Myocarditis in Broiler Chickens Reared at High Altitude

Abstract

The pathology and incidence of heart failure in a broiler hybrid at high altitude was surveyed in La Paz, Bolivia. From 4 lots of birds on a single farm (altitude 10,800 ft), 1172 birds were examined post-mortem; of these, 565 were diagnosed as cases of cardiac failure. The incidence of the disease in each of the 4 lots was 3.5, 6.1, 11.8, and 12.0%. The most conspicuous feature of the gross pathology was acute myocarditis with cardiac dilatation, congestion and ascites. Severe congestion and extensive inflammation were demonstrated microscopically in the heart, liver and kidney. The mean value for the hematocrit of healthy birds in La Paz was significantly higher than that in healthy birds of the same age and breed (but on a different feeding regime) in Cochabamba (altitude 8500 ft), where heart failure does not occur.