The Stability and Efficacy of Tricaine Methanesulfonate (MS222) Solution After Long-Term Storage.

Tricaine methanesulfonate (MS222) is widely used for the anesthesia and euthanasia of laboratory zebrafish. Fresh solutions have been recommended for each use; however, researchers often mix and store concentrated stock solutions for convenience and to reduce occupational exposure and environmental waste. While this is common practice, published guidelines are often inconsistent. Thus, the objective of this study was to evaluate the stability and anesthetic efficacy of MS222 after long-term storage and to develop specific storage parameters. Stock solutions (100 mg/mL MS222) were mixed and stored in amber jars at 4 °C and -20 °C for 2- and 6-mo. Stability of the solutions was analyzed using liquid chromatography-ion trapmass spectrometry and compared with fresh MS222. Fifty adult (30 male, 20 female) wildtype AB zebrafish (Danio rerio) wererandomly anesthetized with 150 mg/L of one of the following MS222 solutions to evaluate anesthetic efficacy: 1) freshly prepared(0m); 2) 2 mo at 4 °C (2m4); 3) 2 mo at -20 °C (2m-20); 4) 6 mo at 4 °C (6m4); 5) 6 mo at -20 °C (6m-20). Time to cessation of swimming, loss of equilibrium, lack of response to von Frey (VF) stimulation, return of equilibrium, and resumption of swimming were compared between groups. Two fish from each group were euthanized at 24-h and 2-wk after anesthesia, and histopathology was performed. All solutions were determined to be stable under all storage conditions. No clinically significant differences were observed between the fresh and stored stock groups during anesthetic testing. No evidence ofanesthetic-related histologic changes were noted in the gills, skin, kidneys, muscle, and central nervous system. Hepatic megalocytosis and a reduction in hepatic vacuolation were seen to varying degrees across all groups, but did not follow a treatment-related trend. Therefore, 100 mg/mL solutions of MS222 can be stored in amber jars at 4 °C or -20 °C for 6 mo and still used to effectively anesthetize zebrafish.

Once daily oral extended-release hydrocodone as analgesia following tibial plateau leveling osteotomy in dogs.

OBJECTIVE: To determine the efficacy of oral extended-release hydrocodone compared with oral firocoxib for analgesia following tibial plateau leveling osteotomy surgery in dogs in a hospital setting. STUDY DESIGN: Prospective, randomized, blinded, clinical trial. ANIMALS: Thirty-six client-owned dogs weighing 25-43 kg with unilateral hindlimb lameness and cranial cruciate ligament rupture. METHODS: Dogs were assigned to 1 of 2 groups (n = 18/group). Group 1 received hydrocodone 3 mg/kg orally every 24 hours, and group 2 received firocoxib 5 mg/kg orally every 24 hours. Both hydrocodone and firocoxib (according to group assignment) were provided as preemptive analgesia 10 hours before induction to anesthesia and then every 24 hours for the remainder of the study period The level of analgesia was compared between treatments on the basis of a modified Glasgow Composite Pain Score (mGCPS) in each dog, the number of dogs requiring rescue analgesia (hydromorphone 0.05 mg/kg subcutaneously), pressure platform stance data, and number of adverse events. RESULTS: Nine of 18 dogs that received hydrocodone and 2/18 dogs that received firocoxib had an mGCPS ≥6 (P = .02). Two dogs had an mGCPS ≥6 three times, and 1 had an mGCPS ≥6 two times; all 3 of these dogs were in the hydrocodone group. Average postoperative peak pressure placed on the affected limb was lower in dogs that received hydrocodone (P = .01). Regurgitation and decreased appetite were more common in the dogs that received hydrocodone. CONCLUSION: Dogs that were treated with hydrocodone exhibited higher pain scores and lower limb function than dogs treated with firocoxib under the conditions of our study. CLINICAL SIGNIFICANCE: Our results do not provide evidence to justify the administration of extended-release hydrocodone at 3 mg/kg orally every 24 hours rather than firocoxib at 5 mg/kg orally every 24 hours in dogs undergoing tibial plateau leveling osteotomy.

Evaluation of the Environmental Bias on Accelerometer-Measured Total Daily Activity Counts and Owner Survey Responses in Dogs with Osteoarthritis.

Objective To determine if environmental variables affect the average daily activity counts (AC) of dogs with osteoarthritis (OA) and/or owners' perception of their dog's clinical signs or quality of life. Methods The AC and Canine Brief Pain Inventory (CBPI) owner questionnaires of 62 dogs with OA were compared with daily environmental variables including the following: average temperature (°C), high temperature (°C), low temperature (°C), relative humidity (%), total precipitation (mm), average barometric pressure (hPa) and total daylight hours. Results Daily AC significantly correlated with average temperature and total daylight hours, but average temperature and total daylight hours accounted for less than 1% of variation in AC. No other significant relationships were found between daily AC and daily high temperature, low temperature, relative humidity, total precipitation or average barometric pressure. No statistical relationship was found between daily AC and the CBPI, nor between environmental variables and the CBPI. Canine Brief Pain Inventory scores for pain severity and pain interference decreased significantly over the test period. Clinical Significance The relationship between daily AC and average temperature and total daylight hours was significant, but unlikely to be clinically significant. Thus, environmental variables do not appear to have a clinically relevant bias on AC or owner CBPI questionnaires. The decrease over time in CBPI pain severity and pain interference values suggests owners completing the CBPI in this study were influenced by a caregiver placebo effect.