North American Veterinary Licensing Examination (NAVLE) Practice Test

In dairy cows with a displaced abomasum, the most likely acid-base abnormality is metabolic alkalosis. This condition can develop due to the loss of chloride and sometimes potassium when the cow experiences vomiting or if there is a lack of adequate chloride due to an abomasal outflow obstruction.

The presence of a displaced abomasum can lead to changes in gastric motility and secretion. When the cow vomits or there is reduced outflow, the accumulation of digesta in the abomasum can cause electrolyte imbalances, particularly involving sodium and chloride, which are crucial for maintaining acid-base balance. The loss of hydrochloric acid through these processes leads to a decrease in hydrogen ions, resulting in alkalosis. This is why metabolic alkalosis is the more likely outcome in this situation, especially in the acute phase following displacement.

In contrast, metabolic acidosis typically occurs from conditions like diarrhea or renal failure, where there is an accumulation of acids or loss of bicarbonate, which is not the primary issue seen with abomasal displacement. Respiratory alkalosis and respiratory acidosis are primarily governed by respiratory function and are less commonly associated with the underlying processes involved in a displaced abomasum. Thus, the pattern of metabolic alkalosis aligns with