedated with medetomidine was evaluated. On the day of experiment, five minutes prior to medetomidine ($40\;{\mu}g$/kg, IM) injection, dexamethasone was administered intravenously at the doses of 0.25, 0.5 and 1.0 mg/kg. Control group was received at 0.1 ml/kg of saline instead of dexamethasone. The dose of 0.5 and 1.0 mg/kg of dexamethasone significantly reduced emetic episode. The degree of sedation determined by visual sedation scoring was not influenced by dexamethasone pretreatments. In addition, the values of complete blood counts and blood chemistry did not show significant changes and were within normal ranges before and the day after experiment. These results show that the doses of 0.5 and 1.0 mg/kg of dexamethasone are useful and safe method to prevent emetic episode inducing by medetomidine in dogs, without evidence of any clinically relevant influences.