Pharmacokinetics of intra-articular buprenorphine in horses with lipopolysaccharide-induced synovitis.

The objective of this study was to describe the pharmacokinetics of intra-articular (IA) administered buprenorphine in horses with lipopolysaccharide (LPS)-induced synovitis. Radiocarpal synovitis was induced in six healthy adult horses with the IA injection of LPS (0.5 ng/joint) on two occasions in a randomized cross-over design. Treatments (IA buprenorphine (IAB) at 5 µg/kg plus intravenous saline; and intravenous buprenorphine (IVB) at 5 µg/kg plus IA saline) were administered 4 h following LPS injection. Concentrations of buprenorphine were assessed in plasma and synovial fluid (SF) at 0.5, 2, 6, 12, and 24 h after administration. Pharmacokinetic parameters after IVB and IAB in plasma and synovial fluid were calculated using a nonlinear mixed effects model. IAB was detectable in SF of all horses at 24 h [median concentration of 6.2 (3.46-22.6) ng/mL]. IAB resulted in a median plasma concentration of 0.59 (0.42-1.68) ng/mL at 0.5 h and was detectable in all subjects for up to 6 h and in two horses for up to 12 h. IVB resulted in SF concentrations detected up to 6 h in all horses [median concentration of 0.12 (0.07-0.82) ng/mL]. Results suggest that IA buprenorphine remains present in the inflamed joint for at least 24 h and systemic absorption occurs.

Buprenorphine has a concentration-dependent cytotoxic effect on equine chondrocytes in vitro.

OBJECTIVE: To investigate the cytotoxic effects of 2 different concentrations of buprenorphine and compare them with bupivacaine and morphine on healthy equine chondrocytes in vitro. SAMPLE: Primary cultured equine articular chondrocytes from 3 healthy adult horses. PROCEDURES: Chondrocytes were exposed for 0 and 2 hours to the following treatments: media (CON; negative control); bupivacaine at 2.2 mg/mL (BUPI; positive control); morphine at 2.85 mg/mL (MOR); buprenorphine at 0.12 mg/mL (HBUPRE); or buprenorphine at 0.05 mg/mL (LBUPRE). Chondrocyte viability was assessed using live/dead staining, water-soluble tetrazolium salt-8 (WST-8) cytotoxic assay, LDH assay, and flow cytometry. All continuous variables were evaluated with a mixed ANOVA with treatment, time, and their interactions as the fixed effects and each horse as the random effect. RESULTS: Buprenorphine showed a concentration-dependent chondrotoxic effect. The viability of chondrocytes was significantly decreased with exposure to HBUPRE and BUPI compared to CON, MOR, and LBUPRE. CLINICAL RELEVANCE: Negligible chondrotoxic effects were observed in healthy cultured equine chondrocytes exposed to 0.05 mg/mL of buprenorphine, whereas higher concentrations (0.12 mg/mL) showed a marked cytotoxic effect. Based on these results, low concentrations of buprenorphine appear to be safe for intra-articular administration. Further evaluation of this dose in vivo is needed before recommending its clinical use.

Comparison of blind and endoscopic-guided orotracheal intubation on laryngeal and tracheal damage in domestic rabbits (Oryctolagus cuniculus).

OBJECTIVE: To compare blind and endoscopic-guided techniques for orotracheal intubation in rabbits and the number of intubation attempts with laryngeal/tracheal damage. STUDY DESIGN: Prospective, randomized experimental study. ANIMALS: A total of 24 healthy, intact female New Zealand White rabbits, weighing 2.2 ± 0.2 kg (mean ± standard deviation). METHODS: Rabbits were randomly assigned to blind (group B) or endoscopic-guided (group E) orotracheal intubation with a 2.0 mm internal diameter uncuffed tube. Intramuscular (IM) alfaxalone (7 mg kg-1), hydromorphone (0.1 mg kg-1) and dexmedetomidine (0.005 mg kg-1) were administered, and additional IM alfaxalone (3-5 mg kg-1) and dexmedetomidine (0.025 mg kg-1) were administered to rabbits with strong jaw tone. An intubation attempt was defined as the advancement of the endotracheal tube from the incisors to the laryngeal entrance. Tracheal intubation was confirmed via capnography and anesthesia was maintained with isoflurane for 2 hours. Following euthanasia, laryngeal and tracheal tissues were submitted for histopathology. Quality of anesthesia for orotracheal intubation, intubation procedure and tissue damage were numerically scored. Data were analyzed using Poisson regression, Spearman's correlation, t test, mixed anova, Mann-Whitney U test, Friedman and Chi square tests as appropriate. RESULTS: Median (range) intubation attempts were 2 (1-8) and 1 (1-3) for groups B and E, respectively. More rabbits in group E (91.6%) required additional alfaxalone and dexmedetomidine than in group B (16.7%). Median (range) cumulative histopathology scores were 6 (3-10) and 6 (2-9) for groups B and E, respectively. Scores were highest in the cranial trachea, but there was no difference between groups and no correlation between laryngeal/tracheal damage and the number of intubation attempts. CONCLUSIONS AND CLINICAL RELEVANCE: Both orotracheal intubation techniques were associated with laryngeal/tracheal damage. Although blind orotracheal intubation was associated with a higher number of attempts, the tissue damage was similar between groups.

Assessment of intramuscular administration of three doses of alfaxalone combined with hydromorphone and dexmedetomidine for endoscopic-guided orotracheal intubation in domestic rabbits (Oryctolagus cuniculus).

OBJECTIVE: To determine the dose of alfaxalone for IM administration combined with dexmedetomidine and hydromorphone that would allow endoscopic-guided orotracheal intubation in rabbits without causing a decrease in respiratory rate or apnea. ANIMALS: 15 sexually intact (9 females and 6 males) healthy Miniature Lop rabbits weighing a mean ± SD of 2.3 ± 0.3 kg and ranging in age from 4 to 9 months. PROCEDURES: In a randomized, controlled clinical trial, rabbits received 0.1 mg of hydro-morphone/kg and 0.005 mg of dexmedetomidine/kg, plus alfaxalone at either 2 mg/kg (5 rabbits), 5 mg/kg (5 rabbits), or 7 mg/kg (5 rabbits). Drugs were mixed in a single syringe and administered IM. Semiquantitative rating scales were used to evaluate quality of anesthesia and intubation. Orotracheal intubation was attempted with endoscopy and confirmed by capnography. RESULTS: The number of successful intubations was 0, 3, and 4 in rabbits receiving 2, 5, and 7 mg of alfaxalone/kg, respectively. Median (range) anesthesia quality scores (scale, 0 to 12; 12 = deepest anesthesia) were 3 (2 to 5), 6 (5 to 6), and 6 (4 to 9) for rabbits receiving 2, 5, and 7 mg of alfaxalone/kg, respectively. The median (range) intubation quality scores (scale, 0 to 3 [ie, intubation not possible to easiest intubation]) were 0 (0 to 0), 2 (0 to 3), and 2 (0 to 3) for rabbits receiving 2, 5, and 7 mg of alfaxalone/kg, respectively. None of the rabbits experienced a decrease in respiratory rate or apnea. CONCLUSIONS AND CLINICAL RELEVANCE: Increasing doses of alfaxalone combined with hydromorphone and dexmedetomidine increased the success rate of endoscopic-guided orotracheal intubation. Increasing the dose of alfaxalone had no effect on respiratory rate.

Intraocular pressure following four different intravenous sedation protocols in normal horses.

BACKGROUND: Intravenous sedation is frequently necessary for ophthalmic examination in horses. Common sedation protocols have not been directly compared in terms of relative intraocular pressure (IOP) reduction, duration of IOP reduction and time to maximum IOP reduction. OBJECTIVES: To compare the effects of standing sedation protocols on IOP. STUDY DESIGN: Randomised cross-over experiment. METHODS: Twelve healthy horses received four intravenous sedation protocols with a 48 hours washout: 0.5 mg/kg xylazine and 0.01 mg/kg butorphanol (SED1); 10 µg/kg detomidine and 0.01 mg/kg of butorphanol (SED2); 10 µg/kg detomidine (SED3); 0.5 mg/kg xylazine (SED4). IOP was measured with rebound tonometry before sedation (Tpre) and 5, 10, 15, 30, 45 and 60 minutes post-sedation (Tpost). Post-sedation readings were taken with the head elevated to the Tpre position. Separately, IOP readings were also obtained following sedation with the head not elevated (TpostHeadDown). IOP values were compared using mixed ANOVA and ANCOVA models respectively with significance at P < .05. RESULTS: All protocols decreased IOP compared with baseline with greatest reduction at Tpost5. IOP at Tpre (mean ± SD) was 21.8 ± 4.4 mm Hg. At Tpost5, IOP was 16.3 ± 3.8 mm Hg (SED1), 14.5 ± 2.9 mm Hg (SED2), 17.1 ± 3.8 mm Hg (SED3) and 16.9 ± 4.2 mm Hg (SED4). SED2 Tpost5 IOP was lower than other treatments. Considering all time points following sedation, SED3 IOP readings were higher than other treatments. TpostHeadDown IOPs were higher than readings taken with the head elevated (P < .001). MAIN LIMITATIONS: Animals with ocular disease were not studied. No animals received mock sedation or equivalent. CONCLUSIONS: A combination of detomidine and butorphanol causes greater IOP reduction 5 minutes following sedation than other commonly used sedation protocols. IOP reduction is less pronounced when detomidine is used alone. Consideration of head height is important when performing IOP measurements in horses.

Effect of multiple head positions on intraocular pressure in healthy, anesthetized horses during hoisting.

OBJECTIVE: To evaluate changes in intraocular pressure (IOP) with variable head position in healthy, anesthetized horses in hoisted inversion and to assess the influence of various cofactors (age, sex, body weight, body condition score, and neck length) on IOP changes during hoisting. ANIMALS STUDIED: Seventeen healthy adult horses without significant ocular abnormalities. PROCEDURES: Subjects were administered intravenous xylazine/butorphanol premedication and ketamine/midazolam induction with xylazine/ketamine boluses for anesthetic maintenance. While hoisted, IOP was measured in triplicate for each eye via rebound tonometry (TonoVet) at neutral head position (ie, eyes level with the withers), at multiple 5 cm increments above and below neutral (-20 cm through +20 cm) using foam pads for head support, and with eyes above heart level via manual support. RESULTS: In hoisted positions, IOP ranged from 18 to 51 mmHg. Intraocular pressure significantly decreased with head position elevated ≥+15 cm from neutral and significantly increased when lowered ≤-5 cm from neutral. Neck length significantly influenced IOP (P = .0328) with linear regression indicating a median (range) increase of 0.244 (0.034-0.425) mmHg in IOP for every 1 cm increase in neck length. Age, sex, breed, body weight, body condition score, and eye (OD vs OS) did not significantly influence IOP. Intraocular pressure only varied significantly between eyes at +10 cm above neutral (OS > OD, 1.7 ± 0.6 mm Hg, P = .0044). CONCLUSIONS: Intraocular pressure in healthy, anesthetized horses varies with head position during hoisting; increased neck length may be associated with larger changes in IOP during hoisting.

Effects of a priming dose of alfaxalone on the total anesthetic induction dose for and cardiorespiratory function of sedated healthy cats.

OBJECTIVE: To investigate the effects of a priming dose of alfaxalone on the total anesthetic induction dose for and cardiorespiratory function of sedated healthy cats. ANIMALS: 8 healthy adult cats. PROCEDURES: For this crossover study, cats were sedated with dexmedetomidine and methadone administered IM. Cats next received a priming induction dose of alfaxalone (0.25 mg/kg, IV) or saline (0.9% NaCl) solution (0.025 mL/kg, IV) over 60 seconds and then an induction dose of alfaxalone (0.5 mg/kg/min, IV) until orotracheal intubation was achieved. Cardiorespiratory variables were recorded at baseline (immediately prior to priming agent administration), immediately after priming agent administration, after orotracheal intubation, and every 2 minutes until extubation. The total induction dose of alfaxalone was compared between the 2 priming agents. RESULTS: Mean ± SD total anesthetic induction dose of alfaxalone was significantly lower when cats received a priming dose of alfaxalone (0.98 ± 0.28 mg/kg), compared with when cats received a priming dose of saline solution (1.41 ± 0.17 mg/kg). Mean arterial blood pressure was significantly higher when alfaxalone was used as the priming dose. No cats became apneic or had a hemoglobin oxygen saturation of < 90%. Expired volume per minute was not significantly different between the 2 priming agents. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of a priming dose of alfaxalone to healthy sedated cats reduced the total dose of alfaxalone needed to achieve orotracheal intubation, maintained mean arterial blood pressure, and did not adversely impact the measured respiratory variables.

Validation of the oscillometric blood pressure monitor Vet20 SunTech in anesthetized healthy cats.

OBJECTIVE: To evaluate a veterinary-specific oscillometric noninvasive blood pressure (NIBP) system according to the guidelines of the American College of Veterinary Internal Medicine (ACVIM) Consensus Statement. STUDY DESIGN: Prospective clinical study. ANIMALS: A total of 33 client-owned cats (20 females and 13 males). METHODS: Cats were premedicated with methadone (0.3 mg kg-1) and alfaxalone (2 mg kg-1) intramuscularly. After 15 minutes anesthesia was induced with isoflurane (3%) in 100% oxygen by facemask while breathing spontaneously. A 22 gauge catheter was placed in the median caudal artery and systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressures were measured. NIBP measurements were collected by placing the cuff (40% of limb circumference) on the right or left antebrachium. The agreement between the two methods was evaluated with the Bland-Altman methods, and the oscillometric NIBP device was evaluated using the ACVIM guidelines for validation of devices. RESULTS: Data from 30 of the 33 cats were analyzed. Five paired measurements were taken from each cat, totaling 150 paired measurements. Mean bias (limits of agreements) for SAP, DAP and MAP were 2.7 (-22.7 to 28.1), 0.9 (-22.3 to 24.2) and 1.3 (-20.4 to 23.0). The oscillometric NIBP passed all validation criteria, except correlation which was <0.9 for SAP, DAP and MAP. CONCLUSIONS AND CLINICAL RELEVANCE: The Vet20 did not meet all validation criteria by the ACVIM. However, all criteria except correlation were met.

Sedative and cardiorespiratory effects of intramuscular administration of alfaxalone and butorphanol combined with acepromazine, midazolam, or dexmedetomidine in dogs.

OBJECTIVE: To evaluate the sedative and cardiorespiratory effects of IM administration of alfaxalone and butorphanol combined with acepromazine, midazolam, or dexmedetomidine in dogs. ANIMALS: 6 young healthy mixed-breed hounds. PROCEDURES: Dogs received each of 3 treatments (alfaxalone [2 mg/kg] and butorphanol [0.4 mg/kg] combined with acepromazine [0.02 mg/kg; AB-ace], midazolam [0.2 mg/kg; AB-mid], or dexmedetomidine [0.005 mg/kg; AB-dex], IM) in a blinded, randomized crossover-design study with a 1-week washout period between treatments. Sedation scores and cardiorespiratory variables were recorded at predetermined time points. Data were analyzed by use of mixed-model ANOVA and linear generalized estimating equations with post hoc adjustments. RESULTS: All treatments resulted in moderate to deep sedation (median score, ≥ 15/21) ≤ 5 minutes after injection. Sedation scores did not differ among treatments until the 40-minute time point, when the score was higher for AB-dex than for other treatments. Administration of AB-dex resulted in median scores reflecting deep sedation until 130 minutes, versus 80 and 60 minutes for AB-ace and AB-mid, respectively, after injection. Heart rate, cardiac output, and oxygen delivery decreased significantly after AB-dex, but not AB-ace or AB-mid administration. Respiratory variables remained within clinically acceptable ranges after all treatments. Undesirable recovery characteristics were observed in 4 dogs after AB-mid treatment. Four dogs required atipamezole administration 180 minutes after AB-dex injection. CONCLUSIONS AND CLINICAL RELEVANCE: All protocols produced reliable sedation. The results indicated that in young, healthy dogs, AB-mid may produce undesirable recovery characteristics; AB-dex treatment caused cardiovascular depression and should be used with caution.

Effect of Cranial Flexion of Pelvic Limbs on Interlaminar Length of the Lumbosacral Space in Sternally and Laterally Recumbent Juvenile Duroc and Adult Yucatan Pigs.

Epidural puncture in swine is technically challenging. Several combinations of limb and body positions have been suggested to increase lumbosacral interlaminar space (LSS) and lumbosacral angle (LSA). This study investigated whether cranial hyperflexion of pelvic limbs increased LSS and LSA in laterally and sternally recumbent juvenile Duroc and adult Yucatan pigs and assessed which position produced the largest LSS. Juvenile Duroc (n = 7) and adult Yucatan (n = 7) pigs were euthanized and randomly placed in 4 positions: sternal with neutral limbs, sternal with cranially hyperflexed limbs, lateral with neutral limbs, and lateral with hyperflexed limbs. LSS and LSA were measured on transverse axial CT images of the spine and compared by using multivariate ANOVA and the Student t test. In both age groups, LSS was greater in lateral flexed (juvenile, 7.0 ± 0.7 mm; adult, 15.9 ± 1.1 mm) and sternal flexed (juvenile, 7.5 ± 1 mm; adult, 17.1 ± 1.1 mm) positions than in lateral neutral (juvenile, 5.4 ± 0.9 mm; adult, 9.6 ± 1.6 mm) position. In addition, in both age groups, LSS and LSA in lateral neutral position were smaller than lateral flexed, sternal neutral, and sternal flexed positions. In adults, LSS was greater in lateral flexed and sternal flexed than in sternal neutral position. Hyperflexion of pelvic limbs increases LSS and LSA in sternally recumbent adult Yucatan pigs and laterally recumbent adult Yucatan and juvenile Duroc swine. Increased LSS from positioning pigs with pelvic limbs flexed in sternal or lateral recumbence may facilitate epidural puncture compared with neutral limb positioning.

Assessment of a commercially available veterinary blood pressure device used on awake and anesthetized dogs.

OBJECTIVE: To compare results of a commercially available device for oscillometrically measured blood pressure (OBP) with invasively measured blood pressure (IBP) in awake and anesthetized dogs. ANIMALS: 19 adult dogs (mean ± SD body weight, 17.8 ± 7.5 kg). PROCEDURES: Blood pressures were measured in dogs while they were awake and anesthetized with isoflurane. The OBP was recorded on a thoracic limb, and IBP was simultaneously recorded from the median caudal artery. Agreement between OBP and IBP was evaluated with the Bland-Altman method. Guidelines of the American College of Veterinary Internal Medicine (ACVIM) were used for validation of the oscillometric device. RESULTS: In awake dogs, mean bias of the oscillometric device was -11.12 mm Hg (95% limits of agreement [LOA], -61.14 to 38.90 mm Hg) for systolic arterial blood pressure (SAP), 9.39 mm Hg (LOA, -28.26 to 47.04 mm Hg) for diastolic arterial blood pressure (DAP), and -0.85 mm Hg (LOA, -40.54 to 38.84 mm Hg) for mean arterial blood pressure (MAP). In anesthetized dogs, mean bias was -12.27 mm Hg (LOA, -47.36 to 22.82 mm Hg) for SAP, -3.92 mm Hg (LOA, -25.28 to 17.44 mm Hg) for DAP, and -7.89 mm Hg (LOA, -32.31 to 16.53 mm Hg) for MAP. The oscillometric device did not fulfill ACVIM guidelines for the validation of such devices. CONCLUSIONS AND CLINICAL RELEVANCE: Agreement between OBP and IBP results for awake and anesthetized dogs was poor. The oscillometric blood pressure device did not fulfill ACVIM guidelines for validation. Therefore, clinical use of this device cannot be recommended.

COMPARISON OF SURFACE, ESOPHAGEAL, AND CLOACAL TEMPERATURES IN DIFFERENT REPTILE SPECIES.

The objective of this study was to compare surface, esophageal, and cloacal temperatures in awake iguanas, chameleons, and snakes at two different ambient temperatures and in alligators at one ambient temperature. Surface, esophageal, and cloacal temperatures were measured in all animals twice, with exception of the alligators, where temperatures were taken once. The first set of temperature readings was done at lower environmental temperature. An analysis of variance (ANOVA) with a mixed-effect model was used to analyze the temperature difference between esophageal and cloacal temperature against each other, and against surface temperature. Significance was set at P < 0.05. In all animals, surface, esophageal, and cloacal temperatures increased significantly (P < 0.0001) with increased ambient temperature. Esophageal and cloacal temperature were not significantly different from each other in iguanas and chameleons at lower environmental temperature or in snakes and chameleons at high ambient temperature. In snakes, esophageal temperature 26.1 ± 1.6°C was significantly higher than cloacal temperature 25.2 ± 0.9°C (P = 0.0016) at lower ambient temperature. In alligators no difference between esophageal and cloacal temperature was observed at the given ambient temperature. Surface temperature was significantly lower than esophageal and cloacal temperature in all species investigated, except iguanas at lower ambient temperature. The results of this study suggest that in healthy awake iguanas and chameleons at any ambient temperature and in snakes at high ambient temperature, cloacal temperatures are reflective of esophageal temperature in the species evaluated. In alligators, rectal temperature reflected esophageal temperature at the given ambient temperature. Surface temperature in contrast was underestimating esophageal temperature in all species investigated.

Cardiovascular, respiratory and sedative effects of intramuscular alfaxalone, butorphanol and dexmedetomidine compared with ketamine, butorphanol and dexmedetomidine in healthy cats.

Objectives The aim of the study was to evaluate the cardiorespiratory effects, quality of sedation and recovery of intramuscular alfaxalone-dexmedetomidine-butorphanol (ADB) and ketamine-dexmedetomidine-butorphanol (KDB), in cats. Methods Nine adult, healthy cats (6.63 ± 1.42 kg) were enrolled in a blinded, randomized, crossover experimental design. Cats were sedated twice intramuscularly, once with ADB (alfaxalone 1 mg/kg, dexmedetomidine 0.005 mg/kg, butorphanol 0.2 mg/kg), and once with KDB (ketamine 5 mg/kg, dexmedetomidine 0.005 mg/kg, butorphanol 0.2 mg/kg), in random order. Data collected included heart rate (HR), arterial blood pressure and blood gas analysis, respiratory rate and sedation score. Analysis of variance with Bonferroni post-hoc correction was used for parametric data, and a Wilcoxon signed rank test was used for non-parametric data. Significance was set at P <0.05. Results Total sedation time was shorter for ADB (90.71 ± 15.12 mins vs 147.00 ± 47.75 mins). Peak sedation was observed within 15 mins in both groups. Quality of recovery was excellent in both groups. HR decreased over time in both groups. Diastolic and mean arterial pressure decreased over time for ADB, becoming significant after 30 mins. All cardiovascular variables were within the clinically acceptable range in both groups. Arterial partial pressure of oxygen was significantly decreased from baseline for KDB at all time points (73 ± 2.5 mmHg [9.7 ± 0.3 kPa] vs ADB 83 ± 2.6 mmHg [11 ± 0.3 kPa]). Hypoventilation was not observed. Conclusions and relevance Both protocols produced acceptable cardiovascular stability. Sedation and recovery quality were good, albeit sedation was shorter with ADB. Although oxygenation was better maintained in the ADB group, all sedated cats should receive oxygen supplementation.

Assessment of maxillary and infraorbital nerve blockade for rhinoscopy in sevoflurane anesthetized dogs.

OBJECTIVE: To investigate the efficacy of maxillary and infraorbital nerve blocks for prevention of cardiovascular and qualitative responses to rhinoscopy, as well as response to skin clamping after assigned nerve block placement. STUDY DESIGN: Randomized, blinded, placebo-controlled cross-over experimental study. ANIMALS: Eight random-source mixed breed dogs > 1 year old and weighing between 13 and 22 kg. METHODS: Within three anesthetic episodes, separated by at least 3 days, dogs were assigned to receive either 1 mL lidocaine 2% maxillary nerve block (ML); 0.5 mL lidocaine 2% infraorbital nerve block (IOL); or equal amounts of saline for maxillary or infraorbital nerve block combined as control treatment (S). Monitoring included temperature, respiratory rate, end-tidal CO2 , ECG, heart rate (HR), systolic, diastolic and mean arterial pressure (SAP, DAP, MAP). Posterior (pR) and anterior rhinoscopies (aR) were performed and scored. Differences from baseline for outcome parameters HR, SAP, DAP, MAP were analyzed using repeated-measures anova, and results reported as mean ± SD. Binary scores for rhinoscopy were analyzed using logistic regression, and odds ratio was reported. RESULTS: Changes from baseline for HR and SAP were significant for all treatments, besides ML for pR. Difference in changes from baseline among treatments was statistically significant for HR during pR with ML < S, and for SAP, DAP and MAP in right and left aR with ML < S and IOL > ML, except for DAP in left aR with only IOL > ML. Analysis of the binary score showed that the probability of a response for S and IOL treatments was nearly triple that of the ML treatment. None of the dogs, regardless of the treatments applied, responded to skin clamping. CONCLUSION AND CLINICAL RELEVANCE: Cardiovascular parameters do not seem to reflect the occurrence of adverse reactions during rhinoscopy. The maxillary nerve block is superior to the infraorbital nerve block, as applied in this study, in preventing adverse reactions during posterior rhinoscopy.

A comparison of cardiopulmonary and anesthetic effects of an induction dose of alfaxalone or propofol in dogs.

OBJECTIVE: To compare the physiological parameters, arterial blood gas values, induction quality, and recovery quality after IV injection of alfaxalone or propofol in dogs. STUDY DESIGN: Prospective, randomized, blinded crossover. ANIMALS: Eight random-source adult female mixed-breed dogs weighing 18.7 ± 4.5 kg. METHODS: Dogs were assigned to receive up to 8 mg kg(-1) propofol or 4 mg kg(-1) alfaxalone, administered to effect, at 10% of the calculated dose every 10 seconds. They then received the alternate drug after a 6-day washout. Temperature, pulse rate, respiratory rate, direct blood pressure, and arterial blood gases were measured before induction, immediately post-induction, and at 5-minute intervals until extubation. Quality of induction, recovery, and ataxia were scored by a single blinded investigator. Duration of anesthesia and recovery, and adverse events were recorded. RESULTS: The mean doses required for induction were 2.6 ± 0.4 mg kg(-1) alfaxalone and 5.2 ± 0.8 mg kg(-1) propofol. After alfaxalone, temperature, respiration, and pH were significantly lower, and PaCO2 significantly higher post-induction compared to baseline (p < 0.03). After propofol, pH, PaO2 , and SaO2 were significantly lower, and PaCO2 , HCO3 , and PA-aO2 gradient significantly higher post-induction compared to baseline (p < 0.03). Post-induction and 5-minute physiologic and blood gas values were not significantly different between alfaxalone and propofol. Alfaxalone resulted in significantly longer times to achieve sternal recumbency (p = 0.0003) and standing (p = 0.0004) compared to propofol. Subjective scores for induction, recovery, and ataxia were not significantly different between treatments; however, dogs undergoing alfaxalone anesthesia were more likely to have ≥ 1 adverse event (p = 0.041). There were no serious adverse events in either treatment. CONCLUSIONS AND CLINICAL RELEVANCE: There were no clinically significant differences in cardiopulmonary effects between propofol and alfaxalone. A single bolus of propofol resulted in shorter recovery times and fewer adverse events than a single bolus of alfaxalone.

Effects of acepromazine maleate or morphine on tear production before, during, and after sevoflurane anesthesia in dogs.

OBJECTIVE: To investigate the effects of acepromazine maleate and morphine on aqueous tear production before, during, and after sevoflurane anesthesia in dogs. ANIMALS: 6 mixed-breed dogs. PROCEDURES: In a Latin square study design, dogs underwent i.m. administration of morphine (1 mg/kg), acepromazine (0.05 mg/kg), or saline (0.9% NaCl) solution (0.05 mL/kg), followed by induction and maintenance of anesthesia with sevoflurane for 30 minutes. The protocol was repeated until all dogs had received all treatments, with a minimum of 7 days between anesthetic episodes. Aqueous tear production was measured via Schirmer tear test I before treatment (baseline); before anesthetic induction; 5, 10, 20, and 30 minutes after anesthetic induction; immediately once dogs recovered from anesthesia; and 2 and 10 hours after recovery. RESULTS: Aqueous tear production for all treatments was significantly lower 10, 20, and 30 minutes (but not 5 minutes) after anesthetic induction than at baseline, before anesthetic induction, at recovery, and 2 and 10 hours after recovery. Aqueous tear production was significantly higher after saline solution administration than after morphine administration at the preinduction measurement point and 2 hours after recovery. No other differences were detected among the 3 treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Aqueous tear production after anesthesia did not differ significantly from baseline values after any treatment following 30 minutes of sevoflurane anesthesia, suggesting premedication with morphine or acepromazine does not contribute to a decrease in lacrimation in these circumstances.

Quantitative ultrasonography for assessment of bone mineral density in the canine radius and tibia.

Quantitative ultrasound allows noninvasive assessment of cortical bone density. Potential applications include monitoring of fracture healing, rehabilitation, and skeletal diseases. The objectives of this study were to determine the three most accessible portals to obtain speed of sound measurements of the radius and tibia with an Omnisense multisite quantitative ultrasound device and to determine probe-dependent intra- and interoperator variability for speed of sound measurements of the radius and tibia in six healthy hounds. The radius was most accessible at the cranial proximal metaphysis, the cranial middiaphysis, and medial distal metaphysis. Speed of sound measurements were possible at these sites on the radius with acceptable intra- and interoperator variation (1.6-4.6%). Measurements differed significantly when performed with different probes at the cranial proximal radial metaphysis. The tibia was most accessible at the cranial proximal metaphysis, the medial middiaphysis, and medial distal metaphysis. The medial middiaphyseal and mediodistal tibial sites allowed measurements with lowest intra- and interoperator variation (< 3.5%). A smaller probe allowed tibial measurements with lowest interoperator variation. Measurements did not differ significantly at each tibial site when different probes were used. Measurements did not differ significantly between observers when measuring with the same probe at each specific site on radius and tibia. A medium-size probe allowed for most time-efficient measurements and the least number of failed measurements on the radius and tibia. Speed of sound can be consistently measured by different observers on the radius and tibia in healthy hounds.