A whistle cuts through other noise and the sound travels a long way, so you can control your dog from a distance. If the command you are giving is crucial, for example to stop your dog in his tracks, a whistle gives you a higher chance of success than you’d have by just yelling. But the whistle forms only part of your training arsenal. If your dog has aggression problems, it’s essential to correct this at home and to never put him in a position where he may attack. You can train him to stop whatever he’s doing when he hears the whistle, enabling you to prevent attacks.
Put Fido on a leash and socialize him with other dogs and people. It’s best to do this with people and dogs that you know to be friendly and with whom Fido is familiar, such as family friends or neighbors.
Figure out what causes your dog to be aggressive. Observe him interacting with other dogs and people. Look at his body language. For example, he may growl and bare his teeth at a dog who’s giving him unwelcome attention. This is a classic warning of impending attack.
Guide Fido away from the situation if he becomes aggressive. According to the Centers for Disease Control and Prevention, proper socialization is essential in reducing dog attacks.
Make a list of triggers and determine his tolerance threshold. For example, Fido may only become aggressive if disturbed when eating. Or he may have a distinct intolerance of dogs entering his home. By knowing the triggers and the signs that precede aggressive behavior, you can anticipate more accurately when your dog is likely to attack.
Hold a treat to Fido’s nose. Let him get the scent, then move it over his head and behind him.
Blow the whistle as he follows it. Use a distinctive blowing pattern, such as two short blasts or one short, one long. It doesn’t matter, as long as it's distinctive. Eventually, Fido will park his bottom on the floor to get a better look at the treat.
Release the treat as soon as he sits and give him lots of praise. Graduate from using the treat as a lure to just using hand signals. With sufficient practice, Fido will learn to sit upon hearing the whistle command.
Put Fido on a long leash and let him interact with other dogs and people.
Observe his behavior and use what you learned earlier to anticipate aggressive behavior.
Give the whistle command when you spot him becoming agitated or unsettled. By making him sit, you distract him from what was upsetting him. The key to success is to divert his attention to you before he even thinks about attacking.
Praise him verbally when he turns his attention to you.