Administration Of Xylazine Research Articles

Effects of medetomidine and xylazine on intraocular pressure and pupil size in healthy Beagle dogs

ObjectiveTo determine the effects of intramuscular (IM) administration of medetomidine and xylazine on intraocular pressure (IOP) and pupil size in normal dogs. Study designProspective, randomized, experimental, crossover trial. AnimalsFive healthy, purpose-bred Beagle dogs. MethodsEach dog was administered 11 IM injections of, respectively: physiological saline; medetomidine at doses of 5, 10, 20, 40 and 80 μg kg−1, and xylazine at doses of 0.5, 1.0, 2.0, 4.0 and 8.0 mg kg−1. Injections were administered at least 1 week apart. IOP and pupil size were measured at baseline (before treatment) and at 0.25, 0.50, 0.75, 1, 2, 3, 4, 5, 6, 7, 8 and 24 hours post-injection. ResultsA significant decrease in IOP was observed at 6 hours after 80 μg kg−1 medetomidine compared with values at 0.25 and 0.50 hours, although there were no significant changes in IOP from baseline. In dogs treated with 8.0 mg kg−1 xylazine, significant reductions in IOP were observed at 4 and 5 hours compared with that at 0.25 hours after administration. In dogs treated with 5, 10, 20 and 40 μg kg−1 medetomidine and 0.5, 1.0 and 2.0 mg kg−1 xylazine, there were no significant changes in IOP. Pupil size did not change significantly after any of the medetomidine or xylazine treatments compared with the baseline value. Conclusions and clinical relevanceLow or moderate doses of medetomidine or xylazine did not induce significant changes in IOP or pupil size. In contrast, high doses of medetomidine or xylazine induced significant changes up to 8 hours after treatment, but values remained within the normal canine physiological range. The results of this study suggest a lack of significant change in IOP and pupil size in healthy dogs administered low or moderate doses of xylazine or medetomidine.

EFFECT OF REPEATED INTRAVENOUS ADMINISTRATION OF XYLAZINE ON SEDATION, ANALGESIA AND ECG PARAMETERS IN DONKEYS (EQUUS ASINUS)

Xylazine Hcl was generally used in veterinary medicine for its sedative and moderate analgesic effect. This experimental study was undertaken to determine the effect of repeated intravenous (IV) administration of xylazine on sedation and analgesia as well as cardiac arrhythmia using ECG in donkeys. Three repeated injections of xylazine (0.5 mg/kg) with 10 minute interval were injected IV in six healthy adult donkeys. Sedation score, analgesic score, heart rate (HR), respiratory rate, rectal temperature and ECG parameters were recorded before and after 2, 5 and 10 minutes from injection for each injection and then at 5 minutes intervals until complete recovery from sedation and the normal ECG was recorded. Deep sedation was obtained 5 minutes after the second injection in all donkeys, and the length of sedation lasted 71 ± 6 minutes. The deep analgesia was obtained 5 minutes after the third injection in all donkeys, and the length of analgesia lasted 62 ± 5 minutes. There was a highly significant decrease in HR after the third injection (P < 0.01). Normal HR was obtained in all donkeys after 75 ± 10 minutes of the third injection. Cardiac arrhythmia as atrial fibrillation and AV block were recorded after second and third injection but this arrhythmia was transient. We can conclude that repeated injection of xylazine Hcl give acceptable results either for sedation or ECG parameters in donkeys.

Analgesic and adjunct actions of nalbuphine hydrochloride in xylazine or xylazine and acepromazine premedicated horses

The study was conducted in eighteen clinical cases of horses for diagnostic and surgical procedures requiring general anaesthesia were randomly divided into three groups, group I, group II and group III, each consisting of six cases. All the horses were premedicated with glycopyrrolate at the dose rate of 0.02 mg/kg body weight, intravenously. Horses in Group I and Group II were administered xylazine hydrochloride at the dose rate of 1.10 mg/kg body weight intravenously, whereas in Group III at the dose rate of 0.50 mg/kg body weight intravenously. In Group III, acepromazine was injected after xylazine administration, at the dose rate of 0.02mg/kg body weight, intravenously. Before induction of anaesthesia, nalbuphine hydrochloride was administered for Group II and Group III at the dose rate of 0.75 mg/kg body weight intravenously. Ketamine hydrochloride was administered intravenously to induce anaesthesia at the dose rate of 2.20 mg/kg body weight and maintained with 0.50 mg/kg body weight in required cases to maintain for duration of 15 ± 1.04 minutes. The mean time for induction in group I, group II and group III were 1.78 ± 0.27, 1.73 ± 0.10 and 1.85 ± 0.28 minutes respectively. The mean total number of additional doses of ketamine for standard duration of 15 ± 1.04 minutes surgery required in group I, group II and group III were 5.00 ± 0.36, 1.66 ± 0.33 and 2.00 ± 0.36 respectively. The quality of induction was 100 per cent smooth in group III, 83.33 per cent smooth and 16.67 per cent rough in group II and 66.66 per cent smooth and 33.34 per cent rough in group I. The quality of analgesia in group I, group II and group III were 2.83 ± 0.47, 1.83 ± 0.30 and 1.33 ± 0.21 respectively. The quality of muscle relaxation in group I, group II and group III were 3.16 ± 0.30, 1.50 ± 0.22 and 1.33 ± 0.21 respectively. The mean time for recovery in group I, group II and group III were 23.00 ± 1.52, 33.00 ± 0.93 and 41.98 ± 1.32 minutes respectively. The mean number of attempts for unassisted standing in group I, group II and group III were 6.66 ± 0.71, 5.00 ± 0.57 and 5.00 ± 0.36 respectively. The quality of recovery was 83.33 per cent smooth and 16.67 per cent rough in group III, 66.66 per cent smooth and 33.34 per cent rough in group II and 50.00 per cent smooth and 50.00 per cent rough in group I. None of the animals in any groups showed any intra and post operative complication.

Interactions Among Different Devices and Electrical Stimulus on the Electroejaculation of Captive Agoutis (Dasyprocta leporina).

The interactions among different electroejaculation devices associated with serial or continuous stimuli were investigated to improve the efficiency of the electroejaculation for semen collection in agoutis. Ten sexually matured male Dasyprocta leporina were restrained by the intramuscular administration of xylazine-ketamine association. Each individual was randomly subjected to four electroejaculation protocols, by combining two devices (one presenting longitudinal electrodes emitting square waves and other presenting ring electrodes emitting sine waves) and two electrical stimuli protocols (serial or continuous). A total of 40 attempts for electroejaculation were conducted in agoutis, being 10 per treatment. The most efficient treatment in providing ejaculates containing sperm (p<0.05) was that using and electroejaculator connected to a probe with ring electrodes and associated with serial stimuli (4/7; 57%). In spite of semen parameters obtained by sine waves were adequate for using the samples for assisted reproduction, higher values for sperm motility and functional membrane integrity were obtained in the use of the square wave, independently of the electric stimulation protocol used (p<0.05). In conclusion, we verified that the use of a device presenting a probe with ring electrodes and emitting sine waves, associated with a serial stimuli protocol, improves the efficiency for semen obtaining by electroejaculation in adults D.leporina.

Evaluation of efficacy and safety of glycopyrrolate - xylazine - propofol anesthesia in buffalo calves.

Aim:To evaluate the efficacy and safety of glycopyrrolate - xylazine - propofol anesthesia in buffalo calves.Materials and Methods:The study was conducted on six clinically healthy male buffalo calves, 6-12 months of age, and weighing between 130 and 170 kg. In all the animals; glycopyrrolate (0.01 mg/kg, IM), xylazine (0.1 mg/kg, IM) and 1% propofol as single bolus (1.5 mg/kg, intravenous), were administered. The parameters observed included behavioral changes, physiological; hematological and blood biochemical parameters.Results:Muzzle and nostrils became dry in all the animals after glycopyrrolate administration. A decrease in spontaneous activity and mild cutaneous analgesia was noticed after xylazine administration. After administration of propofol, loss of swallowing reflex, palpebral reflex, corneal reflexes, periosteal reflex and complete analgesia was observed. There was no significant change in rectal temperature and heart rate. However, heart rate remained elevated during anesthesia. Respiratory rate decreased significantly after propofol administration. There was a significant increase in plasma glucose after the xylazine and propofol administration which remained elevated till recovery. A significant decrease in chloride level was seen after propofol administration.Conclusions:Glycopyrrolate - xylazine - propofol anesthetic combination may safely be used for short duration anesthesia in buffalo calves.

Evaluation of halothane anaesthesia after xylazine/ketamine administration in dromedary camels (Camelus dromedarius)

Objective was to evaluate halothane as an inhalation anaesthetic after premedication with xylazine and induction with ketamine in camels. Six healthy, adult female dromedary camels were used as prospective controlled study. Camels were premedicated with xylazine (0.2 mg/kg, IV). Twenty minutes later, anaesthesia was induced with ketamine (2 mg/kg, IV) and was maintained with halothane in 100% oxygen. Onset and duration of anaesthesia were recorded. Rectal temperature, respiratory rate, heart rate, oxygen haemoglobin saturation, and systolic, diastolic, and mean arterial blood pressure were measured before and 20 min after administration of xylazine and then every 10 min until recovery. Lead II electrocardiogram was used to constantly monitor camels for presence of arrhythmias. Depth of anaesthesia was determined by recording reflexes. Venous and arterial blood samples were taken for haematological examination and blood gases and pH, respectively, at the same intervals. Results revealed a significant decrease in respiratory rate after xylazine and ketamine administration and significant decrease in rectal temperature and arterial blood pressure during halothane anaesthesia. A noticeable increase in the heart and respiratory rates was observed during halothane anaesthesia if compared to xylazine/ketamine values. However, the percentage of oxygen haemoglobin saturation and arterial pO2 increased significantly with significant decrease in arterial pH during halothane anaesthesia. There were non-significant changes in the CBC values. The quality of anaesthesia was good in the majority of camels and recovery ranged from marginal to excellent. In conclusions, halothane resulted in good maintenance of anaesthesia and marginal to excellent recovery in dromedary camels. Precautions should be taken to avoid ruminal regurgitation. Oxygen administration is recommended during early recovery.

Quantification of horse plasma proteins altered by xylazine using the fluorogenic derivatization-liquid chromatography-tandem mass spectrometry.

ABSTRACTIn the doping tests currently used in horse racing, prohibited substances or their metabolites are usually directly detected in urine or blood samples. However, despite their lasting pharmaceutical effects, some prohibited substances are rapidly eliminated from horse urine and blood, making them difficult to detect. Therefore, new indirect biomarkers for doping, such as plasma proteins that are increased by the prohibited substances, have recently attracted much attention. Here, a fluorogenic derivatization-liquid chromatography-tandem mass spectrometry (FD-LC-MS/MS) method was adopted for horse plasma proteomics analysis, in order to identify plasma proteins whose concentrations were altered in response to xylazine in Thoroughbred horses. Xylazine, which is rapidly absorbed and eliminated and has possibility of the change in the levels of plasma proteins, was selected as a model drug. Of the ten plasma proteins identified, four proteins, including three acute phase proteins (haptoglobin, ceruloplasmin, and α-2-macroglobulin-like), were significantly increased after xylazine administration. Therefore, our present approach might be useful in identifying indirect biomarkers of drug administration.

Efficacy of caudal epidural injection of lidocaine, xylazine and xylazine plus hyaluronidase in reducing discomfort produced by electroejaculation in bulls.

To test the hypothesis that epidural administration of lidocaine, xylazine or xylazine plus hyaluronidase provides reduced pain and stress during electroejaculation in bulls, eight 30-month-old Nellore bulls received saline solution (control), 2% lidocaine, 2% xylazine or 2% xylazine plus hyaluronidase injected into the first intercoccygeal (Co1–Co2) epidural space in randomized order. Heart rate, respiratory rate, mean arterial pressure, analgesia, animal behavior and motor blockade were evaluated before treatment and at predetermined intervals during and after treatment. Pain and stress were scored subjectively, and semen quality was evaluated. The onset of anesthetic action was significantly faster with lidocaine (3.0 ± 1.2 min) than with xylazine or xylazine plus hyaluronidase (8.9 ± 1.5 and 5.5 ± 2.6 min, P=0.021 and P=0.012, respectively), and the onset of anesthesia with xylazine plus hyaluronidase was significantly faster than that with xylazine alone (P=0.032). Treatment with xylazine or xylazine plus hyaluronidase resulted in less discomfort than treatment with lidocaine, as indicated by animal behavior. Changes in heart rate, respiratory rate and arterial pressure were within acceptable limits. Penile protrusion and semen emission occurred in all animals during all four treatments. Our results suggest that xylazine plus hyaluronidase reduced discomfort during electroejaculation more effectively than xylazine or lidocaine alone. Further experiments are necessary to determine whether electroejaculation with xylazine plus hyaluronidase is feasible for obtaining semen from Nellore bulls unaccustomed to being handled or restrained.

Xylazine-ketamine immobilization and propofol anesthesia for surgical excision of sebaceous adenoma in a jaguar (Panthera onca)

Aim: A captive male jaguar (Panthera onca) was anaesthetized for surgical excision of a tumor at the left belly fold under xylazine-ketamine immobilization and propofol anesthesia. The objective was to assess the dose of xylazine and ketamine required to abolish ear flick reflex for safe approach when the jaguar was under chemical immobilization and efficacy of propofol induced anesthesia. Materials and Methods: A male jaguar (P. onca) aged 14 years and weighing approximately 90 kg was subjected to chemical immobilization using a combination of xylazine and ketamine using a blow pipe. The jaguar was approached after the absence of ear flick reflex and transported to zoo Operation Theater. Propofol was administered intravenously to induce and maintain anesthesia. The tumor was excised using thermocautery and subjected to histopathology. Results: Ear flick reflex was stimulated at 5 and 10 min after immobilization and observed shaking of head and movement of fore limb following administration of xylazine and ketamine. Dose of xylazine and ketamine required for chemical immobilization, characterized by absence of ear flick reflex was 1.0 and 3.5 mg/kg body weight respectively, and was achieved in 13 min. The surgical plane of anesthesia was maintained for 11 min following administration of propofol at a dose of 2 mg/kg body weight intravenously. The jaguar recovered in 41 min following surgery. The excised tumor was confirmed as sebaceous adenoma on histopathological examination. The animal recovered uneventfully, and no recurrence of the tumor was noticed in 3 months follow-up period. Conclusion: The total dose xylazine and ketamine required for chemical immobilization with absence of ear flick reflex was 1.0 and 3.5 mg/kg body weight respectively. Further, administration of propofol intravenously, at a dose of 2 mg/kg maintained anesthesia for 11 min. Histopathological examination of the excised tumor at the belly fold was confirmed as sebaceous adenoma.

Evaluation of cardiorespiratory and biochemical effects of ketamine-propofol and guaifenesin-ketamine-xylazine anesthesia in donkeys (Equus asinus)

ObjectivesTo evaluate the cardiorespiratory and biochemical effects of ketamine-propofol (KP) or guaifenesin-ketamine-xylazine (GKX) anesthesia in donkeys. Study designProspective crossover trial. AnimalsEight healthy, standard donkeys, aged 10 ± 5 years and weighing 153 ± 23 kg. MethodsDonkeys were premedicated with 1.0 mg kg−1 of xylazine (IV) in both treatments. Eight donkeys were administered ketamine (1.5 mg kg−1) and propofol (0.5 mg kg−1) for induction, and anesthesia was maintained by constant rate infusion (CRI) of ketamine (0.05 mg kg−1 minute−1) and propofol (0.15 mg kg−1 minute−1) in the KP treatment. After 10 days, diazepam (0.05 mg kg−1) and ketamine (2.2 mg kg−1) were administered for induction, and anesthesia was maintained by a CRI (2.0 mL kg−1 hour−1) of ketamine (2.0 mg mL−1), xylazine (0.5 mg mL−1) and guaifenesin (50 mg mL−1) solution. Quality of anesthesia was assessed along with cardiorespiratory and biochemical measurements. ResultsAnesthetic induction took longer in GKX than in KP. The induction was considered good in 7/8 with KP and in 6/8 in GKX. Anesthetic recovery was classified as good in 7/8 animals in both treatments. Xylazine administration decreased heart rate (HR) in both treatments, but in KP the HR increased and was higher than GKX throughout the anesthetic period. Respiratory rate was higher in GKX than in KP. PaO2 decreased significantly in both groups during the anesthetic period. Glucose concentrations [GLU] increased and rectal temperature and PCV decreased in both treatments. Arterial lactate [LAC] increased at recovery compared with all time points in KP. [GLU] and calcium were higher in GKX than in KP at recovery. Conclusion and clinical relevanceThese protocols induced significant hypoxemia but no other cardiorespiratory or metabolic changes. These protocols could be used to maintain anesthesia in donkeys, however, they were not tested in animals undergoing surgery.

Comparison of sedative and analgesic effects of xylazine, detomidine, and medetomidine in sheep.

ABSTRACTThe present study was carried out to compare the sedative and analgesic effects after intravenous administration of xylazine (0.2 mg/Kg), detomidine (40 g/Kg) and medetomidine (6 g/Kg) in sheep. The onset of sedation occurred within 60 seconds, 116.25  8.85 seconds and 71.25  5.50 seconds which lasted for 67.13  2.83 minutes, 64.63  1.30 and 52.88  1.74 minutes with xylazine, detomidine and medetomidine respectively. The duration of sedation was significantly higher (P < 0.05) with xylazine as compared to detomidine and medetomidine. Xylazine produced medium to deep degree of sedation whereas detomidine and medetomidine produced light to medium degree of sedation. Skin analgesia and recumbence were produced with xylazine while no analgesia was achieved after administration of detomidine and medetomidine. Some common side effects like salivation, frequent urination, defaecation, staggering, head drooping, wobbling, snoring and bellowing were observed after administration of xylazine, detomidine or medetomidine. It is concluded that all these alpha2 adrenergic agonists studied are safe to be used in sheep. At doses studied both the detomidine and medetomidine have lesser sedative and analgesic effects in sheep.

Pharmacokinetics and pharmacodynamics of xylazine administered by the intravenous or intra-osseous route in adult horses.

In certain situations, an alternate route for parenteral drug administration in horses may be useful. The intra-osseous (IO) route may provide a safe alternative to the intravenous (i.v.) route for administration of sedatives to horses when the i.v. route is inaccessible or undesirable. Six adult horses were administered xylazine i.v. or IO in a block-randomized crossover design. For the i.v. trial, both jugular veins were catheterized, and one was used for xylazine administration, while the other was used for blood collection. For the IO trial, one jugular vein was catheterized for blood collection and an intra-osseous device was placed in the tuber coxae using a powered driver for xylazine administration. Heart rate, respiratory rate, and head position were measured, and concentration of sedation was assessed at various times up to 90min. Xylazine concentrations were measured using high-performance liquid chromatography and noncompartmental analysis was performed. General linear mixed modeling and Wilcoxon signed-rank tests were used for statistical analysis, with P≤0.05. There were no significant differences in heart rate, respiratory rate, head position, concentration of sedation, Cmax , Tmax , half-life, or AUC between the i.v. and the IO routes of drug administration. No complications were observed following placement of the intra-osseous device. Intra-osseous xylazine administration provides a useful option in emergent and other settings in which i.v. access is difficult or contraindicated.

A pharmacokinetic/clinical approach to postulate a local action of intra‐articular xylazine administration in the horse: a preliminary study

The study aims to evaluate whether the analgesic effect of intra-articular (IA) route of xylazine administered to horses following arthroscopic surgery is due to a local or a systemic action. Two connected studies were performed. In the first, 1mg/kg b.w. of xylazine was injected IA, and blood samples were taken to assess drug systemic absorption. In addition, systemic effects of the drug (sedation, ataxia or reduction of respiratory and cardiac rate) were registered. Control horses injected with saline IA were included in the study to exclude the influence of anaesthesia in the occurrence of these manifestations. In the second study, 1mg/kg b.w. of xylazine was administered intravenously (i.v.) in healthy horses. Blood samples were collected to determine the concentrations of xylazine, and the same signs of systemic effects of the drug were recorded. By correlating these parameters, a systemic 'no effect' concentration was defined. Pharmacokinetic data after IA administration resulted in some xylazine absorption (bioavailability equal to 58.12%) with values above the systemic 'no effect' concentration. The occurrence of some signs related to systemic effects in horses receiving IA xylazine was significant compared with horses receiving saline. In conclusion, a systemic action of the drug after IA administration cannot be excluded.

Effect of body position on intra-abdominal pressures and abdominal perfusion pressures measured at three sites in horses anesthetized with short-term total intravenous anesthesia

To assess effects of body position on direct measurements of intra-abdominal pressure (IAP) and abdominal perfusion pressure (APP) in horses anesthetized with total intravenous anesthesia (TIVA). 9 healthy adult horses. Instrumentation in unsedated standing horses involved insertion of an arterial catheter for blood pressure measurements and 3 intraperitoneal cannulas (left flank, right flank, and ventral abdomen) for IAP measurements. Baseline values were measured for heart rate, respiratory rate, systolic arterial blood pressure, mean arterial blood pressure (MAP), diastolic arterial blood pressure, and IAP. Horses were medicated with xylazine, and pressures were measured again. Anesthesia was induced with ketamine-diazepam and maintained with a ketamine-guaifenesin infusion. Horses were positioned twice into left lateral recumbency, right lateral recumbency, or dorsal recumbency. Hemodynamic pressures and accessible abdominal pressures were measured for each recumbency position. The APP was calculated as MAP - IAP. Differences in IAP, MAP, APP and sedation (standing horses) or body position (anesthetized horses) were compared by means of repeated-measures ANOVA or paired t tests. Baseline hemodynamic and IAPs were not different after xylazine administration. Ventral abdomen IAP and MAP were lower for horses in dorsal recumbency than in right or left lateral recumbency. Ventral abdomen APP remained unchanged. For lateral recumbencies, flank IAP was lower and APP was higher than pressure measurements at the same sites during dorsal recumbency. Body position affected IAP and APP in healthy anesthetized horses. These effects should be considered when developing IAP acquisition methods for use in horses with abdominal disease.

Xylazine-induced reduction of tissue sensitivity to insulin leads to acute hyperglycemia in diabetic and normoglycemic monkeys

BackgroundThe α2-adrenoceptor agonist xylazine as an anesthetic has been widely used either alone or in combination with other anesthetics, such as ketamine, in veterinary clinic and research. In the last decade xylazine has been used in drug abusers in certain geographic area. This study investigated the effects of xylazine on blood glucose level and insulin secretion in normoglycemic and insulin-dependent diabetic monkeys.MethodsBoth adult cynomolgus (n = 10) and rhesus (n = 8) monkeys with either sex were used in the study. Xylazine (1–2 mg/kg) was administrated intramuscularly. Blood glucose, insulin, glucagon and glucagon-like peptide 1 in overnight-fasted monkeys were measured immediately before and after xylazine administration. The hyperinsulinemic-euglycemic clamp method was used in the study for assessing the potential mechanism of xylazine-induced hyperglycemia.ResultsXylazine administration increased the blood glucose levels from 58 ± 3 to 108 ± 12 mg/dL in normoglycemic (n = 5, p < 0.01) and from 158 ± 9 to 221 ± 13 mg/dL in insulin-dependent diabetic (n = 5, p < 0.01) monkeys and was not accompanied by any significant changes in blood insulin, glucagon, and glucagon-like peptide-1. Xylazine-induced hyperglycemia occurred within 10 min and reached the peak at 35 min after injection. Xylazine-induced hyperglycemia declined slowly in diabetic animals. The α2-adrenoceptor antagonist yohimbine was administrated to bring down the elevated glucose level to the pre-xylazine one in 4 out of 5 diabetic animals. To assess the potential mechanism, the hyperinsulinemic-euglycemic clamp was used to maintain a nearly saturated and constant insulin level for minimizing endogenous insulin glucoregulation. Xylazine administration decreased glucose infusion rate, from 14.3 ± 1.4 to 8.3 ± 0.8 mg/min/kg (n = 6, p < 0.01) in normoglycemic rhesus monkeys, which indicates that the glucose metabolic rate (M rate) was decreased by xylazine. In addition, after clamping blood glucose level in a range of 55 to 75 mg/dL for 40 min with constant glucose infusion, xylazine administration still increased blood glucose concentration.ConclusionsWe conclude that xylazine administration induces hyperglycemia in normoglycemic and insulin-dependent diabetic monkeys potentially via stimulation of α2-adrenoceptors and then reducing tissue sensitivity to insulin and glucose uptake.

Effect of postoperative xylazine administration on cardiopulmonary function and recovery quality after isoflurane anesthesia in horses

To evaluate equine cardiopulmonary function and recovery quality after administration of 0.25 or 0.50 mg/kg xylazine intravenously (IV) during recovery. Randomized, blinded, prospective, clinical study. Horses (n = 20). During recovery after 3 hours of isoflurane anesthesia for arthroscopic surgery, horses were administered either 0.25 mg/kg (G25, n = 10) or 0.50 mg/kg (G50, n = 10) xylazine intravenously. Vital signs and arterial blood samples were obtained during recovery before sedation (baseline), 5, 10, 20, 30, and 45 minutes after xylazine and 30 minutes after standing. The quality of recovery scores ranged from 10 to 72 (10 = best, 72 = worst). G25 horses recovered faster (mean ± SD, 33 ± 5 min) than G50 horses (50 ± 7 min, P < .0001). Mean maximal decrease in arterial oxygen tension was 55 ± 11 mmHg in G25 (at 10 minutes; P < .05) and 54 ± 7 mmHg in G50 (at 20 minutes; P < .01). G25 group had a total recovery score (23 [range 18-29]) and number of attempts to stand (4 ± 2) greater than the G50 group (18 [10-23] and 1 ± 1, respectively; P < .001). Both doses of xylazine promoted a moderate and transient hypoxemia during recovery; however, the 0.5 mg/kg dose produced a longer and improved quality of recovery from anesthesia.

Ischaemic heart preconditioning in rats with adjuvant-induced arthritis

Adjuvant-induced arthritis (AIA) in rats is a model of chronic systemic inflammation and a model of rheumatoidarthritis in humans. To investigate effectiveness of ischaemic preconditioning (IPC) in reducing the area of myocardial infarction in rats with AIA. The study was performed in vivo in male SPRD/Mol/Lod rats. Animals were assigned to the experimental group (n = 15) or the control group (n = 14). In the experimental group, AIA was induced by subcutaneous administration of 1 mLof Freund's complete adjuvant, and the experiment was performed after 14 days. In control (healthy) animals, no procedures were performed prior to the proper experiment. Animals were anaesthesized (by intraperitoneal administration of ketamineand xylazine) and put on a ventilator. Then, myocardial infarction was induced, preceded by IPC in some animals. To induceinfarction, left main coronary artery (LMCA) was occluded for 30 min, followed by 60 min of reperfusion. IPC protocol consisted of LMCA occlusion for 3 min, followed by 5 min of reperfusion and a second LMCA occlusion for 7 min. Weevaluated a percentage ratio of the infarct size to the risk area (IS/RA). Necrosis area was stained with tetrazolium, and thearea supplied by LMCA was determined using Evans blue. All areas were determined by planimetry. We used nonparametric Kruskal-Wallis rank ANOVA with multiple comparisons, and the results were shown as median values and 25th and 75th percentiles. P < 0.05 was considered statistically significant. In the control group with IPC (n = 7), the IS/RA ratio of 25% (23-38) was significantly reduced compared to thecontrol group without IPC (n = 7) (58% [57-63], p < 0.05). In the AIA group with IPC (n = 7), the IS/RA ratio of 58% (51-65)did not differ significantly compared to the AIA group without IPC (n = 8) (65% [62-71]). Our findings indicate that IPC in rats with AIA does not result in a significant reduction of myocardial necrosisarea induced by 30 min of ischaemia and 60 min of reperfusion. This effect might have been related to the presence ofchronic systemic inflammation. Absent or reduced benefits of IPC may be one reason for an increased cardiovascular risk inpatients with rheumatoid arthritis.

Effects of ketamine, propofol, or thiopental administration on intraocular pressure and qualities of induction of and recovery from anesthesia in horses

To assess the effects of ketamine hydrochloride, propofol, or compounded thiopental sodium administration on intraocular pressure (IOP) and qualities of induction of and recovery from anesthesia in horses. 6 healthy adult horses. Horses were sedated with xylazine hydrochloride (0.5 mg/kg), and anesthesia was induced with guaifenesin followed by ketamine (2 mg/kg), propofol (3 mg/kg), or thiopental (4 mg/kg) in a crossover study with ≥ 1 week between treatments. For each horse, IOP in the right eye was measured with a handheld applanation tonometer before and after xylazine administration, at the time of recumbency, and every 3 minutes after induction of anesthesia until spontaneous movement was observed. Cardiorespiratory responses and venous blood measurements were recorded during anesthesia. Induction of and recovery from anesthesia were subjectively evaluated by investigators who were unaware of the anesthetic treatment of each horse. Data were analyzed via a repeated-measures ANOVA with Holm-Ŝidák post hoc comparisons. Compared with findings after xylazine administration (mean ± SD, 17 ± 3 mm Hg), thiopental decreased IOP by 4 ± 23%, whereas propofol and ketamine increased IOP by 8 ± 11% and 37 ± 16%, respectively. Compared with the effects of ketamine, propofol and thiopental resulted in significantly lower IOP at the time of recumbency and higher heart rates at 3 minutes after induction of anesthesia. No other significant differences among treatments were found. These findings support the use of thiopental or propofol in preference to ketamine for horses in which increases in IOP should be minimized.

Influence of detomidine and xylazine on spleen dimensions and on splenic response to epinephrine infusion in healthy adult horses

ObjectiveTo compare the changes in splenic length and thickness and in packed cell volume (PCV) following detomidine or xylazine administration and subsequent epinephrine infusion. Hypothesis: Spleen relaxation occurs following xylazine or detomidine administration and interferes with subsequent splenic contractile response to epinephrine. Study designRandomized non‐blinded crossover experimental study. Animals6 healthy adult mares. MethodsThe mares received an intravenous (IV) epinephrine infusion (1 μg kg−1minute−1 over 5 minutes) one hour after IV administration of detomidine (0.01 mg kg−1), xylazine (0.5 mg kg−1) or no drug (control), with a withdrawal period of at least 7 days between experiments. The splenic length measured in two different axes, the splenic thickness, and the PCV were measured prior to sedation (T0), 30 minutes later, and at 5‐minute intervals from the start of the epinephrine infusion (T1) until T1 + 40 minutes. Changes from base‐line and between treatments were compared using a two‐way anova for repeated measures. Significance was set at p < 0.05. ResultsSplenic length was significantly increased and PCV was significantly decreased after detomidine administration compared to baseline. Epinephrine infusion resulted in a significant decrease in splenic length and thickness, and a significant increase in PCV, irrespective of prior treatment with detomidine or xylazine. ConclusionsDetomidine administration was followed by a sonographically detectable increase of splenic length. Neither detomidine nor xylazine interfered with the ability of the spleen to contract following subsequent administration of an epinephrine infusion given one hour later. Clinical relevancePrevious sedation with alpha‐2 agonists does not preclude the efficiency of epinephrine as a medical treatment of left dorsal displacement of the large colon, but further investigations are required with other drug doses and different time intervals between administrations.

The Reliability of Two Different Protocols for Pharmacologically Induced Ejaculation in Donkeys (Equus asinus)

The aim of this study was to pharmacologically induce ejaculation in male donkeys. Two methods for pharmacological ejaculation were used. The first method was the administration of xylazine (0.66 mg/kg, intravenous); the second method was the administration of detomidine chloride (0.02 mg/kg, intramuscular), and when ejaculation was not achieved in 15 minutes, the administration of a half dose of detomidine chloride (0.01 mg/kg, intramuscular) was repeated. Both of these methods were used in all animals. In the study, 10 male donkeys were used. After the administration of xylazine, no ejaculation was observed. After the administration of detomidine, ejaculation was achieved in 20% of the cases (2 of 10). We assume that these methods are not satisfactory for ex-copula induction of ejaculation in male donkeys.