Which of the following is NOT a vital sign that must be monitored during general anesthesia?

Blood pressure is indeed an important parameter during general anesthesia; however, the question specifically asks for a vital sign that is NOT typically monitored as a "must" during every case of general anesthesia.

Respiratory rate, pulse rate, and body temperature are routinely assessed to ensure patient safety and responsiveness to anesthetic agents. These parameters provide essential information about the animal's physiological status during the procedure. While blood pressure monitoring is critical in many situations, particularly in high-risk patients or those undergoing longer surgeries, it may not be performed as a mandatory measure in all general anesthesia cases, especially in less invasive procedures or in certain veterinary practices.

Therefore, the understanding here is that while all vital signs are important for overall assessment, blood pressure monitoring may not be universally required in every general anesthetic scenario, making it the correct choice in this context.