What is the term for an animal's normal breathing rate at rest?

The term for an animal's normal breathing rate at rest is known as the respiratory rate. This is a vital sign that indicates how many breaths an animal takes per minute while at rest, providing important information about its respiratory health and overall physiological status.

Monitoring the respiratory rate can help identify potential respiratory distress or disease. In healthy animals, the respiratory rate can vary by species, age, size, and other factors, but it remains a crucial metric for veterinary assessments.

The other terms do not refer specifically to breathing. Heart rate relates to the number of heartbeats per minute, circulatory rate is not commonly used and could refer to blood flow but does not indicate breathing, and metabolic rate describes the speed of metabolism in the body, which is unrelated to the rate of breathing. Therefore, respiratory rate is the clear answer here as it directly addresses the question about the normal rate of breathing at rest.