Cold stress, heart failure, and esophageal occlusion cause the death of a West Indian manatee Trichechus manatus in Alabama, USA

Cold stress is the leading cause of mortality in West Indian manatees Trichechus manatus in the northcentral Gulf of Mexico. This report describes an adult male manatee that stranded alive with signs of cold stress in Alabama (USA) waters in January 2022 and died during the rescue intervention. Postmortem examination and histopathologic review revealed multiple contributors to death. While the animal had evidence of cold stress syndrome, there was aortic stenosis and concentric left ventricular hypertrophy as well as an esophageal foreign body (plastic bag). Main findings from blood analysis indicated systemic inflammation and possible disseminated intravascular coagulation. Histopathologic findings from the cardiovascular system included aortic fibromuscular dysplasia, mitral and tricuspid valve endocardiosis, left ventricular myocardial hypertrophy, and right myocardial atrophy. A cause of the cardiovascular findings was not determined. This report is the first to document a case of cold stress syndrome complicated by aortic stenosis and esophageal occlusion in this species.