What type of K-9 behavior signifies a positive alert on an item?

The behavior that signifies a positive alert on an item is scratching at the item. In canine training, particularly for detection work, specific behaviors indicate that the dog has identified a target substance or item of interest. Scratching is often trained as a clear signal that the dog has found something and wants to draw the handler's attention to it.

This behavior is reinforced during training to ensure that the dog understands it should alert the handler in a distinct manner when it locates a target, which can be essential in various situations such as search and rescue, narcotics detection, or explosives detection. The scratching behavior is particularly effective because it communicates the dog's discovery in a way that is easy for the handler to interpret and respond to.

Other behaviors, such as excessive barking or running away from the item, do not indicate a positive alert and can suggest distraction, anxiety, or an avoidance response, which is not desirable in detection work. Ignoring the item is also not a positive signal; it implies that the dog has not detected or recognized the target.