Toxopathology of gout induced in laying pullets by sodium bicarbonate toxicity

A total of 60, 3-week-old, laying pullets were used in the present experime nt. The exposed birds received excess sodium bicarbonate (SB) in their drin king water for 35 days at the levels of: 2 g/l (0.2%). 7.5 g/l (0.75%), 20 g/l (2%) and 40 g/l (4%). All birds were subjected to pathological and toxi cological examination. Birds of the 0.75% and 2%-groups developed gross pic ture of visceral gout, while birds of 4%-group showed acute kidney damage w ithout manifesting visceral urate deposition. Erythrocytic count, packed ce ll volume (PCV), and hemoglobin (Hb) levels were all increased in the expos ed birds. There were dose-related increments in the serum level of sodium ( Na+). Serum levels of chloride (Cl-), and potassium (K+) were relatively de creased in some cases. Serum levels of uric acid were increased in a dose-r elated pattern. Blood pH of the treated birds was shifted toward the alkali ne side. Microscopic examination revealed significant renal changes in bird s manifesting visceral gout and these changes included urate deposits assoc iated with tubular necrotic changes. Some birds in the third group (2%) dev eloped urate granulomas (tophi) in their renal interstitium. It was conclud ed that development of gout in birds may be related to a state of metabolic alkalosis which is associated with significant changes of the electrolyte balance. (C) 1999 Published by Elsevier Science B.V. All rights reserved.