Backgrounds, there are limited choice of analgesic agent in horse medicine, and mostly because of side effects usage of analgesics is contraindicated in horses. Objectives, introduction of compounds which have little side effects whith good analgesic affects. Methods, this study was undertakan in 6 healthy horses, in control group they received normal saline. In treatment group CRI of lidocaine and xylasine has been administered, and data was recorded at the beginning of infusion and 10, 20, 30, 40 and 50 minutes after starting the infusion at time 50 infusion was stopped and 15, 30 and 60 minutes after that data was recorded as well. Analgesic effect was evaluated by algometer. NIBP, Temperature, Heart rate, respiratory rate, sedation, intestinal sounds was evaluated at each time points. Results, 30 minutes after starting the infusion analgesic effect has started and there was significant difference between control and treatment group this effect last until the end of infusion and after the CRI this effect disappeared gradually. Conclusions, simultaneous infusion of xylasine and lidocanie has significant analgesic effect. But it needs more study in fields like laminitis cases to prove the efficacy of combination of xylazine and lidocaine.

Xylazine, a type of α₂-adrenoceptors, is a commonly used drug in veterinary medicine. Xylazine-induced changes in the content of amino acid neurotransmitters – glycine (Gly) and aspartic acid (Asp), in different brain regions and neurons were studied. Wistar rats were administered 50 mg/kg or 70 mg/kg of xylazine by intraperitoneal injection. In addition, in vitro experiments were conducted, in which neurons were treated with 15 μg/mL, 25 μg/mL, 35μg/mL, and 45 μg/mL of xylazine. Test methods were based on the enzyme-linked immunosorbent assays (ELISA). During anaesthesia, Asp levels in each brain area were significantly lower compared to the control group. Except for the cerebrum, levels of Gly in other brain areas were significantly increased during the anaesthesia period. In vitro, xylazine-related neuron secretion of Gly increased significantly compared to the control group at 60 min and 90 min. Moreover, xylazine caused a significant decrease in the levels of Asp secreted by neurons at 20 min, but gradually returned to the level of the control group. The data showed that during anaesthesia the overall levels of Asp decreased and overall levels of Gly increased. In addition, the inhibitory effect of xylazine on Asp and the promotion of Gly were dose-dependent. Our data showed that different effects of xylazine on excitatory and inhibitory neurotransmitters provided a theoretical basis for the mechanism of xylazine activity in clinical anaesthesia.

Introduction: Tiletamine-xylazine-tramadol (XFM) has few side effects and can provide good sedation and analgesia. Adenosine 5’-monophosphate-activated protein kinase (AMPK) can attenuate trigeminal neuralgia. The study aimed to investigate the effects of XFM and its specific antagonist on AMPK in different regions of the brain. Material and Methods: A model of XFM in the rat was established. A total of 72 Sprague Dawley (SD) rats were randomly divided into three equally sized groups: XFM anaesthesia (M group), antagonist (W group), and XFM with antagonist interactive groups (MW group). Eighteen SD rats were in the control group and were injected intraperitoneally with saline (C group). The rats were sacrificed and the cerebral cortex, cerebellum, hippocampus, thalamus, and brain stem were immediately separated, in order to detect AMPKα mRNA expression by quantitative PCR. Results: XFM was able to increase the mRNA expression of AMPKα1 and AMPKα2 in all brain regions, and the antagonist caused the opposite effect, although the effects of XFM could not be completely reversed in some areas. Conclusion: XFM can influence the expression of AMPK in the central nervous system of the rat, which can provide a reference for the future development of anaesthetics for animals.

In recent years, various anaesthetic agents and mixtures had been evaluated for caudal epidural analgesia in cattle with a variety of results. Caudal epidural analgesia is a routine and established technique for a variety of surgical and obstetrical procedures in cattle and might depend on the volume of local analgesic. The objective of the present work to compare between the analgesic efficacy of xylazine alone and that of Xylazine-epinephrine combination in caudal epidural analgesia through studying the clinical and behavioral changes as well as estimating degrees of ataxia, sedation and analgesia in cows throughout monitoring their efficacies pre-epidural (Minute 0) injection or post-epidural injection (Minutes 10, 30, 60, 90, 120, 150 and 180). The study was conducted on clinically healthy non-pregnant cross cows (n=20). They were classified into two equal groups. The first one received epidural injection of 0.05 mg/kg xylazine and thus was referred as Xylagr. The second group was epidurally treated through injection of combination of 0.05 mg/kg xylazine and Epinephrine and thus was referred as Xyla-Epingr. All animals were subjected for through clinical examination as well as monitoring of different degrees of ataxia, sedation and analgesia parameters. There was no statistically significant difference in the onset of analgesia between xylazine epidural injection (11.85±1.25 minutes) and xylazine with epinephrine (12.01±1.05 minutes). Epidural administration of xylazine with epinephrine produced a significantly longer duration of analgesia (161±7.62 minutes) than that produced by epidural injection xylazine alone (136.20±7.13 minutes). Administration of xylazine alone resulted in mild to moderate sedation with mild ataxia, as well as cutaneous analgesia for the perineal region while xylazine with epinephrine produced mild sedation without ataxia, as well as cutaneous analgesia for the perineal region. The study concluded the higher efficacy of xylazine-epinephrine combinations as a caudal epidural analgesic drug compared with that of xylazine alone. Xylazine-epinephrine combination has more rapid onset of recovery from signs of ataxia and sedation than xylazine alone, which make it more suitable than xylazine in cattle as an intraoperative and postoperative analgesia.

The objective of this study was to evaluate the stability of 3 distinct preparations of ketamine and xylazine, with or without acepromazine, stored at room temperature or at 4°C for 1, 2, and 3 mo. Drug concentrations were compared to fresh solutions, using a high performance liquid chromatography-mass spectrometry/selected-ion monitoring (HPLC-MS/SIM) assay. The concentrations of ketamine and xylazine, diluted in physiological saline, did not change over time at room temperature or at 4°C. However, acepromazine concentrations decreased over time when stored at room temperature. In contrast, undiluted ketamine-xylazine preparations gradually decreased in concentration when stored at room temperature. All of the drug concentrations remained above 90% of their original concentration when stored at 4°C. In conclusion, when diluted in physiological saline, ketamine-xylazine cocktails can be stored for 3 mo, whereas undiluted cocktails can lose efficacy over 3 mo at room temperature. Storage at 4°C could preserve drug stability.

OBJECTIVE To determine effects of anesthesia on plasma concentrations and pulsatility of ACTH in samples obtained from the cavernous sinus and jugular vein of horses. ANIMALS 6 clinically normal adult horses. PROCEDURES Catheters were placed in a jugular vein and into the cavernous sinus via a superficial facial vein. The following morning (day 1), cavernous sinus blood samples were collected every 5 minutes for 1 hour (collection of first sample = time 0) and jugular venous blood samples were collected at 0, 30, and 60 minutes. On day 2, horses were sedated with xylazine hydrochloride and anesthesia was induced with propofol mixed with ketamine hydrochloride. Horses were positioned in dorsal recumbency. Anesthesia was maintained with isoflurane in oxygen and a continuous rate infusion of butorphanol tartrate. One hour after anesthesia was induced, the blood sample protocol was repeated. Plasma ACTH concentrations were quantified by use of a commercially available sandwich assay. Generalized estimating equations that controlled for horse and an expressly automated deconvolution algorithm were used to determine effects of anesthesia on plasma ACTH concentrations and pulsatility, respectively. RESULTS Anesthesia significantly reduced the plasma ACTH concentration in blood samples collected from the cavernous sinus. CONCLUSIONS AND CLINICAL RELEVANCE Mean plasma ACTH concentrations in samples collected from the cavernous sinus of anesthetized horses were reduced. Determining the success of partial ablation of the pituitary gland in situ for treatment of pituitary pars intermedia dysfunction may require that effects of anesthesia be included in interpretation of plasma ACTH concentrations in cavernous sinus blood.

OBJECTIVE To determine the temporal effects on tear flow measurements obtained by use of a Schirmer tear test (STT) I after IM administration of various doses of medetomidine or xylazine to healthy dogs. ANIMALS 5 healthy purpose-bred male Beagles. PROCEDURES Each dog received IM injections of 2.0 mL of physiologic saline (0.9% NaCl) solution (control treatment); 0.1% medetomidine hydrochloride (5, 10, 20, and 40 μg/kg), and 2.0% xylazine hydrochloride (0.5, 1.0, 2.0, and 4.0 mg/kg). Treatments were injected into the semimembranosus muscles; there was at least a 1-week interval between successive injections. Order of treatments was determined via a randomized Latin square crossover design. The STT I was performed on both eyes before (baseline) and 0.25, 0.50, 0.75, 1, 2, 3, 4, 5, 6, 7, 8, and 24 hours after each injection.RESULTS STT I values decreased significantly within 45 minutes after injection of medetomidine or xylazine, which was followed by gradual recovery. The lowest mean STT I value was < 10 mm/min for all sedation treatments, except when dogs received 5 μg of medetomidine/kg. Linear regression of the area under the curve for the 8 hours after administration yielded significant effects for all sedation treatments. CONCLUSIONS AND CLINICAL RELEVANCE IM administration of medetomidine or xylazine to dogs reduced tear flow in a dose-related manner. Artificial tear solution or ophthalmic ointment should be used to protect the ocular surface when these drugs are administered to dogs.