A dog wagging its tail is commonly thought to signal friendliness, but experts warn it can also indicate aggression. Sharon Bolt, a BBC dog trainer, explains that owners must observe the entire body language to understand their pet's true emotions. According to Bolt, a tail wagging to one side may suggest the dog is feeling threatened. She emphasizes that other signals, such as yawning or looking away, can also mean the dog is uncomfortable or anxious. These behaviors, she says, are often overlooked by pet owners who assume a wagging tail always means a happy dog. Bolt advises that understanding the full context of a dog's body language is essential for ensuring safety, both for the dog and those around it. She recommends that owners pay attention to subtle cues like the position of the ears, the posture of the body, and the direction of the gaze. This knowledge can help prevent misunderstandings and potential conflicts. The BBC expert highlights that while tail wagging is a common sign, it is not always a reliable indicator of a dog's emotional state. By learning to read the full range of canine signals, pet owners can better interpret their dog's behavior and respond appropriately.