North American Veterinary Licensing Examination (NAVLE) Practice Test

The primary concern for a calf that has recently died from vigorous exercise and shows symptoms indicative of white muscle disease is related to Vitamin E and selenium deficiency. White muscle disease, also known as nutritional myodegeneration, is caused by a deficiency of these essential nutrients, which are crucial for muscle health. Selenium and Vitamin E work as antioxidants that protect the muscle tissues from oxidative damage. When calves are deficient in these nutrients, especially during times of stress or vigorous activity, muscle degeneration can occur.

In this scenario, the association between recent vigorous exercise and the symptoms observed aligns well with the pathophysiology of white muscle disease. The stress of exercise could exacerbate the impact of the deficiency, leading to muscle damage and potentially sudden death. This condition is most often observed in younger animals, particularly in regions where soil selenium levels are low, further supporting the diagnosis based on the calf's recent history and clinical signs.

While ionophore toxicity, myocardial infarction, and bovine leukosis are serious conditions that could affect calves, they do not specifically correlate with the symptoms presented or the context of exercise leading to sudden death in a calf known to have white muscle disease.