Successful Surgical Removal of the Crystalline Lenses in a Black-Necked Swan (Cygnus melancoryphus).

A captive-bred, adult, male, black-necked swan (Cygnus melancoryphus) was presented for evaluation of apparent vision loss due to cataract formation of an unknown duration. The animal was having difficulty navigating its enclosure, and lenticular opacities had been previously noted in both eyes. On examination, bilateral hypermature cataracts were diagnosed. Following preoperative diagnostic testing, surgical removal of the crystalline lenses in both eyes was performed using minor modifications of standard techniques. Follow-up examination and behavioral observation at 60 days postsurgery indicated that vision had been successfully restored without complications. We conclude that successful surgical removal of cataracts is possible in this species using modifications of standard techniques.

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.

Pharmacokinetics of oral and compounded intravenous gabapentin in Duroc swine (Sus Scrofa).

The objective of this study was to determine the pharmacokinetics (PK) of oral (OS; 20 mg/kg) and compounded intravenous (IV; 5.5 mg/kg) gabapentin in 6 healthy, adult, Duroc pigs. Subjects were randomized to receive IV and OS gabapentin in a cross-over design, with at least 14 days of wash-out period between the two rounds of drug administrations. Blood samples were obtained before gabapentin administration and at various times up to 24 h, and harvested plasma was stored at -80°C until analysis. Concentration of gabapentin was quantified using a previously validated liquid chromatography/tandem mass spectrometry method, and compartment models were fitted to time-concentration data using non-linear mixed effect (population) analysis. A two-compartment model best fitted the data following IV administration. Typical values for volume of the central compartment and clearance and calculated volume of distribution at steady-state and terminal half-life were 170 ml/kg, 1.2 ml/(kg*min), and 594 ml/kg and 360 min, respectively. For the oral route, absorption half-life, estimated maximal plasma concentration and time to reach maximal plasma concentration were 58 min, 9155 ng/ml, and 194 min, respectively. Estimated oral bioavailability was 47%. Short-lived sedation (approximately 15 min) with sternal or lateral recumbency after IV administration was observed in all subjects without adverse clinical effects. Simulation based on the results of this study suggests that a first oral gabapentin dose of 15 mg/kg and subsequent doses of 8.5 mg/kg every 8 h would achieve and maintain plasma concentrations between 5 and 8 µg/ml in pigs.