Interactions of xylazine and detomidine with alpha2-adrenoceptors in brain tissue from cattle, swine and rats

Dose titration of intravenously administered gamma-hydroxybutyric acid for sedation in Holstein-Friesian calves

Gamma-hydroxybutyric acid (GHB) is a short-chain fatty acid that can potentially provide safe, prolonged sedation with minimal cardiorespiratory effects. This preliminary trial, performed in 10 three-week-old male Holstein-Friesian calves, investigated the effects of GHB administered intravenously over 5 min at a dose of 100 (G100, n=2), 150 (G150, n=4) or 200 mg/kg (G200, n=4). Once lateral recumbency was achieved, scores for sedation depth (range: 0 = no sedation to 3 = marked) and response to noxious stimulation (range: 0 = strong to 3 = absent), heart rate (HR), respiratory rate (RR), mean arterial pressure (MAP) and arterial blood gases were monitored every 15 min until sternal recumbency. Times from end of administration to lateral recumbency and return to sternal/standing positions were recorded. Dose G100 resulted in mild sedation and ataxia without decubitus. Doses G150 and G200 respectively resulted in time to lateral recumbency 8 ± 2 and 9 ± 3 min, lasting 189 ± 41 and 283 ± 29 min, while overall median (range) scores for sedation were 3 (1-3) and 3 (2-3) respectively and response to noxious stimulation 0 (0-3) and 0 (0-3) respectively. The mean ± SD for HR was 110 ± 10 and 106 ± 11 bpm respectively; for MAP 87±9 and 94±5 mmHg respectively; and for RR 28 ± 5 and 26 ± 5 bpm respectively. The mean ± SD for arterial partial pressure of oxygen (PaO2) at these two dose rates was 74 ± 6 and 74 ± 2 mmHg respectively, while the arterial partial pressure of carbon dioxide oxygen (PaCO2) was 53 ± 3 and 47 ± 0.8 mmHg respectively. Based on these preliminary results we conclude that GHB has the potential to be used as a long-acting sedative in calves. Further studies are needed to confirm this.

Use of a rat model to characterize 35 arterial pulse wave parameters in a comparative study of isoflurane and Zoletil/xylazine anesthesia and the effect of Acanthopanax senticosus extract

BACKGROUND

Information obtained from arterial pulse waveforms (APW) can be useful for characterizing the cardiovascular system. To achieve this, it is necessary to know the detailed characteristics of APWs in different states of an organism, which would allow APW parameters (APW-Ps) to be assigned to particular (patho)physiological conditions. Therefore, our work aimed to characterize 35 APW-Ps in rats under the influence of isoflurane (ISO) and Zoletil/xylazine (ZO/XY) anesthesia and to study the effect of root extract from Acanthopanax senticosus (ASRE) in these anesthetic conditions.

METHODS

The right jugular vein of anesthetized rats was cannulated for the administration of ASRE and the left carotid artery for the detection of APWs from which 35 APW-Ps were evaluated.

RESULTS

We obtained data on 35 APW-Ps, which significantly depended on the anesthesia, and thus, they characterized the cardiovascular system under these two conditions. ASRE transiently modulated all 35 APW-Ps, including a transient decrease in systolic and diastolic blood pressure (BP) and heart rate or increases in pulse BP, dP/dtmax , and systolic and diastolic areas. Whereas the transient effects of ASRE were similar, the extract had prolonged disturbing effects on the cardiovascular system in rats under ZO/XY but not under ISO anesthesia. This negative effect can result from the disturbance caused by ZO/XY anesthesia on the cardiovascular system.

CONCLUSIONS

We characterized 35 APW-Ps of rats under ISO and ZO/XY anesthesia and found that ASRE contains compounds that can modulate the properties of the cardiovascular system, which significantly depended on the status of the cardiovascular system. This should be considered when using ASRE as a nutritional supplement by individuals with cardiovascular problems.

Guidance for the use and reporting of anaesthetic agents in BJP manuscripts involving work with animals

Scientists who plan to publish in the British Journal of Pharmacology (BJP) should read this article before undertaking studies utilising anaesthetics in mammalian animals. This editorial identifies certain gaps in the reporting of details on the use of anaesthetics in animal research studies published in the BJP. The editorial also provides guidance, based upon current best practices, for performing in vivo experiments that require anaesthesia. In addition, mechanisms of action and physiological impact of specific anaesthetic agents are discussed. Our goal is to identify best practices and to provide guidance on the information required for manuscripts submitted to the BJP that involve the use of anaesthetic agents in studies with experimental animals.

Comparison of anesthetic and cardiorespiratory effects of tiletamine-zolazepam-detomidine-butorphanol, tiletamine-zolazepam-xylazine-butorphanol, and ketamine-detomidine-butorphanol in pigs

OBJECTIVE

To evaluate and compare the anesthetic, analgesic, and cardiorespiratory effects of tiletamine-zolazepam-detomidine-butorphanol (TZDB), tiletamine-zolazepam-xylazine-butorphanol (TZXB), and ketamine-detomidine-butorphanol (KDB) in pigs and to assess anesthetic recovery duration and quality following administration of tolazoline as a reversal agent.

ANIMALS

11 healthy 2.5-month-old castrated male Landrace mixed-breed pigs.

PROCEDURES

In a randomized, blinded crossover study design, pigs received the following anesthetic combinations, IM: TZDB (tiletamine-zolazepam [3 mg/kg {1.36 mg/lb}], detomidine [0.18 mg/kg {0.08 mg/lb}], and butorphanol [0.12 mg/kg {0.05 mg/lb}]); TZXB (tiletamine-zolazepam [4 mg/kg {1.8 mg/lb}], xylazine [4 mg/kg], and butorphanol [0.2 mg/kg {0.09 mg/lb}]); and KDB (ketamine [8 mg/kg {3.63 mg/lb}], detomidine [0.18 mg/kg], and butorphanol [0.3 mg/kg {0.14 mg/lb}]). A 7-day washout period was provided between treatments. At 45 minutes of anesthesia, pigs received tolazoline (2 mg/kg [0.9 mg/lb], IM; n = 6) treatment or control (5) treatment with saline (0.9% NaCl) solution.

RESULTS

All anesthetic combinations induced anesthesia. Endotracheal intubation was completed within 5 minutes after anesthetic administration in all pigs, except in 2 pigs following administration of KDB. Durations (mean ± SD) of endotracheal intubation and lateral recumbency in pigs that did not receive tolazoline were 55.3 ± 4.8 minutes, 83.8 ± 15.8 minutes, and 28.2 ± 4.5 minutes and 112.4 ± 18.7 minutes, 117.2 ± 16.7 minutes, and 79.7 ± 6.0 minutes, respectively, for the TZDB, TZXB, and KDB anesthetic treatments. Tolazoline significantly shortened the duration of anesthetic recovery for all anesthetic treatments without affecting the recovery quality.

CONCLUSIONS AND CLINICAL RELEVANCE

All 3 anesthetic combinations were suitable for providing anesthesia in pigs. Tolazoline administration shortened the duration of anesthetic recovery without affecting the quality of recovery.

Xylazine or detomidine in dairy calves: a comparison of clinically relevant pharmacodynamic parameters under sedation

OBJECTIVE

Chemical restraint in dairy calves is necessary to enable diagnostic and surgical procedures. It is unclear whether xylazine or detomidine differ with regard to desirable and unwanted effects.

MATERIAL AND METHODS

In a prospective randomized interventional study, 10 healthy Holstein-Friesian calves (age range 3-6 month) were sedated with either xylazine (0.1 mg/kg, Group X, n = 5) or detomidine (0.03 mg/kg, Group D, n = 5) intravenously, followed by butorphanol (0.1 mg/kg i. v.) in all animals. Characteristics of sedation and selected pharmacodynamic parameters were compared between groups using a non-parametric Mann-Whitney U test.

RESULTS

All calves (5/5) in Group X and (3/5) calves in Group D became laterally recumbent within 5 minutes. Two calves (40 %) in Group D remained standing and could not been positioned in lateral recumbency 15 minutes after initial administration of the sedation agents. Sedation scores, onset and duration of sedation did not differ between groups. Heart and respiratory rate decreased in both groups. Mean arterial pressure was with around 30 mmHg significantly higher in Group D (t₂₅, t₃₀, t₃₅, t₄₀ with p = 0.018, 0.036, 0.029 and 0.016, respectively). In Group X, glucose level (t₆₀) and packed cell volume (t₃₀) were significantly lower (p = 0.032 and 0.048, respectively).

CONCLUSION

and clinical relevance The xylazine-butorphanol combination provided reliable recumbent chemical restraint. With detomidine-butorphanol recumbency failed in some individuals, but a sufficient clinical sedation was achieved. Based on the limited monitoring used in this study, the side effects are of minor clinical relevance in healthy individuals.