Effect of yohimbine on xylazine-induced hypoinsulinemia and hyperglycemia in mares

Serum insulin and plasma glucose concentrations were determined in 8 mares. Four IV treatments were studied: xylazine (1.1 mg/kg of body weight); yohimbine (0.125 mg/kg); yohimbine (0.125 mg/kg) followed 5 minutes later by xylazine (1.1 mg/kg); and 5 ml of isotonic saline solution as a control. Blood samples were collected before (time 0) and at 5, 15, 30, 60, 120, and 180 minutes after drug administration. Serum insulin concentration decreased and plasma glucose concentration increased in mares given xylazine. Plasma glucose concentration was unchanged in control mares and in mares given yohimbine or yohimbine followed by xylazine. Serum insulin concentration was unchanged in mares given saline solution, but transiently increased in mares given yohimbine alone. Treatment with yohimbine prevented xylazine-induced hypoinsulinemia and hyperglycemia.     

Effects of alpha2-adrenergic receptor agonists on urine production in horses deprived of food and water

OBJECTIVE: To quantitate the dose- and time-related effects of IV administration of xylazine and detomidine on urine characteristics in horses deprived of feed and water. ANIMALS: 6 horses. PROCEDURE: Feed and water were withheld for 24 hours followed by i.v. administration of saline (0.9% NaCI) solution, xylazine (0.5 or 1.0 mg/kg), or detomidine (0.03 mg/kg). Horses were treated 4 times, each time with a different protocol. Following treatment, urine and blood samples were obtained at 15, 30, 60, 120, and 180 minutes. Blood samples were analyzed for PCV and serum concentrations of total plasma solids, sodium, and potassium. Urine samples were analyzed for pH and concentrations of glucose, proteins, sodium, and potassium. RESULTS: Baseline (before treatment) urine flow was 0.30 +/- 0.03 mL/kg/h and did not significantly change after treatment with saline solution and low-dose xylazine but transiently increased by 1 hour after treatment with high-dose xylazine or detomidine. Total urine output at 2 hours following treatment was 312 +/- 101 mL versus 4,845 +/- 272 mL for saline solution and detomidine, respectively. Absolute values of urine concentrations of sodium and potassium also variably increased following xylazine and detomidine administration. CONCLUSIONS AND CLINICAL RELEVANCE: Xylazine and detomidine administration in horses deprived of feed and water causes transient increases in urine volume and loss of sodium and potassium. Increase in urine flow is directly related to dose and type of alpha2-adrenergic receptor agonist. Dehydration in horses may be exacerbated by concurrent administration of alpha2-adrenergic receptor agonists.     

Effect of sodium bicarbonate infusion on serum osmolality, electrolyte concentrations, and blood gas tensions in cats.

The effects of single IV injections of sodium bicarbonate (0.5 mEq/kg of body weight, 1 mEq/kg, 2 mEq/kg, and 4 mEq/kg) on serum osmolality, serum sodium, chloride, and potassium concentrations, and venous blood gas tensions in 6 healthy cats were monitored for 180 minutes. Serum osmolality increased and remained significantly (P less than 0.05) increased for 120 minutes in cats given 4 mEq of sodium bicarbonate/kg. Serum sodium was increased significantly (P less than 0.05) for 30 minutes in cats given 4 mEq of sodium bicarbonate/kg. Serum sodium decreased and remained significantly (P less than 0.05) decreased for 120 minutes in cats given 1 g of 20% mannitol/kg, and serum osmolality was significantly (P less than 0.05) decreased at 30 and 60 minutes. Serum chloride decreased significantly (P less than 0.05) for 10 minutes in cats given 1 mEq of sodium bicarbonate/kg, and was significantly decreased for 30 minutes in cats given 2 mEq and 4 mEq of sodium bicarbonate/kg. Serum chloride decreased and remained significantly (P less than 0.05) decreased for 30 minutes in cats given 1 g of 20% mannitol/kg. Serum sodium and serum osmolality did not change significantly (P less than 0.05) in cats given 4 ml of 0.9% sodium chloride/kg. Serum potassium decreased significantly (P less than 0.05) for 10 minutes in cats given 1 mEq of sodium bicarbonate/kg, and for 120 minutes in cats given 2 mEq/kg or 4 mEq/kg. There was a significantly (P less than 0.05) greater decrease in serum potassium that lasted for 30 minutes after given sodium bicarbonate at the dosage of 4 mEq/kg, compared with other dosages given.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of xylazine on cecal mechanical activity and cecal blood flow in healthy horses

Mechanical activity of the cecal body, lateral cecal arterial blood flow, carotid arterial pressure, and heart rate were measured in 6 conscious healthy horses 30 minutes before and for 120 minutes after IV administration of xylazine at dosages of 1.1 mg/kg of body weight, 0.55 mg/kg, and 0.275 mg/kg. Xylazine at a dosage of 1.1 mg/kg reduced the mean motility index (the product of the mean amplitude of contractions and the total duration of contractile activity divided by the recording time) of the circular and longitudinal muscle layers for the first, second, third, and fourth 30-minute periods after administration of xylazine. Xylazine at a dosage of 0.55 mg/kg reduced the motility index of the circular and longitudinal muscle layers for the first and second 30-minute periods after administration of xylazine. Xylazine at a dosage of 0.275 mg/kg reduced the motility index of the circular and longitudinal muscle layers for the first 30-minute period after administration of xylazine. Mean lateral cecal arterial blood flow was significantly (P less than 0.05) lower than the base-line value at 2 and 4 minutes after administration of all 3 xylazine dosages and at 8 minutes after administration of xylazine dosages of 1.1 mg/kg and 0.55 mg/kg. All dosages of xylazine caused transient hypertension and bradycardia, followed by hypotension.     

Effects of ketamine, xylazine, and a combination of ketamine and xylazine in Pekin ducks

Effects of ketamine, xylazine, and a combination of ketamine and xylazine were studied in 12 male Pekin ducks (7 to 12 weeks old; mean [+/- SD] body weight, 3.1 +/- 0.3 kg). After venous and arterial catheterization and fixation of a temperature probe in the cloaca, each awake duck was confined, but not restrained, in an open box in a dimly lit room. Blood pressure and lead-II ECG were recorded. Three arterial blood samples were collected every 15 minutes over a 45-minute period (control period) and were analyzed for pHa, PaCO2 and PaO2. After the control period, each duck was assigned at random to 1 of 3 drug groups: (1) ketamine (KET; 20 mg/kg of body weight, IV), (2) xylazine (XYL; 1 mg/kg, IV), and (3) KET + XYL (KET 20 mg/kg and XYL, 1 mg/kg; IV). Measurements were made at 1, 5, 10, 15, 30, 45, 60, and 90 minutes after drug administration. All ducks survived the drug study. Cloacal temperature was significantly (P less than or equal to 0.05) increased above control cloacal temperature at 90 minutes after the administration of ketamine, and from 10 through 90 minutes after administration of ketamine plus xylazine. In ducks of the KET group, pHa, PaCO2, and PaO2, remained unchanged after administration of the drug. In ducks of the XYL group, pHa and PaO2 decreased significantly (P less than or equal to 0.05) from control values for all time points up to and including 15 minutes after drug administration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of xylazine on cerebrospinal fluid pressure in conscious horses.

Lumbosacral CSF pressure was measured in 6 horses via a catheter inserted through the lumbosacral space. Heart rate, facial artery pressure, central venous pressure, and CSF pressure were measured before IV injection of a saline solution control, for 15 minutes after saline solution injection, and for 60 minutes after the IV injection of 1.1 mg of xylazine/kg of body weight. Arterial pH and blood gases were analyzed before saline solution injection, 15 minutes after saline solution injection, and at 15, 30, and 60 minutes after xylazine injection. Constant craniocervical posture was maintained during sedation. Lumbosacral CSF pressure was significantly decreased for 15 minutes after xylazine injection. Diastolic arterial pressure was significantly increased 4 minutes after xylazine administration and diastolic and mean arterial pressure were increased at 6 and 8 minutes after xylazine administration. Small increases in systolic arterial blood pressure and central venous pressure, and a small decrease in heart rate were observed. There were no significant differences in the arterial blood gas values. It was concluded that IV injection of xylazine causes a decrease in intracranial pressure in healthy conscious horses. The effects may be different in horses with neurologic disease or cerebral trauma.     

Effect of general anesthesia and minor surgical trauma on urine and serum measurements in horses

OBJECTIVE: To characterize the effect of general anesthesia and minor surgery on renal function in horses. ANIMALS: 9 mares with a mean (+/- SE) age and body weight of 9+/-2 years and 492+/-17 kg, respectively. PROCEDURE: The day before anesthesia, urine was collected (catheterization) for 3 hours to quantitate baseline values, and serum biochemical analysis was performed. The following day, xylazine (1.1 mg/kg, IV) was administered, and general anesthesia was induced 5 minutes later with diazepam (0.04 mg/kg, IV) and ketamine (2.2 mg/kg, IV). During 2 hours of anesthesia with isoflurane, Paco2 was maintained between 48 and 52 mm Hg, and mean arterial blood pressure was between 70 and 80 mm Hg. Blood and urine were collected at 30, 60, and 120 minutes during and at 1 hour after anesthesia. RESULTS: Baseline urine flow was 0.92+/-0.17 ml/kg/h and significantly increased at 30 and 60 minutes after xylazine administration (2.14+/-0.59 and 2.86+/-0.97 ml/kg/h respectively) but returned to baseline values by the end of anesthesia. Serum glucose concentration increased from 12+/-4 to 167+/-8 mg/dl at 30 minutes. Glucosuria was not observed. CONCLUSIONS AND CLINICAL RELEVANCE: Transient hyperglycemia and an increase in rine production accompanies a commonly used anesthetic technique for horses. The increase in urine flow is not trivial and should be considered in anesthetic management decisions. With the exception of serum glucose concentration and urine production, the effect of general anesthesia on indices of renal function in clinically normal horses is likely of little consequence in most horses admitted for elective surgical procedures.     

Xylazine causes transient dose-related hyperglycemia and increased urine volumes in mares

Xylazine given IV at doses of 0.5, 1.0, and 1.5 mg/kg to mares caused a significant (P less than 0.05) dose-related increase in serum glucose concentration and urine volume. Serum glucose concentrations as much as 150 mg/dl were recorded in mares after they were given the largest xylazine dose. The greatest urine volume, similar to changes in peak glucose concentration, always occurred during the first hour after dosing with xylazine and averaged 1.82, 3.93, and 5.68 ml/kg/hour after the 0.5-, 1.0-, and 1.5-mg/kg doses, respectively, were given. Urine osmolality and specific gravity were significantly (P less than 0.05) inversely related to urine volume. Although serum glucose concentrations were significantly increased above those measured after IV injection of saline solution, significant glucosuria was not detected.     

Antinociceptive,physiologic and biochemical effects of electroacupuncture combined with xylazine in hybrid goats

ObjectiveTo elucidate the antinociceptive, physiologic and biochemical effects of electroacupuncture (EA) and xylazine in hybrid goats.Study designProspective experimental study.AnimalsA total of 30 female hybrid goats aged 1–2 years and weighing 25 ± 2.9 kg (mean ± standard deviation).MethodsThe goats were divided into five groups and administered xylazine (0.1 mg kg⁻¹; group XYL.1), xylazine (0.3 mg kg⁻¹; group XYL.3), EA (group EA), EA + xylazine (0.1 mg kg⁻¹; group XYL.1-EA) and 0.9% saline (0.3 mL; control group CON). Nociceptive threshold and serum glucose concentration were measured at time 0 and at 15, 30, 45, 60 minutes and 24 hours after treatment. Nociceptive threshold was measured by passing potassium ions through the skin using potassium iontophoresis. Mean arterial pressure (MAP), heart rate (HR), respiratory frequency (f_R) and rectal temperature (RT) were recorded at times 0 and at 5, 10, 15, 20, 30, 45, 60 minutes and 24 hours. Repeated-measures analyses were performed for each response variable; p < 0.05 was considered significant for all analyses.ResultsAntinociceptive effects in groups XYL.1 and XYL.3 were increased significantly at 15–60 minutes compared with group CON. Antinociceptive effect was higher in group XYL.1-EA than groups XYL.1 or EA at 15–60 minutes (p < 0.05). No significant difference in the nociceptive threshold was recorded in groups XYL.1-EA and XYL.3, except at 30 minutes. HR, MAP, f_R, RT values were higher in group XYL.1-EA than in groups XYL.1 or XYL.3. Serum glucose concentration was higher in group XYL.3 at 15–60 minutes than in CON.Conclusions and clinical relevanceThe XYL.1 and EA combination was effective for antinociception with minimum physiologic alteration, suggesting that the combination may be a new and effective strategy for pain relief during clinical procedures in goats.     

Effect of xylazine in heifers under thermoneutral or heat stress conditions

A study was performed to assess the effect of xylazine HCl (0.1 mg/kg of body weight, IV) in heifers maintained at thermoneutrality (18 C, 42% humidity) or under heat stress (33 C, 63% humidity) conditions. Xylazine caused 50 and 70% decreases in serum insulin concentrations in the thermoneutral and heat-stressed heifers, respectively. Xylazine-induced hypoinsulinemia was associated with hyperglycemia. In the thermoneutral group, serum glucose concentrations increased from a basal concentration of 75 mg/dl to 150 mg/dl after 15 minutes. In the heat stress group, the serum glucose concentration increased from 65 mg/dl to 105 mg/dl. Hyperglycemia peaked at 2 hours and remained high for 6 hours after xylazine administration. Heat-stressed heifers took a longer time (107 minutes) to stand than did heifers under thermoneutral conditions (41 minutes). The time to regain sensation to pain was significantly prolonged in heat-stressed heifers. Xylazine had no effect on body temperature and respiration rate in heifers under the thermoneutral condition, whereas it markedly induced hyperthermia and suppressed respiration rate in the heat-stressed heifers. Furthermore, the pulse rate was slightly decreased in thermoneutral heifers and was markedly decreased in the heat-stressed heifers.     

Hematologic and serum chemical effects of a ketamine/xylazine combination when used for immobilizing springbok

A ketamine hydrochloride/xylazine combination was found effective for immobilizing springbok. Following intramuscular injection by hand, the onset of immobilization ranged from 3 to 10 minutes and duration of immobilization ranged from 1 hour to 2 hours 20 minutes. Hematologic and serum chemical values before and after immobilization were compared. Serum alanine transaminase and serum glucose values were significantly higher after immobilization, whereas serum potassium was significantly lower.     

The Effect of Sedation on Gastric Emptying of a Liquid Marker in Ponies

OBJECTIVE: The effect of sedation on gastric emptying was evaluated in six ponies by monitoring serum concentrations of acetaminophen (AP) after intragastric administration. EXPERIMENTAL DESIGN: Prospective randomized experimental study. ANIMALS: Six adult ponies, 135 to 275 kg. METHODS: Fifteen minutes after the intravenous administration of xylazine (1 mg/kg), butorphanol (0.05 mg/kg), acepromazine (0.05 mg/kg) or saline, ponies were given AP (20 mg/kg in 350 mL water) by stomach tube. Blood for AP analysis was collected at baseline and 15, 30, 45, 75, 90, 105, and 120 minutes after AP administration. The time (Tmax) to reach peak serum concentration (Cmax), and the area under the AP serum concentration versus time curve (AUC) were determined for each treatment group. RESULTS: Tmax was 31 mins in the control group, and this increased significantly (P<.05) after sedation. Cmax decreased (P<.05) after xylazine administration, and AUC decreased (P<.05) after acepromazine. CONCLUSIONS: This study indicated that sedation has a significant effect on the gastric emptying rate of a liquid in ponies.     

Antagonistic effects of yohimbine in pigs anaesthetised with tiletamine/zolazepam and xylazine

Twelve healthy two-month-old Landrace x Yorkshire pigs of both sexes were randomly assigned to receive either tiletamine and xylazine (zx) or zolazepam and xylazine followed 20 minutes later by yohimbine (zxy). The pigs' scores for immobilisation and analgesia, and their rectal temperature, heart rate, respiration rate, pO(2), pCO(2), alkaline phosphatase, aspartate aminotransferase, glucose and total plasma proteins were determined before and five, 25, 45, 65 and 85 minutes after the administration of the tiletamine/zolazepam and xylazine. The mean total scores for immobilisation and analgesia of the zxy pigs were significantly lower than those of the zx pigs after 85 minutes. The mean rectal temperatures of the zxy pigs were significantly lower than those of zx pigs after 25, 45 and 65 minutes. The mean respiratory rates of the zx pigs were significantly lower than those of zxy pigs after five minutes. The mean pCO(2) of the zxy pigs were significantly lower than those of zx pigs five minutes after the administration of yohimbine. The mean glucose concentration of the zxy pigs were significantly lower than those of zx pigs after 65 and 85 minutes. The mean concentration total protein of the zxy pigs were significantly lower than those of zx pigs throughout the period of anaesthesia. Both groups became laterally recumbent within three minutes. When recovering from anaesthesia, the pigs treated with yohimbine took significantly less time to achieve sternal recumbency (mean [sd] 52.2 [8.9] v 76.2 [20.6] minutes) and less time to be able to stand (mean [sd] 77.0 [9.8] v 98.7 [15.8] minutes), and walk (mean [sd] 81.3 [11.3] v 110.8 [18.6] minutes).     

Cardiorespiratory effects of a tiletamine/zolazepam-ketamine-detomidine combination in horses.

OBJECTIVE: To determine cardiorespiratory effects of a tiletamine/zolazepam-ketamine-detomidine (TZKD) combination in horses. ANIMALS: 8 healthy adult horses. PROCEDURE: Horses were instrumented for measurement of cardiorespiratory, acid-base, and electrolyte values. Each horse was given xylazine (0.44 mg/kg of body weight, IV) 10 to 15 minutes prior to induction of recumbency by administration of the TZKD combination. Cardiorespiratory, acid-base, and electrolyte values were measured at 5-minute intervals for > or =30 minutes. RESULTS: All horses became recumbent within 1 minute after IV administration of TZKD. Mean +/- SD duration of recumbency was 40+/-8 minutes. All horses regained standing position after < or =2 attempts. Quality of anesthesia and analgesia was determined to be satisfactory in all horses. Xylazine induced decreases in respiratory rate, heart rate, cardiac output, maximum rate of increase of right ventricular pressure, and rate pressure product. The PaCO2, right atrial pressure, and peripheral vascular resistance increased, whereas blood temperature, PO2, pHa, HCO3-, PCV, total solids, Na, and K values remained unchanged. Subsequent administration of TZKD caused right atrial pressure and PaCO2 to increase and PaO2 to decrease, compared with values obtained after xylazine administration. Remaining cardiorespiratory, acid-base, hematologic, and electrolyte values did not differ from those obtained after xylazine administration. CONCLUSION: IV administration of TZKD induces short-term anesthesia in horses. Potential advantages of this drug combination are the small volume of drug administered; minimal cardiorespiratory depression; quality of induction and maintenance of, and recovery from, anesthesia; and duration of drug effects.     

Effect of adrenergic drugs on glucose and plasma glucagon and insulin responses to xylazine in sheep

Xylazine was administered intravenously (0.16 mg/kg) to sheep. This was associated with a transient hyperglucagonaemia, hypoinsulinaemia and hyperglycaemia. The rate of glucose appearance as determined by isotope dilution techniques was increased three to four fold during the first 20 minutes after xylazine administration. Phentolamine prevented the xylazine-induced increase in the rate of appearance of glucose, and in concentrations of glucose and glucagon in plasma. The insulin response was not altered by phentolamine. Propranolol had no effect on the glucose and hormonal responses due to xylazine. The xylazine-induced effects on glucose metabolism and secretion by glucagon and insulin appear to be mediated by the alpha-adrenoceptors.     

Postoperative Catecholamine Response to Onychectomy in Isoflurane-anesthetized Cats Effect of Analgesics

Twenty-four healthy adult cats were anesthetized with isoflurane in oxygen. Six cats (group 1) served as controls; onychectomy of the forefeet was performed in the other three groups. Saline was administered intravenously to group 1, and morphine, xylazine, and salicylate were administered to groups 2, 3, and 4, respectively. Mixed venous blood samples were drawn for catecholamine analysis before induction of anesthesia, after recovery from anesthesia, and 30 minutes and 60 minutes after administration of the analgesic agent. Plasma catecholamine concentrations were determined by high performance liquid chromatography. Isoflurane anesthesia alone induced a transient increase in epinephrine concentration. Norepinephrine and epinephrine concentrations increased significantly after onychectomy. Morphine and xylazine significantly decreased postoperative norepinephrine and epinephrine concentrations; salicylate did not.     

Influence of Medetomidine on Acid-base Balance and Urine Excretion in Goats

Raekallio M., M. Hackzell and L. Eriksson: Influence of medetomidine on acid-base balance and urine excretion in goats. Acta vet. scand. 1994,35,283-288.– Seven goats were given medetomidine 5 μg/kg as an iv bolus injection. Venous blood samples were taken repeatedly and urine was collected continuously via a catheter up to 7h after the injection.Medetomidine caused deep clinical sedation. Base excess, pH and PCO₂ in venous blood rose after medetomidine administration. There were no significant changes in plasma concentrations of sodium, calcium, magnesium, creatinine or osmolality, whereas potassium and bicarbonate concentrations increased, and phosphate and chloride decreased. Medetomidine increased plasma glucose concentration, and in 4 of 7 goats glucose could also be detected in urine. Medetomidine did not influence urine flow rate, free water clearance, bicarbonate and phosphate excretion or pH, but renal chloride, sodium, potassium, calcium, magnesium and creatinine excretion were reduced.The results suggest that the metabolic alkalosis recorded after medetomidine administration is not caused by increased renal acid excretion.     

Udder edema in cattle: effects of diuretics (furosemide, hydrochlorothiazide, acetazolamide, and 50% dextrose) on serum and urine electrolytes

Blood and urine chemical values at parturition in clinically normal Holstein cows (n = 12) were compared with the same values in Holstein cows developing udder edema (n = 12). There was no statistically significant mean difference between the 2 groups for the serum and urine chemical data. Furosemide (500 mg) given IV caused a significant increase in serum calcium and sodium, urine chloride, potassium, and sodium, and fractional excretional ratio of chloride, potassium, and sodium. There was a significant mean decrease in the serum potassium, urine creatinine, osmolality, pH, and specific gravity. Hydrochlorothiazide (250 mg) given IV caused a significant mean increase in serum chloride, urine chloride, potassium, and sodium, and fractional excretion ratio of chloride, potassium, and sodium. There was a significant mean decrease in serum potassium and sodium, urine osmolality, pH, and specific gravity. Acetazolamide (500 mg) given IV caused a significant mean increase in blood urea nitrogen, serum chloride and glucose, urine sodium, and fractional excretion ratio of sodium, while causing a significant mean decrease in serum potassium, sodium, and phosphorus, and urine creatinine. Dextrose (500 g) given IV as a 50% solution caused a statistical mean increase in serum glucose, urine chloride, potassium, and sodium, and fractional excretion ratio of chloride and potassium. A statistical mean decrease occurred in the packed cell volume, blood urea nitrogen, serum calcium, potassium, sodium, and phosphorus, urine creatinine, osmolality, and pH.     

Analgesic and systemic effects of ketamine,xylazine, and lidocaine after subarachnoid administration in goats

OBJECTIVE: To determine the effects of ketamine hydrochloride, xylazine hydrochloride, and lidocaine hydrochloride after subarachnoid administration in goats. ANIMALS: 6 healthy goats. PROCEDURE: In each goat, ketamine (3 mg/kg), xylazine (0.1 mg/kg), lidocaine (2.5 mg/kg), and saline (0.9% NaCI) solution were injected into the subarachnoid space between the last lumbar vertebra and first sacral vertebra (time 0). Analgesic, ataxic, sedative, cardiovascular, and respiratory effects and rectal temperature were evaluated before (baseline) and 2, 5, 10, 15, and 30 minutes after administration and at 30-minute intervals thereafter as needed. RESULTS: Administration of anesthetics induced varying degrees of analgesia. Onset of the analgesic effect was more delayed for xylazine (mean +/- SD, 9.5 +/- 2.6 minutes) than for ketamine (6.7 +/- 2.6 minutes) or lidocaine (3.5 +/- 1.2 minutes). Duration of analgesia induced by xylazine (88.3 +/- 15 minutes) was twice as long as the duration of analgesia induced by ketamine (48.8 +/- 13.5 minutes) but similar to that induced by lidocaine (66.5 +/- 31 minutes). Xylazine induced bradycardia, whereas ketamine caused a nonsignificant increase in heart rate. Xylazine induced a reduction in arterial pressure, whereas ketamine or lidocaine did not affect arterial pressure. CONCLUSIONS AND CLINICAL RELEVANCE: Subarachnoid administration of xylazine in goats resulted in longer duration of analgesia of the tail, perineum, hind limbs, flanks, and caudodorsal rib areas than administration of ketamine or lidocaine. However, xylazine caused bradycardia and respiratory depression. Additional studies are needed to determine whether the analgesia would be sufficient to allow clinicians to perform surgical procedures.     

Influence of furosemide treatment on fluid and electrolyte balance in horses

Alterations in electrolyte and acid-base balance were studied in 6 horses for 8 hours after furosemide administration (1 mg/kg of body weight, IM), and the results were compared with those for 5 healthy untreated horses (controls) kept under identical environmental conditions. In the treated group, decreases in plasma potassium, chloride, and calcium concentrations and increases in total plasma protein content persisted for the 8-hour observation period, whereas there was no change in plasma sodium concentration, osmolality, or packed cell volume. Plasma bicarbonate concentration and PCO2 remained high throughout the study, during which time venous blood pH was modestly increased only at the 6-hour sampling time. Furosemide treatment resulted in decreases in urine pH, specific gravity, osmolality, and potassium and calcium concentrations and increases in urine volume and total urine sodium, chloride, and calcium excretion. Body weight decreased 19.2 +/- 5.2 kg (mean +/- SD) in treated horses (4 +/- 1% of body weight), compared with a weight loss of 8 +/- 2.1 kg in untreated horses (1.5 +/- 0.4% of body weight) during the 8-hour experimental period. The increased fluid losses induced by the diuretic did not cause any obvious clinical signs in the horses. Pulse pressure, skin turgor, capillary refill time, and jugular distensibility remained unchanged throughout the experimental period.