First, we have a study on the analgesic efficacy of tramadol compared with meloxicam in ducks (Cairina moschata domestica). While meloxicam is an NSAID that preferentially inhibits COX 2 and has a very short half-life, tramadol is a synthetic mu-opioid agonist with variable efficacy depending on species. Twelve ducks were randomly separated into 3 equal groups of 4 birds each: water control, tramadol treatment, and meloxicam treatment. Temporary arthritis was induced in all groups through injection, under anesthesia, of a 3% monosodium urate (MSU) solution into the intertarsal joint. One hour after MSU injection, birds were orally gavage fed 1 mL of tap water (control), tramadol (30 mg/kg), or meloxicam (1 mg/kg). Pressure-sensitive walkway (PSW) was evaluated before MSU injection and at 1, 2, 3, 4, 8, and 24 hours after MSU injection. No differences were found between tramadol and meloxicam-treated birds, so this study supports use of tramadol or meloxicam for analgesia in arthritic ducks, and both drugs improved specific gait variables as assessed by PSW. This study was the first to report efficacy of tramadol and its effect on an arthritis model in birds!

Second, we have a study on the pharmacokinetics of fentanyl after IV injection in red-tailed hawks (Buteo jamaicensis) and Hispaniolan Amazon parrots (Amazona ventralis). Six adult red-tailed hawks (RTH) and six adult Hispaniolan Amazon parrots (HAP) were anesthetized with isoflurane; afterwards fentanyl (20 mcg/kg) was administered IV. Arterial (red-tailed hawks) or jugular venous (Hispaniolan Amazon parrots) blood samples were obtained immediately before and 1, 2, 4, 8, 15, 30, 60, 120, 180, 240, and 480 minutes (red-tailed hawks) and 1, 5, 10, 15, 30, 60, 120, and 180 minutes (Hispaniolan Amazon parrots) after fentanyl administration.  Results showed that pharmacokinetic results for fentanyl in isoflurane-anesthetized red-tailed hawks and Hispaniolan Amazon parrots indicated large differences and should strongly discourage extrapolation of doses between these 2 species, which makes sense as they are very distant taxonomically. The results also suggest that HAP circulation was more rapid, as clearance of fentanyl was more rapid in HAP than in any other species; while RTH had slower clearance than other species. While this study could provide information in determination of suitable fentanyl loading and infusion doses for isoflurane anesthetized RTHA, based on results for HAP, further evaluation is necessary.

Lastly, we have a paper on the pharmacokinetics and egg residues of oral meloxicam in Bantam Cochin chickens. Six healthy adult bantam Cochin hens were given a single oral dose of meloxicam (1 mg/kg). Meloxicam plasma concentrations and egg residues were analyzed by high-performance liquid chromatography. Meloxicam was detected in egg whites for 4.8 ± 1.5 days and egg yolks for 9.8 ± 2.4 days. Results were compared with previous studies in white leghorn and Columbian Wyandotte hens, and this study showed that Bantam Cochin hens demonstrated a significantly longer mean apparent terminal half-life, greater area under the curve, smaller elimination rate constant, and longer egg residue times compared with white leghorn hens. However, the pharmacokinetic results from the bantam Cochin hens did not significantly differ from those reported for the Columbian Wyandotte hens. These results better inform appropriate dosing of meloxicam in domestic hens, as well as recommended withdrawal times for egg consumption.