Although head collars have many advantages, they also have some disadvantages. To begin with, if you get too carried away, the dog can become dependent on the tool, and not apply the training he has received without it. Dogs can sometimes quickly identify the differences between their normal collar and the head collar, and will adjust their behavior accordingly.
Also, there are some canines, particularly those who may not be used to wearing a head collar, who will dislike it so much that they will continually kick, scratch, or continue to pull on it excessively. If you are trying to use one on a rebellious dog that is doing this, your best bet is to keep the dog moving and distracted until he gets used to wearing a head collar. You can also make the dog sit by pulling on him as another corrective move.
There is also a minor problem with the head collar. A lot of people will react and treat it like a muzzle, when it really isn’t. This causes people to react to the dog as if he might bite them. This is not a big setback, there are those who find it worrying.
In general, if you plan to wear a head collar for training, do the following. Read the instructions that come with the collar first. Have a game plan for dog training and make sure you use good solid training methods in combination with the collar. Just using this tool alone is not a lifesaver.