Furosemide does not facilitate pulmonary vasodilation in broilers during chronic or acute unilateral pulmonary arterial occlusion

Furosemide (FURO) is a diuretic and a putative pulmonary vasodilator that, when added to broiler diets, previously has been shown to reduce the cumulative pulmonary hypertension syndrome (PHS) mortality induced by cold temperatures. The objective of the present study was to evaluate the influence of dietary FURO on the pulmonary vasculature in broilers undergoing chronic or acute unilateral pulmonary arterial occlusion. Broilers were fed a standard ration throughout the entire experiment (Control group) or the same ration supplemented with 0.015% (wt/wt) FURO from Day 14 to 42 (FURO group). In the present study chicks were chosen at random at 16 to 18 d of age to undergo sham surgery or a chronic unilateral pulmonary artery clamp (PAC) procedure. Diet and surgical treatments resulted in Control-Sham, FURO-Sham, Control-PAC, and FURO-PAC groups. The Control-PAC and FURO-PAC groups did not differ in body weight or right:total ventricular weight ratios (RV:TV). The postsurgical mortality, ascites mortality, and mortality due to other causes did not differ between the Control-PAC and FURO-PAC groups. Plasma Na+ (P < or = 0.05) was lower in the FURO-Sham group than in the Control-Sham group. Broilers from the same hatch were fed Control or FURO diets and surgically prepared for acute unilateral pulmonary arterial occlusion by using a snare. Tightening of the snare triggered characteristic increases in pulmonary blood flow, pulmonary arterial pressure, and pulmonary vascular resistance. Across all of these variables, the Control and FURO groups did not differ during any sample interval. Dietary FURO did not affect body weight, hematocrit, or RV:TV. Dietary FURO at 0.015% (wt/wt) does not appear to influence the pulmonary vasculature in broilers, but it may prolong the survival of broilers during the pathophysiological progression of PHS.