Which of the following behaviors is considered a repetitive response to anxiety in dogs?

Walking in circles is considered a repetitive response to anxiety in dogs, as it often indicates a behavior stemming from stress or discomfort. This behavior can arise when a dog is feeling anxious, nervous, or is trying to cope with an overwhelming environment. Walking in circles may serve as a way for the dog to self-soothe or find some form of relief from their anxiety.

In contrast, wagging their tail is generally a sign of excitement or happiness rather than anxiety. Sleeping more than usual can indicate a range of issues, including depression or health problems, but it is not typically classified as a direct response to anxiety. Nipping at the air can sometimes be a sign of playful behavior or an instinctual action, rather than a clear repetitive coping mechanism related to anxiety. Thus, walking in circles is distinctly linked to anxiety and is a recognized repetitive behavior in dogs experiencing such feelings.