In which situation should a muzzle not be used?

A muzzle should not be used when a dog has breathing problems because it can further obstruct airflow, potentially leading to increased stress or medical complications. Muzzles are designed to prevent a dog from biting, but if a dog is already struggling to breathe, restricting its mouth can exacerbate the situation and hinder its ability to get the oxygen it needs. It's essential to prioritize the animal's health and breathe freely, especially if it is experiencing respiratory distress.

In other scenarios, such as during grooming or with overly excited dogs, a muzzle may be appropriate to ensure safety for both the dog and the person handling it, as long as the dog's overall condition allows for it. Similarly, in cases where a dog is displaying aggression, a muzzle can serve as a temporary measure to protect others while a more suitable solution is found. However, in the case of a dog with breathing difficulties, safety and comfort must take precedence.