Physical endurance in dogs is related to which of the following?

Physical endurance in dogs is primarily linked to their overall muscle tone. Muscle tone is a reflection of the strength and condition of a dog's muscles, which plays a crucial role in its ability to sustain physical activity over time. Dogs with well-developed muscle tone have a greater capacity to exert themselves and engage in prolonged exercise without excessive fatigue.

Strong muscle fibers contribute directly to stamina, enabling a dog to perform tasks that require endurance, such as running, searching, or tracking, which are essential capabilities in narcotics detection work. While coordination, mental focus, and other factors may affect a dog’s performance in different contexts, they do not directly determine physical endurance as muscle tone does. Thus, muscle tone is a foundational physiological aspect that supports endurance in various activities.