Myocardial Toxicity in a Group of Greyhounds Administered Ractopamine

• Published in: Veterinary pathology Vol. 49; no. 3; pp. 569 - 573
• Main Authors: Yaeger, M. J., Mullin, K., Ensley, S. M., Ware, W. A., Slavin, R. E.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.05.2012
• Subjects: Administration, Oral; Adrenergic beta-Agonists - administration & dosage; Adrenergic beta-Agonists - adverse effects; Adrenergic beta-Agonists - urine; Animals; Arrhythmias, Cardiac - chemically induced; Arrhythmias, Cardiac - veterinary; Dog Diseases - chemically induced; Dogs; Muscle, Skeletal - drug effects; Muscle, Skeletal - pathology; Myocardium - pathology; Necrosis - pathology; Necrosis - veterinary; Performance-Enhancing Substances - administration & dosage; Performance-Enhancing Substances - adverse effects; Performance-Enhancing Substances - urine; Phenethylamines - administration & dosage; Phenethylamines - adverse effects; Phenethylamines - urine; Substance Abuse Detection - methods; Substance Abuse Detection - veterinary; Troponin - metabolism; muscle skeletal; toxicity; ractopamine; arteries; canine; myocardium; cardiotoxin
• ISSN: 0300-9858; 1544-2217
• DOI: 10.1177/0300985811424752

Ractopamine, a synthetic β2-adrenoceptor agonist, is widely used as a feed additive in the United States to promote a reduction in body fat and enhance muscle growth in cattle, pigs, and turkeys. It has the potential for illegal use in show and racing animals because it may affect performance via its β-adrenergic agonist properties or anabolic activities. Nine greyhounds were orally administered 1 mg/kg of ractopamine to investigate the ability to detect the drug in urine. Postdosing, 7 of 9 dogs developed cardiac arrhythmias and had elevated troponin levels indicating myocardial damage. One dog necropsied 4 days postdosing had massive myocardial necrosis, mild to focally moderate skeletal muscle necrosis, and widespread segmental arterial mediolysis. A second dog necropsied 17 days postdosing had mild myocardial necrosis and fibrosis. Scattered arteries exhibited segmental medial and perimedial fibromuscular dysplasia. This is the first reported case of arterial, cardiac, and skeletal muscle damage associated with ractopamine.