Effects of different rates of propofol with or without S-ketamine on ventricular function in healthy cats - a randomized study.

Propofol is used for anesthetic induction in cats and procedural sedation in countries where alfaxalone is not available. Studies have reported propofol-related effects in echocardiography variables in dogs and humans. However, there is a lack of echocardiography studies investigating propofol-related effects on cats. This study aimed to use echocardiography to investigate echocardiographic changes in three protocols using propofol: propofol-slow (2 mg/kg/min, PS); propofol-fast (8 mg/kg/min, PF); propofol-ketamine (S-ketamine 2 mg/kg bolus followed by propofol 2 mg/kg/min; PK) in healthy premedicated (gabapentin-buprenorphine-acepromazine; 200 mg/cat, 0.4, and 0.1 mg/kg, respectively), non-intubated cats. Echocardiographic measurements were obtained at three time points: baseline (before the administration of propofol), end of propofol titration (end-point, T0), and 15 min after T0 (T15). Propofol at a lower rate continued from T0 to T15. Echocardiographic and physiological variables included fractional shortening (FS%), ejection fraction (EF%), HR, BP, and others. Propofol requirements at T0 for PF, PS, and PK groups were 5.0 ± 0.9, 3.8 ± 0.7, and 2.4 ± 0.5 mg/kg, respectively. EF% neither change over time nor between groups. PF and PK showed a reduction in FS% at T0 (47 ± 6 to 34 ± 6 and 42 ± 6 to 36 ± 5, respectively). BP reduced significantly in PF and PS groups (136 ± 26 to 105 ± 13 and 137 ± 22 to 115 ± 15 mmHg, respectively). It is unclear whether changes in echocardiography variables were of clinical relevance related to treatment groups or a result of within-group individual responses.

Reliability and Validity of UNESP-Botucatu Cattle Pain Scale and Cow Pain Scale in Bos taurus and Bos indicus Bulls to Assess Postoperative Pain of Surgical Orchiectomy.

Pain assessment guides decision-making in pain management and improves animal welfare. We aimed to investigate the reliability and validity of the UNESP-Botucatu cattle pain scale (UCAPS) and the cow pain scale (CPS) for postoperative pain assessment in Bos taurus (Angus) and Bos indicus (Nelore) bulls after castration. METHODS: Ten Nelore and nine Angus bulls were anaesthetised with xylazine-ketamine-diazepam-isoflurane-flunixin meglumine. Three-minute videos were recorded at -48 h, preoperative, after surgery, after rescue analgesia and at 24 h. Two evaluators assessed 95 randomised videos twice one month apart. RESULTS: There were no significant differences in the pain scores between breeds. Intra and inter-rater reliability varied from good (>0.70) to very good (>0.81) for all scales. The criterion validity showed a strong correlation (0.76-0.78) between the numerical rating scale and VAS versus UCAPS and CPS, and between UCAPS and CPS (0.76). The UCAPS and CPS were responsive; all items and total scores increased after surgery. Both scales were specific (81-85%) and sensitive (82-87%). The cut-off point for rescue analgesia was >4 for UCAPS and >3 for CPS. CONCLUSIONS: The UCAPS and CPS are valid and reliable to assess postoperative pain in Bos taurus and Bos indicus bulls.

Multilingual validation of the short form of the Unesp-Botucatu Feline Pain Scale (UFEPS-SF).

Background: Pain is the leading cause of animal suffering, hence the importance of validated tools to ensure its appropriate evaluation and treatment. We aimed to test the psychometric properties of the short form of the Unesp-Botucatu Feline Pain Scale (UFEPS-SF) in eight languages. Methods: The original scale was condensed from ten to four items. The content validation was performed by five specialists in veterinary anesthesia and analgesia. The English version of the scale was translated and back-translated into Chinese, French, German, Italian, Japanese, Portuguese and Spanish by fluent English and native speaker translators. Videos of the perioperative period of 30 cats submitted to ovariohysterectomy (preoperative, after surgery, after rescue analgesia and 24 h after surgery) were randomly evaluated twice (one-month interval) by one evaluator for each language unaware of the pain condition. After watching each video, the evaluators scored the unidimensional, UFEPS-SF and Glasgow composite multidimensional feline pain scales. Statistical analyses were carried out using R software for intra and interobserver reliability, principal component analysis, criteria concurrent and predictive validities, construct validity, item-total correlation, internal consistency, specificity, sensitivity, the definition of the intervention score for rescue analgesia and diagnostic uncertainty zone, according to the receiver operating characteristic (ROC) curve. Results: UFEPS-SF intra- and inter-observer reliability were ≥0.92 and 0.84, respectively, for all observers. According to the principal component analysis, UFEPS-SF is a unidimensional scale. Concurrent criterion validity was confirmed by the high correlation between UFEPS-SF and all other scales (≥0.9). The total score and all items of UFEPS-SF increased after surgery (pain), decreased to baseline after analgesia and were intermediate at 24 h after surgery (moderate pain), confirming responsiveness and construct validity. Item total correlation of each item (0.68-0.83) confirmed that the items contributed homogeneously to the total score. Internal consistency was excellent (≥0.9) for all items. Both specificity (baseline) and sensitivity (after surgery) based on the Youden index was 99% (97-100%). The suggestive cut-off score for the administration of analgesia according to the ROC curve was ≥4 out of 12. The diagnostic uncertainty zone ranged from 3 to 4. The area under the curve of 0.99 indicated excellent discriminatory capacity of UFEPS-SF. Conclusions: The UFEPS-SF and its items, assessed by experienced evaluators, demonstrated very good repeatability and reproducibility, content, criterion and construct validities, item-total correlation, internal consistency, excellent sensitivity and specificity and a cut-off point indicating the need for rescue analgesia in Chinese, French, English, German, Italian, Japanese, Portuguese and Spanish.

Clinical validation of the short and long UNESP-Botucatu scales for feline pain assessment.

BACKGROUND: The UNESP-Botucatu multidimensional feline pain assessment scale (UFEPS) is a valid and reliable instrument for acute pain assessment in cats. However, its limitations are that responsiveness was not tested using a negative control group, it was validated only for ovariohysterectomy, and it can be time-consuming. We aimed to evaluate the construct and criterion validity, reliability, sensitivity, and specificity of the UFEPS and its novel short form (SF) in various clinical or painful surgical conditions. METHODS: Ten client-owned healthy controls (CG) and 40 client-owned cats requiring pain management for clinical or surgical care (20 clinical and 20 surgery group (12 orthopedic and eight soft tissue surgeries) were recruited. Three evaluators assessed pain, in real-time, in clinical cases before and 20 min after rescue analgesia and in surgical cases before and up to 6.5 hours postoperatively, by using the visual analog, numerical ratio, and a simple descriptive scale, in this order, followed by the UFEPS-SF, UFEPS and Glasgow multidimensional feline pain (Glasgow CMPS-Feline) in random order. For the surgical group, rescue analgesia (methadone 0.2 mg/kg IM or IV and/or dipyrone 12.5 mg/kg IV) was performed when the UFEPS-SF score was ≥4 or exceptionally according to clinical judgement. If a third interventional analgesia was required, methadone (0.1-0.2 mg/kg IM) and ketamine (1 mg/kg IM) were administered. For the clinical group, all cats received rescue analgesia (methadone 0.1-0.2 mg/kg IM or IV or nalbuphine 0.5 mg/kg IM or IV), according to the clinician in charge, regardless of pain scores. Construct (1-comparison of scores in cats undergoing pain vs pain-free control cats by unpaired Wilcoxon-test and 2-responsiveness to analgesia by paired Wilcoxon test) and concurrent criterion validity (Spearman correlation of the total score among scales), inter-rater reliability, specificity and sensitivity were calculated for each scale (α = 0.05). RESULTS: Reliability ranged between moderate and good for the UFEPS and UFEPS-SF (confidence intervals of intraclass coefficients = 0.73-0.86 and 0.63-0.82 respectively). The Spearman correlation between UFEPS and UFEPS-SF was 0.85, and their correlation with Glasgow CMPS-Feline was strong (0.79 and 0.78 respectively), confirming criterion validity. All scales showed construct validity or responsiveness (higher scores of cats with clinical and postoperative pain vs healthy controls, and the reduction in scores after rescue analgesia). The sensitivity and specificity of the UFEPS, UFEPS-SF and Glasgow CMPS-Feline were moderate (sensitivity 83.25, 78.60% and 74.28%; specificity 72.00, 84.67 and 70.00%, respectively). CONCLUSIONS: Both UFEPS and UFEPS-SF showed appropriate concurrent validity, responsiveness, reliability, sensitivity, and specificity for feline acute pain assessment in cats with various clinical and orthopedic and soft tissue surgical conditions.

Distribution of bupivacaine hydrochloride after sciatic and femoral nerve blocks in cats: A magnetic resonance imaging study.

The objective of this study was to evaluate the distribution of bupivacaine hydrochloride using magnetic resonance imaging (MRI) after electrical nerve stimulator (ENS)-guided sciatic (ScN) and femoral (FN) nerve blocks in cats. Six adult cats (body weight 4.8±0.6kg) were anesthetized with acepromazine-buprenorphine-propofol-isoflurane. Transverse and sagittal plan sequences of pelvic limbs were obtained using a high-field magnet (1.5T). Afterwards, the ScN and FN blocks (one block per limb) were performed using 0.1mL/kg of bupivacaine 0.5% per site and the MRI sequence was repeated after each block. The injection was considered successful when bupivacaine was in contact with the nerve. Injectate location and complications were recorded. The length (mm) of contact (spread) between bupivacaine and nerves was measured and classified as fair (<15mm) or adequate (≥15mm). Five out of six ScN injections were successful; of these, four had adequate spread over the nerve [26 (13-39) mm]. All FN injections were successful, but in one case bupivacaine was administered over the motor branch of FN, distally to the bifurcation between the femoral and saphenous nerve. It was not possible to measure neither the length of contact between bupivacaine and FN nor to identify iatrogenic trauma caused by the injections. MRI can be used for the evaluation of bupivacaine distribution, but not complications, following ENS-guided ScN and FN blocks in cats. Despite most of the injections were considered successful, individual variability regarding the injectate location may explain differences in efficacy in the clinical setting.

Analgesic and antihyperalgesic effects of dipyrone, meloxicam or a dipyrone-meloxicam combination in bitches undergoing ovariohysterectomy.

The analgesic and antihyperalgesic effects of dipyrone, meloxicam or a dipyrone-meloxicam combination were compared in dogs undergoing elective ovariohysterectomy. In a double-blinded, prospective, randomised design, 40 bitches premedicated with intramuscular pethidine (4 mg/kg) and anaesthetised with isoflurane received one of four intravenous treatments (n = 10 per group) before ovariohysterectomy: control (physiological saline), meloxicam (0.2 mg/kg), dipyrone (25 mg/kg) or dipyrone-meloxicam (25 mg/kg and 0.2 mg/kg, respectively). Glasgow composite measure pain scale (GCMPS) and mechanical nociceptive thresholds (MNT) were assessed before anaesthesia and at 1, 2, 3, 4, 6, 8, 12 and 24 h postoperatively. Rescue analgesia (0.5 mg/kg morphine) was administered intramuscularly if the GCMPS was ≥3. The GCMPS and MNT did not differ among groups. The frequency of rescue analgesia was significantly (P <0.05) lower in the dipyrone group (30%) than in controls (50%), but there were no significant differences from the control group in bitches treated with meloxicam (70%) or dipyrone-meloxicam (40%). There was a significant reduction in the total number of rescue treatments in the dypyrone (n = 5) and dipyrone-meloxicam (n = 5) groups when compared with the control (n = 17) and meloxicam (n = 19) groups. Meloxicam and dipyrone-meloxicam significantly reduced the percentage of animals exhibiting severe pain during MNT measurements (30% and 0%, respectively) compared with the control group (50%). Dipyrone produced superior analgesia (reduced morphine consumption), while meloxicam produced better antihyperalgesia (fewer episodes of severe pain) in contrast to controls. When used in tandem, the beneficial effects were combined.

Evaluation of the isoflurane-sparing effects of fentanyl, lidocaine, ketamine, dexmedetomidine, or the combination lidocaine-ketamine-dexmedetomidine during ovariohysterectomy in dogs.

OBJECTIVE: To evaluate the isoflurane-sparing effects of an intravenous (IV) constant rate infusion (CRI) of fentanyl, lidocaine, ketamine, dexmedetomidine, or lidocaine-ketamine-dexmedetomidine (LKD) in dogs undergoing ovariohysterectomy. STUDY DESIGN: Randomized, prospective, blinded, clinical study. ANIMALS: Fifty four dogs. METHODS: Anesthesia was induced with propofol and maintained with isoflurane with one of the following IV treatments: butorphanol/saline (butorphanol 0.4 mg kg(-1), saline 0.9% CRI, CONTROL/BUT); fentanyl (5 µg kg(-1), 10 µg kg(-1) hour(-1), FENT); ketamine (1 mg kg(-1), 40 µg kg(-1) minute(-1), KET), lidocaine (2 mg kg(-1), 100 µg kg(-1) minute(-1), LIDO); dexmedetomidine (1 µg kg(-1), 3 µg kg(-1) hour(-1), DEX); or a LKD combination. Positive pressure ventilation maintained eucapnia. An anesthetist unaware of treatment and end-tidal isoflurane concentration (Fe'Iso) adjusted vaporizer settings to maintain surgical anesthetic depth. Cardiopulmonary variables and Fe'Iso concentrations were monitored. Data were analyzed using anova (p < 0.05). RESULTS: At most time points, heart rate (HR) was lower in FENT than in other groups, except for DEX and LKD. Mean arterial blood pressure (MAP) was lower in FENT and CONTROL/BUT than in DEX. Overall mean ± SD Fe'Iso and % reduced isoflurane requirements were 1.01 ± 0.31/41.6% (range, 0.75 ± 0.31/56.6% to 1.12 ± 0.80/35.3%, FENT), 1.37 ± 0.19/20.8% (1.23 ± 0.14/28.9% to 1.51 ± 0.22/12.7%, KET), 1.34 ± 0.19/22.5% (1.24 ± 0.19/28.3% to 1.44 ± 0.21/16.8%, LIDO), 1.30 ± 0.28/24.8% (1.16 ± 0.18/32.9% to 1.43 ± 0.32/17.3%, DEX), 0.95 ± 0.19/54.9% (0.7 ± 0.16/59.5% to 1.12 ± 0.16/35.3%, LKD) and 1.73 ± 0.18/0.0% (1.64 ± 0.21 to 1.82 ± 0.14, CONTROL/BUT) during surgery. FENT and LKD significantly reduced Fe'Iso. CONCLUSIONS AND CLINICAL RELEVANCE: At the doses administered, FENT and LKD had greater isoflurane-sparing effect than LIDO, KET or CONTROL/BUT, but not at all times. Low HR during FENT may limit improvement in MAP expected with reduced Fe'Iso.

Assessment of postoperative pain after unilateral mastectomy using two different surgical techniques in dogs.

BACKGROUND: There are few studies reporting pain and postoperative analgesia associated with mastectomy in dogs. The aim of this study was to evaluate postoperative pain after unilateral mastectomy using two different surgical techniques in the dog. FINDINGS: Twenty female dogs were assigned (n=10/group) to undergo unilateral mastectomy using either the combination of sharp and blunt dissection (SBD) or the modified SBD (mSBD) technique, in which the mammary chain is separated from the abdominal wall entirely by blunt (hand and finger) dissection except for a small area cranial to the first gland, in a prospective, randomized, clinical trial. All dogs were premedicated with intramuscular acepromazine (0.05 mg/kg) and morphine (0.3 mg/kg). Anesthesia was induced with intravenous ketamine (5 mg/kg) and diazepam (0.25 mg/kg), and maintained with isoflurane. Subcutaneous meloxicam (0.2 mg/kg) was administered before surgery. Postoperative pain was evaluated according to the University of Melbourne pain scale (UMPS) by an observer who was blinded to the surgical technique.. Rescue analgesia was provided by the administration of intramuscular morphine (0.5 mg/kg) if pain scores were >14 according to the UMPS. Data were analyzed using t-tests and ANOVA (P>0.05). There were no significant differences between the groups for age, weight, extubation time, and duration of surgery and anesthesia (P>0.05). There were no significant differences for postoperative pain scores between groups. Rescue analgesia was required in one dog in each group. CONCLUSIONS: The two surgical techniques produced similar surgical times, incidence of perioperative complications and postoperative pain. Multimodal analgesia is recommended for treatment of postoperative pain in dogs undergoing unilateral mastectomy.

Multimodal analgesia for perioperative pain in three cats.

Adequate pain relief is usually achieved with the simultaneous use of two or more different classes of analgesics, often called multimodal analgesia. The purpose of this article is to highlight the use of perioperative multimodal analgesia and the need to individualize the treatment plan based on the presenting condition, and to adjust it based on the response to analgesia for a given patient. This case series presents the alleviation of acute pain in three cats undergoing different major surgical procedures. These cases involved the administration of different classes of analgesic drugs, including opioids, non-steroidal anti-inflammatory drugs, tramadol, ketamine, gabapentin and local anesthetics. The rationale for the administration of analgesic drugs is discussed herein. Each case presented a particular challenge owing to the different cause, severity, duration and location of pain. Pain management is a challenging, but essential, component of feline practice: multimodal analgesia may minimize stress while controlling acute perioperative pain. Individual response to therapy is a key component of pain relief in cats.

Pharmacokinetic and pharmacodynamic modelling of intravenous, intramuscular and subcutaneous buprenorphine in conscious cats.

OBJECTIVE: To describe simultaneous pharmacokinetics (PK) and thermal antinociception after intravenous (i.v.), intramuscular (i.m.) and subcutaneous (SC) buprenorphine in cats. STUDY DESIGN: Randomized, prospective, blinded, three period crossover experiment. ANIMALS: Six healthy adult cats weighing 4.1±0.5 kg. METHODS: Buprenorphine (0.02 mg kg(-1)) was administered i.v., i.m. or s.c.. Thermal threshold (TT) testing and blood collection were conducted simultaneously at baseline and at predetermined time points up to 24 hours after administration. Buprenorphine plasma concentrations were determined by liquid chromatography tandem mass spectrometry. TT was analyzed using anova (p<0.05). A pharmacokinetic-pharmacodynamic (PK-PD) model of the i.v. data was described using a model combining biophase equilibration and receptor association-dissociation kinetics. RESULTS: TT increased above baseline from 15 to 480 minutes and at 30 and 60 minutes after i.v. and i.m. administration, respectively (p<0.05). Maximum increase in TT (mean±SD) was 9.3±4.9°C at 60 minutes (i.v.), 4.6±2.8°C at 45 minutes (i.m.) and 1.9±1.9°C at 60 minutes (s.c.). TT was significantly higher at 15, 60, 120 and 180 minutes, and at 15, 30, 45, 60 and 120 minutes after i.v. administration compared to i.m. and s.c., respectively. I.v. and i.m. buprenorphine concentration-time data decreased curvilinearly. S.c. PK could not be modeled due to erratic absorption and disposition. I.v. buprenorphine disposition was similar to published data. The PK-PD model showed an onset delay mainly attributable to slow biophase equilibration (t(1/2) k(e0)=47.4 minutes) and receptor binding (k(on)=0.011 mL ng(-1) minute(-1)). Persistence of thermal antinociception was due to slow receptor dissociation (t(1/2) k(off)=18.2 minutes). CONCLUSIONS AND CLINICAL RELEVANCE: I.v. and i.m. data followed classical disposition and elimination in most cats. Plasma concentrations after i.v. administration were associated with antinociceptive effect in a PK-PD model including negative hysteresis. At the doses administered, the i.v. route should be preferred over the i.m. and s.c. routes when buprenorphine is administered to cats.

A clinical comparison of remifentanil or alfentanil in propofol-anesthetized cats undergoing ovariohysterectomy.

Sixteen cats were used to compare the cardiovascular and anesthetic effects of remifentanil (REMI) or alfentanil (ALF) in propofol-anesthetized cats undergoing ovariohysterectomy. After premedication with acepromazine, anesthesia was induced and maintained with a constant rate infusion of propofol (0.3 mg/kg/min). REMI or ALF infusions were administered simultaneously with propofol. Heart rate (HR), systolic arterial pressure (SAP), pulse oximetry (SpO(2)), rectal temperature (RT), and response to surgical stimulation were recorded at predefined time points during anesthesia. Data [mean±standard deviation (SD)] were analyzed by analysis of variance (ANOVA) for repeated measures followed by a Dunnett's test and Student t-test (P<0.05). SAP was significantly lower in ALF group than in REMI group. Extubation time was significantly shorter in REMI than in ALF group. Overall infusion rate of REMI and ALF was 0.24±0.05 µg/kg/min and 0.97±0.22 µg/kg/min, respectively. The combination of propofol and REMI or ALF provided satisfactory anesthesia in cats undergoing ovariohysterectomy.

Post-operative analgesic effects of butorphanol or firocoxib administered to dogs undergoing elective ovariohysterectomy.

OBJECTIVE: To compare the post-operative analgesic effects of butorphanol or firocoxib in dogs undergoing ovariohysterectomy. STUDY DESIGN: Prospective, randomized, blinded, clinical trial. ANIMALS: Twenty-five dogs >1 year of age. METHODS: Dogs received acepromazine intramuscularly (IM), 0.05 mg kg(-1) and either butorphanol IM, 0.2 mg kg(-1) (BG, n = 12) or firocoxib orally (PO), 5 mg kg(-1) (FG, n = 13), approximately 30 minutes before induction of anesthesia with propofol. Anesthesia was maintained with isoflurane. Ovariohysterectomy was performed by the same surgeon. Pain scores using the dynamic and interactive visual analog scale (DIVAS) were performed before and at 1, 2, 3, 4, 6, 8 and 20 hours after the end of surgery by one observer, blinded to the treatment. Rescue analgesia was provided with morphine (0.5 mg kg(-1)) IM and firocoxib, 5 mg kg(-1) (BG only) PO if DIVAS >50. Groups were compared using paired t-tests and Fisher's exact test (p < 0.05). Data are presented as mean ± SD. RESULTS: The BG required significantly less propofol (BG: 2.6 ± 0.59 mg kg(-1); FG: 5.39 ± 0.7 mg kg(-1)) (p < 0.05) but the anesthesia time was longer (BG: 14 ± 6, FG: 10 ± 4 minutes). There were no differences for body weight (BG: 7.9 ± 5.0, FG: 11.5 ± 4.6 kg), sedation scores, and surgery and extubation times (BG: 10 ± 2, 8 ± 5 minutes; FG: 9 ± 3, 8 ± 4 minutes, respectively) (p > 0.05). The FG had significantly lower pain scores than the BG at 1, 2 and 3 hours following surgery (p < 0.05). Rescue analgesia was administered to 11/12 (92%) and 2/13 (15%) dogs in the BG and FG, respectively (p < 0.05). CONCLUSION AND CLINICAL RELEVANCE: Firocoxib produced better post-operative analgesia than butorphanol. Firocoxib may be used as part of a multimodal analgesia protocol but may not be effective as a sole analgesic.

Postoperative analgesic effects of intravenous, intramuscular, subcutaneous or oral transmucosal buprenorphine administered to cats undergoing ovariohysterectomy.

OBJECTIVE: To compare the postoperative analgesic effects of intravenous (IV), intramuscular (IM), subcutaneous (SC) or oral transmucosal (OTM) buprenorphine administered to cats undergoing ovariohysterectomy. STUDY DESIGN: Randomized, prospective and blinded clinical trial. ANIMALS: 100 female cats. METHODS: Cats were assigned to receive 0.01 mg kg(-1) of buprenorphine administered by the IV, IM, SC or OTM route (n = 25/group). Buprenorphine was made up to 0.3 mL with 0.9% saline. DIVAS (0-100 mm) and simple descriptive scale (SDS) (from 0 to 4) pain and sedation scores were assigned to each cat before and 1, 2, 3, 4, 6, 8, 12 and 24 hours after ovariohysterectomy. Buprenorphine and carprofen were administered for rescue analgesia. Data were analyzed using anova and Fisher's exact test (p < 0.05). RESULTS: There were no significant differences between groups for breed, body weight, anesthetic time or surgery time (p > 0.05). There were no significant differences between groups for sedation scores at any time. SDS pain scores did not detect any differences between groups (p > 0.05). DIVAS pain scores after OTM administration were significantly higher than IV and IM administration at 1 hour and at 3, 4, 6, 8 and 12 hours, respectively (p < 0.05). DIVAS pain scores after SC administration were significantly higher than IV and IM administration at 2 hours and at 2, 3, 4, 8, 12 and 24 hours (p < 0.05), respectively. Six, four, 13 and 17 cats that received IV, IM, SC and OTM buprenorphine required rescue analgesia, respectively. There was a significantly higher incidence of treatment failure in cats that received SC and OTM buprenorphine compared with cats that received IV and IM buprenorphine (p < 0.05). CONCLUSIONS AND CLINICAL RELEVANCE: IV and IM administration of buprenorphine provided better postoperative analgesia than SC or OTM administration of the drug and these routes of administration should be preferred when buprenorphine is administered to cats.

Effects of the opioid remifentanil on the arrhythmogenicity of epinephrine in halothane-anesthetized dogs.

Opioids may exert a protective effect against ventricular arrhythmias via a vagally mediated mechanism. This study evaluated the effects of the opioid remifentanil on arrhythmogenicity of epinephrine during halothane anesthesia. Eight dogs were assigned to 2 treatments in a randomized crossover design, with 1-week intervals between treatments. Anesthesia was maintained with 1.3% end-tidal halothane in oxygen and mechanical ventilation to maintain eucapnia. A constant rate infusion of remifentanil (0.72 microg/kg/min) was administered throughout the study in the experimental treatment, while control animals received physiologic saline as placebo. The arrhythmogenic dose of epinephrine (ADE), defined as 4 premature ventricular complexes (PVCs) within 15 s, was determined by administering progressively increasing infusion rates of epinephrine (2.5, 5.0, and 10 microg/kg/min), allowing 20 min intervals between each infusion rate. In both treatments, epinephrine infusions induced bradyarrhythmias and atrioventricular conduction disturbances, which were followed by escape beats and PVCs. In the remifentanil treatment, mean +/- s ADE values (11.3 +/- 4.9 microg/kg) did not differ from values observed in control animals (9.9 +/- 6.1 microg/kg). On the basis of the ADE model for assessing the arrhythmogenity of drugs during halothane anesthesia, the present study did not demonstrate a protective effect of remifentanil (0.72 microg/kg/min) against ventricular arrhythmias in dogs.

Antinociceptive effects of tramadol and acepromazine in cats.

Effects of tramadol and acepromazine on pressure and thermal thresholds were examined in eight cats. After baseline measurements, subcutaneous (SC) tramadol 1 mg/kg, acepromazine 0.1 mg/kg, tramadol 1 mg/kg with acepromazine 0.1 mg/kg, or saline 0.3 ml were given. Serial measurements were made for 24 h. Mean thermal thresholds did not change significantly [analysis of variance (ANOVA)] from baseline. The maximum thermal threshold increase above baseline was 2.8+/-2.8 degrees C at 6 h (P>0.05) after tramadol; it was above the 95% confidence interval (CI) at 0.75, 3 and 6 h. Pressure thresholds increased above baseline from 0.25 to 2 h after acepromazine (P<0.05) and from 0.5 to 3 h after the combination (P<0.05), with a maximum increase of 132+/-156 mmHg 0.25 h after acepromazine and 197+/-129 mmHg 0.5 h after the combination. Pressure thresholds were above the 95% CI from 0.25 to 2 h after acepromazine and from 0.5 to 3 h after the combination. SC tramadol at 1 mg/kg in cats had limited effect on thermal and pressure nociception, but this was enhanced by acepromazine. Acepromazine alone had pressure antinociceptive effects.

Effects of buprenorphine, carprofen and saline on thermal and mechanical nociceptive thresholds in cats.

OBJECTIVE: To evaluate a prototype pressure stimulus device for use in the cat and to compare with a known thermal threshold device. ANIMALS: Eight healthy adult cats weighing between 3.0 and 4.9 kg. METHODS: Pressure stimulation was given via a plastic bracelet taped around the forearm. Three 2.4 mm diameter ball bearings, in a 10-mm triangle, were advanced against the craniolateral surface of the antebrachium by manual inflation of a modified blood pressure bladder. Pressure in the cuff was recorded at the end point (leg shake and head turn). Thermal threshold was also tested. Stimuli were stopped if they reached 55 degrees C or 450 mmHg without response. After four pressure and thermal threshold baselines, each cat received SC buprenorphine 0.01 mg kg(-1), carprofen 4 mg kg(-1) or saline 0.3 mL in a three period cross-over study with a 1-week interval. The investigator was blinded to the treatment. Measurements were made at 0.25. 0.5, 0.75, 1, 2, 3, 4, 6, 8, and 24 hours after injection. Data were analyzed by using ANOVA. RESULTS: There were no significant changes in thermal or pressure threshold after administration of saline or carprofen, but thermal threshold increased from 60 minutes until 8 hours after administration of buprenorphine (p < 0.05). The maximum increase in threshold from baseline (DeltaT(max)) was 3.5 +/- 3.1 degrees C at 2 hours. Pressure threshold increased 2 hours after administration of buprenorphine (p < 0.05) when the increase in threshold above baseline (DeltaP(max)) was 162 +/- 189 mmHg. CONCLUSIONS AND CLINICAL RELEVANCE: This pressure device resulted in thresholds that were affected by analgesic treatment in a similar manner but to a lesser degree than the thermal method. Pressure stimulation may be a useful additional method for analgesic studies in cats.

Evaluation of adverse effects of long-term oral administration of carprofen, etodolac, flunixin meglumine, ketoprofen, and meloxicam in dogs.

OBJECTIVE: To evaluate adverse effects of long-term oral administration of carprofen, etodolac, flunixin meglumine, ketoprofen, and meloxicam in dogs. ANIMALS: 36 adult dogs. PROCEDURES: Values for CBC, urinalysis, serum biochemical urinalyses, and occult blood in feces were investigated before and 7, 30, 60, and 90 days after daily oral administration (n = 6 dogs/group) of lactose (1 mg/kg, control treatment), etodolac (15 mg/kg), meloxicam (0.1 mg/kg), carprofen (4 mg/kg), and ketoprofen (2 mg/kg for 4 days, followed by 1 mg/kg daily thereafter) or flunixin (1 mg/kg for 3 days, with 4-day intervals). Gastroscopy was performed before and after the end of treatment. RESULTS: For serum gamma-glutamyltransferase activity, values were significantly increased at day 30 in dogs treated with lactose, etodolac, and meloxicam within groups. Bleeding time was significantly increased in dogs treated with carprofen at 30 and 90 days, compared with baseline. At 7 days, bleeding time was significantly longer in dogs treated with meloxicam, ketoprofen, and flunixin, compared with control dogs. Clotting time increased significantly in all groups except those treated with etodolac. At day 90, clotting time was significantly shorter in flunixin-treated dogs, compared with lactose-treated dogs. Gastric lesions were detected in all dogs treated with etodolac, ketoprofen, and flunixin, and 1 of 6 treated with carprofen. CONCLUSIONS AND CLINICAL RELEVANCE: Carprofen induced the lowest frequency of gastrointestinal adverse effects, followed by meloxicam. Monitoring for adverse effects should be considered when nonsteroidal anti-inflammatory drugs are used to treat dogs with chronic pain.

Evaluation of the isoflurane-sparing effects of lidocaine and fentanyl during surgery in dogs.

OBJECTIVE: To evaluate the isoflurane-sparing effects of lidocaine and fentanyl administered by constant rate infusion (CRI) during surgery in dogs. DESIGN: Randomized prospective study. Animals-24 female dogs undergoing unilateral mastectomy because of mammary neoplasia. PROCEDURES: After premedication with acepromazine and morphine and anesthetic induction with ketamine and diazepam, anesthesia in dogs (n = 8/group) was maintained with isoflurane combined with either saline (0.9% NaCl) solution (control), lidocaine (1.5 mg/kg [0.68 mg/lb], IV bolus, followed by 250 microg/kg/min [113 microg/lb/min], CRI), or fentanyl (5 microg/kg [2.27 microg/lb], IV bolus, followed by 0.5 microg/kg/min [0.23 microg/lb/min], CRI). Positive-pressure ventilation was used to maintain eucapnia. An anesthetist unaware of treatment, endtidal isoflurane (ETiso) concentration, and vaporizer concentrations adjusted a nonprecision vaporizer to maintain surgical depth of anesthesia. Cardiopulmonary variables and ETiso values were monitored before and after beginning surgery. RESULTS: Heart rate was lower in the fentanyl group. Mean arterial pressure did not differ among groups after surgery commenced. In the control group, mean +/- SD ETiso values ranged from 1.16 +/- 0.35% to 1.94 +/- 0.96%. Fentanyl significantly reduced isoflurane requirements during surgical stimulation by 54% to 66%, whereas the reduction in ETiso concentration (34% to 44%) observed in the lidocaine group was not significant. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of fentanyl resulted in greater isoflurane sparing effect than did lidocaine. However, it appeared that the low heart rate induced by fentanyl may partially offset the improvement in mean arterial pressure that would be expected with reduced isoflurane requirements.