How can you directly visualize an animal's respiratory rate?

Observing the movements of the chest or ribcage over a period of time is the most direct method to visualize an animal's respiratory rate. This technique allows you to count each inhalation and exhalation, providing a clear and accurate measurement of how many breaths the animal takes in one minute. The chest rises and falls visibly with each breath, making it straightforward to observe.

Counting heartbeats, while related to the animal's overall health, does not provide information about respiratory rate and does not involve the visualization of breathing itself. Similarly, measuring pulse at the femoral artery relates to cardiovascular function and not to respiratory function. Lastly, assessing the color of the tongue can indicate oxygenation status but does not provide a direct count of respiratory activity. Hence, observing the movements of the chest or ribcage is the most effective way to measure respiratory rate directly.