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1.

Objective

To investigate the effects of a low dose of dexmedetomidine (DEX) followed by constant rate infusion (CRI) and reversal with atipamezole on systolic and diastolic functions in isoflurane-anesthetized healthy cats.

Study design

Prospective cohort study.

Animals

A group of 11 client-owned adult cats.

Methods

Baseline transthoracic echocardiography (TTE) was performed, followed by intramuscular (IM) administration of DEX (5 μg kg?1). After 10 minutes, sedation was scored, adverse effects were recorded and another TTE performed. Approximately 40 minutes after DEX administration, anesthesia was induced by isoflurane mask and maintained with 1.2% end-tidal isoflurane and DEX CRI (1 μg kg?1 hour?1) for 80 minutes. Physiological variables were recorded every 10 minutes, and TTE was repeated 10, 30 and 60 minutes after the start of anesthesia. CRI was stopped, atipamezole (30 μg kg?1) was administered IM and a final TTE was performed after 10 minutes. Repeated measures over time were submitted to one-way analysis of variance or Kruskal–Wallis test according to data distribution; significance was assumed at p < 0.05.

Results

After DEX premedication, mild sedation and a slight but significant increase in systolic arterial pressure occurred, and vomiting was a common adverse effect. The cardiac output (CO) and heart rate decreased during anesthesia, with no changes after administration of atipamezole. Trivial valvular insufficiencies were commonly seen after DEX premedication and during CRI. Myocardial radial and longitudinal systolic functions were not affected by sedation or by anesthesia. The late phase of diastole on both right and left ventricles was affected by isoflurane–DEX CRI. Global left ventricular myocardial performance was not impaired.

Conclusions

and clinical relevance Decreased CO and late diastolic impairment were observed in healthy cats administered a low dose of DEX for premedication followed by anesthesia with isoflurane and DEX CRI.  相似文献   

2.

Objective

To evaluate the efficacy and side effects of alfaxalone administered intramuscularly (IM) as a sedative agent in guinea pigs undergoing survey radiographs.

Study design

Prospective clinical trial.

Animals

A total of 30 client-owned guinea pigs.

Methods

Following baseline assessments, 5 mg kg?1 alfaxalone was administered IM. Heart rate, arterial haemoglobin oxygen saturation, respiratory rate, rectal body temperature, palpebral reflex, response to toe and ear pinch, righting reflex, posture, jaw tone and reaction to manipulation were assessed before and after sedation at 5-minute intervals. The time elapsed from onset of sedation to return of locomotion and coordinated limb movements, the quality of recovery and the occurrence of undesired effects were observed and recorded.

Results

The mean ± standard deviation onset of sedation was 2.7 ± 0.6 minutes. The physiological variables remained within normal ranges until completion of the procedure. Palpebral reflex and responsiveness to both ear and toe pinch were maintained during sedation. Neither hypoxaemia nor hypothermia was observed. The duration of sedation was 29.3 ± 3.2 minutes. Sedation and recovery were uneventful, and adverse effects were not observed.

Conclusions and clinical relevance

In conclusion, 5 mg kg?1 of IM alfaxalone represents a valuable sedation protocol for healthy guinea pigs undergoing minor noninvasive procedures. Further trials are required to investigate its cardiovascular effects, clinical usefulness in unhealthy patients and its combined use with analgesics for procedures associated with nociception.  相似文献   

3.

Objective

To describe the anaesthetic, physiological and side effects of intramuscular (IM) medetomidine and ketamine, followed by inhalational anaesthesia with sevoflurane, in Nile crocodiles (Crocodylus niloticus).

Study design

Observational trial.

Animals

Ten juvenile captive-bred Nile crocodiles undergoing surgical implantation of skeletal beads and muscular electrodes.

Methods

During preanaesthetic examination, the following variables were assessed: heart (HR) and respiratory (fR) rates, and response to palpebral, corneal and toe- and tail-pinch withdrawal reflexes. The crocodiles were injected IM with an initial combination of medetomidine and ketamine and re-evaluated at 5 minute intervals for 20 minutes, or until they appeared unresponsive. If that did not occur, the drugs were redosed according to a decision tree based on the observed effects. The righting, biting and palatal valve reflexes were assessed in the unresponsive crocodiles, and used to confirm anaesthetic induction. Anaesthesia was maintained with sevoflurane in oxygen. At the end of surgery, medetomidine was antagonized with IM atipamezole.

Results

The decision tree identified 0.3 mg kg?1 medetomidine and 15 mg kg?1 ketamine as a useful drug combination, which resulted in anaesthetic induction and surgical anaesthesia 16 ± 8 and 16 (25–20) minutes after injection, respectively. Compared to baseline, HR and fR significantly decreased after anaesthetic induction (p < 0.001), but then remained stable throughout surgery. Intraoperatively, cloacal temperature [27 (26–30) °C] did not change over time (p = 0.48). The total dose of atipamezole was 2 (1–3) mg kg?1 and time to recovery was 36 (20–60) minutes. Perioperative complications were not observed.

Conclusions

and clinical relevance Medetomidine and ketamine, injected IM and followed by sevoflurane anaesthesia, may be regarded as a useful anaesthetic technique for juvenile Nile crocodiles undergoing minimally invasive experimental surgery.  相似文献   

4.

Objective

The fixed-dose combination of butorphanol, azaperone and medetomidine (BAM; 30, 12 and 12 mg mL?1, respectively) with subsequent antagonism by naltrexone–atipamezole was evaluated for reversible immobilization of captive blesbok (Damaliscus pygargus phillipsi).

Study design

Prospective, clinical trial.

Animals

Sixteen blesbok (four males and twelve females), weighing 52.5?71.0 kg, were immobilized in South Africa.

Methods

The total dose of BAM ranged from 0.5 to 0.7 mL for females and 0.7 to 0.9 mL for males. In seven animals chosen randomly, 8000 units of hyaluronidase was added to the dart. Physiologic variables were recorded every 5 minutes beginning at 10?20 minutes after darting. Arterial blood samples were collected three times at 20, 30 and 40 minutes after darting for analysis of blood acid-base status.

Results

The mean administered doses of BAM were as follows: butorphanol (0.34 ± 0.08 mg kg?1), azaperone (0.14 ± 0.03 mg kg?1) and medetomidine (0.14 ± 0.03 mg kg?1). The inductions were calm and smooth. The mean induction time was 9.6 ± 3.2 minutes with just BAM and 5.1 ± 0.8 minutes with BAM and hyaluronidase combination. Heart rate (45 ± 6 beats minute?1) and respiratory frequency (38 ± 4 breaths minute?1) were stable throughout immobilization. The mean arterial blood pressure for all animals was stable but elevated (137 ± 7 mmHg). Rectal temperature slightly increased over time but remained within an acceptable range. The recovery time after administering naltrexone and atipamezole was 4.8 ± 0.7 minutes.

Conclusion and clinical relevance

The BAM combination proved to be reliable and effective in blesbok.  相似文献   

5.
6.

Objective

To characterize alfaxalone administered subcutaneously (SC) in guinea pigs, both alone and in combination with dexmedetomidine and buprenorphine.

Study design

Prospective, blinded, crossover study.

Animals

A total of 15 healthy female guinea pigs weighing 400–600 g.

Methods

Alfaxalone (10, 20 and 40 mg kg?1) was administered SC to three guinea pigs as a pilot dose-finding study. Alfaxalone (20 mg kg?1; A20) was selected for comparison against combination protocols of alfaxalone (15 and 20 mg kg?1) with dexmedetomidine (0.25 mg kg?1) and buprenorphine (0.05 mg kg?1; A15DB, A20DB). Each protocol was randomly administered to 12 guinea pigs separated by ≥7 days. Time and quality of induction and recovery, heart rate, respiratory rate, peripheral hemoglobin oxygen saturation, rectal temperature, pedal withdrawal reflex and adverse effects were recorded.

Results

The median time to induction for A20, A15DB and A20DB was 6.8–8.0 minutes with no significant difference between treatments. Mean duration of recumbency for A20 was 73.6 ± 19.6 minutes. Recumbency duration for A15DB and A20DB extended to 90 minutes, at which time dexmedetomidine was antagonized using atipamezole (0.025 mg kg?1 SC). Physiological variables were within normal limits with the exception of one animal that died 45 minutes following treatment with A20DB. Pedal withdrawal reflex remained intact with all treatments. Minor side effects such as twitching or bruxism occurred sporadically with treatment A20 but not with A15DB and A20DB.

Conclusions and clinical relevance

SC alfaxalone produced uncomplicated sedation that may be recommended for nonpainful procedures that do not require complete immobility. The addition of dexmedetomidine and buprenorphine increased the duration of sedation and immobility, but did not result in general anesthesia. This combination sedation protocol may be useful for nonpainful procedures requiring extended immobility.  相似文献   

7.

Objective

To evaluate whether intratesticular and incisional ropivacaine infiltration produces sufficient intra- and postoperative analgesia for castrating dogs under sedation.

Study design

Randomized, blinded, controlled clinical study.

Animals

Twenty-three healthy dogs weighing 5.8–35.6 kg admitted for castration.

Methods

Dogs were sedated with medetomidine (0.01 mg kg?1), butorphanol (0.2 mg kg?1) and midazolam (0.2 mg kg?1) intramuscularly, and were randomly assigned to group R, 0.2–0.4 mL kg?1 of ropivacaine 0.5%, or group S, an equivalent volume of saline injected intratesticularly and along the incision line. If persistent motion was observed during surgery, sedation was considered to be insufficient and general anaesthesia was induced. Carprofen 2.2 mg kg?1 was administered postoperatively. Pain was evaluated in all dogs before sedation and postoperatively following atipamezole administration at 1, 2, 4, 8 and 24 hours using an interactive visual analogue scale (IVAS; 0–100), the Glasgow composite pain scale-short form (CMPS-SF; 0–24), and a mechanical algometer. Methadone 0.3 mg kg?1 was administered intravenously to dogs if IVAS >30 or CMPS-SF >4.

Results

There was no significant difference between groups for the number of dogs administered general anaesthesia. The time from the beginning of surgery to induction of general anaesthesia was significantly shorter [median (range)] in group S [6 (3–25) minutes] than in group R [56 (36–76) minutes]. At 8 hours IVAS was significantly higher in group S (14 ± 10) than in group R (6 ± 4).

Conclusions and clinical relevance

Intratesticular and incisional ropivacaine infiltration delayed the time to anaesthesia induction, and provided analgesia after castration performed under deep sedation in dogs. Intratesticular local anaesthesia can be an important part of the anaesthetic plan for castration.  相似文献   

8.
9.

Objective

The butorphanol-azaperone-medetomidine fixed-dose combination (BAM, respectively, 30-12-12 mg mL?1) with subsequent antagonism by naltrexone-atipamezole was evaluated for reversible immobilization of captive cheetahs (Acinonyx jubatus).

Study design

Prospective, clinical trial.

Animals

Twelve cheetahs (six males and six females, weighing 37–57 kg) housed in enclosures, were immobilized at Hoedspruit Endangered Species Centre in the Republic of South Africa.

Methods

BAM volume dose rate was 0.009–0.014 mL kg?1 (mean ± standard deviation 0.010 ± 0.001 mL kg?1). Total dose in all animals was 0.5 mL. The actual doses were as follows: butorphanol (0.29 ± 0.04 mg kg?1), azaperone (0.12 ± 0.01 mg kg?1) and medetomidine (0.12 ± 0.01 mg kg?1). Physiologic variables and quality of immobilization were recorded every 5 minutes beginning at 15–20 minutes after darting. Arterial blood samples were collected three times at 20, 30 and 40 minutes after darting from all animals for analysis of blood oxygenation and acid-base status.

Results

The inductions were calm and smooth and mean induction time was 4.0 ± 1.1 minutes. Heart rate (50 ± 9 beats minute?1) and respiratory frequency (20 ± 3 breaths minute?1) were stable throughout immobilization. The recovery time after reversing with naltrexone and atipamezole was 9.1 ± 3.6 minutes.

Conclusions

and clinical relevance BAM proved to be a reliable and cardiovascular stable drug combination for immobilization of cheetahs.  相似文献   

10.

Objective

To assess quality of sedation following intramuscular (IM) injection of two doses of alfaxalone in combination with butorphanol in cats.

Study design

Prospective, randomized, ‘blinded’ clinical study.

Animals

A total of 38 cats undergoing diagnostic imaging or noninvasive procedures.

Methods

Cats were allocated randomly to be administered butorphanol 0.2 mg kg?1 combined with alfaxalone 2 mg kg?1 (group AB2) or 5 mg kg?1 (group AB5) IM. If sedation was inadequate, alfaxalone 2 mg kg?1 IM was administered and cats were excluded from further analysis. Temperament [1 (friendly) to 5 (aggressive)], response to injection, sedation score at 2, 6, 8, 15, 20, 30, 40, 50 and 60 minutes, overall sedation quality scored after data collection [1 (excellent) to 4 (inadequate)] and recovery quality were assessed. Heart rate (HR), respiratory rate (fR) and arterial haemoglobin saturation (SpO2) were recorded every 5 minutes. Groups were compared using t tests and Mann–Whitney U tests. Sedation was analysed using two-way anova, and additional alfaxalone using Fisher's exact test (p < 0.05).

Results

Groups were similar for sex, age, body mass and response to injection. Temperament score was lower in group AB2 [2 (1–3)] compared to AB5 [3 (1–5)] (p = 0.006). Group AB5 had better sedation at 6, 8, 20 and 30 minutes and overall sedation quality was better in AB5 [1 (1–3)], compared to AB2 [3 (1–4)] (p = 0.0001). Additional alfaxalone was required for 11 cats in AB2 and two in AB5 (p = 0.005). Recovery quality, HR, fR and SpO2 were similar. Seven cats required oxygen supplementation. Complete recovery times were shorter in AB2 (81.8 ± 24.3 versus 126.6 ± 33.3 minutes; p = 0.009). Twitching was the most common adverse event.

Conclusions and clinical relevance

In combination with butorphanol, IM alfaxalone at 5 mg kg?1 provided better quality sedation than 2 mg kg?1. Monitoring of SpO2 is recommended.  相似文献   

11.

Objective

To evaluate intravenous (IV) detomidine with methadone in horses to identify a combination which provides sedation and antinociception without adverse effects.

Study design

Randomized, placebo-controlled, blinded, crossover.

Animals

A group of eight adult healthy horses aged (mean ± standard deviation) 7 ± 2 years and 372 ± 27 kg.

Methods

A total of six treatments were administered IV: saline (SAL); detomidine (5 μg kg?1; DET); methadone (0.2 mg kg?1; MET) alone or combined with detomidine [2.5 (MLD), 5 (MMD) or 10 (MHD) μg kg?1]. Thermal, mechanical and electrical nociceptive thresholds were measured, and sedation, head height above ground (HHAG), cardiopulmonary variables and intestinal motility were evaluated at 5, 15, 30, 45, 60, 75, 90, 120 and 180 minutes. Normal data were analyzed by mixed-model analysis of variance and non-normal by Kruskal–Wallis (p < 0.05).

Results

Nociceptive thresholds in horses administered methadone with the higher doses of detomidine (MMD, MHD) were increased above baseline to a greater degree and for longer duration (MMD: 15–30 minutes, MHD: 30–60 minutes) than in horses administered low dose with methadone or detomidine alone (MLD, DET: 5–15 minutes). No increases in nociceptive thresholds were recorded in SAL or MET. Compared with baseline, HHAG was lower for 30 minutes in MMD and DET, and for 45 minutes in MHD. No significant sedation was observed in SAL, MET or MLD. Intestinal motility was reduced for 75 minutes in MHD and for 30 minutes in all other treatments.

Conclusions

Methadone (0.2 mg kg?1) potentiated the antinociception produced by detomidine (5 μg kg?1), with minimal sedative effects.

Clinical relevance

Detomidine (5 μg kg?1) with methadone (0.2 mg kg?1) produced antinociception without the adverse effects of higher doses of detomidine.  相似文献   

12.

Objective

To evaluate dexmedetomidine, midazolam and dexmedetomidine–midazolam for sedation and antinociception in tegus.

Study design

Prospective, crossover, randomized, blinded study.

Animals

Six healthy tegus (Salvator merianae) weighing 1.6 ± 0.3 kg.

Methods

Tegus were administered intramuscularly saline (0.5 mL; CON), dexmedetomidine (0.2 mg kg?1; DX), midazolam (1 mg kg?1; MZ) and dexmedetomidine–midazolam (same doses; DM). Heart rate (HR) and respiratory frequency (fR) were recorded before treatment (baseline) and 15, 30 minutes, 1, 2, 3, 4, 6, 8, 12 and 24 hours after the treatments. Sedation scores were recorded according to resistance to manual restraint, posture and response to noxious stimulus, at baseline and 5, 10, 15, 30 minutes, 1, 2, 3, 4, 6, 8, 12 and 24 hours after the treatments. Antinociception was evaluated by measurement of latency of limb withdrawal reflex (LWR) to thermal stimulus, recorded at baseline and 15 minutes, 1, 2, 4, 8, 12 and 24 hours after the treatments.

Results

Lower HR (DX and DM) and fR (MZ, DX and DM) than CON were measured 15 minutes after the treatment and for up to 6 hours. Sedation was mild to moderate in MZ, deep in DM and absent in DX, although animals showed behavioral changes in DX, with increase in aggressiveness. Median (interquartile range) duration of sedation were 170 (50; 235) minutes in MZ and 230 (115; 235) minutes in DM. Recovery period was prolonged in both treatments, surpassing the duration of the experiment. Higher LWR than CON was detected from 15 minutes until 12 hours in DX and DM.

Conclusions and clinical relevance

Midazolam provided sedation without antinociception, and dexmedetomidine provided antinociception without sedation. Drug combination increased the duration of sedation but not antinociception. Due to increased duration of sedation, reversal of effects with flumazenil and atipamezole should be considered after conclusion of clinical procedures.  相似文献   

13.

Objective

To evaluate the clinical effects and quality of sedation, induction, maintenance and recovery in Lemur catta after dexmedetomidine–butorphanol–midazolam sedation and alfaxalone anaesthesia.

Study design

Prospective, observational study.

Animals

Six male L. catta weighing 3.0 ± 0.6 kg undergoing surgical castration.

Methods

Lemurs were sedated with intramuscular dexmedetomidine (0.015 mg kg?1), butorphanol (0.2 mg kg?1) and midazolam (0.2 mg kg?1). Anaesthesia was induced with intravenous alfaxalone 0.5 mg kg?1 over 60 seconds; further boluses were administered until tracheal intubation was feasible and final dose recorded. Alfaxalone continuous infusion was used to maintain anaesthesia. Atipamezole (0.15 mg kg?1) was administered during recovery. The quality of sedation, induction, intubation, maintenance and recovery was assessed using a scoring system. Physiological parameters were recorded during sedation, maintenance and recovery.

Results

Sedation was achieved in 13.6 ± 5.6 minutes and no reactions were observed during handling or venepuncture. The mean dose of alfaxalone required for induction and maintenance was 2.09 ± 0.65 and 0.08 ± 0.02 mg kg?1 minute?1, respectively. Quality of induction, intubation and maintenance was good in almost all animals. Mild self-limiting muscle twitching was observed after alfaxalone administration in three animals. Cardiorespiratory function was stable in all animals but one. One lemur showed respiratory depression and required oxygen administration and manual ventilation. The mean maintenance time was 29.2 ± 7.4 minutes. The mean times from the end of alfaxalone administration to extubation, atipamezole administration and full recovery were: 15.3 ± 8.0, 22.2 ± 4.6 and 60.0 ± 8.4 minutes, respectively. Recovery was considered good in all animals.

Conclusions and clinical relevance

Dexmedetomidine–butorphanol–midazolam combination provided reliable sedation and adequate muscle relaxation in L. catta. Alfaxalone proved to be a useful drug for induction and maintenance of anaesthesia and might be considered an option for injectable anaesthesia in lemurs.  相似文献   

14.
15.

Objective

Propranolol has been suggested for anxiolysis in horses, but its sedation efficacy and side effects, both when administered alone and in combination with α2-adrenoceptor agonists, remain undetermined. This study aimed to document the pharmacokinetics and pharmacodynamics of propranolol, romifidine and their combination.

Study design

Randomized, crossover study.

Animals

Six adult horses weighing 561 ± 48 kg.

Methods

Propranolol (1 mg kg?1; treatment P), romifidine (0.1 mg kg?1; treatment R) or their combination (treatment PR) were administered intravenously with a minimum of 1 week between treatments. Alertness, behavioral responsiveness (visual and tactile) and physiologic variables were measured before and up to 960 minutes after drug administration. Blood was collected for blood gas and acid-base analyses and measurement of plasma drug concentrations. Data were analyzed using repeated-measures analysis of variance or Friedman with Holm–Sidak and Wilcoxon rank-sum tests (p < 0.05).

Results

Systemic clearance significantly decreased and the area under the concentration-time curve significantly increased for both drugs in PR compared with P and R. Both PR and R decreased behavioral responsiveness and resulted in sedation for up to 240 and 480 minutes, respectively. Sedation was deeper in PR for the first 16 minutes. Heart rate significantly decreased in all treatments for at least 60 minutes, and PR significantly increased the incidence of severe bradycardia (<20 beats minute?1).

Conclusions and clinical relevance

Although not associated with reduced behavioral responsiveness or sedation alone, propranolol augmented romifidine sedation, probably through alterations in romifidine pharmacokinetics, in horses administered PR. The occurrence of severe bradycardia warrants caution in the co-administration of these drugs at the doses studied.  相似文献   

16.

Objective

We determined the possible effects of a peripherally acting α2-adrenoceptor antagonist, MK-467, on the absorption of intramuscularly (IM) coadministered medetomidine, butorphanol and midazolam.

Study design

Randomized, experimental, blinded crossover study.

Animals

Six healthy Beagle dogs.

Methods

Two IM treatments were administered: 1) medetomidine hydrochloride (20 μg kg–1) + butorphanol (100 μg kg–1) + midazolam (200 μg kg–1; MBM) and 2) MBM + MK-467 hydrochloride (500 μg kg–1; MBM–MK), mixed in a syringe. Heart rate was recorded at regular intervals. Sedation was assessed with visual analog scales (0–100 mm). Drug concentrations in plasma were analyzed with liquid chromatography–tandem mass spectrometry, with chiral separation of dex- and levomedetomidine. Maximum drug concentrations in plasma (Cmax) and time to Cmax (Tmax) were determined. Paired t-tests, with Bonferroni correction when appropriate, were used for comparisons between the treatments.

Results

Data from five dogs were analyzed. Heart rate was significantly higher from 20 to 90 minutes after MBM–MK. The Tmax values for midazolam and levomedetomidine (mean ± standard deviation) were approximately halved with coadministration of MK-467, from 23 ± 9 to 11 ± 6 minutes (p = 0.049) for midazolam and from 32 ± 15 to 18 ± 6 minutes for levomedetomidine (p = 0.036), respectively.

Conclusions and clinical relevance

MK-467 accelerated the absorption of IM coadministered drugs. This is clinically relevant as it may hasten the onset of peak sedative effects.  相似文献   

17.

Objective

To evaluate the anaesthetic effects of three different alfaxalone doses to induce anaesthesia in goldfish.

Study design

Prospective, randomized, clinical study.

Animals

Thirty goldfish undergoing skin scraping, gill examination and stool collection.

Methods

Each fish was transferred to an individual 4 L induction tank and randomly allocated into one of three groups (n = 10), in which alfaxalone was administered at concentrations of 6, 7 or 9 mg L–1. The depth of anaesthesia was evaluated by approach reaction, equilibrium, opercular movement and reaction to tactile stimuli. Sedation, light anaesthesia, surgical anaesthesia and recovery times were recorded. Data were analyzed with analysis of variance. A p value <0.05 was considered significant.

Results

Surgical anaesthesia was achieved in all fish. Goldfish induced with alfaxalone 7 and 9 mg L–1 showed a mild excitement phase. Time to sedation of the 6 mg L–1 dose (5.89 ± 0.40 minutes) was significantly longer compared to the 7 mg L–1 (3.97 ± 0.40 minutes) and 9 mg L–1 doses (3.94 ± 0.40 minutes). Times to light anaesthesia and surgical anaesthesia of the 9 mg L–1 dose (7.65 ± 1.04 and 9.60 ± 1.84 minutes, respectively) were significantly faster compared with those of the 6 mg L–1 dose (13.79 ± 1.04 and 19.75 ± 1.84 minutes, respectively) and the 7 mg L–1 dose (13.55 ± 1.04 and 21.24 ± 1.84 minutes, respectively). No significant differences were recorded in recovery time. Cessation of opercular movement was recorded in two fish induced with 7 mg L–1 and in two induced with 9 mg L–1. No mortality occurred.

Conclusions

and clinical relevance Alfaxalone is a reliable agent for immersion anaesthesia in goldfish. Immersion in water containing 6 mg alfaxalone L–1 provided smooth induction of anaesthesia, and no obvious side effects were encountered. Higher doses shortened induction time and caused respiratory depression and excitatory movements.  相似文献   

18.

Objective

We investigated the plasma concentrations and cardiovascular effects of intramuscularly (IM) administered medetomidine, administered alone or with three different doses of MK-467.

Study design

Prospective, randomized, open, crossover trial.

Animals

Eight purpose-bred healthy Beagle dogs.

Methods

Each dog was administered four treatments: medetomidine 20 μg kg–1 IM alone or mixed in the same syringe with MK-467 (200 μg kg–1, 400 μg kg–1 or 600 μg kg–1). Instrumentation was performed under standardized anaesthesia. The dogs were allowed to recover before measurement of baseline values. Composite sedation scores, cardiovascular variables, i.e., heart rate (HR), cardiac output (CO), mean arterial and central venous blood pressures (MAP and CVP) and arterial blood gases were recorded at baseline and for 60 minutes after treatment. Drug concentrations in venous plasma were analysed. Generalized linear mixed models for repeated measures with post hoc Bonferroni correction were used with statistical significance level set at α = 0.05.

Results

All treatments initially demonstrated the effects of medetomidine: HR and CO decreased and CVP increased. MAP transiently increased and then significantly decreased from baseline with the two highest MK-467 doses. The cardiovascular effects of medetomidine disappeared more rapidly with MK-467 than with medetomidine alone. With medetomidine alone, sedation scores remained high until the end of the 60 minute follow-up. Maximum concentrations of medetomidine were more rapidly achieved and were higher with MK-467.

Conclusions and clinical relevance

Initial haemodynamic effects of medetomidine were not prevented by MK-467, but these effects were attenuated and their duration shortened by MK-467, independently of dose. Absorption of medetomidine was accelerated by MK-467, when administered concomitantly IM, resulting in faster sedation; addition of MK-467 shortened the sedative effect of medetomidine.  相似文献   

19.

Objective

To compare dexmedetomidine–midazolam with alfaxalone–midazolam for sedation in leopard geckos (Eublepharis macularius).

Study design

Prospective, randomized, blinded, complete crossover study.

Animals

Nine healthy adult leopard geckos.

Methods

Geckos were administered a combination of dexmedetomidine (0.1 mg kg?1) and midazolam (1.0 mg kg?1; treatment D–M) or alfaxalone (15 mg kg?1) and midazolam (1.0 mg kg?1; treatment A–M) subcutaneously craniodorsal to a thoracic limb. Heart rate (HR), respiratory rate (fR), righting reflex, palpebral reflex, superficial and deep pain reflexes, jaw tone and escape response were assessed every 5 minutes until reversal. Conditions for intubation and response to needle prick were evaluated. Antagonist drugs [flumazenil (0.05 mg kg?1) ± atipamezole (1.0 mg kg?1)] were administered subcutaneously, craniodorsal to the contralateral thoracic limb, 45 minutes after initial injection, and animals were monitored until recovery.

Results

HR, but not fR, decreased significantly over time in both treatments. HR was significantly lower than baseline at all time points in D–M and for all but the 5 and 10 minute time points in A–M. HR was significantly higher in A–M at all time points after drug administration when compared with D–M. Sedation scores between protocols were similar for most time points. All animals in A–M lost righting reflex compared with seven out of nine (78%) geckos in D–M. Geckos in A–M lost righting reflex for significantly longer time. Mean ± standard deviation time to recovery after antagonist administration was 6.1 ± 2.2 minutes for D–M and 56 ± 29 minutes for A–M, and these times were significantly different.

Conclusions and clinical relevance

Combination D–M or A–M provided sedation of a level expected to allow physical examinations and venipuncture in leopard geckos. A–M provided a faster onset of sedation compared with D–M. Recovery was significantly faster following antagonist reversal of D–M, compared with A–M.  相似文献   

20.

Objective

To describe the sedative and physiologic effects of two doses of alfaxalone administered intramuscularly in dogs.

Study design

Randomized, blinded, crossover experimental trial.

Animals

Ten adult mixed-breed dogs.

Methods

Dogs were assigned randomly to be administered one of three intramuscular injections [saline 0.1 mL kg?1 (S), alfaxalone 1 mg kg?1 (A1) or alfaxalone 2 mg kg?1 (A2)] on three occasions. Heart rate (HR), respiratory rate (fR) and sedation score were assessed before injection (T0) and at 5 (T5), 10 (T10), 15 (T15), 20 (T20), 30 (T30), 45 (T45) and 60 (T60) minutes postinjection. Rectal temperature was determined at T0 and T60. Adverse events occurring between the time of injection and T60 were recorded.

Results

Sedation scores were higher in group A2 at T15 and T30 compared with group S. There were no additional differences between groups in sedation score. The A2 group had higher sedation scores at T15, T20 and T30 compared with T0. The A1 group had higher sedation scores at T10 and T30 compared with T0. Temperature was lower in groups A1 and A2 compared with S at T60, but was not clinically significant. There were no differences between or within groups in HR or fR. Adverse effects were observed in both A1 and A2 groups. These included ataxia (17/20), auditory hyperesthesia (5/20), visual disturbance (5/20), pacing (4/20) and tremor (3/20).

Conclusions and clinical relevance

While alfaxalone at 2 mg kg?1 intramuscularly resulted in greater median sedation scores compared with saline, the range was high and adverse effects frequent. Neither protocol alone can be recommended for providing sedation in healthy dogs.  相似文献   

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