What is one of the key indicators of a dog's state of arousal?

A key indicator of a dog's state of arousal is raised hackles on the neck and back. This physical response is often associated with various emotional states such as excitement, aggression, or fear. When a dog’s hackles are raised, it signifies heightened alertness and can serve as a warning signal to other animals or humans. This response is part of the dog's instinctive reactions in social interactions and can indicate that the dog is feeling defensive or is experiencing stress, making it essential for handlers to recognize this behavior in order to assess the dog's readiness to engage or to provide reassurance.

Tail wagging slowly, while it can signal interest or hesitation, does not universally indicate high arousal and might be a sign of a dog being calm or submissive. Ears pinned back is often a sign of submission or fear, not arousal, and a mouth completely closed typically suggests a dog is feeling anxious or reserved rather than highly aroused. By understanding these indicators, handlers can better interpret a dog's behavior and respond appropriately.