Epidural anesthesia with bupivacaine, bupivacaine and fentanyl, or bupivacaine and sufentanil during intravenous administration of propofol for ovariohysterectomy in dogs

OBJECTIVE: To compare cardiovascular and systemic effects and analgesia during the postoperative period of epidural anesthesia performed with bupivacaine alone or with fentanyl or sufentanil in bitches maintained at a light plane of anesthesia with continuous infusion of propofol. STUDY DESIGN: Prospective randomized masked clinical trial. ANIMALS: 30 female dogs of various breeds. PROCEDURES: Dogs were allocated into 3 groups of 10 each. One group received fentanyl (2 microg/kg [0.91 microg/lb]) and bupivacaine (1 mg/kg [0.45 mg/lb]), 1 group received sufentanil (1 microg/kg) and bupivacaine (1 mg/kg), and 1 group received bupivacaine (1 mg/kg). All dogs received acepromazine (0.1 mg/kg [0.045 mg/lb]) and continuous infusion of propofol for sedation. The agents were administered into the lumbosacral space and diluted in saline (0.9% NaCl) solution to a total volume of 0.36 mL/kg (0.164 mL/lb). Cardiac and respiratory rates, arterial blood pressures, pH, and blood gases were evaluated. Analgesia, sedation level, serum cortisol concentrations, and plasma catecholamine concentrations were measured regularly for 6 hours. RESULTS: No important changes in cardiovascular, respiratory, or sedation variables were observed. Degree of analgesia in the postoperative period was higher in the sufentanil group, although use of fentanyl and bupivacaine also resulted in a sufficient level of analgesia. CONCLUSIONS AND CLINICAL RELEVANCE: Use of the 3 anesthetic techniques permitted ovariohysterectomy with sufficient analgesia and acceptable neuroendocrine modulation of pain with minimal adverse effects.     

Effects of preoperative administration of ketoprofen on anesthetic requirements and signs of postoperative pain in dogs undergoing elective ovariohysterectomy

OBJECTIVE: To determine the effects of preoperative administration of ketoprofen on anesthetic requirements and signs of postoperative pain in dogs undergoing elective ovariohysterectomy. DESIGN: Randomized, controlled clinical trial. ANIMALS: 22 clinically normal client-owned dogs. PROCEDURE: 60 minutes before induction of anesthesia, 11 dogs were given ketoprofen (2 mg/kg [0.9 mg/lb], i.m.), and the other 11 were given saline (0.9% NaCl) solution. Dogs were premedicated with glycopyrrolate, acepromazine, and butorphanol and anesthetized with thiopental; anesthesia was maintained with isoflurane. Ovariohysterectomy was performed by an experienced surgeon, and butorphanol was given 15 minutes before completion of the procedure. Objective behavioral scores and numerical pain scores at rest and with movement were recorded every 2 hours for 12 hours after surgery and then every 4 hours for an additional 12 hours. RESULTS: Preoperative administration of ketoprofen did not reduce the dose of thiopental required to induce anesthesia or the end-tidal concentration of isoflurane required to maintain anesthesia. Activity levels and median objective behavioral scores were significantly higher 4 and 6 hours after surgery in dogs given ketoprofen than in dogs given saline solution. However, mean numerical pain scores in dogs given ketoprofen were not significantly different from scores for dogs given saline solution at any time. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that preoperative administration of ketoprofen does not reduce anesthetic requirements in dogs undergoing elective ovariohysterectomy but may reduce signs of pain after surgery. Results also suggest that the objective behavioral score may be a more sensitive measure of acute postoperative pain than traditional numerical pain scores.     

Use of low doses of ketamine administered by constant rate infusion as an adjunct for postoperative analgesia in dogs

OBJECTIVE: To compare indicators of postoperative pain and behavior in dogs with and without a low-dose ketamine infusion added to usual perioperative management. DESIGN: Prospective, randomized, blinded clinical study. ANIMALS: 27 dogs undergoing forelimb amputation. PROCEDURE: Dogs were anesthetized with glycopyrrolate, morphine, propofol, and isoflurane. Thirteen dogs were treated with ketamine IV, as follows: 0.5 mg/kg (0.23 mg/lb) as a bolus before surgery, 10 microg/kg/min (4.5 microg/lb/min) during surgery, and 2 microg/kg/min (0.9 microg/lb/min) for 18 hours after surgery. Fourteen dogs received the same volume of saline (0.9% NaCl) solution. All dogs received an infusion of fentanyl (1 to 5 microg/kg/h [0.45 to 2.27 pg/lb/h]) for the first 18 hours after surgery. Dogs were evaluated for signs of pain before surgery, at the time of extubation, and 1, 2, 3, 4, 12, and 18 hours after extubation. Owners evaluated their dogs' appetite, activity, and wound soreness on postoperative days 2, 3, and 4. RESULTS: Dogs that received ketamine infusions had significantly lower pain scores 12 and 18 hours after surgery and were significantly more active on postoperative day 3 than dogs that received saline solution infusions. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that perioperative administration of low doses of ketamine to dogs may augment analgesia and comfort in the postoperative surgical period.     

Cardiorespiratory responses and plasma cortisol concentrations in dogs treated with medetomidine before undergoing ovariohysterectomy

OBJECTIVE: To evaluate effects of medetomidine on anesthetic dose requirements, cardiorespiratory variables, plasma cortisol concentrations, and behavioral pain scores in dogs undergoing ovariohysterectomy. DESIGN: Randomized, prospective study. ANIMALS: 12 healthy Walker-type hound dogs. PROCEDURE: Dogs received medetomidine (40 micrograms/kg [18.2 micrograms/lb] of body weight, i.m.; n = 6) or saline (0.9% NaCl) solution (1 ml, i.m.; 6) prior to anesthesia induction with thiopental; thiopental dose needed for endotracheal intubation was compared between groups. Ovariohysterectomy was performed during halothane anesthesia. Blood samples were obtained at various times before drug administration until 300 minutes after extubation. Various physiologic measurements and end-tidal halothane concentrations were recorded. RESULTS: In medetomidine-treated dogs, heart rate was significantly lower than in controls, and blood pressure did not change significantly from baseline. Plasma cortisol concentrations did not increase significantly until 60 minutes after extubation in medetomidine-treated dogs, whereas values in control dogs were increased from time of surgery until the end of the recording period. Control dogs had higher pain scores than treated dogs from extubation until the end of the recording period. CONCLUSION AND CLINICAL RELEVANCE: Administration of medetomidine reduced dose requirements for thiopental and halothane and provided postoperative analgesia up to 90 minutes after extubation. Dogs undergoing ovariohysterectomy by use of thiopental induction and halothane anesthesia benefit from analgesia induced by medetomidine administered prior to anesthesia induction. Additional analgesia is appropriate 60 minutes after extubation.     

Effects of intramuscular administration of low doses of medetomidine and medetomidine-butorphanol in middle-aged and old dogs.

OBJECTIVE: To determine effects of low doses of medetomidine administered with and without butorphanol and glycopyrrolate to middle-aged and old dogs. DESIGN: Prospective randomized clinical trial. ANIMALS: 88 healthy dogs > or = 5 years old. PROCEDURE: Dogs were assigned randomly to receive medetomidine (2, 5, or 10 micrograms/kg [0.9, 2.3, or 4.6 micrograms/lb] of body weight, i.m.) alone or with glycopyrrolate (0.01 mg/kg [0.005 mg/lb], s.c.), medetomidine (10 micrograms/kg) and butorphanol (0.2 mg/kg [0.1 mg/lb], i.m.), or medetomidine (10 micrograms/kg), butorphanol (0.2 mg/kg), and glycopyrrolate (0.01 mg/kg). Anesthesia was induced with thiopental sodium and maintained with isoflurane. Degree of sedation and analgesia were determined before and after medetomidine administration. Respiratory rate, heart rate, and mean arterial blood pressure were determined 10 and 30 minutes after medetomidine administration. Adverse effects and amounts of thiopental and isoflurane used were recorded. RESULTS: Sedation increased after medetomidine administration in 79 of 88 dogs, but decreased in 7 dogs that received 2 or 5 micrograms of medetomidine/kg. Mean postsedation analgesia score and amounts of thiopental and isoflurane used were less in dogs that received medetomidine and butorphanol, compared with other groups. Respiratory rate, heart rate, and blood pressure were not different among groups. Significantly more adverse effects developed in dogs that did not receive glycopyrrolate. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of medetomidine (10 micrograms/kg, i.m.) and butorphanol (0.2 mg/kg, i.m.) induced sedation and analgesia and reduced amounts of thiopental and isoflurane required for anesthesia in middle-aged and old dogs. Glycopyrrolate decreased frequency of medetomidine-associated adverse effects.     

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.     

Evaluation of intraperitoneal and incisional lidocaine or bupivacaine for analgesia following ovariohysterectomy in the dog

Objective To determine if intraperitoneal (IP) and incisional (SC) lidocaine or bupivacaine provide analgesia following ovariohysterectomy (OHE). Study Design Prospective, randomized, controlled, blinded clinical trial. Animals Thirty dogs presenting to the Veterinary Teaching Hospital for elective OHE. Methods Dogs were pre‐medicated with acepromazine and butorphanol, induced with thiopental and maintained with isoflurane. They were randomly assigned to three groups: 10 received 8.8 mg kg^?1 2% lidocaine with epinephrine IP (LID); 10 received 4.4 mg kg^?1 0.75% bupivacaine IP (BUP); and 10 received 0.9% saline IP (SAL) upon completion of OHE. All IP doses were standardized to 0.88 mL kg^?1 with saline. An additional 2 mL of undiluted solution was placed SC prior to incisional closure. Dogs were scored at 0.5, 1, 2, 3, 6, 8 and 18 hours post‐extubation by one observer. Dogs were evaluated using a visual analogue scale (VAS) for pain and sedation, and a composite pain scale (CPS) that included physiologic and behavioral variables. Dogs were treated with 0.22 mg kg^?1 butorphanol + acepromazine if their VAS (pain) score was >50. Parametric variables were analyzed using Student's t‐test or repeated measures anova as appropriate. Non‐parametric variables were analyzed by χ²‐test. Results There were no significant differences in age, weight, incision length, surgery time, anesthesia time, or total thiopental dose among groups. Peak post‐surgical pain scores for all groups occurred at 0.5 hours and returned to baseline by 18 hours. Dogs in the BUP group had significantly lower VAS‐pain scores overall than dogs in the SAL group. Seven out of 10 dogs in the SAL group, 4/10 in the LID group and 2/10 in the BUP group were treated with supplemental acepromazine and butorphanol. No differences between groups were detected with the CPS. No adverse side‐effects were observed. Conclusions and clinical relevance Our findings support the use of IP and SC bupivacaine for post‐operative analgesia following OHE in the dog.     

Use of a combination of propofol and fentanyl, alfentanil, or sufentanil for total intravenous anesthesia in cats

OBJECTIVE: To determine the cardiorespiratory effects of an i.v. infusion of propofol alone or in association with fentanyl, alfentanil, or sufentanil in cats and, for each combination, the minimal infusion rate of propofol that would inhibit a response to noxious stimuli. DESIGN: Randomized crossover study. ANIMALS: 6 cats. PROCEDURE: Cats were anesthetized 4 times in random order. After i.v. administration of fentanyl, alfentanil, sufentanil, or saline (0.9% NaCl) solution, anesthesia was induced with propofol (7 mg/kg 13.2 mg/lb], i.v.) and maintained for 90 minutes with a continuous infusion of propofol in conjunction with fentanyl (0.1 microg/kg/min [0.045 microg/lb/min]), alfentanil (0.5 microg/kg/min [0.23 microg/lb/min]), sufentanil (0.01 microg/kg/min [0.004 microg/lb/min]), or saline solution (0.08 mL/kg/min [0.036 mL/lb/min]). RESULTS: Minimal infusion rate of propofol required to prevent a response to a noxious stimulus was higher when cats received saline solution. After 70 minutes, minimal infusion rate of propofol was significantly higher with fentanyl than with sufentanil. Decreases in heart rate, systolic blood pressure, rectal temperature, and respiratory rate were detected with all treatments. Oxygen saturation did not change significantly, but end-tidal partial pressure of carbon dioxide increased with all treatments. There were no significant differences in recovery times or sedation and recovery scores among treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that infusion of propofol in combination with fentanyl, alfentanil, or sufentanil results in satisfactory anesthesia in cats.     

Sedative and cardiorespiratory effects of medetomidine, medetomidine-butorphanol, and medetomidine-ketamine in dogs

OBJECTIVE: To determine sedative and cardiorespiratory effects of i.m. administration of medetomidine alone and in combination with butorphanol or ketamine in dogs. DESIGN: Randomized, crossover study. ANIMALS: 6 healthy adult dogs. PROCEDURES: Dogs were given medetomidine alone (30 micrograms/kg [13.6 micrograms/lb] of body weight, i.m.), a combination of medetomidine (30 micrograms/kg, i.m.) and butorphanol (0.2 mg/kg [0.09 mg/lb], i.m.), or a combination of medetomidine (30 micrograms/kg, i.m.) and ketamine (3 mg/kg [1.36 mg/lb], i.m.). Treatments were administered in random order with a minimum of 1 week between treatments. Glycopyrrolate was given at the same time. Atipamezole (150 micrograms/kg [68 micrograms/lb], i.m.) was given 40 minutes after administration of medetomidine. RESULTS: All but 1 dog (given medetomidine alone) assumed lateral recumbency within 6 minutes after drug administration. Endotracheal intubation was significantly more difficult when dogs were given medetomidine alone than when given medetomidine and butorphanol. At all evaluation times, percentages of dogs with positive responses to tail clamping or to needle pricks in the cervical region, shoulder region, abdominal region, or hindquarters were not significantly different among drug treatments. The Paco2 was significantly higher and the arterial pH and Pao2 were significantly lower when dogs were given medetomidine and butorphanol or medetomidine and ketamine than when they were given medetomidine alone. Recovery quality following atipamezole administration was unsatisfactory in 1 dog when given medetomidine and ketamine. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that a combination of medetomidine with butorphanol or ketamine resulted in more reliable and uniform sedation in dogs than did medetomidine alone.     

Effects of preemptive atropine administration on incidence of medetomidine-induced bradycardia in dogs

OBJECTIVE: To determine the cardiorespiratory effects of preemptive atropine administration in dogs sedated with medetomidine. DESIGN: Randomized crossover trial. ANIMALS: 12 healthy adult dogs. PROCEDURES: Dogs underwent 6 treatments. Each treatment consisted of administration of atropine (0.04 mg/kg [0.018 mg/lb] of body weight, IM) or saline solution (0.9% NaCl, 1 ml, IM) and administration of medetomidine (10, 20, or 40 microg/kg [4.5, 9.1, or 18.2 microg/lb], IM) 10 minutes later. Treatments were administered in random order, with a minimum of 1 week between treatments. Cardiorespiratory effects before and after atropine and medetomidine administration were assessed. Duration of lateral recumbency and quality of sedation and recovery were assessed. RESULTS: Bradycardia (heart rate < 60 beats/min) was seen in all dogs when saline solution was administered followed by medetomidine, and the dose of medetomidine was not associated with severity or frequency of bradycardia or second-degree heart block. However, a medetomidine dose-dependent increase in mean and diastolic blood pressures was observed, regardless of whether dogs received saline solution or atropine. Preemptive atropine administration effectively prevented bradycardia and second-degree heart block but induced pulsus alternans and hypertension. The protective effects of atropine against bradycardia lasted 50 minutes. Blood gas values were within reference limits during all treatments and were not significantly different from baseline values. Higher doses of medetomidine resulted in a longer duration of lateral recumbency. CONCLUSIONS AND CLINICAL RELEVANCE: Preemptive administration of atropine in dogs sedated with medetomidine effectively prevents bradycardia for 50 minutes but induces hypertension and pulsus alternans.     

Effects of preoperative administration of ketoprofen on whole blood platelet aggregation,buccal mucosal bleeding time,and hematologic indices in dogs undergoing elective ovariohysterectomy

OBJECTIVE: To determine effects of preoperative administration of ketoprofen on whole blood platelet aggregation, buccal mucosal bleeding time, and hematologic indices in dogs after elective ovariohysterectomy. DESIGN: Randomized, masked clinical trial. ANIMALS: 22 healthy dogs. PROCEDURE: 60 minutes before induction of anesthesia, 11 dogs were given 0.9% NaCl solution (control), and 11 dogs were given ketoprofen (2 mg/kg [0.9 mg/lb], IM). Thirty minutes before induction of anesthesia, glycopyrrolate (0.01mg/kg [0.005 mg/lb]), acepromazine (0.05 mg/kg [0.02 mg/lb]), and butorphanol (0.2 mg/kg 10.09 mg/lb]) were given IM to all dogs. Anesthesia was induced with thiopental (5 to 10 mg/kg [2.3 to 4.5 mg/lb], IV) and maintained with isoflurane (1 to 3%). Ovariohysterectomy was performed and butorphanol (0.1 mg/kg [0.05 mg/lb], IV) was given 15 minutes before completion of surgery. Blood samples for measurement of variables were collected at intervals before and after surgery. RESULTS: In dogs given ketoprofen, platelet aggregation was decreased 95 +/- 10% and 80 +/- 35% (mean +/- SD) immediately after surgery and 24 hours after surgery, respectively, compared with preoperative values. At both times, mean values in dogs given ketoprofen differed significantly from those in control dogs. Significant differences between groups were not observed for mucosal bleeding time or hematologic indices. CONCLUSIONS AND CLINICAL RELEVANCE: Preoperative administration of ketoprofen inhibited platelet aggre gation but did not alter bleeding time. Ketoprofen can be given before surgery to healthy dogs undergoing elective ovariohysterectomy, provided that dogs are screened for potential bleeding problems before surgery and monitored closely after surgery.     

Effects of exercise-induced stress and dexamethasone on plasma hormone and glucose concentrations and sedation in dogs treated with dexmedetomidine

OBJECTIVE: To compare the effects of pretreatment with dexamethasone, physical stress (exercise), or both on sedation and plasma hormone and glucose concentrations in dogs treated with dexmedetomidine (DEX). ANIMALS: 6 healthy purpose-bred Beagles. PROCEDURE: Dogs received 4 treatments each in a randomized order prior to i.v. administration of DEX (5 fLg/kg). Pretreatments were as follows: (1) i.v. administration of saline (0.9% NaCI) solution and no exercise (control group); (2) IV administration of dexamethasone (0.05 mg/kg) and no exercise (DM group); (3) i.v. administration of saline solution and exercise (EX group; 15 minutes of trotting on a treadmill at a speed of 2 m/s); and (4) i.v. administration of dexamethasone and exercise (DM+EX group). RESULTS: Following DEX administration, all dogs had similar times to recumbency and sedation index values, irrespective of pretreatment with values, irrespective of pretreatment with dexam-d ethasone or exercise. Plasma catecholamine concentrations decreased after DEX administration. Compared with control group dogs, plasma cortisol concentrations were higher in EX-group dogs prior to DEX administration and lower in DM- and DM+EX-group dogs following DEX administration. Administration of DEX decreased plasma cortisol concentration in EX-group dogs only. Plasma glucose concentration was not influenced by exercise or dexamethasone administration was lower than baseline concentrations at 30 minutes after DEX administration and returned to baseline values by 90 minutes. Heart and respiratory rates and rectal temperature increased during exercise. After DEX administration, these values decreased below baseline values. The decrease in heart rate was of shorter duration in dogs that underwent pretreatment with dexamethasone, exercise, or both than in control group dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Pretreatment with dexamethasone, moderate physical stress (exercise), or both did not influence sedation or cause adverse effects in healthy dogs treated with DEX.     

The use of intraoperative fentanyl in spontaneously breathing dogs undergoing orthopaedic surgery

Nineteen dogs were assigned randomly to one of three groups. Animals in Group 1 were pre-medicated with acepromazine, 50 μg/kg bodyweight (bwt) intramuscularly (im) and received 10 ml of 0.9 per cent saline intravenously (iv) at the time of skin incision. Dogs in Group 2 were pre-medicated with acepromazine, 50 μg/kg bwt im, and received fentanyl 2 μg/kg bwt iv at skin incision. Dogs in Group 3 were pre-medicated with acepromazine, 50 μg/kg bwt and atropine, 30 to 40 μg/kg bwt, im and received fentanyl, 2 μg/kg bwt iv at skin incision. Pulse rate, mean arterial blood pressure, respiratory rate and end tidal carbon dioxide were measured before and after fentanyl or saline injection. Fentanyl caused a short-lived fall in arterial blood pressure that was significant in dogs premedicated with acepromazine, but not in dogs pre-medicated with acepromazine and atropine. A significant bradycardia was evident for 5 mins in both fentanyl treated groups. The effect on respiratory rate was most pronounced in Group 3, in which four of seven dogs required intermittent positive pressure ventilation (IPPV) for up to 14 mins. Two of six dogs in Group 2 required IPPV, whereas respiratory rate remained unaltered in the saline controls. The quality of anaesthesia was excellent in the fentanyl treated groups; however, caution is urged with the use of even low doses of fentanyl in spontaneously breathing dogs under halothane-nitrous oxide anaesthesia.     

Effect of acepromazine, butorphanol, or N-butylscopolammonium bromide on visceral and somatic nociception and duodenal motility in conscious horses

OBJECTIVE: To evaluate effects of butorphanol, acepromazine, and N-butylscopolammonium bromide (NBB) on visceral and somatic nociception and duodenal motility in conscious, healthy horses. ANIMALS: 6 adult horses. PROCEDURES: Visceral nociception was evaluated by use of colorectal distention (CRD) and duodenal distention (DD) threshold. Somatic nociception was evaluated via thermal threshold (TT). Nose-to-ground height, heart rate, and respiratory rate were also measured. Each horse received each treatment in randomized order; investigators were not aware of treatments. Butorphanol was administered IV as a bolus (18 microg/kg) followed by constant rate infusion at 13 microg/kg/h for 2 hours, whereas acepromazine (0.04 mg/kg), NBB (0.3 mg/kg), and saline (0.9% NaCl) solution (2 mL) were administered IV as a bolus followed by constant rate infusion with saline solution (10 mL/h) for 2 hours. Variables were measured before and for 3 hours after treatment. Data were analyzed by use of a 3-factor ANOVA followed by a Bonferroni t test for multiple comparisons. RESULTS: Nose-to-ground height decreased after acepromazine. Respiratory rate decreased after acepromazine and increased after butorphanol. Heart rate increased briefly after NBB. Some horses had an increase in TT after butorphanol and acepromazine, but there was not a significant treatment effect over time. Drug effect on DD or motility was not evident. The CRD threshold increased significantly at 5, 65, 155, and 185 minutes after acepromazine and from 5 to 65 minutes after NBB. CONCLUSIONS AND CLINICAL RELEVANCE: Each drug caused predictable changes in sedation and vital signs, but consistent anti-nociceptive effects were not evident.     

Effects of acepromazine or methadone on midazolam-induced behavioral reactions in dogs

This study evaluated whether acepromazine or methadone reduced behavioral parameters, overall excitement, and activity associated with midazolam administration to healthy dogs. Dogs received midazolam (M) alone [M: 0.25 mg/kg body weight (BW)] or with methadone (MM) (MM: 0.75 mg/kg BW) or acepromazine (MA) (MA: 0.03 mg/kg BW) or saline (S) solution alone, all intramuscularly. Two blinded observers evaluated behavioral parameters using video recordings 30 min before and after injection of drugs. Accelerometery was used to evaluate “total activity counts” (TAC) at baseline and post-treatment. Post-treatment excitement scores were significantly higher in M and MA compared to baseline, M and MM compared to S, and M compared to MA. Behavioral parameters showed significantly higher proportions of “pacing” post-treatment in all groups receiving midazolam, and “restlessness,” “chewing/licking,” and “sniffing” in M. No significant differences were found for TAC at baseline and post-treatment. Midazolam-induced paradoxical behavioral changes (excitation, panting, pacing, restlessness, licking/chewing, and vocalization) were not prevented by acepromazine or methadone in healthy dogs.     

The pharmacokinetics of DPH after the administration of a single intravenous or intramuscular dose in healthy dogs

The objective of this study was to determine the pharmacokinetics of diphenhydramine (DPH) in healthy dogs following a single i.v. or i.m. dose. Dogs were randomly allocated in two treatment groups and received DPH at 1 mg/kg, i.v., or 2 mg/kg, i.m. Blood samples were collected serially over 24 h. Plasma concentrations of DPH were determined by high‐performance liquid chromatography, and noncompartmental pharmacokinetic analysis was performed with the commercially available software. Cardio‐respiratory parameters, rectal temperature and effects on behaviour, such as sedation or excitement, were recorded. Diphenhydramine Cl_area, Vd_area and T_1/2 were 20.7 ± 2.9 mL/kg/min, 7.6 ± 0.7 L/kg and 4.2 ± 0.5 h for the i.v. route, respectively, and Cl_area/F, Vd_area/F and T_1/2 20.8 ± 2.7 mL/kg/min, 12.3 ± 1.2 L/kg and 6.8 ± 0.7 h for the i.m. route, respectively. Bioavailability was 88% after i.m. administration. No significant differences were found in physiological parameters between groups or within dogs of the same group, and values remained within normal limits. No adverse effects or changes in mental status were observed after the administration of DPH. Both routes of administration resulted in DPH plasma concentrations which exceeded levels considered therapeutic in humans.     

Experimental pharmacodynamics and analgesic efficacy of liposome-encapsulated hydromorphone in dogs

The purpose of this study was to determine the experimental side effects of liposome-encapsulated hydromorphone (LE-Hydro) in beagles and to evaluate LE-Hydro analgesia in dogs undergoing ovariohysterectomies (OVH). Beagles were injected subcutaneously with 1-3 mg/kg LE-Hydro or 0.1 mg/kg hydromorphone. Dogs were evaluated for sedation, temperature, respiratory rate, and heart rate. OVH dogs were injected with 2 mg/kg LE-Hydro subcutaneously or 0.2 mg/kg morphine and 0.05 mg/kg acepromazine intramuscularly. Side effects of LE-Hydro were within clinically acceptable limits. The analgesic efficacy was superior in dogs administered LE-Hydro at 12 hr postsurgically. LE-Hydro provided adequate, durable analgesia in dogs undergoing OVH.     

Comparison of Intra-articular and Epidural Morphine for Analgesia Following Stifle Arthrotomy in Dogs

We prospectively studied 18 dogs that presented for exploratory stifle arthrotomy, with or without meniscectomy, and lateral extracapsular stabilization as a result of cranial cruciate ligament rupture. Dogs were premedicated with acepromazine, induced with thiopental, and maintained with halothane in oxygen. Preoperatively, dogs were assigned to one of three groups. Group 1 (n = 6) received intra-articular morphine (0.1 mg/kg diluted in 1 mL/10 kg body weight of saline) and epidural saline (1 mL/5 kg body weight saline plus the volume of saline representing 0.1 mg/kg of morphine). Group 2 (n = 6) received intra-articular saline (1 mL/10 kg body weight of saline plus the volume of saline representing 0.1 mg/kg of morphine) and epidural saline (1 mL/5 kg body weight saline plus the volume of saline representing 0.1 mg/kg of morphine). Group 3 (n = 6) received intra-articular saline (1 mL/10 kg body weight of saline plus the volume of saline representing 0.1 mg/kg of morphine) and epidural morphine (0.1 mg/kg of morphine diluted in 1 mL/5 kg body weight saline). The efficacy of each analgesia regimen was evaluated for 6 hours postoperatively with a pain score based on subjective and objective variables. Serum Cortisol and blood glucose concentrations were measured. Butorphanol was used to provide analgesia as needed based on a predetermined maximum pain score. Supplemental analgesics were required postoperatively every 2 to 3 hours for 6 hours in all dogs that did not initially receive analgesics (group 2). Pain scores were significantly lower in dogs administered morphine intra-articularly (group 1) and epidurally (group 3) at 30 minutes and 30, 120, and 360 minutes, respectively, compared with dogs that did not initially receive analgesics (group 2). One dog in group 1 and one dog in group 3 required supplemental analgesia with butorphanol. There was no difference between analgesia produced by intra-articular morphine compared with that of epidural morphine. Side effects after intra-articular or epidural morphine were not observed. Intra-articular administration of morphine can produce effective analgesia in dogs comparable with that produced by epidural administration of morphine.     

A comparison of the postoperative analgesic and sedative effects of flimixin and pap aver etum in the dog

Twenty-nine dogs undergoing a variety of surgical procedures were assigned randomly to one of two groups. All animals were premedicated with acepromazine (0–05 mg/kg) intramuscularly. Induction of anaesthesia was achieved with thiopentone sodium, or propofol in the case of sight hounds, and maintained with halothane in an oxygen/nitrous oxide mixture using a non-rebreathing circuit. Dogs in group 1 were given flunixin (1 mg/kg made up to 5 ml with 0–9 per cent saline) slowly intravenously 10 minutes before the halothane was switched off. Group 2 dogs received papaveretum (0–2 mg/kg made up to 5 ml with saline] administered as before. Using a visual analogue scale, the dogs were scored for sedation and for pain by trained theatre staff who were unaware of the analgesic used. Scoring was at 15, 30, 60, 120 , 240 and 360 minutes after analgesic administration. Seven dogs were withdrawn from the trial (three from the papaveretum group and four from the group which received flunixin) because analgesia was deemed unsatisfactory and these animals were given pethidine (3 mg/kg intramuscularly) which produced adequate analgesia within 15 minutes in all cases. Clinically, flunixin proved to be as effective a postoperative analgesic as papaveretum for up to six hours and was associated with less sedation, Pain scores were significantly different at two and four hours with flunixin providing more analgesia than papaveretum and at the four hour time point, flunixin was associated with significantly less sedation than papaveretum. From this study it was concluded that flunixin has a place in the treatment of acute post surgical pain, either alone or in combination with opioid analgesics where pain is refractory to treatment with clinical doses of opioids alone.