Sedative, analgesic and cardiorespiratory effects of romifidine in cats

OBJECTIVE: To evaluate the sedative, analgesic, and cardiorespiratory effects of intramascular (IM) romifidine in cats. STUDY DESIGN: Prospective, randomized experimental trial. ANIMALS: Ten healthy adult cats. METHODS: Romifidine (100, 200, and 400 microg kg(-1)) or xylazine (1 mg kg(-1)) was given IM in a cross-over study design. Heart rate (HR), respiratory rate (RR), rectal temperature (RT), hemoglobin saturation, oscillometric arterial pressure, and scores for sedation, muscle relaxation, position, auditory response, and analgesia were determined before and after drug administration. Time to recumbency, duration of recumbency, and time to recover from sedation were determined. Subjective evaluation and cardiorespiratory variables were recorded before and at regular intervals for 60 minutes after drug administration. RESULTS: Bradycardia developed in all cats that were given romifidine or xylazine. No other significant differences in physiologic parameters were observed from baseline values or between treatments. Increasing the dose of romifidine did not result in increased sedation or muscle relaxation. Cats given xylazine showed higher sedation and muscle relaxation scores over time. Analgesia scores were significantly higher after administration of romifidine (400 microg kg(-1)) and xylazine (1 mg kg(-1)) than after romifidine at 100 or 200 microg kg(-1). Duration of lateral recumbency was not significantly different between treatments; however, cats took longer to recover after administration of 400 micro g kg(-1) romifidine. CONCLUSIONS AND CLINICAL RELEVANCE: Bradycardia is the most important adverse effect after IM administration of romifidine at doses ranging from 100 to 400 microg kg(-1) or 1 mg kg(-1) of xylazine in cats. The sedative effects of romifidine at 200 microg kg(-1) are comparable to those of 1 mg kg(-1) of xylazine, although muscle relaxation and analgesia were significantly less with romifidine than with xylazine.     

Comparison of sedative effects of romifidine following intravenous, intramuscular, and sublingual administration to horses.

OBJECTIVE: To compare sedative effects of romifidine following IV, IM, or sublingual (SL) administration in horses. ANIMALS: 30 horses that required sedation for routine tooth rasping. PROCEDURE: Horses (n = 10/group) were given romifidine (120 microg/kg) IV, IM, or SL. Heart rate, respiratory rate, head height, distance between the ear tips, thickness of the upper lip, response to auditory stimulation, response to tactile stimulation, and degree of ataxia were recorded every 15 minutes for 180 minutes. Tooth rasping was performed 60 minutes after administration of romifidine, and overall adequacy of sedation was assessed. RESULTS: IV and IM administration of romifidine induced significant sedation, but SL administration did not induce significant sedative effects. Scores for overall adequacy of sedation after IV and IM sedation were not significantly different from each other but were significantly different from scores for horses given romifidine SL. Sedative and other effects varied among groups during the first 60 minutes after drug administration; thereafter, effects of IV and IM administration were similar. CONCLUSIONS AND CLINICAL RELEVANCE: Onset of action was fastest and degree of sedation was greater after IV, compared with IM, administration of romifidine, but duration of action was longer after IM administration. Sublingual administration did not result in clinically important sedative effects.     

Romifidine, medetomidine or xylazine before propofol-halothane-N2O anesthesia in dogs.

The objective of this paper was to evaluate romifidine as a premedicant in dogs prior to propofol-halothane-N2O anesthesia, and to compare it with the other alpha2-agonists (medetomidine and xylazine). For this, ten healthy dogs were anesthetized. Each dog received 3 preanesthetic protocols: atropine (10 microg/kg BW, IM), and as a sedative, romifidine (ROM; 40 microg/kg BW, IM), xylazine (XYL; 1 microg/kg, IM), or medetomidine (MED; 20 microg/kg BW, IM). Induction of anesthesia was delivered with propofol 15 min later and maintained with halothane and N2O for one hour in all cases. The following variables were registered before preanesthesia, 10 min after the administration of preanesthesia, and at 5-minute intervals during maintenance: PR, RR, rectal temperature (RT), MAP, SAP, and DAP. During maintenance, arterial oxygen saturation (SpO2), end-tidal CO2 (EtCO2) and percentage of halothane necessary for maintaining anesthesia (%HAL) were also recorded. Induction dose of propofol (DOSE), time to extubation (TE), time to sternal recumbency (TSR) and time to standing (TS) were also registered. The statistical analysis was carried out during the anesthetic period. ANOVA for repeat measures revealed no differences between the 3 groups for PR and RR; however, MAP, SAP and DAP were higher in the MED group; SpO2 was lower in MED and EtCO2 was lower in ROM; %HAL was higher in XYL. No statistical differences were observed in DOSE, TE, TSR or TS. Percentage of halothane was lower in romifidine and medetomidine than in xylazine premedicated dogs also anesthetized with propofol. All the cardiorespiratory variables measured were within normal limits. The studied combination of romifidine, atropine, propofol, halothane and N2O appears to be a safe and effective drug combination for inducing and maintaining general anesthesia in healthy dogs.     

Comparison of romifidine and medetomidine pre-medication in propofol-isoflurane anaesthetised dogs

The objective of this paper was to evaluate romifidine as a pre-medicant in dogs prior to propofol-isoflurane anaesthesia, and to compare it with medetomidine. For this, eight healthy dogs were anaesthetised. Each dog received three pre-anaesthetic protocols: R40 (romifidine, 40 microg/kg, IV), R80 (romifidine, 80 microg/kg, IV) or MED (medetomidine, 10 microg/kg, IV). Induction of anaesthesia was delivered with propofol and maintained with isoflurane. The following variables were studied before sedative administration and 10 min after sedative administration: heart rate (HR), mean arterial pressure (MAP), systolic arterial pressure (SAP) and diastolic arterial pressure (DAP) and respiratory rate (RR). During maintenance, the following variables were recorded at 5-min intervals: HR, MAP, SAD, DAP, arterial oxygen saturation (SpO(2)), end-tidal CO(2)(EtCO(2)), end-tidal concentration of isoflurane (EtISO) required for maintenance of anaesthesia and tidal volume (TV). Time to extubation, time to sternal recumbency and time to standing were also registered. HR and RR experimented a significantly decreased during sedation in all protocols respect to baseline values. Mean HR, MAP, SAP, DAP, SpO(2), EtCO(2), and TV during anaesthesia were similar for the three protocols. End tidal of isoflurane concentration was statistically similar for all protocols. Recovery time for R40 was significantly shorter than in R80 and MED. The studied combination of romifidine, propofol and isoflurane appears to be an effective drug combination for inducing and maintaining general anaesthesia in healthy dogs.     

Medetomidine, a new sedative-analgesic for use in the dog and its reversal with atipamezole

The sedative and physiological effects of intramuscular medetomidine (20 and 40 μg/kg) in dogs were compared with those of xylazine (2 mg/kg). The efficacy of atipamezole (200 μg/kg), as an antagonist given 15 or 45 minutes after medetomidine (40 μg/kg) was studied. Following medetomidine, onset of sedation was rapid, and depth and duration of sedation were dose dependent. The higher dose produced jaw relaxation, depression of the pedal reflex, downward rotation of the eye and dogs could be positioned for radiography of the hips. Side effects were similar after either medetomidine or xylazine, and included bradycardia, a fall in respiratory rate and muscle tremor. Vomiting during induction was less frequent after medetomidine than after xylazine. Intramuscular administration of atipamezole rapidly reversed the sedative effects of medetomidine. Signs of arousal were seen within three minutes; all dogs could stand within 10 minutes and appeared clinically normal. Heart and respiratory rates rose, but did not return to presedation values. Relapse to sedation was not noted.     

Sedative effects of romifidine in the dog

The sedative and physiological effects of intravenous romifidine at 0, 20, 40, 80 and 120 μg/kg were investigated in five clinically normal adult male beagle dogs in a blind study using a Latin square design. Following the injection of romifidine, the dogs became ataxic and stood with a wide-based stance, they exhibited signs of skeletal muscle relaxation and their heads were lowered. All the dogs became recumbent and there was a reduction in the heart and respiratory rates. Increasing the dose from 20 to 40 μg/kg, or higher, produced a significant reduction in heart rate. There was an increase in the sedation score following even low doses of romifidine, and although measures of sedation showed no differences among romifidine doses, subjectively, the higher doses produced a more consistent effect. Dogs given lower doses of romifidine regained a standing position more rapidly than following the higher doses, although this effect was not significantly different. A second blind study compared the sedative effects of intravenous romifidine, at 40 and 80 μg/kg, with mede-tomidine at 10 μg/kg in six adult beagles. The cardiopulmonary and sedative effects were not significantly different between all regimens, although medetomidine at 10 μg/kg appeared to be intermediate in effect between romifidine at 40 and 80 μ/kg. The sedative and physiological effects of romifidine in dogs appear to be similar to other α₂-adrenoceptor agonists. Intravenous administration provided sedation which might be clinically useful.     

Sedative and analgesic effects of medetomidine in dogs

The sedative and analgesic effects of medetomidine were studied in 18 laboratory beagles in a randomized cross-over study which was carried out in a double-blind fashion. Xylazine was included as a positive control and placebo as a negative control. Medetomidine was used at doses of 10, 30, 90 and 180 micrograms/kg i.m. compared to a dose of 2.2 mg/kg xylazine i.m. Parameters closely related to sedation were used to measure the degree of sedation. These were a posture variable (including evaluation of the dog's posture without external disturbance and resistance when laid recumbent) and a relaxation variable (including relaxation of the jaws, upper eyelids and anal sphincter). The first signs of sedation were recorded 1.5-3.5 min after administration of both drugs. The dogs sat down at 0.6-2.6 min post-injection and became prone at 1.9-5.9 min. Medetomidine dose-dependently affected the posture of the dogs and the relaxation variable--the higher the dose, the stronger and longer lasting the effect recorded. The sedative effect of xylazine was comparable to a medetomidine dose of 30 micrograms/kg. The analgesic effect was assessed as changes in the response to superficial pain induced by electrical stimuli. The response threshold increased significantly with both drugs and the effect of medetomidine was dose-dependent. The effects of the doses of 30 micrograms/kg medetomidine and 2.2 mg/kg xylazine did not differ significantly. In summary, medetomidine possessed an excellent sedative effect associated with analgesia in dogs.     

Effect of romifidine and romifidine-butorphanol for sedation in dogs

The sedative and physiological effects of intravenous romifidine at 120 μg/kg were compared with intravenous romifidine (120 μg/kg) followed immediately by intravenous butorphanol (01 mg/kg) in 18 clinically normal adult beagles in a blinded randomised change-over study. Following the injection of romifidine alone the dogs became recumbent and there was an increase in a subjective score awarded to the degree of sedation. Heart rate and respiratory rate decreased and minor bradyarrhythmias were noted. The romifidine-butorphanol combination produced a significant decrease in the time to the onset of sedation and increase in the sedative effect and duration of action compared with romifidine alone. With the exception of a further decrease in heart rate and respiratory rate, there were no additional side effects following the use of the romifidine-butorphanol combination. The marked sedative effect associated with this combination would appear to be useful in the clinical situation where an increased degree of sedation is required.     

Cardiorespiratory effects of desflurane in dogs given romifidine or medetomidine before induction of anesthesia with propofol

The objective of this study was to evaluate the use of desflurane after induction of anesthesia with propofol in dogs sedated with romifidine or medetomidine. Each of 8 healthy dogs received intravenously, in random order, 3 preanesthetic protocols: romifidine, 40 microg/kg of body weight (BW) (R40); romifidine, 80 microg/kg BW (R80); and medetomidine, 10 microg/kg BW (MED). Cardiovascular and respiratory variables were recorded during the procedure. Time to extubation, time to sternal recumbency, and time to standing were also recorded. Heart rate and respiratory rate decreased significantly during sedation from baseline values, but there were no differences between the means for the 3 preanesthetic protocols. Mean values for heart rate, mean arterial blood pressure, systolic arterial pressure, diastolic arterial pressure, respiratory rate, tidal volume, arterial oxygen saturation, end-tidal CO2 level, pH, and arterial blood gas values during anesthesia were similar for the 3 protocols. The mean end-tidal desflurane concentration was significantly lower with the R80 protocol than with the R40 protocol. The mean time to extubation was significantly shorter with the R40 protocol than with the R80 and MED protocols.     

Results of cystometry and urethral pressure profilometry in dogs sedated with medetomidine or xylazine

OBJECTIVE: To compare effects of medetomidine and xylazine hydrochloride on results of cystometry and micturition reflexes in healthy dogs and results of urethral pressure profilometry (UPP) in sedated and conscious dogs. ANIMALS: 20 dogs. PROCEDURES: Urodynamic testing was performed 6 times in each dog (3 times after administration of xylazine [1 mg/kg of body weight, IV] and 3 times after administration of medetomidine (30 microg/kg, IM). Before each episode of sedation, UPP was performed. Heart and respiratory rates and indirect blood pressures were recorded prior to and 5, 10, 20, and 30 minutes after injection of sedative. Cystometry measurements included threshold volume, threshold pressure, and tonus limb. The UPP measurements included maximal urethral closure pressure (MUCP), functional profile length, and, in male dogs, plateau pressure. RESULTS: Mean MUCP was decreased markedly in xylazine- and medetomidine-sedated dogs. Xylazine and medetomidine also decreased plateau pressure in male dogs. The MUCP measurements were consistent among days for conscious and xylazine-sedated dogs but were inconsistent for medetomidine-sedated female dogs. The proportion of valid cystometry measurements was greater for xylazine (39 of 60) than for medetomidine (27 of 60). Cystometry was considered invalid when bladder pressure reached 30 cm H2O without initiation of a micturition reflex. CONCLUSIONS AND CLINICAL RELEVANCE: Medetomidine and xylazine have similar effects on measurement of UPP and cystometry. Medetomidine was less consistent among days for UPP in female dogs and produced fewer valid cystometry tests, compared with xylazine. For urodynamic evaluations, medetomidine administered IM cannot be substituted for xylazine administered IV.     

Cardiopulmonary and sedative effects of intravenous administration of low doses of medetomidine and xylazine to adult horses

OBJECTIVE: To determine the cardiopulmonary and sedative effects of medetomidine hydrochloride in adult horses and to compare those effects with effects of an equipotent dose of xylazine hydrochloride. ANIMALS: 10 healthy adult female horses. PROCEDURE: 5 horses were given medetomidine (4 microg/kg of body weight, i.v.), and the other 5 were given xylazine (0.4 mg/kg, i.v.). Heart rate, respiratory rate, arterial blood pressures, pulmonary arterial blood pressures, and cardiac output were recorded, and sedation and ataxia scores were assigned before and every 5 minutes after drug administration for 60 minutes. Rectal temperature and blood gas partial pressures were measured every 15 minutes after drug administration. RESULTS: Arterial blood pressure was significantly decreased throughout the study among horses given medetomidine and was significantly decreased for 40 minutes among horses given xylazine. Compared with baseline values, cardiac output was significantly decreased 10, 20, and 40 minutes after administration of medetomidine and significantly increased 40 and 60 minutes after administration of xylazine. Despite the significant decrease in respiratory rate in both groups, results of blood gas analyses were not significantly changed over time. Ataxia and sedation scores were of similar magnitude for the 2 groups, but ataxia persisted slightly longer among horses given medetomidine. Horses resumed eating hay 10 to 55 minutes after drug administration. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that equipotent low doses of medetomidine and xylazine induce comparable levels of ataxia and sedation and similar cardiopulmonary changes in adult horses.     

Evaluation of sedative and cardiorespiratory effects of romifidine and romifidine-butorphanol in cats

OBJECTIVE: To determine sedative and cardiorespiratory effects of romifidine alone and romifidine in combination with butorphanol and effects of preemptive atropine administration in cats sedated with romifidine-butorphanol. DESIGN: Randomized crossover study. ANIMALS: 6 healthy adult cats. PROCEDURES: Cats were given saline (0.9% NaCl) solution followed by romifidine alone (100 microg/kg [45.4 microg/lb], i.m.), saline solution followed by a combination of romifidine (40 microg/kg [18.1 microg/lb], i.m.) and butorphanol (0.2 mg/kg [0.09 mg/lb], i.m.), or atropine (0.04 mg/kg [0.02 mg/lb], s.c.) followed by romifidine (40 microg/kg, i.m.) and butorphanol (0.2 mg/kg, i.m.). Treatments were administered in random order, with > or = 1 week between treatments. Physiologic variables were determined before and after drug administration. Time to recumbency, duration of recumbency, time to recover from sedation, and subjective evaluation of sedation, muscle relaxation, and analgesia were assessed. RESULTS: Bradycardia developed in all cats that received saline solution and romifidine-butorphanol or romifidine alone. Preemptive administration of atropine prevented bradycardia for 50 minutes in cats given romifidine-butorphanol. Oxyhemoglobin saturation was significantly decreased 10 minutes after romifidine-butorphanol administration in atropine-treated cats. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that administration of romifidine alone or romifidine-butorphanol causes a significant decrease in heart rate and that preemptive administration of atropine in cats sedated with romifidine-butorphanol effectively prevents bradycardia for 50 minutes.     

Cardiovascular effects of romifidine in dogs

OBJECTIVE: To characterize the cardiovascular effects of romifidine at doses ranging from 5 to 100 microg/kg of body weight, IV. ANIMALS: 25 clinically normal male Beagles. PROCEDURE: Romifidine was administered IV at a dose of 5, 10, 25, 50, or 100 microg/kg (n = 5/group). Heart rate, arterial pressure, central venous pressure, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, body temperature, cardiac output, and PCV were measured immediately prior to and at selected times after romifidine administration. Cardiac index, stroke index, rate-pressure product, systemic and pulmonary vascular resistance indices, and left and right ventricular stroke work indices were calculated. Degree of sedation was assessed by an observer who was blinded to the dose administered. RESULTS: Romifidine induced a decrease in heart rate, pulmonary arterial pressure, rate-pressure product, cardiac index, and right ventricular stroke work index and an increase in central venous pressure, pulmonary capillary wedge pressure, and systemic vascular resistance index. In dogs given romifidine at a dose of 25, 50, or 100 microg/kg, an initial increase followed by a prolonged decrease in arterial pressure was observed. Arterial pressure immediately decreased in dogs given romifidine at a dose of 5 or 10 microg/kg. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that IV administration of romifidine induces dose-dependent cardiovascular changes in dogs. However, the 2 lowest doses (5 and 10 microg/kg) induced less cardiovascular depression, and doses > or = 25 microg/kg induced similar cardiovascular changes, suggesting that there may be a ceiling on the cardiovascular effects of romifidine.     

Evaluation of the sedative and cardiorespiratory effects of dexmedetomidine,dexmedetomidine-butorphanol,and dexmedetomidine-ketamine in cats

OBJECTIVE: To determine sedative and cardiorespiratory effects of dexmedetomidine alone and in combination with butorphanol or ketamine in cats. DESIGN: Randomized crossover study. ANIMALS: 6 healthy adult cats. PROCEDURES: Cats were given dexmedetomidine alone (10 microg/kg [4.5 mg/lb], IM), a combination of dexmedetomidine (10 microg/kg, IM) and butorphanol (0.2 mg/kg [0.09 mg/lb], IM), or a combination of dexmedetomidine (10 microg/kg, IM) and ketamine (5 mg/kg [2.3 mg/lb], IM). Treatments were administered in random order, with > or = 1 week between treatments. Physiologic variables were assessed before and after drug administration. Time to lateral recumbency, duration of lateral recumbency, time to sternal recumbency, time to recovery from sedation, and subjective evaluation of sedation, muscle relaxation, and auditory response were assessed. RESULTS: Each treatment resulted in adequate sedation; time to lateral recumbency, duration of lateral recumbency, and time to recovery from sedation were similar among treatments. Time to sternal recumbency was significantly greater after administration of dexmedetomidine-ketamine. Heart rate decreased significantly after each treatment; however, the decrease was more pronounced after administration of dexmedetomidine-butorphanol, compared with that following the other treatments. Systolic and diastolic blood pressure measurements decreased significantly from baseline with all treatments; 50 minutes after drug administration, mean blood pressure differed significantly from baseline only when cats received dexmedetomidine and butorphanol. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that in cats, administration of dexmedetomidine combined with butorphanol or ketamine resulted in more adequate sedation, without clinically important cardiovascular effects, than was achieved with dexmedetomidine alone.     

Sedative and analgesic effects of romifidine in camels (Camelus dromedarius)

ObjectiveTo evaluate the clinical effectiveness and the sedative and analgesic effects of intravenous (IV) romifidine in camels.Study designRandomized prospective study.AnimalsEighteen healthy adult Dromedary camels.MethodsRomifidine was administered IV to camels (n = 6) at three different doses (40, 80 or 120 μg kg^?1). Time of onset, degree and duration of sedation and analgesia were recorded immediately after drug administration. Heart rate, respiratory rate, ruminal contractions, muscle relaxation, response to auditory and tactile stimulation, distance between ears, distance from lower lip to the ground, and degree of ataxia were also recorded pre-administration and at 5, 15, 30, 45, 60, 90, 120 and 180 minutes post-administration. Plasma glucose, blood urea nitrogen and creatinine were measured.ResultsRomifidine produced dose dependent sedation and analgesia. Significant decreases in heart rate (p < 0.001), ruminal contractions (p < 0.05), distance from lower lip to the ground (p < 0.001), response to auditory and tactile stimuli (p < 0.01), and significant increases in the degree of ataxia (p < 0.01), distance between the ear tips (p < 0.001) and blood glucose (p < 0.01) concentration were recorded after administration of romifidine until recovery. However, no significant changes in rectal temperature and respiratory rate were recorded.Conclusions and clinical relevanceIntravenous administration of romifidine at three different doses appeared to be an effective sedative and analgesic agent for camels. Bradycardia, ruminal atony, and hyperglycemia were the most important adverse effects after IV administration of romifidine. The IV administration of romifidine at a dose rate of 120 μg kg^?1 caused profound sedation and analgesia. Romifidine could be used for chemical restraint for a variety of diagnostic and minor surgical procedures in camels.     

Sedative effects of three doses of romifidine in comparison with medetomidine in cats

ObjectiveTo compare the sedative effects of three doses of romifidine with one dose of medetomidine.Study designProspective blinded experimental cross-over.AnimalsFive adult Domestic Short Hair cats.MethodsCats were administered romifidine at 80, 120 and 160 μg kg^?1 or medetomidine at 20 μg kg^?1 (M20) intramuscularly (IM). Sedative effects were assessed for 3 hours by summing the scores given to posture, auditory response, resistance to positioning, muscular relaxation, and response to noxious stimuli, giving a total sedation score (TS). The area under the curve (AUC) of TS ≥7 (the score considered as clinically useful sedation) was calculated. Times to stages of sedation were determined. Some physiological parameters were measured. Data to compare treatments were analysed by anova or Kruskal–Wallis test as relevant.ResultsAll treatments gave a TS considered clinically useful. There were no significant differences between treatments for times to onset of sedation, maximum TS reached, or AUC. Differences between romifidine treatments for other sedation parameters were not significant but the time to maximum TS and to recovery was shortest in M20. Heart rate (HR) fell significantly with all treatments and, although with M20 it recovered at 65 minutes, it remained significantly depressed for 3 hours after all romifidine treatments. Most cats vomited, and/or hypersalivated after all treatments.ConclusionsDoses of 80, 120 and 160 μg kg^?1 romifidine IM produce sedation in cats which is similar to that following medetomidine 20 μg kg^?1. Recovery from sedation and of physiological parameters was quickest after M20.Clinical relevanceDoses of romifidine considerably lower than those investigated by previous authors give a clinically useful level of sedation, and their use might result in less side effects and a quicker recovery.     

A comparison of the sedative effects of three α2-adrenoceptor agonists (romifidine, detomidine and xylazine) in the horse

The sedative effects of a new alpha 2-adrenoceptor agonist, romifidine, were compared with those of xylazine and detomidine. Five horses were treated with two doses of romifidine (40 micrograms/kg body weight and 80 micrograms/kg body weight), two doses of detomidine (10 micrograms/kg body weight and 20 micrograms/kg body weight) and one dose of xylazine (1 mg/kg body weight) given by intravenous injection using a Latin-square design. The dose of 80 micrograms/kg romifidine appeared equipotent to 1 mg/kg xylazine and 20 micrograms/kg detomidine, although at these doses both xylazine and detomidine had a shorter action. Detomidine 20 micrograms/kg and xylazine both produced greater lowering of the head and a greater degree of ataxia than romifidine at either dose. Romifidine produced sedation similar to that of the other drug regimes. The effect upon imposed stimuli was similar.     

Sedation and Pain Management with Intravenous Romifidine−Butorphanol in Standing Horses

The objective of this study was to determine the sedation, analgesia, and clinical reactions induced by an intravenous combination of romifidine and butorphanol in horses. The study was conducted on six saddle horses weighing 382 to 513 kg (mean ± SD; 449 ± 54 kg) and aged 6 to 14 years. The horses each underwent three treatments: intravenous romifidine 0.1 mg/kg body weight (RM; mean dose, 4.5 mL); intravenous butorphanol 0.05 mg/kg body weight (BT; mean dose, 2.4 mL); and intravenous romifidine 0.1 mg/kg body weight plus butorphanol 0.05 mg/kg body weight (RMBT; mean dose, 7.0 mL). The order of treatments was randomized. Heart rate, arterial pressure, respiratory rate, rectal temperature, sedation, and analgesia were measured at two times before treatments, 15 minutes apart (times –15 and 0) and at 5, 10, 15, 30, 45, 60, 75, 90, 120, 150, and 180 minutes after drug administration. The onset of sedation was approximately 5 minutes after intravenous injection of RM and RMBT, whereas BT did not present this effect. The duration of complete sedation was approximately 60 minutes for RMBT and approximately 35 minutes for RM. The RMBT treatment provided 30 minutes and the RM treatment 20 minutes of complete analgesia. Heart rate decreased significantly (P < .05) from basal values in the RM and RMBT treatments. Only RM caused significant decreases (P < .05) in the respiratory rate. Arterial pressure did not change significantly (P > .05) in any treatment. Intravenous administration of a romifidine−butorphanol combination to horses resulted in longer duration of sedation and analgesia than administration of romifidine or butorphanol alone. These effects probably resulted from a synergistic effect of the two drugs.     

Cardiopulmonary effects of romifidine/ketamine or xylazine/ketamine when used for short duration anesthesia in the horse

The cardiovascular changes associated with anesthesia induced and maintained with romifidine/ketamine versus xylazine/ ketamine were compared using 6 horses in a cross over design. Anesthesia was induced and maintained with romifidine (100 microg/kg, IV)/ketamine (2.0 mg/kg, IV) and ketamine (0.1 mg/kg/min, IV), respectively, in horses assigned to the romifidine/ ketamine group. Horses assigned to the xylazine/ketamine group had anesthesia induced and maintained with xylazine (1.0 mg/kg, IV)/ketamine (2.0 mg/kg, IV) and a combination of xylazine (0.05 mg/kg/min, IV) and ketamine (0.1 mg/kg/min, IV), respectively. Cardiopulmonary variables were measured at intervals up to 40 min after induction. All horses showed effective sedation following intravenous romifidine or xylazine and achieved recumbency after ketamine administration. There were no significant differences between groups in heart rate, arterial oxygen partial pressures, arterial carbon dioxide partial pressures, cardiac index, stroke index, oxygen delivery, oxygen utilization, systemic vascular resistance, left ventricular work, or any of the measured systemic arterial blood pressures. Cardiac index and left ventricular work fell significantly from baseline while systemic vascular resistance increased from baseline in both groups. The oxygen utilization ratio was higher in the xylazine group at 5 and 15 min after induction. In conclusion, the combination of romifidine/ketamine results in similar cardiopulmonary alterations as a xylazine/ketamine regime, and is a suitable alternative for clinical anesthesia of the horse from a cardiopulmonary viewpoint.     

Effects of dexamethasone on emesis in cats sedated with xylazine hydrochloride

OBJECTIVE: To determine antiemetic efficacy of prophylactic administration of dexamethasone and its influence on sedation in cats sedated with xylazine hydrochloride. ANIMALS: 6 healthy adult cats (3 males and 3 females). PROCEDURE: The prophylactic antiemetic effect of 4 doses of dexamethasone (1, 2, 4, and 8 mg/kg of body weight, IM) or saline (0.9% NaCl) solution (0.066 ml/kg, IM) administered 1 hour before administration of xylazine (0.66 mg/kg, IM) was evaluated. Cats initially were given saline treatment (day 0) and were given sequentially increasing doses of xylazine on days 7, 14, 21, and 28. After xylazine injection, all cats were observed for 30 minutes to allow assessment of frequency of emesis and time until onset of the first emetic episode.The influence of dexamethasone on xylazine-induced sedation in these cats also was evaluated. RESULTS: Prior treatment with 4 or 8 mg/kg of dexamethasone significantly reduced the frequency of emetic episodes and also significantly prolonged the time until onset of the first emetic episode after xylazine injection. Time until onset of the first emetic episode also was significantly prolonged for dexamethasone at a dose of 2 mg/kg. Time until onset of sedation after administration of xylazine was not altered by administration of dexamethasone. CONCLUSIONS AND CLINICAL RELEVANCE: Dexamethasone (4 or 8 mg/kg, IM) significantly decreased the frequency of emetic episodes induced by xylazine without compromising sedative effects in cats. Dexamethasone may be used prophylactically as an antiemetic in cats treated with xylazine.