North American Veterinary Licensing Examination (NAVLE) Practice Test

The choice of white muscle disease, enterotoxemia, and colibacillosis as the three diseases commonly associated with sudden death in a young, fast-growing calf is accurate due to the pathophysiological mechanisms and clinical presentations of these conditions.

White muscle disease, resulting primarily from selenium or vitamin E deficiency, leads to oxidative damage in skeletal and cardiac muscle tissues. In young calves, this can manifest acutely, leading to sudden collapse and death, especially during periods of rapid growth or stress.

Enterotoxemia, often caused by overgrowth of Clostridium perfringens type D, occurs when high-carbohydrate diets cause a rapid multiplication of the bacteria in the gut. This leads to the release of potent toxins that can cause sudden onset of severe gastrointestinal disease and death, particularly in calves that are being fed high-energy diets.

Colibacillosis is primarily caused by specific strains of Escherichia coli, which can produce enterotoxins that result in severe diarrhea and dehydration. In young calves, the rapid progression of this disease can also lead to sudden death, particularly if the calf experiences severe systemic effects such as shock or septicemia.

Collectively, these diseases encompass both nutritional deficiencies and infectious processes that can