Clinicopathologic, Gross Necropsy, and Histopathologic Effects of High-Dose, Repeated Meloxicam Administration in Rhode Island Red Chickens (Gallus gallus domesticus)

Meloxicam is a commonly prescribed non-steroidal anti-inflammatory drug for backyard poultry that has demonstrated pharmacodynamic efficacy at a single high dose of 5 mg/ kg. This study characterized the adverse effects of meloxicam administered in chickens at an approximate dose of 5 mg/kg orally twice daily for 5 days. Twenty-one adult Rhode Island Red hens (Gallus gallus domesticus), judged to be healthy based on an external physical examination, complete blood count (CBC), and plasma biochemistry panel, were recruited for this study. The subject birds were randomly assigned to a treatment (n = 11) or control group (n = 10) and received a 15-mg tablet of meloxicam or a nonmedicated feed pellet, respectively, orally twice daily. Physical examinations and body weight measurements were performed daily, and observation for clinical signs occurred twice daily. Following completion of the 5-day treatment course, an external physical examination, blood collection for a CBC and plasma biochemistry panel, euthanasia, necropsy, and measurement of meloxicam tissue residues were performed. During the treatment course, 1 hen from the treatment group died with peracute clinical signs, 2 hens from the treatment group died suddenly with no clinical signs, and 1 hen from the treatment group became acutely lethargic and was euthanized. Within the meloxicam group, 7 out of 11 hens had gross and histologic evidence of varying levels of renal acute tubular injury and gout. Plasma uric acid concentrations were above the species reference intervals in all affected hens in the treatment group that were still available for testing. The control group had no evidence of renal injury or gout based on postmortem examinations. Based on the results of this study, repeated oral dosing of meloxicam in chickens at 5 mg/kg twice daily is not recommended.