After anesthesia, which of the following must be true before an animal can be considered stable?

For an animal to be deemed stable after anesthesia, it is essential that the animal can swallow and is extubated. This indicates that the animal has regained sufficient consciousness and is capable of maintaining its airway independently, which reflects an important aspect of post-anesthetic recovery. Extubation is a critical step; it suggests that the anesthetic effects are diminishing and that the animal can breathe effectively on its own.

While the other options provide important indicators of an animal's health and recovery, they do not solely define stability. For example, a normal heart rate is significant, but it can vary based on the individual animal's condition or underlying health issues. A body temperature exceeding 100 degrees Fahrenheit can indicate recovery, but this is also influenced by factors such as the length of anesthesia and the method of cooling or warming used. Lastly, while being fully awake and responsive is a positive indicator, certain procedures may leave an animal in a period of ataxia or drowsiness that does not necessarily indicate instability.

Thus, the ability to swallow and extubation signifies a key milestone in post-anesthetic recovery, marking that the animal is transitioning back into a stable state.