Retrospective computed tomography analysis of endotracheal tube constriction and mispositioning in cats and dogs.

OBJECTIVE: To discover the prevalence of endotracheal tube (ETT) constriction and rostral and caudal mispositioning in anaesthetized cats and dogs, and to identify associated risk factors. STUDY DESIGN: Retrospective analysis. ANIMALS: A total of 146 cats and 670 dogs. METHODS: Computed tomography images of the head/neck/thorax from orotracheally intubated cats and dogs were visually assessed for constriction or mispositioning of the ETT. If constriction was present, measurements of the cross-sectional area (CSA) of the ETT lumen at constricted and un-constricted locations were compared. Location and cause of constriction were noted and the expected increase in resistance to gas flow was calculated. Animal information was collected from clinical records. Normality of continuous variables was assessed via the Shapiro-Wilk test. Chi-square tests examined associations between variables. Kendall's tau-b test was performed between measured ETT size and degree of constriction. RESULTS: The ETT extended rostrally beyond incisors in 52% of cases; the connector was within the oral cavity in 19% of cases. The ETT extended beyond the first rib in 25.5% of cases. The prevalence of ETT constriction was 22.7%. Median reduction in CSA was 7.68% (0.14-64.19%). Median increase in resistance assuming laminar and turbulent flow was 16.5% (0.3-680%) and 21% (0.3-1200%), respectively. The most common cause of constriction was the presence of a radiotherapy mouth gag. Significant associations existed between presence of constriction and rostral mispositioning, and caudal mispositioning and extreme brachycephaly. Increased severity of constriction was more likely in smaller ETT. CONCLUSIONS AND CLINICAL RELEVANCE: Constriction and mispositioning of ETT occurred very commonly in this population. Checking the ETT within the oral cavity for constriction and mispositioning is recommended. Radiotherapy mouth gags increase the risk of ETT compression. Smaller ETT are at greater risk of severe constriction. Brachycephalic dogs are at particular risk of caudal mispositioning.

Investigating the effect of anxiety on pain scores in dogs.

OBJECTIVE: To investigate the relationship between anxiety and pain scores using the Glasgow Composite Measure Pain Scale-Short Form (CMPS-SF) in dogs. STUDY: Prospective observational study. ANIMALS: A group of 18 dogs undergoing surgical management of stifle disease. METHODS: Preoperatively dogs were scored using the CMPS-SF, the anxiety behaviour-based Reactivity Evaluation Form (REF), a Visual Analogue Scale (VAS) for anxiety and a sedation score. Assessments of pain, anxiety and sedation were repeated approximately 2-6 hours postoperatively. Dogs were divided into groups based on preoperative REF ('Low REF' and 'High REF'), and VAS scores ('Low VAS' and 'High VAS'). Scores (CMPS-SF, REF, VAS and sedation) were compared between groups using Mann-Whitney U tests. Preoperative and postoperative CMPS-SF, REF and VAS scores were compared using Wilcoxon signed-rank tests. Relationships between anxiety and CMPS-SF scores were assessed using a Spearman rank correlation coefficient. Scores are presented as median (range). A p value of < 0.05 was considered significant. RESULTS: When divided based on REF, CMPS-SF scores did not differ between groups preoperatively [Low REF: 2 (0-3), High REF: 2 (1-3); p = 0.509] or postoperatively [Low REF: 3 (2-5), High REF: 3 (2-5); p = 0.624]. When divided based on VAS, CMPS-SF scores did not differ between groups preoperatively [Low VAS: 2 (0-2), High VAS: 2 (1-3); p = 0.215] or postoperatively [Low VAS: 3 (2-5), High VAS: 3 (2-5); p = 1]. Postoperative REF [pre: 4.5 (2-8), post: 5 (4-10); p = 0.0105] and CMPS-SF scores [pre: 2 (0-3), post: 3 (2-5); p = 0.0318] increased significantly compared with preoperative scores. CONCLUSIONS AND CLINICAL RELEVANCE: No apparent relationship exists between baseline anxiety levels and CMPS-SF scores. Understanding the influence of anxiety when using the CMPS-SF is important when assessing pain in dogs. Anxiety and pain may increase postoperatively in dogs undergoing orthopaedic surgery.

The Short Form of the Glasgow Composite Measure Pain Scale in Post-operative Analgesia Studies in Dogs: A Scoping Review.

The measurement and treatment of acute pain in animals is essential from a welfare perspective. Valid pain-related outcome measures are also crucial for ensuring reliable and translatable findings in veterinary clinical trials. The short form of the Glasgow Composite Measure Pain Scale (CMPS-SF) is a multi-item behavioral pain assessment tool, developed and validated using a psychometric approach, to measure acute pain in the dog. Here we conduct a scoping review to identify prospective research studies that have used the CMPS-SF. We aim to describe the contexts in which it has been used, verify the correct use of the scale, and examine whether these studies are well-designed and adequately powered. We identify 114 eligible studies, indicating widespread use of the scale. We also document a limited number of modifications to the scale and intervention level, which would alter its validity. A variety of methods, with no consensus, were used to analyse data derived from the scale. However, we also find many deficiencies in reporting of experimental design in terms of the observers used, the underlying hypothesis of the research, the statement of primary outcome, and the use of a priori sample size calculations. These deficiencies may predispose to both type I and type II statistical errors in the small animal pain literature. We recommend more robust use of the scale and derived data to ensure success of future studies using the tool ensuring reliable and translatable outcomes.

Comparison between dexmedetomidine and acepromazine in combination with methadone for premedication in brachycephalic dogs undergoing surgery for brachycephalic obstructive airway syndrome.

OBJECTIVE: To compare dexmedetomidine with acepromazine for premedication combined with methadone in dogs undergoing brachycephalic obstructive airway syndrome (BOAS) surgery. STUDY DESIGN: Randomized, blinded clinical study. ANIMALS: A group of 40 dogs weighing mean (± standard deviation) 10.5 ± 6 kg, aged 2.6 ± 1.9 years. METHODS: Dogs received either acepromazine 20 µg kg-1 (group A) or dexmedetomidine 2 µg kg-1 (group D) intramuscularly with methadone 0.3 mg kg-1. Anaesthesia was induced with propofol and maintained with sevoflurane. Sedation (0-18), induction (0-6) and recovery (0-5) qualities were scored. Propofol dose, hypotension incidence, mechanical ventilation requirement, extubation time, additional sedation, oxygen supplementation, regurgitation and emergency intubation following premedication or during recovery were recorded. Data were analysed using t tests, Mann-Whitney U or Chi-square tests. RESULTS: Group A dogs were less sedated [median (range): 1.5 (0-12)] than group D [5 (1-18)] (p = 0.021) and required more propofol [3.5 (1-7) versus 2.4 (1-8) mg kg-1; p = 0.018]. Induction scores [group A: 5 (4-5); group D 5 (3-5)] (p = 0.989), recovery scores [group A 5 (4-5); group D 5(3-5)](p = 0.738) and anaesthesia duration [group A:93 (50-170); group D 96 (54-263) minutes] (p = 0.758) were similar between groups. Time to extubation was longer in group A 12.5 (3-35) versus group D 5.5 (0-15) minutes; (p = 0.005). During recovery, two dogs required emergency intubation (p > 0.99) and five dogs required additional sedation (p > 0.99). Oxygen supplementation was required in 16 and 12 dogs in group A and D, respectively (p = 0.167); no dogs in group A and one dog in group D regurgitated (p = 0.311). CONCLUSIONS AND CLINICAL RELEVANCE: Dexmedetomidine 2 µg kg-1 produces more sedation but similar recovery quality to acepromazine 20 µg kg-1 combined with methadone in dogs undergoing BOAS surgery.

Attitudes of dog owners in Edinburgh towards canine blood donation.

The establishment of animal blood banks following legislative changes in the UK in 2005 has led to increasing accessibility and use of animal blood products. However, the supply of animal blood is currently not meeting demand. This study aims to identify potential methods of increasing donor recruitment to meet this demand. A questionnaire was constructed, consisting of three sections designed to evaluate owner perceptions, identify incentives for donation and to obtain demographic data. Seventy-nine responses were included, 76 of which were previous non-donors. The top three reasons for not donating in this group were uncertainty over where to donate, veterinarians not expressing the need for donors and lack of awareness. Considering these results, one method of potentially increasing donor recruitment is encouraging more veterinarians to actively advertise local donor programmes. Emphasising the mandatory inclusion of a free annual health check in the donor process may also be helpful as many respondents rated this highly. It is the authors' hope that this preliminary data may lead to increased willingness of owners to nominate their dogs for donation by guiding the provision of appropriate incentives and education to quell owner concerns as highlighted by this study.

Effect of predosing versus slow administration of propofol on the dose required for anaesthetic induction and on physiologic variables in healthy dogs.

OBJECTIVE: To investigate the effects of the timing of propofol administration on the dose required for induction of anaesthesia and commonly measured physiological effects. STUDY DESIGN: Randomized, investigator-blinded clinical study. ANIMALS: A group of 32 healthy dogs aged 6-144 months and weighing 3.5-47.2 kg. METHODS: Premedication was intramuscular acepromazine (0.025 mg kg-1) and methadone (0.25 mg kg-1). After 30 minutes, one of three treatments was administered to the dogs: propofol (0.5 mg kg-1; group PP), an equivalent volume of saline (group CP) or a propofol infusion (1.3 mg kg-1 minute-1; group SI). Two minutes later, a propofol infusion (4 mg kg-1 minute-1) was started in PP and CP, whereas the propofol infusion was continued in SI. At this stage an investigator, blinded to the group assignments, entered the room and decided when each animal was ready for intubation and stopped the propofol infusion. After intubation, management of anaesthesia was standardized. Pulse rate (PR), respiratory rate (fR) and mean arterial pressure (MAP) were recorded before induction, 2 minutes later and 0, 2 and 5 minutes after intubation. Apnoea >30 seconds was recorded and managed. Sedation, quality of induction and endotracheal intubation were scored using simple descriptive scales. Data are presented as mean±standard deviation. RESULTS: Propofol dose requirement was lower in SI (3.5±1.2 mg kg-1) compared with PP and CP (5.0±0.9 and 4.8±0.6 mg kg-1; p=0.002 and 0.012), respectively. No statistically significant differences were found among groups for PR, fR, MAP or incidence of apnoea. Sedation score and quality of induction were similar among groups. CONCLUSIONS: Slow administration of propofol reduced the anaesthetic induction dose required compared with predosing and control groups. Effects on PR, fR, MAP and apnoea were similar among groups. CLINICAL RELEVANCE: Slower injection of propofol reduces the dose required for induction of anaesthesia.

Suspected bilateral phrenic nerve damage following a mediastinal mass removal in a 17-week-old pug.

The anesthetic management of a pediatric pug for removal of a mediastinal mass is described. During recovery from anesthesia, the dog's respiratory pattern was compatible with bilateral diaphragmatic paralysis. Incidence, complications, possible treatments of phrenic nerve injury, problems of long-term mechanical ventilation, and alternative case management are discussed.

Lésion bilatérale suspectée du nerf phrénique après l'ablation d'une masse médiastinale chez un Pug âgé de 17 semaines. Nous décrivons la gestion anesthésique d'un Pug pédiatrique présenté pour l'ablation d'une masse médiastinale. Durant le réveil après l'anesthésie, le profil respiratoire du chien était compatible avec la paralysie diaphragmatique bilatérale. L'incidence, les complications et les traitements possibles d'une blessure du nerf phrénique, les problèmes de la ventilation mécanique à long terme et les solutions pour la gestion du cas sont discutés.(Traduit par Isabelle Vallières).

Possible delayed respiratory depression following intrathecal injection of morphine and bupivacaine in an alpaca.

OBJECTIVE: To describe general anesthesia and successful treatment of an alpaca, which developed respiratory arrest 2 hours after intrathecal injection of morphine and bupivacaine. CASE SUMMARY: A 10-day-old female alpaca weighing 7.3 kg was presented to our hospital with a fractured right tibia. The cria was anesthetized to repair the fracture with a dynamic compression plate. Anesthesia was induced with IV propofol and maintained with sevoflurane in 100% oxygen. Prior to the start of surgery the alpaca received an unintended intrathecal injection of 0.6 mL of a solution of 0.5 mg morphine (0.068 mg/kg) and 1.5 mg bupivacaine (0.2 mg/kg), after an attempted lumbo-sacral epidural. The alpaca developed respiratory arrest 120 minutes after the intrathecal injection was administered. Adequate hemoglobin-oxygen saturation was maintained despite minimal intermittent manual ventilation, but marked hypercapnia developed (PaCO2 of 17.3 KPa [130 mm Hg]). Delayed respiratory depression resulting from cephalad migration of intrathecal morphine was suspected. Ventilation was supported until the end of surgery when sevoflurane was discontinued. The trachea remained intubated, 100% oxygen was supplied, and ventilation was supported at 2-4 breaths/min for the next 60 minutes, but no attempts to breathe spontaneously were detected. Intravenous naloxone (0.3 mg [0.04 mg/kg]) was administered slowly to effect until adequate spontaneous ventilation and full consciousness returned. The anesthetic recovery of the alpaca was rapid and uneventful after the opioid antagonist was given. NEW INFORMATION PROVIDED: Delayed respiratory depression is a potential complication after intrathecal administration of morphine. Careful dose-adjustment may reduce the risk, and close monitoring will result in early detection and treatment of this complication.

Anaesthetic complications in pigs undergoing MRI guided convection enhanced drug delivery to the brain: a case series.

OBSERVATIONS: A total of 13 intracerebral infusions were performed at approximately 1 month intervals in three NIH miniature pigs over the age range of 31-59 weeks. Pigs received azaperone and ketamine premedication to allow venous cannulation and propofol induction of anaesthesia. Anaesthesia was maintained with isoflurane throughout cranial surgery and MRI scanning. Physiological monitoring during surgery consisted of blood pressure, pulse, temperature and oxygen saturation monitoring, ECG and capnography. Analgesia consisted of meloxicam and morphine. However, during MRI scanning blood pressure and ECG monitoring had to be discontinued. Anaesthetized pigs underwent intermittent intraputamenal convection enhanced delivery (CED) of gadolinium with real-time magnetic resonance imaging. Progressive tachycardia was consistently observed in all pigs during CED with a mean ± SD maximum increase of 41 ± 22 beats minute(-1) from a baseline heart rate of 96 ± 9 minute(-1) . The heart rate remained elevated until recovery. A mean reduction in body temperature of 2.8 ± 0.6 °C from the start of anaesthesia was also observed during the period of MRI scanning. All pigs recovered from anaesthesia smoothly and heart rates returned to normal during the recovery period. CONCLUSIONS: Hypothermia is common in pigs undergoing this sedation and anaesthesia protocol. Convection enhanced delivery of drugs in healthy anaesthetized pigs may result in tachycardia.

Comparison of direct and Doppler arterial blood pressure measurements in rabbits during isoflurane anaesthesia.

OBJECTIVE: To measure the level of agreement between Doppler measured (DOP) arterial blood pressure (ABP) in the forelimb and directly measured (DIR) auricular systolic ABP (SAP) and mean ABP (MAP) in isoflurane-anaesthetized rabbits. STUDY DESIGN: Prospective clinical study. ANIMALS: Data were analysed from 17 of 24 healthy rabbits, weighing 1.3-2.8 kg. METHODS: Rabbits were anaesthetized for neutering using a standardized protocol. A 26G catheter placed in an auricular artery was connected via heparinised saline filled non-compliant tubing (regularly flushed) to a calibrated pressure transducer (zeroed level with the thoracic inlet) to obtain DIR ABP. A cuff was placed proximal to the carpus (approximately level with the thoracic inlet) and a Doppler transducer sited over the dorsal carpal branch of the radial artery to obtain DOP ABP. Simultaneous DIR and DOP ABP recordings were made every 5-10 minutes during anaesthesia. Agreement was assessed as described by Bland JM & Altman (2007). RESULTS: Mean ± SD cuff width: limb circumference ratio was 0.50 ± 0.04. Mean between-method differences ± SD, DIR SAP- DOP and DIR MAP- DOP, were +1 ± 8 and -13 ± 8 mmHg respectively. The 95% limits of agreement between DIR SAP and DOP and between DIR MAP and DOP were -14 to +17 and -28 to +2 mmHg respectively. Differences between DIR SAP and DOP were ≤ 10 mmHg 85% of the time. Defining hypotension as either DIR SAP < 80 mmHg or DIR MAP < 60 mmHg, and taking DOP ABP of <80 mmHg to indicate hypotension, sensitivity and specificity were 92% and 67% respectively. CONCLUSIONS: Good agreement was found between DIR SAP and DOP. Doppler measurements below 80 mmHg are a reliable indicator of arterial hypotension. CLINICAL RELEVANCE: DOP is acceptable for monitoring ABP in isoflurane-anaesthetized rabbits and is useful for detection of hypotension.

Fentanyl or midazolam for co-induction of anaesthesia with propofol in dogs.

OBJECTIVE: Propofol may cause adverse effects (e.g. apnoea, hypotension) at induction of anaesthesia. Co-induction of anaesthesia may reduce propofol requirements. The effect of fentanyl or midazolam on propofol dose requirements and cardiorespiratory parameters was studied. STUDY DESIGN: Randomized, controlled, blinded clinical study. ANIMALS: Sixty-six client owned dogs (35 male, 31 female, ASA I-II, age 6-120 months, body mass 4.7-48.0 kg) were selected. METHODS: Pre-medication with acepromazine (0.025 mg kg(-1)) and morphine (0.25 mg kg(-1)) was administered by intramuscular injection. After 30 minutes group fentanyl-propofol (FP) received fentanyl (2 microg kg(-1)), group midazolam-propofol (MP) midazolam (0.2 mg kg(-1)) injected over 30 seconds via a cephalic catheter and in a third group, control-propofol (CP), the IV catheter was flushed with an equivalent volume of heparinized saline. Anaesthesia was induced 2 minutes later, with propofol (4 mg kg(-1)minute(-1)) administered to effect. After endotracheal intubation anaesthesia was maintained with a standardized anaesthetic protocol. Pulse rate, respiratory rate (RR) and mean arterial pressure (MAP) were recorded before the co-induction agent, before induction, and 0, 2 and 5 minutes after intubation. Apnoea >or=30 seconds was recorded and treated. Sedation after pre-medication, activity after the co-induction agent, quality of anaesthetic induction and endotracheal intubation were scored. RESULTS: Propofol dose requirement was significantly reduced in FP [2.90 mg kg(-1)(0.57)] compared to CP [3.51 mg kg(-1) (0.74)] and MP [3.58 mg kg(-1)(0.49)]. Mean pulse rate was higher in MP than in CP or FP (p = 0.003). No statistically significant difference was found between groups in mean RR, MAP or incidence of apnoea. Activity score was significantly higher (i.e. more excited) (p = 0.0001), and quality of induction score was significantly poorer (p = 0.0001) in MP compared to CP or FP. Intubation score was similar in all groups. CONCLUSIONS AND CLINICAL RELEVANCE: Fentanyl decreased propofol requirement but did not significantly alter cardiovascular parameters. Midazolam did not reduce propofol requirements and caused excitement in some animals.

A comparison of ketamine-midazolam and ketamine-medetomidine combinations for induction of anaesthesia in rabbits.

OBJECTIVE: To compare ketamine-midazolam (KMZ) and ketamine-medetomidine (KMT) anaesthesia in rabbits using anaesthetic induction, maintenance and recovery data. STUDY DESIGN: Randomized, prospective, blinded clinical trial. ANIMALS: Fifty rabbits (25 male, 25 female) of different breeds undergoing ovariohysterectomy or castration. Rabbits were 12.7 +/- 9.8 months old with body mass 2.24 +/- 0.61 kg. STUDY DESIGN: Randomized, prospective, blinded clinical trial. METHODS: Ketamine (15 mg kg(-1)) and midazolam (3 mg kg(-1)) or medetomidine (0.25 mg kg(-1)) were administered by intramuscular (IM) injection. Ten minutes after IM injection, blind intubation of the trachea was attempted. The time taken, the number of attempts and a subjective score of the ease of intubation were recorded. Isoflurane (range 0-3.6%) in 100% oxygen was delivered via a Jackson Rees modification of an Ayre's T-piece non-rebreathing system. Carprofen (3 mg kg(-1)) and dextrose saline (5 mL kg(-1) hour(-1)) were administered intravenously (IV). During surgery heart rate (HR), respiratory rate (RR) and arterial oxygen saturation of haemoglobin (SpO(2)) were monitored. Times to extubation and first head lift were recorded. Group KMT received atipamezole (0.5 mg kg(-1)) IM 30 minutes after discontinuation of isoflurane. Activity was scored at 30, 60 and 120 minutes after volatile agent discontinuation. Mean time to loss of righting reflex (LRR), body mass, RR and vaporizer setting were compared using a two-tailed t-test. Median values for all other data were compared using a Mann-Whitney test. RESULTS: Mean time to LRR (+/-SD) was significantly shorter with KMT (1.64 +/- 0.55 minutes) compared with KMZ (2.28 +/- 0.66 minutes). Intubation was not possible in seven rabbits (three with KMT, four with KMZ) and three with KMT developed laryngospasm. Mean HR, SpO(2) and vaporizer settings were all significantly lower in group KMT. CONCLUSION AND CLINICAL RELEVANCE: KMT has a faster onset of action and a greater isoflurane-sparing effect when compared with KMZ. Rabbits with KMT were more prone to laryngospasm and had significantly lower HR.

Peri-operative body temperatures in isoflurane-anaesthetized rabbits following ketamine-midazolam or ketamine-medetomidine.

OBJECTIVE: To investigate alterations in peri-operative body temperatures and oesophageal-skin temperatures in isoflurane-anaesthetized rabbits following either ketamine-midazolam or ketamine-medetomidine induction of anaesthesia. ANIMAL POPULATION: Fifty client-owned rabbits, (25 male, 25 female) of different breeds anaesthetized for elective neutering (age range: 3-42 months; mass range: 1.15-4.3 kg). STUDY DESIGN: Randomized, blinded clinical study. METHODS: Pre-anaesthetic rectal temperature was measured. A 24 SWG catheter was placed in a marginal ear vein after local anaesthesia. Ketamine (15 mg kg(-1)) with medetomidine (0.25 mg kg(-1)) (group KMT) or with midazolam (3 mg kg(-1)) (group KMZ) was injected intramuscularly (IM). Following endotracheal intubation anaesthesia was maintained with isoflurane in oxygen. Carprofen (3 mg kg(-1)) and glucose saline (5 mL kg(-1) hour(-1)) were administered through the intravenous catheter. Room temperature and humidity, skin temperature (from tip of pinna) and oesophageal temperature were measured during anaesthesia. Ovariohysterectomy or castration was performed. Rectal temperature was taken when isoflurane was discontinued (time zero) and 30, 60 and 120 minutes thereafter. Atipamezole (0.5 mg kg(-1)) was administered IM to rabbits in group KMT at zero plus 30 minutes. Mass, averaged room temperature and duration of anaesthesia data were compared using a two-tailed t-test. Age, averaged room humidity, rectal temperature decrease, oesophageal temperature decrease and oesophageal-skin difference data were compared using a Kruskal-Wallis test. p < 0.05 was considered significant. RESULTS: The averaged oesophageal-skin temperature difference was significantly greater in group KMT [median 9.85 degrees C (range 6.42-13.85 degrees C)] than in group KMZ [4.38 degrees C (2.83-10.43 degrees C)]. Rectal temperature decreased over the anaesthetic period was not significantly different between the two groups; however, oesophageal temperature decrease was significantly less in group KMT [1.1 degrees C (-0.1-+2.7 degrees C)] than in group KMZ [1.4 degrees C (0.6-3.1 degrees C)]. CONCLUSIONS: Oesophageal-skin temperature difference is larger in rabbits anaesthetized with ketamine-medetomidine combination than ketamine-midazolam. CLINICAL RELEVANCE: The oesophageal temperature in rabbits anaesthetized with ketamine-medetomidine and isoflurane decreases significantly less than in animals anaesthetized with ketamine-midazolam and isoflurane, during anaesthesia.

A comparison between pre-operative carprofen and a long-acting sufentanil formulation for analgesia after ovariohysterectomy in dogs.

OBJECTIVE: To assess the analgesic efficacy and adverse effects of a novel, long-acting sufentanil preparation in dogs undergoing ovariohysterectomy (OHE). STUDY DESIGN: Blinded, positively controlled, randomized field trial with four parallel treatment groups. ANIMALS: Eighty client owned dogs undergoing elective OHE randomly allocated into four treatment groups (each n = 20). MATERIALS AND METHODS: Three groups received intramuscular (IM) sufentanil (at 10, 15 and 25 microg kg(-1), respectively) and the control group received subcutaneous (SC) carprofen 4 mg kg(-1) SC plus acepromazine 0.05 mg kg(-1) IM as pre-anaesthetic medication. OHE was performed under thiopental/halothane anaesthesia. Visual Analogue Scale (VAS) scores for pain and sedation were awarded and mechanical nociceptive thresholds were measured at the wound and hock before surgery and up to 24 hours after tracheal extubation. Serum cortisol was measured before surgery, during surgery and up to 24 hours after tracheal extubation. Animals with inadequate post-operative analgesia were given rescue medication. RESULTS: In the carprofen group, VAS pain scores were significantly higher, wound tenderness was greater and requirement for rescue analgesia was more than in the sufentanil-treated groups. Sufentanil produced dose dependent analgesia and sedation. All treatment groups showed similar patterns of change for cortisol concentrations. Use of the sufentanil preparation was associated with a relatively high incidence of adverse events. CONCLUSIONS: The long-acting preparation of sufentanil provided excellent post-operative analgesia that was significantly better than that provided by carprofen. However, use of this formulation, in the anaesthetic technique used in the study, resulted in a relatively high incidence of adverse effects. CLINICAL RELEVANCE: Full mu (MOP) opioid agonists provide significantly better post-operative analgesia than nonsteroidal anti-inflammatory drugs after moderately painful surgery. However, the widely recognized adverse effects of opioids may preclude the use of these agents.

Morphine administration in horses anaesthetized for upper respiratory tract surgery.

OBJECTIVE: To determine the effect of morphine administration on commonly monitored cardio-respiratory variables and recovery quality in horses undergoing anaesthesia and surgery. STUDY DESIGN: Prospective, randomized clinical study. ANIMALS: Thirty-eight thoroughbred horses, 32 geldings and six mares, 3-13 years old, weighing 411-600 kg. MATERIALS AND METHODS: A standard anaesthetic technique was used. Twenty minutes after induction of anaesthesia horses received 0.1 mg kg(-1) (0.1 m) or 0.2 mg kg(-1) (0.2 m) morphine by intravenous injection. A control group did not receive morphine. Heart rate, respiratory rate (fr), mean arterial pressure (MAP) and blood gases were measured before morphine administration and every 10 minutes thereafter. Horses were positioned for 35 minutes in right lateral recumbency for tension palatoplasty by cautery and were then moved into dorsal recumbency for additional intraluminal surgery comprising one or more of aryepiglottic fold resection, sub-epiglottal mucosal resection, ventriculectomy and cordectomy. A subjective recovery score from 0 (worst) to 5 (best) was assigned by a single observer who was unaware of treatment group. Two-way repeated measures anova, one-way anova, Kruskal-Wallis test, Mann-Whitney test, Pearson and Spearman correlation coefficients, and chi-squared tests were used to analyse the data where appropriate. RESULTS: Arterial partial pressure of oxygen (PaO(2)) decreased significantly over time and was significantly lower in horses that received morphine. One horse in the control group and two horses in each of the morphine groups had a PaO(2) <13 kPa. No other significant cardiopulmonary effects were detected. Recovery scores [median (range)] were higher in morphine recipients: 4 (2-5) in 0.1 m, 4 (3-5) in 0.2 m compared with 3 (2-4) in the control group. CONCLUSIONS AND CLINICAL RELEVANCE: The lower PaO(2) in morphine recipients did not appear to be of clinical significance in healthy horses because the number of horses with a low PaO(2) was similar between groups. The quality of recovery was significantly better in morphine recipients. These results indicate that morphine may be considered for use in clinical cases although further work is required to assess the analgesic properties of the drug in this species.

Assessment of the influence of surgical technique on postoperative pain and wound tenderness in cats following ovariohysterectomy.

Elective ovariohysterectomy was performed on 66 cats. Surgical approach was flank (group F) or midline (group M) allocated by block randomisation. Pre-anaesthetic medication was acepromazine (0.1 mg/kg) via intramuscular injection. Anaesthesia was induced with intravenous thiopentone, and maintained with halothane in 100% oxygen. Carprofen (4 mg/kg) was administered by the subcutaneous route immediately after induction of anaesthesia. Postoperative pain and wound tenderness were assessed at 1, 3, 6, 9, 11-12 and 20-24h after the end of surgery, and the assessment outcome marked on visual analogue scales (VAS). Intervention analgesia (if pain VAS was >40 mm) was pethidine 4 mg/kg via intramuscular injection. Area under the curve (AUC) for VAS for pain and VAS for wound tenderness for each cat were calculated. AUC for wound tenderness was significantly greater for group F (P = 0.007). There was no significant difference for AUC for pain between the groups. In conclusion, wounds after flank ovariohysterectomy are significantly more tender than after midline ovariohysterectomy in the cat. This indicates that interactive methods, including wound palpation, must be used to assess postoperative pain and the findings should be appropriately weighted in the overall assessment.