Changes in myocardial ultrastructure during development of furazolidone-induced cardiomyopathy in turkeys.

Ultrastructural alterations were studied in spontaneous round heart and furazolidone (FZ)-induced cardiomyopathy in turkey poults 20 to 31 days after hatching. The two most consistent morphological changes were abnormal accumulation of cytoplasmic glycogen and myofibrillar lysis. These alterations were more extensive in the drug-induced condition, which suggests that more myocytes are affected than in the spontaneous form of the disease. Data indicate that the myocyte contractile proteins sustain the major injury while other organelles appear to be involved only in an incidental manner. These findings corroborate previous suppositions which pointed toward a metabolic defect as the basic mechanism underlying the development of both spontaneous round heart and FZ-induced cardiomyopathy in turkey poults.