Comparison of ultrasound-guided lumbar plexus and sciatic nerve blocks with ropivacaine and sham blocks with saline on perianesthetic analgesia and recovery in dogs undergoing tibial plateau leveling osteotomy surgery.

OBJECTIVE: To assess the effects of ultrasound-guided lumbar plexus and sciatic nerve blocks on perianesthetic analgesia and recovery quality in dogs undergoing tibial plateau leveling osteotomy (TPLO). ANIMALS: A group of twenty 20 dogs. STUDY DESIGN: Prospective, randomized, blinded, clinical study. METHODS: Dogs were administered lumbar plexus and sciatic nerve blocks with ropivacaine (1.5 mg kg-1; group RA) or sham blocks with saline (group CON). Dogs were administered hydromorphone (0.2 mg kg-1) and atropine (0.02 mg kg-1) subcutaneously before anesthesia was induced with intravenous propofol and maintained with isoflurane. Variables included duration to perform nerve blocks, intraoperative rescue analgesia, recovery score, postoperative pain scores (modified University of Melbourne, Colorado State University and visual analog pain scales), postoperative rescue analgesia-sedation and complications observed. Two-tailed Student t test, Mann-Whitney test, repeated measures analysis of variance, Friedman test and Fisher exact test were used for comparison. Significance was p < 0.05. RESULTS: Time to perform nerve blocks was [median (range)] 4.3 (2.6-6.1) minutes after aseptic skin preparation. Total fentanyl requirements were 14.2 ± 9 µg kg-1 and 25.4 ± 10 µg kg-1 (p = 0.02) and incidence of hypotension (mean arterial pressure < 60 mmHg) was 40% and 80% (p = 0.16) for groups RA and CON, respectively. Six of eight group CON dogs required more intensive treatment for hypotension than group RA dogs. Recovery scores were 1 (1-4) and 2.5 (1-4) for groups RA and CON, respectively (p = 0.04). RA dogs were less likely to require fentanyl rescue analgesia during the postoperative period (p = 0.04). CONCLUSION AND CLINICAL RELEVANCE: As part of a multimodal analgesia regimen, ultrasound-guided lumbar plexus and sciatic nerve blocks provided greater analgesia and improved recovery quality in dogs during TPLO surgery.

Financial impact of ultrasound-guided lumbar plexus and sciatic nerve blocks with electrostimulation for tibial plateau leveling osteotomy surgery in dogs.

OBJECTIVE: To determine the anesthesia cost from ultrasound-guided lumbar plexus and sciatic nerve blocks confirmed with electrostimulation for unilateral tibial plateau leveling osteotomy (TPLO) surgery in dogs. STUDY DESIGN: Prospective, randomized, blinded clinical trial. ANIMALS: A group of 20 dogs weighing 33.9 ± 6.0 kg (mean ± standard deviation). METHODS: All dogs were administered hydromorphone and atropine, propofol for induction of anesthesia and isoflurane for maintenance. Hydromorphone and carprofen were administered for recovery. The dogs were randomly assigned to one of two groups, lumbar plexus and sciatic nerve blocks with ropivacaine [regional anesthesia (RA)] or sham blocks with saline [control (CON)]. Fentanyl was administered for rescue analgesia intraoperatively and postoperatively. The cost to manage anesthesia was divided into fixed and variable costs using the micro-costing method. The variable costs were compared using Student's t test or Mann-Whitney U test. RESULTS: The fixed anesthesia costs were equal between groups at US$354.00 per case. The variable anesthesia cost range was US$27.90-100.10 for RA and US$21.00-180.50 for CON. Overall, cost per dog in CON was from -US$6.9 to US$80.4 compared with RA. For 160 TPLO cases per year, hospital cost when RA is performed decreased the cost by $12,864 per year up to increased cost by $1104 per year, depending on the requirements for systemic drugs and incidence/severity of anesthesia complications. The estimated fee charge per case for service necessary to reimburse the cost of a new ultrasound (US$25,000.00) and nerve locator (US$925.00) over their life span of 6 and 10 years, respectively, is US$26.62. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasound-guided lumbar plexus and sciatic nerve blocks with electrostimulation confirmation can increase the anesthesia cost through use of specific equipment. However, in most cases, the anesthesia cost decreased as a result of decreased costs for pain management and treatment of complications.

Psoas compartment and sacral plexus block via electrostimulation for pelvic limb amputation in dogs.

OBJECTIVE: To assess the efficacy of psoas compartment and sacral plexus block for pelvic limb amputation in dogs. STUDY DESIGN: Prospective clinical study. ANIMALS: A total of 16 dogs aged 8±3 years and weighing 35±14 kg (mean±standard deviation). METHODS: Dogs were administered morphine (0.5 mg kg-1) and atropine (0.02 mg kg-1); anesthesia was induced with propofol and maintained with isoflurane. Regional blocks were performed before surgery in eight dogs with bupivacaine (2.2 mg kg-1) and eight dogs were administered an equivalent volume of saline. The lumbar plexus within the psoas compartment was identified using electrolocation lateral to the lumbar vertebrae at the fourth-fifth, fifth-sixth and sixth-seventh vertebral interspaces. The sacral plexus, ventrolateral to the sacrum, was identified using electrolocation. Anesthesia was monitored using heart rate (HR), invasive blood pressure, electrocardiography, expired gases, respiratory frequency and esophageal temperature by an investigator unaware of the group allocation. Pelvic limb amputation by coxofemoral disarticulation was performed. Dogs that responded to surgical stimulation (>10% increase in HR or arterial pressure) were administered fentanyl (2 µg kg-1) intravenously for rescue analgesia. Postoperative pain was assessed at extubation; 30, 60 and 120 minutes; and the morning after surgery using a visual analog scale (VAS). RESULTS: The number of intraoperative fentanyl doses was fewer in the bupivacaine group (2.7±1.1 versus 6.0±2.2; p<0.01). Differences in physiologic variables were not clinically significant. VAS scores were lower in bupivacaine dogs at extubation (0.8±1.9 versus 3.8±2.5) and at 30 minutes (1.0±1.4 versus 4.3±2.1; p<0.05). CONCLUSIONS AND CLINICAL RELEVANCE: Psoas compartment (lumbar plexus) and sacral plexus block provided analgesia during pelvic limb amputation in dogs.

Effect of prolonged general anesthesia with sevoflurane and laparoscopic surgery on gastric and small bowel propulsive motility and pH in dogs.

OBJECTIVE: To determine if general anesthesia with sevoflurane and laparoscopic surgery changed gastric and small bowel propulsive motility or pH in dogs. STUDY DESIGN: Prospective, controlled trial. ANIMALS: Twelve, 19-24 months old, female, Treeing Walker Hound dogs, weighing 23-30 kg. METHODS: Dogs were anesthetized for a median of 8.5 hours during another study to determine the minimum alveolar concentration of sevoflurane using a visceral stimulus. Gastric and small bowel motility were determined using a sensor capsule that measures pressure, pH and temperature. Gastric transit time and motility index were calculated. For 8/12 dogs, gastric motility, pH and transit time were measured. In 4/12 dogs, small bowel motility and pH were measured. RESULTS: Anesthesia decreased gastric and small bowel motility but did not change luminal pH. Mean gastric contraction force decreased from median (range) 11 (8-20) to 3 (1-10) mmHg (p < 0.01) and gastric motility index decreased from 0.63 (0-1.58) to 0 (0-0.31; p = 0.01). Frequency of contractions did not change, 3.7 (1.6-4.4) versus 2.8 (0.1-5.1) contractions minute(-1) (p = 0.1). Gastric motility returned to normal 12-15 hours following anesthesia. Gastric emptying was prolonged from 12 (5.3-16) to 49 (9.75-56.25) hours (p < 0.01). Mean small bowel contraction force decreased from 34 (24-37) to 3 (0.9-17) mmHg (p < 0.02) and motility index decreased from 3.75 (1-4.56) to 0 (0-1.53; p = 0.02). Frequency of contractions did not change, 0.5 (0.3-1.4) versus 1.4 (0.3-4.6) contractions minute(-1) (p = 0.11). Small bowel motility returned within 2 hours after anesthesia. Laparoscopy did not result in changes to gastric or small bowel parameters beyond those produced by general anesthesia. CONCLUSIONS AND CLINICAL RELEVANCE: The force of gastric and small bowel contractions decreased during sevoflurane anesthesia for laparoscopy. Although gastric motility returned to normal within 12-15 hours the impairment of gastric emptying lasted 30-40 hours, predisposing dogs to postoperative ileus.

Use of subcutaneous maropitant at two dosages for pain management in domestic rabbits (Oryctolagus cuniculus) undergoing elective ovariohysterectomy or orchiectomy.

OBJECTIVE: To describe the effect of two doses of maropitant on pain scores, food intake, and fecal output in domestic rabbits (Oryctolagus cuniculus) undergoing elective ovariohysterectomy or orchiectomy. ANIMALS: 26 (11 female, 15 male) rabbits from three institutions. PROCEDURES: Rabbits were randomly assigned to one of three treatment groups: low-dose maropitant (LDM; 2 mg/kg SC once; n=8), moderate-dose maropitant (MDM; 4 mg/kg SC once; n=10), and control (saline equivalent to 4 mg/kg maropitant SC once; n=8), administered prior to surgery. Following surgery, all rabbits were provided buprenorphine (0.06 mg/kg q 8 hours) and meloxicam (1 mg/kg q 24 hours) intramuscularly. Rabbits were monitored using video surveillance postoperatively until 24 hours after surgery or discharge from the hospital, whichever came first. Pain scores were assessed by three blinded observers, and results were grouped into early (0-4 hours), mid (5-8 hours), and late (12-24 hours) time frames. Food intake and fecal output were compared between groups. Statistical analysis was performed using Chi square, Fisher's exact tests, and a mixed model approach. RESULTS: There were no adverse effects with maropitant administration. Rabbits that received MDM had significantly lower pain scores in the mid-time frame and behavior scores in the late-time frame compared to controls. Male rabbits consumed more food than females and rabbits hospitalized longer than 12 hours consumed more food than those that were discharged prior. No significant differences were detected in facial grimace scale scores, food intake, or fecal production among treatment groups. CONCLUSIONS AND CLINICAL RELEVANCE: Moderate dose maropitant decreased pain related behaviors in the mid-time frame and behavior scores in the late-time frame after surgery. Further studies are necessary to better characterize the potential use of maropitant in postoperative analgesia.

Cardiovascular, respiratory, electrolyte and acid-base balance during continuous dexmedetomidine infusion in anesthetized dogs.

OBJECTIVE: To evaluate the cardiovascular, respiratory, electrolyte and acid-base effects of a continuous infusion of dexmedetomidine during propofol-isoflurane anesthesia following premedication with dexmedetomidine. STUDY DESIGN: Prospective experimental study. ANIMALS: Five adult male Walker Hound dogs 1-2 years of age averaging 25.4 ± 3.6 kg. METHODS: Dogs were sedated with dexmedetomidine 10 µg kg(-1) IM, 78 ± 2.3 minutes (mean ± SD) before general anesthesia. Anesthesia was induced with propofol (2.5 ± 0.5 mg kg(-1) ) IV and maintained with 1.5% isoflurane. Thirty minutes later dexmedetomidine 0.5 µg kg(-1) IV was administered over 5 minutes followed by an infusion of 0.5 µg kg(-1)  hour(-1) . Cardiac output (CO), heart rate (HR), ECG, direct blood pressure, body temperature, respiratory parameters, acid-base and arterial blood gases and electrolytes were measured 30 and 60 minutes after the infusion started. Data were analyzed via multiple linear regression modeling of individual variables over time, compared to anesthetized baseline values. Data are presented as mean ± SD. RESULTS: No statistical difference from baseline for any parameter was measured at any time point. Baseline CO, HR and mean arterial blood pressure (MAP) before infusion were 3.11 ± 0.9 L minute(-1) , 78 ± 18 beats minute(-1) and 96 ± 10 mmHg, respectively. During infusion CO, HR and MAP were 3.20 ± 0.83 L minute(-1) , 78 ± 14 beats minute(-1) and 89 ± 16 mmHg, respectively. No differences were found in respiratory rates, PaO2 , PaCO2 , pH, base excess, bicarbonate, sodium, potassium, chloride, calcium or lactate measurements before or during infusion. CONCLUSIONS AND CLINICAL RELEVANCE: Dexmedetomidine infusion using a loading dose of 0.5 µg kg(-1) IV followed by a constant rate infusion of 0.5 µg kg(-1)  hour(-1) does not cause any significant changes beyond those associated with an IM premedication dose of 10 µg kg(-1) , in propofol-isoflurane anesthetized dogs. IM dexmedetomidine given 108 ± 2 minutes before onset of infusion showed typical significant effects on cardiovascular parameters.

Effect of maropitant, a neurokinin-1 receptor antagonist, on the minimum alveolar concentration of sevoflurane during stimulation of the ovarian ligament in cats.

OBJECTIVE: Determine if maropitant decreases the minimum alveolar concentration (MAC) of sevoflurane during stimulation of the ovarian ligament in cats. STUDY DESIGN: Prospective study. ANIMALS: Fifteen, female cats weighing 2.5 ± 0.6 kg (mean ± SD). METHODS: Anesthesia was induced and maintained with sevoflurane. The right ovary was accessed via laparoscopy. A suture around the ovary and ovarian ligament was exteriorized through the abdominal wall for stimulation. A stimulus-response curve was created to identify the optimal force for MAC comparisons. In 10 cats, MAC was determined with only sevoflurane (baseline) then after 1 and 5 mg kg(-1) intravenous maropitant administration. The stimulation tension force used was 4.9 N. Repeated measures anova was used to compare the groups. MAC was defined as the average of the cross-over concentrations and reported MAC is adjusted to sea-level and depicted as mean ± SD. RESULTS: The stimulus-response curve was hyperbolic and plateaued at 4.3 ± 3 N. The optimal tension force chosen to compare MAC was 4.9 N. The baseline sevoflurane MAC was 2.96 ± 0.3%. Maropitant, 1 mg kg(-1) , decreased the MAC to 2.51 ± 0.3% (15%, p < 0.01). The higher maropitant dose of 5 mg kg(-1) did not change MAC further when compared to the low dose (2.46 ± 0.4%, p = 0.33). CONCLUSION AND CLINICAL RELEVANCE: The ovarian ligament stimulation model is suitable to determine MAC during visceral stimulation in cats. Maropitant decreased the anesthetic requirements during visceral ovarian and ovarian ligament stimulation in cats. Maropitant (1 mg kg(-1) ) decreases MAC by 15%; a higher dose had no additional effect.

Effect of epidural and intravenous use of the neurokinin-1 (NK-1) receptor antagonist maropitant on the sevoflurane minimum alveolar concentration (MAC) in dogs.

OBJECTIVE: To determine the effect of maropitant, an NK-1 receptor antagonist on the minimum alveolar concentration (MAC) of sevoflurane after intravenous and epidural administration to dogs. STUDY DESIGN: Prospective experimental study. ANIMALS: Seven, adult, spayed-female dogs (24.8 ± 1.9 kg). METHODS: Each dog was anesthetized twice with sevoflurane in oxygen, with at least 10 days separating the anesthetic events. The minimum alveolar concentration (MAC) of sevoflurane was determined using the tail-clamp technique. During the first anesthetic event, the MAC of sevoflurane was determined initially and again after intravenous administration of maropitant (5 mg kg(-1)) and an infusion (150 µg kg(-1) hour(-1)). During the second anesthetic event, an epidural catheter was advanced to the 4th lumbar vertebra and MAC was determined after administration of saline and maropitant (1 mg kg(-1)) epidurally. All MAC determinations were done in duplicate. The MAC values were adjusted to sea level and compared using student's t-test. RESULTS: The baseline MAC for sevoflurane was 2.08 ± 0.25%. Intravenous maropitant decreased (p < 0.05) MAC by 16% (1.74 ± 0.17%). In contrast, epidural administration of either saline or maropitant did not change (p > 0.05) the MAC (2.17 ± 0.34% and 1.92 ± 0.12%, respectively). CONCLUSION AND CLINICAL RELEVANCE: Maropitant decreased the MAC of sevoflurane when administered intravenously to dogs but not after epidural administration.

Strongly acidic gastroesophageal reflux and esophageal lumen pH before and after esophageal lavage with water or two bicarbonate concentrations in anesthetized dogs.

OBJECTIVE: To increase acidic esophageal lumen pH in dogs that developed gastroesophageal reflux (GER) during anesthesia. We compared water and 2 different bicarbonate concentrations. ANIMALS: 112 healthy, nonbrachycephalic dogs presented for ovariectomy. PROCEDURES: Following standard anesthesia and surgery protocols for ovariectomy in all dogs, esophageal lumen impedance and pH were monitored using a dedicated probe. Esophageal impedance indicates the presence of GER whereas pH indicates the acidity level. Dogs with strongly acidic GER and an esophageal lumen pH value < 4.0 were included in the study, and lavage was performed with either tap water, bicarbonate 1%, or bicarbonate 2% until the pH increased to > 4.0. The effect of lavage on esophageal pH was compared using the Kruskal-Wallis and Wilcoxon 2 sample tests. Associations between lavage and pH changes were determined. RESULTS: Of 48/112 dogs with strongly acidic GER, 33% neutralized their esophageal pH during surgery. For the 32 dogs that maintained an esophageal lumen pH value < 4, esophageal lavage with water increased the lumen pH to > 4 in 78.6% of dogs, whereas both bicarbonate concentrations increased it in 100% of the dogs to a more neutral pH (P < .0001). The dogs in the water group were more likely to regurgitate after anesthesia (36% vs 0% in both bicarbonate groups, P = .028). CLINICAL RELEVANCE: Bicarbonate 1% and 2% increased esophageal lumen pH to more than 4 after strongly acidic GER. Lavage with water was mildly effective, but required large volumes and predisposed to further regurgitation after anesthesia.

Correlation between jugular and central venous pressures in laterally recumbent horses.

OBJECTIVE: To compare and correlate right atrial pressure, which represents central venous pressure (CVP) to jugular vein pressure (JVP) in laterally recumbent horses under anesthesia. STUDY DESIGN: Retrospective clinical trial. ANIMALS: Seven adult healthy horses (411 ± 8.7 kg). METHODS: Horses were sedated with IV xylazine and anesthesia was obtained with IV ketamine and diazepam. Anesthesia was maintained with sevoflurane in oxygen. All horses were positioned in left lateral recumbency. An 8F catheter introducer was inserted into the right jugular vein to measure JVP. An 8F catheter introducer was inserted into the left jugular vein to be used as the port for a 7F 110 cm catheter that reached the right atrium to measure CVP. Both, CVP and JVP were measured simultaneously with a water calibrated aneroid manometer using the sternum as the 0 cmH(2) O reference point. Measurements were compared using Spearman correlation and the Bland-Altman plot. RESULTS: Twenty paired samples were obtained over a period of 2 hours. The CVP ranged from 7 to 31 cmH(2) O, while the JVP ranged from 5 to 30 cmH(2) O. The Spearman correlation coefficient indicated that CVP and JVP had a strong correlation with r = 0.88. The Bland-Altman plot showed a bias of 0.7 cmH(2) O. CONCLUSION AND CLINICAL RELEVANCE: Jugular vein pressure showed a strong correlation with CVP in healthy, euvolemic, laterally recumbent anesthetized adult horses. Thus, JVP cannot replace CVP but it may be used clinically to monitor CVP in laterally recumbent horses.

A dog model to study ovary, ovarian ligament and visceral pain.

OBJECTIVE: A dog model was developed to study visceral pain by stimulating the ovarian ligament. STUDY DESIGN: Prospective experimental trial. ANIMALS: Twelve 1-year old female hound dogs weighing 25.7 ± 3.6 kg. METHODS: Dogs were anesthetized with sevoflurane. The right ovary was accessed via laparoscopy. A suture was placed around the ovarian ligament and exteriorized through the abdominal wall for stimulation. The noxious stimulus consisted of pulling the ovary and ovarian ligament with a force transducer. The response to noxious stimulation was determined using the anesthetic minimum alveolar concentration requirement (MAC) for sevoflurane. The ovarian MAC was compared to the standardized somatic noxious stimulation tail clamp MAC. The results are depicted as mean ± SD and corrected to sea-level. RESULTS: The stimulus-response curve during ovarian stimulation in three dogs was hyperbolic and best represented by a three-parameter logistic growth curve model. The curve plateaued at 7.12 ± 4.19 N. From the stimulus-response curve, we chose 6.61 N to test the consistency and repeatability of the model in nine dogs. The ovarian stimulation MAC for sevoflurane in these dogs was 2.16 ± 0.46%. The ovarian stimulation confidence interval and limits are comparable to the results from tail stimulation MAC. The tail stimulation MACs before and after laparoscopy surgery were not different (1.86 ± 0.28% and 1.77 ± 0.38% respectively; p > 0.05) but lower when compared to the ovarian MAC (p < 0.01). The dogs recovered from anesthesia without complications. CONCLUSIONS AND CLINICAL RELEVANCE: The ovarian stimulation model is an adequate and repeatable means of producing visceral stimulation to determine MAC. The model may provide a humane mechanism to study the effectiveness of analgesics for acute ovarian pain.

Effects of morphine on histamine release from two cell lines of canine mast cell tumor and on plasma histamine concentrations in dogs with cutaneous mast cell tumor.

OBJECTIVE: To determine the effects of morphine on histamine release from 2 canine mast cell tumor (MCT) cell lines and on plasma histamine concentrations in dogs with cutaneous MCTs. ANIMALS: 10 dogs with cutaneous MCT and 10 dogs with soft tissue sarcoma (STS). PROCEDURES: The study consisted of 2 phases. First, 2 canine MCT cell lines were exposed to 3 pharmacologically relevant morphine concentrations, and histamine concentrations were determined by an ELISA. Second, dogs with MCT or STS received 0.5 mg of morphine/kg, IM, before surgery for tumor excision. Clinical signs, respiratory rate, heart rate, arterial blood pressure, rectal temperature, and plasma histamine concentrations were recorded before and 5, 15, 30, and 60 minutes after morphine administration but prior to surgery. Data were compared by use of a 2-way ANOVA with the Sidak multiple comparisons test. RESULTS: In the first phase, canine MCT cell lines did not release histamine when exposed to pharmacologically relevant morphine concentrations. In the second phase, no differences were noted for heart rate, arterial blood pressure, and rectal temperature between MCT and STS groups. Plasma histamine concentrations did not significantly differ over time within groups and between groups. CONCLUSIONS AND CLINICAL RELEVANCE: No significant changes in histamine concentrations were noted for both in vitro and in vivo study phases, and no hemodynamic changes were noted for the in vivo study phase. These preliminary results suggested that morphine may be used safely in some dogs with MCT.

Cadaveric Evaluation of Injectate Distribution for Two Maxillary Nerve Block Techniques in Cats.

Regional nerve blocks have been shown to decrease general anesthetic drug requirements and improve pain management in patients undergoing surgery. Regional nerve blocks are used routinely in patients undergoing oral surgery, such as dental extractions. There is little published information regarding the efficacy of feline maxillary and infraorbital nerve blocks. The goal of the study was to compare injectate distributions of the infraorbital foramen and percutaneous maxillary nerve block techniques in feline cadavers using a combined dye and radiopaque contrast media solution to simulate an injection. There was no significant difference in length of stained nerve between the two different techniques. It was not necessary to advance the needle into the infraorbital canal to achieve effective staining of the maxillary nerve. There was no significant difference in injectate distribution between two different injectate volumes, 0.2 and 0.4 ml, indicating that the smaller volume injected at the infraorbital foramen resulted in adequate nerve staining.

Fluid balance, glomerular filtration rate, and urine output in dogs anesthetized for an orthopedic surgical procedure.

OBJECTIVE: To determine fluid retention, glomerular filtration rate, and urine output in dogs anesthetized for a surgical orthopedic procedure. ANIMALS: 23 dogs treated with a tibial plateau leveling osteotomy. PROCEDURES: 12 dogs were used as a control group. Cardiac output was measured in 5 dogs, and 6 dogs received carprofen for at least 14 days. Dogs received oxymorphone, atropine, propofol, and isoflurane for anesthesia (duration, 4 hours). Urine and blood samples were obtained for analysis every 30 minutes. Lactated Ringer's solution was administered at 10 mL/kg/h. Urine output was measured and glomerular filtration rate was estimated. Fluid retention was measured by use of body weight, fluid balance, and bioimpedance spectroscopy. RESULTS: No difference was found among control, cardiac output, or carprofen groups, so data were combined. Median urine output and glomerular filtration rate were 0.46 mL/kg/h and 1.84 mL/kg/min. Dogs retained a large amount of fluids during anesthesia, as indicated by increased body weight, positive fluid balance, increased total body water volume, and increased extracellular fluid volume. The PCV, total protein concentration, and esophageal temperature decreased in a linear manner. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs anesthetized for a tibial plateau leveling osteotomy retained a large amount of fluids, had low urinary output, and had decreased PCV, total protein concentration, and esophageal temperature. Evaluation of urine output alone in anesthetized dogs may not be an adequate indicator of fluid balance.

Evaluation of cardiovascular, respiratory and biochemical effects, and anesthetic induction and recovery behavior in horses anesthetized with a 5% micellar microemulsion propofol formulation.

OBJECTIVE: To characterize cardiovascular, respiratory and biochemical effects and recovery behavior associated with a 3-hour continuous infusion of a micellar microemulsion propofol formulation in horses. STUDY DESIGN: Prospective experimental trial. ANIMALS: Six healthy adult horses, 9 +/- 2 years old and weighing 557 +/- 14 kg. METHODS: All horses received xylazine (1 mg kg(-1), IV) 5 minutes prior to anesthetic induction. Each horse was anesthetized on two occasions with a 5% micellar microemulsion propofol formulation (2 mg kg(-1), IV); first as a single bolus (phase I) and then as a 3-hour continuous infusion (phase II). Propofol pharmacokinetics were obtained from phase I and used to determine the starting infusion rates in phase II. Anesthetic induction and recovery characteristics were quantitatively and qualitatively assessed. Cardiovascular, respiratory and biochemical parameters were monitored during anesthesia and recovery. RESULTS: Induction quality varied, ranging from good to poor. Standing and overall recovery quality scores were consistently excellent in phase I but more variability was observed among horses in phase II. Heart rate (HR) and mean arterial pressure (MAP) were adequately maintained but marked hypoventilation developed. There were only minimal changes in blood biochemical analytes following anesthesia. CONCLUSIONS AND CLINICAL RELEVANCE: The micellar microemulsion propofol formulation, administered as a 3-hour continuous infusion, showed similar results compared to those previously described with a commercially available propofol preparation. However, based on present findings, use of propofol as a primary anesthetic in horses for prolonged periods of anesthesia requires further study to determine the limits of safety and clinical applicability.

Computed Tomography Analysis of the Feline Infraorbital Foramen and Canal.

Feline skull anatomic variation is plain to see with casual observation. Obtaining an in-depth understanding of this anatomic variability is critical to performing safe and effective regional anesthesia for dental procedures and maxillofacial surgeries. Maxillofacial anatomic variability is proven to impact the placement and efficacy of nerve blocks in dogs and horses, but similar studies have not been performed in cats. This study's main objective was to evaluate the anatomy of the infraorbital foramen and canal in relation to regional anatomic landmarks in brachycephalic and mesaticephalic cats. Significant anatomic variability was identified, particularly among cats with brachycephalic skulls.

Serum D-lactate concentrations in dogs with parvoviral enteritis.

BACKGROUND: Dogs infected with canine parvovirus (CPV) have compromised intestinal epithelial barrier integrity. Production of D-lactate by enteric bacteria may directly reflect disease severity or contribute to metabolic acid-base status in these dogs. HYPOTHESIS: Serum D-lactate concentration will be increased in CPV dogs compared to healthy controls and correlate with markers of disease severity and acid-base status. ANIMALS: Dogs with CPV undergoing treatment (n = 40) and healthy control dogs (n = 9). METHODS: Prospective observational study. Dogs with CPV had a baseline and daily CBC, venous blood gas with serum electrolyte concentrations, composite clinical severity score, and serum D-lactate concentration performed. A single serum D-lactate measurement was obtained from healthy control dogs. RESULTS: The CPV dogs had a higher D-lactate concentration (mean ± SD) of 469 ± 173 µM compared to controls, 306 ± 45 µM (P < .001). There was no difference in baseline D-lactate concentrations for CPV survivors (474 ± 28 µM), versus nonsurvivors (424 ± 116 µM; P = .70). D-lactate concentration decreased over the first 4 days of treatment (-9.6 µM/d; P = .46). Dogs hospitalized for <4 days had lower baseline D-lactate concentrations compared to those hospitalized ≥4 days (400 ± 178 µM versus 520 ± 152 µM; P = .03). No sustained correlation over time between serum D-lactate concentration and clinical severity score or recorded acid-base results. CONCLUSIONS AND CLINICAL IMPORTANCE: Serum D-lactate concentrations are higher in dogs with CPV compared to healthy controls but do not appear to be clinically relevant. No relationship identified between serum D-lactate concentrations and markers of CPV disease severity, acid-base status, or outcome.

Assessing the Efficacy of Maropitant Versus Ondansetron in the Treatment of Dogs with Parvoviral Enteritis.

Antiemetics are commonly prescribed during the treatment of canine parvoviral enteritis. This blinded, randomized prospective study compared the quality of clinical recovery and duration of hospitalization in canine parvoviral dogs receiving either maropitant (1 mg/kg [0.45 mg/lb] IV q 24 hr, n = 11) or ondansetron (0.5 mg/kg [0.23 mg/lb] IV q 8 hr, n = 11). All dogs were treated with IV fluids, cefoxitin, and enteral nutrition. Frequency of vomiting and pain scoring were recorded twice daily. Rescue analgesics and antiemetics were administered as dictated by specific pain and vomiting criteria. Clinical severity scoring, body weight, and caloric intake were monitored daily. When comparing dogs receiving maropitant versus ondansetron, respectively, there were no differences in duration of hospitalization (3.36 ± 0.56 versus 2.73 ± 0.38 days, P = .36), requirement of rescue antiemetic (3/11 versus 5/11 dogs, P = .66), duration of vomiting (5 versus 4 days, P = .65), or days to voluntary food intake (2 versus 1.5 days, P = 1.0). Results of this study suggest that maropitant and ondansetron are equally effective in controlling clinical signs associated with parvoviral enteritis.

Effect of hospitalization on gastrointestinal motility and pH in dogs.

OBJECTIVE To determine the effect of hospitalization on gastrointestinal motility and pH in healthy dogs. DESIGN Experimental study. ANIMALS 12 healthy adult dogs. PROCEDURES A wireless motility capsule (WMC) that measured pressure, transit time, and pH within the gastrointestinal tract was administered orally to dogs in 2 phases. In the first phase, dogs received the WMC at the hospital and then returned to their home to follow their daily routine. In the second phase, dogs were hospitalized, housed individually, had abdominal radiography performed daily, and were leash exercised 4 to 6 times/d until the WMC passed in the feces. All dogs received the same diet twice per day in both phases. Data were compared between phases with the Wilcoxon signed rank test. RESULTS Data were collected from 11 dogs; 1 dog was excluded because the WMC failed to exit the stomach. Median gastric emptying time during hospitalization (71.8 hours; range, 10.7 to 163.0 hours) was significantly longer than at home (17.6 hours; range, 9.7 to 80.8 hours). Values of all other gastric, small bowel, and large bowel parameters (motility index, motility pattern, pH, and transit time) were similar between phases. No change in gastric pH was detected over the hospitalization period. High interdog variability was evident for all measured parameters. CONCLUSIONS AND CLINICAL RELEVANCE Hospitalization of dogs may result in a prolonged gastric emptying time, which could adversely affect gastric emptying of meals, transit of orally administered drugs, or assessments of underlying motility disorders.

Evaluation of an outpatient protocol in the treatment of canine parvoviral enteritis.

OBJECTIVE: To compare 2 treatment protocols (standard in-hospital versus modified outpatient) in affecting the duration of treatment or survival of dogs with parvoviral enteritis. DESIGN: Prospective, randomized study. SETTING: University teaching hospital. ANIMALS: Client-owned dogs with naturally acquired parvovirus were randomized to receive either an inpatient (n = 20) or outpatient (n = 20) treatment protocol. INTERVENTIONS: Both groups received intravenous (IV) fluid resuscitation and correction of hypoglycemia at hospital admission. Following stabilization, basic inpatient interventions included administration of IV fluids, administration of cefoxitin (22 mg/kg IV q 8 h), and maropitant (1 mg/kg IV q 24 h). Basic outpatient interventions (provided in-hospital) included administration of subcutaneous (SC) fluid (30 mL/kg q 6 h), administration of maropitant (1 mg/kg SC q 24 h) and cefovecin (8 mg/kg SC once). Using daily electrolyte and glucose evaluations, dextrose and potassium supplementation was provided intravenously (inpatients) or orally (outpatients) as indicated. Rescue criteria were used in both groups for analgesia and nausea. All dogs were syringe fed a commercial canine convalescence diet (1 mL/kg PO q 6 h) until voluntary appetite returned. MEASUREMENTS AND MAIN RESULTS: Protocol success, defined as survival to hospital discharge, was 90% (18/20) for the inpatient group compared to 80% (16/20) for the outpatient group (P = 0.66). There was no difference detected in duration of hospitalization for inpatient dogs (4.6 ± 2 days) versus outpatient dogs (3.8 ± 1.8 days, P = 0.20). Metabolic disturbances were frequent in the outpatient group, with 50% of dogs requiring dextrose supplementation and 60% of dogs requiring potassium supplementation. CONCLUSIONS: An outpatient protocol may be a reasonable alternative for dogs that cannot receive standard in-hospital treatment for parvoviral enteritis. Diligent supportive care and monitoring are still required to optimize treatment of dogs with parvoviral enteritis in an outpatient setting.