A comparison of the motor effects and analgesic efficacy following lumbar plexus block combined with sciatic nerve block or epidural in dogs undergoing tibial plateau leveling osteotomy.

OBJECTIVE: To compare motor effects and analgesic efficacy following an ultrasound-guided lateral approach to lumbar plexus blockade at L7 and sciatic nerve blockade (LPSNB) against epidural injection in dogs undergoing tibial plateau leveling osteotomy (TPLO). STUDY DESIGN: Prospective, randomized, blinded clinical trial. ANIMALS: A total of 27 healthy adult dogs undergoing unilateral TPLO surgery. METHODS: Dogs were allocated to either LPSNB (bupivacaine 2 mg kg-1, 0.75%) or epidural (morphine PF 0.1 mg kg-1 and bupivacaine 0.5 mg kg-1, 0.75%). Other aspects of clinical management were identical, including anesthetic drug protocol, area of presurgical clipping and bladder care. Time to perform the block, response to surgical stimuli, pain scores, rescue analgesia, time to stand and walk, motor score and time to first urination were recorded. One evaluator, unaware of treatment status, performed all evaluations. Student's t-test or Mann-Whitney U test was used to compare continuous variables between groups, and Fisher's exact test for categorical variables. RESULTS: Median (range) times to stand and walk were shorter for LPSNB [60 (40-120) minutes and 90 (60-150) minutes, respectively, p = 0.003] than for epidural [150 (120-240) minutes and 180 (120-360) minutes, respectively, p = 0.006]. Four dogs required rescue intraoperatively (three in epidural group, one in LPSNB group, p = 0.438). Pain scores over the 24 hour evaluation period were similar, and not significantly different, for each group. Time to spontaneous urination [LPSNB, 330 (240-360) minutes; epidural, 300 (120-1440) minutes, p = 1.0] did not differ between groups. CONCLUSIONS AND CLINICAL RELEVANCE: An ultrasound-guided lateral paravertebral approach to the lumbar plexus within the psoas compartment at L7, combined with sciatic nerve blockade, allows faster return to normal motor function, with similar pain control and impact on urination when compared with epidural in dogs after TPLO surgery.

A retrospective study of fecal output and postprocedure colic in 246 horses undergoing standing sedation with detomidine, or general anesthesia with or without detomidine.

OBJECTIVE: To determine time to first passage of feces, total fecal piles and incidence of colic in the first 24 hours postprocedure in horses undergoing standing sedation with detomidine, or general anesthesia with or without detomidine. STUDY DESIGN: Retrospective cohort study. ANIMALS: A total of 246 horses. METHODS: Records of all horses that underwent standing sedation or general anesthesia between December 2012 and March 2016 were reviewed. Horses aged <6 months, admitted for colic or cesarean section, with inadequate data, and those not administered xylazine and/or detomidine were excluded. Records included patient signalment, fasting duration, procedure performed, drugs administered, time to first feces, number of fecal piles during 24 hours postprocedure and mention of colic. Chi-square, Fisher's exact and Tukey's post hoc comparison tests were used. Parametric data were reported as mean ± standard deviation with significance defined as p <0.05. RESULTS: In total, 116 and 57 horses underwent general anesthesia without detomidine (group GA) and with detomidine (group GA-D), respectively, and remaining 73 horses underwent standing sedation with detomidine (group S-D). Detomidine dose was significantly higher in group S-D than in group GA-D. Time to first feces was longer (7.1 ± 4.2 hours), and group S-D horses passed one fewer fecal pile (6.3 ± 2.4) than group GA horses. There was no interaction between detomidine treatment and preprocedure food withholding and the time to first feces or the number of fecal piles in the first 24 hours postprocedure. Overall, seven horses (2.8%) showed signs of colic (five, one and one in GA, GA-D and S-D, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Detomidine administration, as part of an anesthetic protocol or for standing sedation procedures, should not be expected to contribute to postprocedural colic.

Alfaxalone alone or combined with midazolam or ketamine in dogs: intubation dose and select physiologic effects.

OBJECTIVE: To determine the intubation dose and select physiologic effects of alfaxalone alone or in combination with midazolam or ketamine in dogs. STUDY DESIGN: Prospective, clinical study. ANIMALS: Fifty-three healthy client-owned dogs [mean±standard deviation (SD)] 5.1±1.8 years, 27±15.4 kg, scheduled for elective orthopedic surgery. METHODS: After premedication with acepromazine (0.02 mg kg-1) and hydromorphone (0.1 mg kg-1) intramuscularly, alfaxalone (0.25 mg kg-1) was administered intravenously over 15 seconds followed immediately by 0.9% saline (AS), midazolam (0.3 mg kg-1; AM), ketamine (1 mg kg-1; AK1), or ketamine (2 mg kg-1; AK2). Additional alfaxalone (0.25 mg kg-1 increments) was administered as required to permit endotracheal intubation. The incidence of apnea and the time from intubation until spontaneous movement were recorded. Heart rate (HR) and blood pressure were recorded 15 minutes after premedication, after intubation and 2, 5, 10 and 15 minutes thereafter. Blood was collected for measurement of serum glucose and insulin concentrations before induction, after intubation and at 2, 5, 10 and 50 minutes. Data were analyzed by split-plot anova with Bonferroni adjustment for the number of group comparisons. RESULTS: Mean±SD alfaxalone mg kg-1 doses required for endotracheal intubation were AS (1.0±0.4), AM (0.4±0.2), AK1 (0.5±0.3) and AK2 (0.5±0.4) (p=0.0005). Differences in cardiopulmonary variables among groups were minor; HR decreased in AS, while in other groups, HR increased transiently postintubation. Incidence of apnea in AS was 54% with no significant difference among groups. Midazolam significantly prolonged time from intubation until spontaneous movement (p<0.002). CONCLUSIONS AND CLINICAL RELEVANCE: Midazolam and ketamine reduced the alfaxalone dose required for endotracheal intubation. Serum glucose and insulin concentrations were not influenced by administration of alfaxalone alone or when administered with midazolam or ketamine.

Pain and analgesia following onychectomy in cats: a systematic review.

OBJECTIVES: To systematically review published studies evaluating pain associated with onychectomy in cats, and to assess the efficacy of the analgesic therapies applied. DATABASES USED: Four sources were used to identify manuscripts for review. Databases searched were those of the National Library of Medicine, EMBASE and CAB International. In addition, pertinent references in the bibliographies of included articles were retrieved. RESULTS: Twenty manuscripts published in refereed journals were reviewed. These included papers reporting 18 clinical trials and two studies conducted in conditioned research cats. Twelve analgesics were evaluated, including seven opioids, four non-steroidal anti-inflammatory drugs and one local anesthetic. Nine studies involved a direct comparison of analgesic agents. Limb use was abnormal when measured at 2 and 12 days following onychectomy, and neither fentanyl patch nor butorphanol administration resulted in normal use of the surgical limb. In another study, cats evaluated at 6 months after this surgery were not lame. Differing surgical techniques were compared in six studies; the results indicated that pain scores were lower after laser surgery than after scalpel surgery. The difficulties associated with assessing pain in cats and the lack of sensitivity of the evaluation systems utilized were highlighted in many of the studies. Huge variations in dose and dosing strategies had significant impacts on drug efficacy. Statistically significant differences among treatments were found in most studies; however, no clearly superior analgesic treatment was identified. A combination of meloxicam or robenacoxib with an opioid may provide more effective analgesia and should be evaluated.

Comparison of three ultrasound guided approaches to the lumbar plexus in dogs: a cadaveric study.

OBJECTIVE: To assess the accuracy of contrast material injection and the dispersion of injectate following ultrasound guided injections at the level of L6 and L7, in canine cadavers. STUDY DESIGN: Prospective, randomized, experimental study. ANIMALS: Twenty nine mixed breed canine cadavers (28.9 ± 6.0 kg). METHODS: Three ultrasound-guided approaches to the lumbar plexus (LP) were compared: 1) a dorsal pre-iliac approach at the level of L6; 2) a lateral paravertebral approach at mid-L6; and 3) a lateral paravertebral approach at mid-L7. An isovolumic mixture of iodine-based contrast with new methylene blue (0.1 mL kg(-1)) was injected bilaterally in the juxta-foraminal region along the L6 or L7 nerve root. Computed tomography was performed followed by segmentation and 3D reconstruction of the lumbar spine and contrast material volumes using dedicated software. Distances between contrast material and the fifth through seventh lumbar foraminae, and length of femoral (FN) and obturator (ON) nerve staining were measured and compared between approaches (p < 0.05). RESULTS: Injectate moved cranial and caudal to the site of injection, and dispersed into an ovoid shape between the quadratus lumborum, iliopsoas and psoas minor muscles. Injections at L7 resulted in significantly closer contrast proximity to the L6 and L7 foraminae (p < 0.001). Femoral nerve staining was similar for all approaches, ON staining was more consistent after L7 injections (p < 0.001). CONCLUSION AND CLINICAL RELEVANCE: An ultrasound-guided lateral paravertebral approach to the LP proved very practical and accurate, with easy visualization of the plexus and associated nerves. To ensure that the ON is covered by injectate, an approach at the level of L7 is recommended. Further studies are necessary to determine if this correlates with clinically effective local anesthesia.

Prevalence and risk factors for canine post-anesthetic aspiration pneumonia (1999-2009): a multicenter study.

OBJECTIVE: To determine the incidence of canine post-anesthetic aspiration pneumonia (AP) and to identify anesthetic agents, procedures and management factors associated with the development of AP. STUDY DESIGN: Multicenter, randomized, case-controlled retrospective study. ANIMALS: Two hundred and forty dogs affected with AP and 488 unaffected control dogs. METHODS: Electronic medical record databases at six Veterinary colleges were searched for dogs, coded for anesthesia or sedation and pneumonia from January 1999 to December 2009. The resultant 2158 records were hand-searched to determine eligibility for inclusion. Diagnosis of AP was made radiographically. Two unaffected control dogs were randomly selected for each affected dog, from a list of dogs that underwent sedation or anesthesia in the same time period and did not develop aspiration pneumonia. Fifty-seven factors were then evaluated for association with aspiration pneumonia. Data analysis was performed using univariate Chi-square or student t-tests, then multivariate logistic regression. RESULTS: Incidence of post-anesthetic AP was 0.17%, from 140,711 cases anesthetized or sedated over the 10 year period. Two anesthesia-related events were significantly associated with development of AP: regurgitation and administration of hydromorphone at induction. Administration of anticholinergics was not associated with AP. Procedures associated with increased odds of aspiration pneumonia included laparotomy, upper airway surgery, neurosurgery, thoracotomy and endoscopy. Orthopedic surgery, ophthalmologic surgery, dental procedures, MRI, CT, bronchoscopy, cystoscopy, tracheoscopy and neutering were not associated with development of AP. Three patient factors were associated with the development of AP: megaesophagus, and a history of pre-existing respiratory or neurologic disease. Sixty-nine% of dogs with two or more of the above independent predictive variables developed AP. CONCLUSION AND CLINICAL RELEVANCE: Most anesthetic agents and procedures were not associated with the development of AP. We need to devise and evaluate strategies to protect at risk patients.

Use of propofol for induction of anesthesia in dogs undergoing definitive radiation therapy: 31 cases (2006-2009).

OBJECTIVE: To evaluate changes in serial hemograms and serum biochemical profiles in tumor-bearing dogs undergoing daily anesthesia with propofol as an induction agent for radiation therapy. DESIGN: Retrospective case series. ANIMALS: 31 dogs with cutaneous or subcutaneous malignancies over the trunk or limbs. PROCEDURES: Radiation therapy consisted of 18 daily treatments administered Monday through Friday over a period of 24 days. Propofol was administered IV to effect for induction of anesthesia. Complete blood count and serum biochemical data were generated at the beginning, middle, and end of radiation therapy and compared to identify changes over time via either a repeated-measures ANOVA or Friedman test. RESULTS: Leukocyte and platelet parameters did not differ significantly over time. Calculated Hct, erythrocyte count, hemoglobin concentration, and mean corpuscular hemoglobin concentration decreased overtime, whereas mean corpuscular volume increased overtime. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs receiving propofol for induction of anesthesia and radiation therapy had a decrease in RBC count, although these changes were not determined to be of clinical importance in this patient population. The cause of these alterations was not immediately apparent. Propofol appeared to be a safe choice for induction of anesthesia in dogs during daily radiation therapy.

Intravenous tramadol: effects, nociceptive properties, and pharmacokinetics in horses.

OBJECTIVE: To determine the optimal dose, serum concentrations and analgesic effects of intravenous (IV) tramadol in the horse. STUDY DESIGN: Two-phase blinded, randomized, prospective crossover trial. ANIMALS: Seven horses (median age 22.5 years and mean weight 565 kg). METHODS: Horses were treated every 20 minutes with incremental doses of tramadol HCl (0.1-1.6 mg kg(-1)) or with saline. Heart rate, respiratory rate, step frequency, head height, and sweating, trembling, borborygmus and head nodding scores were recorded before and up to 6 hours after treatment. In a second study, hoof withdrawal and skin twitch reflex latencies (HWRL and STRL) to a thermal stimulus were determined 5 and 30 minutes, and 1, 2, 4 and 6 hours after bolus IV tramadol (2.0 mg kg(-1)) or vehicle. Blood samples were taken to determine pharmacokinetics. RESULTS: Compared to saline, tramadol caused no change in heart rate, step frequency or sweating score. Respiratory rate, head height, and head nodding and trembling scores were transiently but significantly increased and borborygmus score was decreased by high doses of tramadol. Following cumulative IV administration of 3.1 mg kg(-1) and bolus IV administration of 2 mg kg(-1), the elimination half-life of tramadol was 1.91 +/- 0.33 and 2.1 +/- 0.9 hours, respectively. Baseline HWRL and STRL were 4.16 +/- 1.0 and 3.06 +/- 0.99 seconds, respectively, and were not significantly prolonged by tramadol. CONCLUSION AND CLINICAL RELEVANCE: IV tramadol at cumulative doses of up to 3.1 mg kg(-1) produced minimal transient side effects but 2.0 mg kg(-1) did not provide analgesia, as determined by response to a thermal nociceptive stimulus.

The effect of topical treatment on esophageal pH during acid reflux in dogs.

OBJECTIVE: To determine the effect of suction, lavage and instillation of sodium bicarbonate solution on esophageal pH during acidic gastro-esophageal reflux (GER) in anesthetized dogs. STUDY DESIGN: Prospective, clinical trial. ANIMALS: Ten healthy dogs, 4.8 +/- 2.4 years old, and weighing 37.1 +/- 7.9 kg. METHODS: Dogs were admitted to the study if they were under general anesthesia and regurgitation occurred. A sensor-tipped catheter was used to measure esophageal pH. On study entry the esophagus was suctioned. After an interval of at least 5 minutes, if the esophageal pH was still less than 4 the esophagus was lavaged with tap water and again suctioned. In 6 dogs 20 mL of dilute bicarbonate solution was instilled into the esophageal lumen. RESULTS: Suctioning fluid from the esophagus did not change the pH significantly. Lavage with tap water caused the pH to increase above 4 in four dogs, with the average pH increasing from 1.2 +/- 0.5 to 3.5 +/- 4.9. In all dogs where dilute bicarbonate solution was instilled, esophageal pH increased to above 6 for up to 180 (mean +/- SD, 89 +/- 81) minutes. CONCLUSIONS AND CLINICAL RELEVANCE: Suctioning refluxate from the esophagus does not change the pH of the esophageal lumen. Instillation of a small volume of bicarbonate solution predictably increased the pH above 4 following an episode of acidic GER. Care must be taken that fluid is instilled into the lumen of the esophagus, and not into the trachea.

Pre-anesthetic meperidine: associated vomiting and gastroesophageal reflux during the subsequent anesthetic in dogs.

OBJECTIVE: To determine the effect of meperidine administered prior to anesthesia on the incidence of vomiting before, and gastroesophageal reflux (GER) and regurgitation during, the subsequent period of anesthesia in dogs. STUDY DESIGN: Randomized, controlled trial. ANIMALS: A total of 60 healthy dogs, 4.3 +/- 2.3 years old, and weighing 35.5 +/- 13.1 kg. METHODS: Dogs were admitted to the study if they were healthy, had no history of vomiting, and were scheduled to undergo elective orthopedic surgery. The anesthetic protocol used was standardized to include thiopental and isoflurane in oxygen. Dogs were randomly selected to receive one of the following pre-medications: morphine (0.66 mg kg(-1) IM) with acepromazine (0.044 mg kg(-1) IM), meperidine (8.8 mg kg(-1) IM) with acepromazine (0.044 mg kg(-1) IM) or meperidine alone (8.8 mg kg(-1) IM). A sensor-tipped catheter was placed to measure esophageal pH during anesthesia. Gastro-esophageal reflux was judged to have occurred if there was a decrease in esophageal pH below four or an increase above 7.5. RESULTS: No dogs vomited after the administration of meperidine, but 50% of dogs vomited after the administration of morphine. When compared with morphine, treatment with meperidine alone or combined with acepromazine before anesthesia was associated with a 55% and 27% reduction in absolute risk of developing GER, respectively. Dogs receiving meperidine alone were significantly less sedate than other dogs in the study, and required more thiopental to induce anesthesia. Arterial blood pressure and heart rate were not significantly different between groups at the start of the measurement period. Cutaneous erythema and swelling were evident in four dogs receiving meperidine. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of meperidine to healthy dogs prior to anesthesia was not associated with vomiting and tended to reduce the occurrence of GER, but produced less sedation when compared with morphine. Meperidine is not a useful addition to the anesthetic protocol if prevention of GER is desired.

Influence of halothane, isoflurane, and sevoflurane on gastroesophageal reflux during anesthesia in dogs.

OBJECTIVE: To determine whether maintenance of anesthesia with halothane or sevoflurane is associated with a lower incidence of gastroesophageal reflux (GER) than the use of isoflurane in dogs undergoing orthopedic surgery. ANIMALS: 90 dogs. PROCEDURES: Dogs were evaluated during elective orthopedic surgery. Dogs with a history of vomiting or that had received any drugs that would alter gastrointestinal tract function were excluded from the study. The anesthetic protocol used was standardized to include administration of acepromazine maleate and morphine prior to induction of anesthesia with thiopental. Dogs were allocated to receive halothane, isoflurane, or sevoflurane to maintain anesthesia. A sensor-tipped catheter was placed to measure esophageal pH during anesthesia. Gastroesophageal reflux was defined as an esophageal pH < 4 or > 7.5. RESULTS: 51 dogs had 1 or more episodes of acidic GER during anesthesia. Reflux was detected in 14 dogs receiving isoflurane, 19 dogs receiving halothane, and 18 dogs receiving sevoflurane. In dogs with GER, mean +/- SD time from probe placement to onset of GER was 36 +/- 65 minutes and esophageal pH remained < 4 for a mean of 64% of the measurement period. There was no significant association between GER and start of surgery or moving a dog on or off the surgery table. Dogs that developed GER soon after induction of anesthesia were more likely to regurgitate. CONCLUSIONS AND CLINICAL RELEVANCE: Maintenance of anesthesia with any of the 3 commonly used inhalant agents is associated with a similar risk for development of GER in dogs.

Influence of metoclopramide on gastroesophageal reflux in anesthetized dogs.

OBJECTIVE: To determine the effect of 2 doses of metoclopramide on the incidence of gastroesophageal reflux (GER) in anesthetized dogs. ANIMALS: 52 healthy dogs undergoing elective orthopedic surgery. PROCEDURE: In this prospective clinical study, dogs were evaluated before and during orthopedic surgery. The anesthetic protocol used was standardized to include administration of acepromazine, morphine, thiopental, and isoflurane. Dogs were randomly selected to receive an infusion of saline (0.9% NaCl) solution, a low dose of metoclopramide, or a high dose of metoclopramide before and during anesthesia. Treatment groups were similar with respect to age, body weight, duration of food withholding before surgery, duration of surgery, and dose of thiopental administered. Dogs were positioned in dorsal recumbency during surgery. A sensor-tipped catheter was inserted to measure esophageal pH during anesthesia. We defined GER as a decrease in esophageal pH to < 4 or an increase to > 7.5 that lasted more than 30 seconds. RESULTS: The high dose of metoclopramide (bolus loading dose of 1.0 mg/kg, IV, followed by continuous infusion at a rate of 1.0 mg/kg/h) was associated with a 54% reduction in relative risk of developing GER. The low dose did not significantly affect the incidence of GER. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of metoclopramide by bolus and constant rate infusion at doses much higher than commonly used will reduce the incidence but not totally prevent GER in anesthetized dogs undergoing orthopedic surgery.

Effects of preanesthetic administration of morphine on gastroesophageal reflux and regurgitation during anesthesia in dogs.

OBJECTIVE: To determine the effect of morphine administered prior to anesthesia on the incidence of gastroesophageal reflux (GER) in dogs during the subsequent anesthetic episode. ANIMALS: 90 dogs (30 dogs/group). PROCEDURE: The randomized prospective clinical study included healthy dogs with no history of vomiting. Dogs were scheduled to undergo elective orthopedic surgery. Food was withheld for (mean+/-SD) 17.8+/-4.1 hours prior to induction of anesthesia. The anesthetic protocol included acepromazine maleate, thiopental, and isoflurane. Dogs were randomly selected to receive morphine at various dosages (0, 0.22, or 1.10 mg/kg, IM) concurrent with acepromazine administration prior to induction of anesthesia. A sensor-tipped catheter was used to measure esophageal pH, and GER was defined as a decrease in pH to < 4 or an increase to > 7.5. RESULTS: 40 dogs had acidic reflux, and 1 had biliary reflux. Proportions of dogs with GER were 8 of 30 (27%), 15 of 30 (50%), and 18 of 30 (60%) for morphine dosages of 0, 0.22, and 1.10 mg/kg, respectively. Mean duration of GER was 91.4+/-56.8 minutes. There was no significant association between GER and age, weight, vomiting after preanesthetic medication, administration of antimicrobials, or start of surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Most healthy dogs vomit after a large dose of morphine, but vomiting does not increase the likelihood of GER during the subsequent anesthetic episode. Administration of morphine prior to anesthesia substantially increases the incidence of GER during the subsequent anesthetic episode.

Postanesthetic esophageal dysfunction in 13 dogs.

Thirteen dogs with postanesthetic esophageal dysfunction were identified; 10 of these animals had esophageal stricture. Regurgitation was noted in six dogs during the inciting anesthetic event. Clinical problems common to all dogs included vomiting/regurgitation and weight loss. Coughing was noted in six dogs, and aspiration pneumonia was present in four of these dogs. The associated mortality rate was 23%. The duration of symptoms ranged from 17 to 150 days, and the diagnosis was often delayed (up to 76 days from onset of clinical signs to diagnosis). Postanesthetic esophageal dysfunction was a debilitating and costly problem that developed in one dog despite current preventative treatment.

The effect of four anesthetic protocols on splenic size in dogs.

OBJECTIVE: To characterize the effects of four anesthetic protocols on the size of the spleen during surgery in dogs. STUDY DESIGN: Prospective experimental trial. ANIMALS: Twenty-four beagle dogs, 1.1 +/- 0.3 years of age and weighing 10.9 +/- 2.7 kg. METHODS: Dogs were allocated to receive one of four anesthetic protocols: 1 - pre-medication with acepromazine and butorphanol, induction with thiopental; 2 - pre-medication with acepromazine and butorphanol, induction with propofol; 3 - pre-medication with medetomidine and butorphanol, induction with propofol; and 4 - pre-medication with medetomidine and butorphanol, induction with ketamine and diazepam. Anesthesia was then maintained with halothane. At laparotomy, the spleen length, width, and height were measured, these were measured again just prior to closure of the abdomen. Splenic area and volume were calculated. Hematocrit and total serum protein (TSP) were measured before and after induction and during laparotomy. RESULTS: Splenic volume was greatest after protocol 4 (161.2 +/- 40.2 cm(3); p < 0.05) and was least after protocol 2. The differences in volume were because of differences in length, width, and height between groups. There was no significant change in area, length, or width over the study period. Hematocrit decreased significantly in all dogs but at different times. The decrease occurred after pre-medication if acepromazine was administered, at induction following protocol 3 and during surgery following protocol 4. CONCLUSIONS: If splenic volume is to be minimized during surgery, then acepromazine and propofol should be used in the anesthetic protocol. The administration of medetomidine, diazepam, and ketamine will produce a greater splenic volume. Lack of correlation between hematocrit and spleen size following the anesthetic protocols studied suggests sequestration of red blood cells in nonsplenic sites.

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

OBJECTIVE: To determine if intraperitoneal (i.p.) and incisional (s.c.) 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 i.p. (LID); 10 received 4.4 mg kg(-1) 0.75% bupivacaine i.p. (BUP); and 10 received 0.9% saline i.p. (SAL) upon completion of OHE. All i.p. doses were standardized to 0.88 mL kg(-1) with saline. An additional 2 mL of undiluted solution was placed s.c. 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 chi2-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 i.p. and s.c. bupivacaine for post-operative analgesia following OHE in the dog.

The cardiopulmonary effects of severe blood loss in anesthetized horses.

OBJECTIVE: To characterize the acute cardiopulmonary effects of severe hemorrhage in anesthetized horses. STUDY DESIGN: Prospective experimental study. ANIMALS: Three geldings and six mares, aged 14.4 +/- 2.7 years, weighing 486 +/- 41 kg (range: 425-550 kg). METHODS: Horses were anesthetized using xylazine, guaifenesin, ketamine and halothane or isoflurane. Cardiovascular variables, hematocrit, total solids, capillary refill time (CRT) and color of mucous membranes were measured as blood was collected from the carotid artery into sterile plastic bags. Arterial blood gas analysis was also performed. RESULTS: The average amount of blood collected from these horses was (mean +/- SD) 53 +/- 4.8 mL kg(-1) bodyweight (range: 23-32 kg) over 39 +/- 4 minutes. Hematocrit decreased from 38 +/- 3 to 32 +/- 2% after induction of anesthesia and did not change significantly over the period of blood loss. Total solids decreased significantly after induction of anesthesia, and over the period of blood loss. Systolic, mean, diastolic and pulse pressures decreased as blood was lost. Heart rate did not change significantly. Capillary refill time increased from 1.6 +/- 0.4 seconds to 4.8 +/- 1.3 seconds as blood loss increased. Mucous membrane color deteriorated progressively. Arterial PO2 decreased significantly over the period of blood loss. CONCLUSIONS: Hematocrit and heart rate do not change significantly during acute severe hemorrhage in the anesthetized horse. Arterial blood pressure, pulse pressure and PaO2 decrease as blood loss increases. Changes in mucous membrane color and CRT also occur as blood loss increases. CLINICAL RELEVANCE: During severe hemorrhage in the inhalant-anesthetized horse, both heart rate and hematocrit remain unchanged. Blood pressure decreases and changes in arterial PO2 correlate most strongly with volume of blood lost.

The cardiopulmonary effects of severe blood loss in anesthetized horses.

OBJECTIVE: To characterize the acute cardiopulmonary effects of severe hemorrhage in anesthetized horses. STUDY DESIGN: Prospective experimental study. ANIMALS: Three geldings and six mares, aged 14.4 ± 2.7 years, weighing 486 ± 41 kg (range: 425-550 kg). METHODS: Horses were anesthetized using xylazine, guaifenesin, ketamine and halothane or isoflurane. Cardiovascular variables, hematocrit, total solids, capillary refill time (CRT) and color of mucous membranes were measured as blood was collected from the carotid artery into sterile plastic bags. Arterial blood gas analysis was also performed. RESULTS: The average amount of blood collected from these horses was (mean ± SD) 53 ± 4.8 mL kg-1 bodyweight (range: 23-32 kg) over 39 ± 4 minutes. Hematocrit decreased from 38 ± 3 to 32 ± 2% after induction of anesthesia and did not change significantly over the period of blood loss. Total solids decreased significantly after induction of anesthesia, and over the period of blood loss. Systolic, mean, diastolic and pulse pressures decreased as blood was lost. Heart rate did not change significantly. Capillary refill time increased from 1.6 ± 0.4 seconds to 4.8 ± 1.3 seconds as blood loss increased. Mucous membrane color deteriorated progressively. Arterial PO2 decreased significantly over the period of blood loss. CONCLUSIONS: Hematocrit and heart rate do not change significantly during acute severe hemorrhage in the anesthetized horse. Arterial blood pressure, pulse pressure and PaO2 decrease as blood loss increases. Changes in mucous membrane color and CRT also occur as blood loss increases. CLINICAL RELEVANCE: During severe hemorrhage in the inhalant-anesthetized horse, both heart rate and hematocrit remain unchanged. Blood pressure decreases and changes in arterial PO2 correlate most strongly with volume of blood lost.