The effect of medetomidine on the regional cerebral blood flow in dogs measured using Technetium-99m-Ethyl Cysteinate Dimer SPECT

Sedatives and anaesthetics are known to cause changes in the regional cerebral blood flow. In dogs intramuscular sedation with medetomidine, a potent sedative frequently used in veterinary medicine, is sometimes indicated prior to intravenous injection of ^99mTechnetium-Ethyl Cysteinate Dimer (^99mTc-ECD) in brain perfusion studies using Single Photon Emission Computed Tomography (SPECT). Based on the knowledge of the distribution of alpha₂-receptors in the brain, we hypothesized altered regional brain perfusion in dogs receiving medetomidine prior to ^99mTc-ECD. Two conditions were compared in 10 dogs; tracer injection before and after intramuscular sedation with medetomidine. In our study, medetomidine caused a significantly higher tracer uptake in all brain regions. Semi-quantification of brain perfusion rendered a lower perfusion index in the subcortical region and an imbalance between left and right cortical perfusion induced by medetomidine. This study shows that caution is needed when quantifying the brain perfusion indices under medetomidine sedation.     

Alfaxalone or ketamine‐medetomidine in cats undergoing ovariohysterectomy: a comparison of intra‐operative parameters and post‐operative pain

ObjectiveTo compare post-operative pain in cats after alfaxalone or ketamine- medetomidine anaesthesia for ovariohysterectomy (OHE) and physiologic parameters during and after surgery.Study designProspective ‘blinded’ randomized clinical study.AnimalsTwenty-one healthy cats.MethodsCats were assigned randomly into two groups: Group A, anaesthesia was induced and maintained with alfaxalone [5 mg kg^?1 intravenously (IV) followed by boli (2 mg kg^?1 IV); Group MK, induction with ketamine (5 mg kg^?1 IV) after medetomidine (30 μg kg^?1 intramuscularly (IM)], and maintenance with ketamine (2 mg kg^?1 IV). Meloxicam (0.2 mg kg^?1 IV) was administered after surgery. Basic physiological data were collected. At time T = -2, 0, 0.5, 1, 2, 4, 6, 8, 12, 16, 20, and 24 hours post-operatively pain was assessed by three methods, a composite pain scale (CPS; 0–24 points), a visual analogue scale (VAS 0–100 mm), and a mechanical wound threshold (MWT) device. Butorphanol (0.2 mg kg^?1 IM) was administered if CPS was scored =13. Data were analyzed using a general linear model, Kruskal–Wallis analyses, Bonferroni-Dunn test, unpaired t-test and Fisher's exact test as relevant. Significance was set at p < 0.05.ResultsVASs were significantly higher at 0.5, 1, 2, 4, and 20 hours in group A; MWT values were significantly higher at 8 and 12 hours in group MK. Post-operative MWT decreased significantly compared to baseline in both groups. There was no difference in CPS at any time point. Five cats required rescue analgesia (four in A; one in MK).Conclusion and clinical relevanceAnaesthesia with ketamine-medetomidine was found to provide better post-surgical analgesia than alfaxalone in cats undergoing OHE; however, primary hyperalgesia developed in both groups. Alfaxalone is suitable for induction and maintenance of anaesthesia in cats undergoing OHE, but administration of additional sedative and analgesic drugs is highly recommended.     

Clinical observations on medetomidine/ ketamine anaesthesia and its antagonism by atipamezole in the cat

A combination of medetomidine and ketamine was administered intramuscularly to produce anaesthesia in 34 cats undergoing elective surgery or diagnostic procedures. Vomiting before the onset of sedation was observed in six cats. Surgical anaesthesia was rapid in onset and of consistently high quality. In order to hasten return to full awareness at the termination of surgery, atipamezole was administered, intramuscularly, in 33 cats. Recovery was smooth in all cases, with return to full consciousness occurring within a short time of the injection of atipamezole.     

A comparative clinical study of three different dosages of intramuscular midazolam-medetomidine-ketamine immobilization in cats

A low dose of midazolam-medetomidine-ketamine (MMK) combination was evaluated in three increasing dosages. Each of the 18 cats was randomly allocated for several times to one of four groups. Five minutes after premedication with intramuscular (IM) 0.04 mg/kg atropine, group A (n = 43), B (n = 40) and C (n = 28) all were anaesthetized with 0.5 mg/kg midazolam, combined with 10, 20 or 30 microg/kg medetomidine, and 1.0, 2.0 or 3.0 mg/kg ketamine, respectively, IM in one syringe. Group D (n = 11) received the established combination of 50 microg/kg medetomidine and 10.0 mg/kg ketamine for comparison. Because this study was in cooperation with a project on dental prophylaxis, cats had to be immobilized for approximately 1 h. Therefore, anaesthesia was prolonged with propofol to effect, if necessary. Duration of MMK anaesthesia was between 30 +/- 15, 45 +/- 19 and 68 +/- 28 min in groups A, B and C respectively. A significant decrease of respiratory rate was observed with increasing dosage, but venous carbon dioxide (pCO(2)) and pH values in combination with arterial oxygen saturation (SpO(2)) values were not alarming. The diastolic blood pressure particularly showed an increase. MMK combination A showed the best cardiovascular results, but it cannot be recommended due to disadvantages like a long induction time sometimes accompanied by excitations and the short duration of surgical immobilization. Dosage C in contrast had fewer side effects but less favourable cardiovascular results and a longer recovery period. However, either dosage B or C was suitable as a repeatable IM immobilization method for non-invasive procedures in healthy cats.     

Evaluation of the effects of premedication on gastroduodenoscopy in cats

OBJECTIVE: To evaluate the effects of hydromorphone, hydromorphone and glycopyrrolate, medetomidine, and butorphanol premedication on the difficulty and time required to pass an endoscope into the stomach and duodenum of cats anesthetized with ketamine and isoflurane. DESIGN: Randomized complete block crossover study. ANIMALS: 8 purpose-bred adult female cats. PROCEDURES: Each cat was premedicated and anesthetized 4 times with an interval of at least 7 days between procedures. Cats were premedicated with hydromorphone, hydromorphone and glycopyrrolate, medetomidine, or butorphanol administered IM. Twenty minutes after premedication, sedation was assessed by use of a subjective ordinal scale. Cats received ketamine administered IM, and 10 minutes later a cuffed orotracheal tube was placed and anesthesia maintained with isoflurane. Cats breathed spontaneously throughout the procedure. When end-tidal isoflurane concentration was stable at 1.4% for 15 minutes, endoscopy was begun. The times required to pass the endoscope through the cardiac and pyloric sphincters were recorded, and the difficulty of endoscope passage was scored by use of a subjective ordinal scale. RESULTS: No significant differences in difficulty or time required to pass the endoscope through the cardiac and pyloric sphincters were found among premedicant groups. Premedication with medetomidine resulted in the greatest degree of sedation and longest time to return to sternal recumbency. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that hydromorphone, hydromorphone and glycopyrrolate, medetomidine, and butorphanol at the doses tested can be used satisfactorily to premedicate cats prior to general anesthesia for gastroduodenoscopy.     

Comparison of the clinical utility of medetomidine/ketamine and xylazine/ketamine combinations for the ovariectomy of cats

A controlled trial was conducted to assess suitability of combinations of medetomidine and ketamine for the ovariectomy of cats, to investigate the possible side effects, and to compare medetomidine/ketamine with a combination of xylazine and ketamine. Three hundred and thirty-seven cats were submitted to surgery; 100 were anaesthetised with 80 micrograms/kg medetomidine and 5 mg/kg ketamine, 137 with 80 micrograms/kg medetomidine and 7.5 mg/kg ketamine, and 100 were anaesthetised with 1 mg/kg xylazine and 10 mg/kg ketamine. The combinations were injected intramuscularly in the same syringe. The anaesthesia provided by the medetomidine/ketamine combinations was characterised by good muscle relaxation, good analgesia and minimal side effects. The only difference between the two doses of ketamine was the length of the period of anaesthesia. The advantages of the medetomidine/ketamine combination in comparison with xylazine/ketamine were the need for a lower dose of ketamine, a longer duration of action and better analgesia. Similar side effects were observed with both medetomidine/ketamine and xylazine/ketamine combinations.     

Clinical evaluation of medetomidine, a novel sedative and analgesic drug for dogs and cats

Medetomidine, a potent alpha 2-adrenoceptor agonist, was investigated in open, multicenter clinical trials with patients of various canine and feline breeds (1736 dogs and 678 cats). The purpose of the study was to find an optimal dose of medetomidine for sedation and analgesia in clinical practice and to study how well the intended procedure could be performed under the influence of the drug. The mean dose (i.m.) of medetomidine used for examinations, clinical procedures and minor surgical interventions was 40 micrograms/kg, and for radiography 30 micrograms/kg. In cats the dose was 80-110 micrograms/kg. On the doses chosen, almost all animals were recumbent and 72% of the dogs and 85% of the cats were in a slight anaesthetic stage, unable to rise. The evaluation of the overall suitability of medetomidine (% of cases) in different indications was "very satisfactory" or "satisfactory" in 95% of dogs and 81-96% of cats. Side effects reported were limited almost exclusively to vomiting and muscle jerking in dogs (12% and 0.5% of the cases) and to vomiting in cats (65%). Medetomidine seems to suffice for pharmacological restraint of dogs and cats. The concomitant use of medetomidine (80-100 micrograms/kg) and ketamine (7 mg/kg) in cats (n = 295) provided a good anaesthesia (20-40 min). The recovery was smooth. The present study shows that medetomidine provides an effective level of sedation and analgesia for clinical use.     

Antagonistic activities of atipamezole, 4-aminopyridine and yohimbine against medetomidine/ketamine-induced anaesthesia in cats

The objectives of this trial were to determine the ability of atipamezole, 4-aminopyridine and yohimbine to reverse the anaesthetic effects of a combination of medetomidine and ketamine in cats. Forty healthy cats were anaesthetised with 80 micrograms/kg medetomidine combined with 5 mg/kg ketamine. Thirty minutes later atipamezole (200 or 500 micrograms/kg), 4-aminopyridine (500 or 1000 micrograms/kg) or yohimbine (250 or 500 micrograms/kg) were injected intramuscularly. The doses of antagonists were randomised, so that each dose was administered to five cats, and 10 cats were injected only with physiological saline. Atipamezole clearly reversed the anaesthesia and bradycardia induced by medetomidine and ketamine. The mean (+/- sd) arousal times were 28 (+/- 4.7), 5.8 (+/- 1.8) and 7 (+/- 2.1) minutes in the placebo group, and the groups receiving 200 and 500 micrograms/kg atipamezole, respectively. The heart rates of the cats receiving 200 micrograms/kg atipamezole rapidly returned to values close to the initial ones, but 15 minutes after the injection of 500 micrograms/kg atipamezole a significant tachycardia was observed. All the cats showed moderate signs of ataxia during the recovery period. A dose of 500 micrograms/kg yohimbine also clearly reversed the anaesthetic effects of medetomidine/ketamine but 250 micrograms/kg was not effective. The dose of 500 micrograms/kg allowed a smooth recovery with no particular side effects except for some signs of incomplete antagonism of the ketamine effects, ie, ataxia and muscular incoordination. With 4-aminopyridine there were no statistically significant effects on the recovery, or the heart and respiratory rates of the cats anaesthetised with medetomidine/ketamine.     

Evaluation of the anaesthetic effects of combinations of ketamine, medetomidine, romifidine and butorphanol in European badgers (Meles meles)

OBJECTIVE: To evaluate the effects of three anaesthetic combinations in adult European badgers (Meles meles). STUDY DESIGN: Prospective, randomized, blinded, experimental trial. ANIMALS: Sixteen captive adult badgers. METHODS: The badgers were each anaesthetized by intramuscular injection using the three techniques assigned in random order: romifidine 0.18 mg kg(-1), ketamine 10 mg kg(-1) and butorphanol 0.1 mg kg(-1) (RKB); medetomidine 0.1 mg kg(-1), ketamine 9 mg kg(-1) and butorphanol 0.1 mg kg(-1) (MKB); and medetomidine 0.1 mg kg(-1) and ketamine 10 mg kg(-1) (MK). Initial drug doses were calculated based on a body mass of 10 kg. Additional anaesthetic requirements, time to drug effect, duration of action and recovery from anaesthesia were recorded. Heart rate and rhythm, respiratory rate and rhythm, rectal and subcutaneous microchip temperature and oxygen saturation were recorded every 5 minutes. Depth of anaesthesia was assessed using: muscle tone; palpebral and pedal reflexes; and tongue relaxation at these time points. Blood samples and a tracheal aspirate were obtained under anaesthesia. Atipamezole was administered if the badger had not recovered within 60 minutes Parametric data were analysed using anova for repeated measures, and nonparametric data using Friedman's, and Cochran's Q tests: p < 0.05 was considered significant. RESULTS: All combinations produced good or excellent muscle relaxation throughout the anaesthetic period. RKB had the shortest duration of anaesthesia (16.8 minutes compared with MKB 25.9 minutes and MK 25.5 minutes) and antagonism was not required. RKB depressed respiratory rate less than MK and MKB. There was no significant difference between techniques for heart rate and rhythm. CONCLUSIONS AND CLINICAL RELEVANCE: All combinations provided anaesthetic conditions suitable for sampling and identification procedures in adult badgers. The RKB protocol provided a significantly shorter period of anaesthesia when compared with the combinations containing medetomidine.     

The influence of the tracer injection–acquisition interval on the distribution of 99mTc-ECD in the brain of laboratory cats

Single-photon emission computed tomography (SPECT) can be used to study the regional distribution of the cerebral blood flow in the feline brain without interference of anesthetics. When the tracer, ^99mtechnetium-ethyl cysteinate dimer (^99mTc-ECD), is injected in the awake animal, the acquisition can be performed afterward under general anesthesia, whereas the tracer distribution still represents the regional cerebral blood flow (rCBF) in the awake animal. The aim of this study was to look at the in vivo stability of ^99mTc-ECD in the feline brain. For this purpose, 6 cats (n = 6) were used, and 3 serial acquisitions were performed starting at 40 (T40), 60 (T60), and 85 (T85) minutes after tracer injection. Total counts and perfusion indices (PIs), normalized to the total brain and to the cerebellum, were calculated. When T85 was compared with T40, total counts decreased, depending on the brain region, with 29% (left thalamus) to 51% (bulbus olfactorius). These regional differences in tracer clearance resulted in significantly altered PIs at T85 as compared with T40. This study shows that ^99mTc-ECD SPECT can be used in cats for studying the rCBF and that the clearance of ^99mTc-ECD in the feline brain is region dependent. As a result, the acquisition should be started between 40 and 60 minutes after tracer injection.     

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.     

Effect of pre-medication on gastroduodenoscopy in isoflurane-anesthetized cats

The pre‐medicant chosen may influence the ease with which gastroduodenoscopy (GD) is performed. The purpose of this study was to evaluate the relative ease of GD in cats under ketamine and isoflurane anesthesia after IM injection of hydromorphone (H, 0.1 mg kg^?1), hydromorphone plus glycopyrrolate (HG, 0.1 mg kg^?1 (H), 0.01 mg kg^?1 (G)), medetomidine (M, 0.03 mg kg^?1), or butorphanol (B, 0.4 mg kg^?1). Eight cats were assigned randomly to receive each treatment in a cross‐over design with at least 7 days between treatments. Twenty minutes after pre‐medication, medetomidine produced greater (p = 0.001) sedation than the other treatments when assessed, using a subjective ordinal scale. The cats were injected with ketamine (10 mg kg^?1 IM), orotracheally intubated, connected to a pediatric circle breathing system, and allowed to spontaneously breathe isoflurane in oxygen. Once end‐tidal isoflurane concentration was stable at 1.4% for 15 minutes, endoscopy was started. A single endoscopist (REG), who was unaware of the treatment used, performed all endoscopies. The endoscopist scored the difficulty of endoscopy subjectively (0–3). The significance of differences between treatments was evaluated using Friedman's test. Time for entering the stomach was 9.4 (4.7–15.9) (median (minimum–maximum)), 6.6 (5.2–11.7), 8.4 (6.3–16.5), and 7.7 (5.1–14.7) seconds and for entering the duodenum from the stomach was 20.5 (13.8–40.9), 18.2 (10.3–39.8), 20.2 (16.2–119.5), and 22.2 (11.8–83.8) seconds for H, HG, M, and B treatments, respectively. There were no significant differences in the time for, or difficulty of, endoscopy. We conclude that any of these drugs can be used satisfactorily at the doses and combinations tested to pre‐medicate cats prior to general anesthesia for GD.     

Comparison of three anaesthetic protocols in Bennett’s wallabies (Macropus rufogriseus)

ObjectiveInvestigate physiological and sedative/anaesthetic effects of xylazine, medetomidine or dexmedetomidine combined with ketamine in free-ranging Bennett's wallabies.Study designProspective clinical trial.AnimalsTwenty-six adult free-ranging Bennett's wallabies.MethodsAnimals were darted intramuscularly with one of three treatments: xylazine and ketamine, 2.0 and 15.0 mg kg^?1, respectively (XK): medetomidine and ketamine 0.1 and 5.0 mg kg^?1 (MK) and dexmedetomidine and ketamine 0.05 and 5.0 mg kg^?1 (DMK). Body weights were estimated. If the animal was still laterally recumbent after 45 minutes of anaesthesia, then an alpha-2 adrenoceptor antagonist, atipamezole, was administered (XK: 0.4 mg kg^?1, MK: 5 mg kg^?1, DMK: 2.5 mg kg^?1). Heart rate (HR) and respiratory rate (f_R) were recorded at 5-minute intervals and temperature at 10-minute intervals. Venous blood was taken 30 minutes after initial injection. Statistical analysis utilized anova. p < 0.05 was considered significant.ResultsAnimals became recumbent rapidly in all groups. XK animals had muscle twitches, responded to external stimuli, and three animals required additional dosing; this was not observed in the MK and DMK groups. HR (mean ± SD beats minute^?1) in XK (81 ± 4) was significantly higher than MK (74 ± 2) and DMK (67 ± 4). There were no differences in f_R, temperature, blood-gas and biochemical values between groups. More animals in MK (9/10) and DMK (5/6) needed antagonism of anaesthesia compared with XK (1/10). There were no adverse effects after anaesthesia.Conclusion and clinical relevanceCardio-respiratory effects were similar in all groups. There were fewer muscle twitches and reactions to external stimuli in MK and DMK. Duration of anaesthesia was shorter in XK; most animals in MK and DMK needed atipamezole to assist recovery. All three treatments provided satisfactory sedation/anaesthesia and are suitable for use in Bennett's wallabies.     

Clinical evaluation of three medetomidine--midazolam--ketamine combinations for neutering of ferrets (Mustela putorius furo)

33 ferrets (Mustela putorius furo, 11 females, 22 males, ASA I-II) were neutered in a combination anaesthesia with medetomidine, midazolam and ketamine. The animals were randomized into 3 groups. All animals received 20 microg/kg BW medetomidine and 0.5 mg/kg BW midazolam. The three groups differed regarding dosis and way of application of ketamine (IM10 = 10 mg/kg BW intramuscularly; IM07 = 7 mg/kg BW intramuscularly; SC10 = 10 mg/kg BW subcutaneously). After 30 minutes anaesthesia was partially antagonised with 100 microg/kg BW atipamezole i.m.. Sedation, muscle relaxation, analgesia, and overall anaesthetic impression were compared by a scoring protocol. Reactions to painful stimuli of clamping the spermatic cord or the ovarial ligament including the A. ovarica were judged, too. All animals lost their righting reflex and could be placed in dorsal recumbency. Induction and recovery time were significantly the shortest in study group IM10 with 1.73 +/- 0.3 and 9.73 +/- 4.6 min respectively. Recovery was significantly prolonged in group SC10 with 30.27 +/- 15.6 min. The MMK-anaesthesia with 10 mg/kg ketamine i.m. is very useful for neutering ferrets. Respiratory depression and bradycardia typically for medetomidine were seen in all three combinations, but quickly reversed after partial antagonisation. Induction and intubation, followed by inhalation anaesthesia, were possible with all three regimes.     

Investigating medetomidine-buprenorphine as preanaesthetic medication in cats

O bjectives : The objective of this study was to investigate medetomidine-buprenorphine preanaesthetic medication in cats.
M ethods : Forty American Society of Anesthesiologists (ASA) I female cats were enrolled in this prospective, blinded, clinical study. Cats were randomised into one of four groups: group M30 were injected intramuscularly with 30 μg/kg medetomidine, groups M10+B, M30+B and M50+B received 10, 30 and 50 μg/kg of medetomidine, respectively, each in combination with 20 μg/kg buprenorphine. After 30 minutes, a sedation score was allocated. Anaesthesia was induced using intravenous propofol and maintained using isoflurane in oxygen, while cats underwent ovariohysterectomy. Heart rate, respiratory rate, end-tidal carbon dioxide tension and oxygen saturation of haemoglobin were recorded. Atipamezole was administered intramuscularly at volatile agent discontinuation. Time taken to lift their head, sit in sternal and stand were recorded along with quality of recovery.
R esults : M30+B cats required significantly less isoflurane compared with M30 cats. Heart rate and oxygen saturation of haemoglobin were significantly lower in M50+B cats than in M30 cats. All M+B groups experienced significantly better recoveries compared with the medetomidine only M30 control group.
C linical S ignificance : The addition of buprenorphine to medetomidine preanaesthetic medication in cats reduces volatile agent vaporiser setting and improves the quality of recovery from anaesthesia.     

Sedative effects of three doses of romifidine in comparison with medetomidine in cats

ObjectiveTo compare the sedative effects of three doses of romifidine with one dose of medetomidine.Study designProspective blinded experimental cross-over.AnimalsFive adult Domestic Short Hair cats.MethodsCats were administered romifidine at 80, 120 and 160 μg kg^?1 or medetomidine at 20 μg kg^?1 (M20) intramuscularly (IM). Sedative effects were assessed for 3 hours by summing the scores given to posture, auditory response, resistance to positioning, muscular relaxation, and response to noxious stimuli, giving a total sedation score (TS). The area under the curve (AUC) of TS ≥7 (the score considered as clinically useful sedation) was calculated. Times to stages of sedation were determined. Some physiological parameters were measured. Data to compare treatments were analysed by anova or Kruskal–Wallis test as relevant.ResultsAll treatments gave a TS considered clinically useful. There were no significant differences between treatments for times to onset of sedation, maximum TS reached, or AUC. Differences between romifidine treatments for other sedation parameters were not significant but the time to maximum TS and to recovery was shortest in M20. Heart rate (HR) fell significantly with all treatments and, although with M20 it recovered at 65 minutes, it remained significantly depressed for 3 hours after all romifidine treatments. Most cats vomited, and/or hypersalivated after all treatments.ConclusionsDoses of 80, 120 and 160 μg kg^?1 romifidine IM produce sedation in cats which is similar to that following medetomidine 20 μg kg^?1. Recovery from sedation and of physiological parameters was quickest after M20.Clinical relevanceDoses of romifidine considerably lower than those investigated by previous authors give a clinically useful level of sedation, and their use might result in less side effects and a quicker recovery.     

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.     

The impact of MK‐467 on plasma drug concentrations,sedation and cardiopulmonary changes in sheep treated with intramuscular medetomidine and atipamezole for reversal

The effect of MK‐467, a peripheral α₂‐adrenoceptor antagonist, on plasma drug concentrations, sedation and cardiopulmonary changes induced by intramuscular (IM) medetomidine was investigated in eight sheep. Additionally, the interactions with atipamezole (ATI) used for reversal were also evaluated. Each animal was treated four times in a randomized prospective crossover design with 2‐week washout periods. Medetomidine (MED) 30 μg/kg alone or combined in the same syringe with MK‐467 300 μg/kg (MMK) was injected intramuscular, followed by ATI 150 μg/kg (MED + ATI and MMK + ATI) or saline intramuscular 30 min later. Plasma was analysed for drug concentrations, and sedation was subjectively assessed with a visual analogue scale. Systemic haemodynamics and blood gases were measured before treatments and at intervals thereafter. With MK‐467, medetomidine plasma concentrations were threefold higher prior to ATI, which was associated with more profound sedation and shorter onset. No significant differences were observed in early cardiopulmonary changes between treatments. Atipamezole reversed the medetomidine‐related cardiopulmonary changes after both treatments. Sedation scores decreased more rapidly when MK‐467 was included. In this study, MK‐467 appeared to have a pronounced effect on the plasma concentration and central effects of medetomidine, with minor cardiopulmonary improvement.