My name is ***** ***** I’ve been involved professionally with dogs in the health and behavioral fields for over 18 years. It will be my pleasure to work with you today.
The first thing that should be done is to rule out a medical cause for the sudden aggression. You can read about these here:
If there is no medical cause for the aggression, then it is strictly behavioral. Dogs are aggressive toward people for a variety of reasons. It might be that they are fearful of people and thus are aggressive before the person can be. In other cases, a dog is aggressive in order to dominate the people. Other causes could be that the dog feels they are the alpha member of the pack and as the alpha member they must protect the pack (you) from threats (people).
In addition, owners sometimes make the situation even worse by tensing up and worrying about what will happen. The dog senses the owner worry and feels that he is justified in his aggressive stance because you are obviously worried about the people. They don't know you are worried about them attacking, they just feel that you are worried and assume it is the people. I'll come to a person's house and we will take their dog for a walk and the dog won't react to people at all. However, when the owner takes the leash, the dog immediately starts the unwanted behavior. It is important to be calm.
You may want to have her wear a muzzle so that she can not bite anyone. It may make you feel more comfortable and let you relax more when walking him or having him loose. If he isn't neutered, having that done might help.
Obedience training can help. This obedience work establishes you as the boss and as boss it is your job to protect the dog and not the dogs job to protect you. Now the dog will still protect you if something should happen because you will be protecting yourself and as part of the pack, he will follow your lead and protect as well. But if you are calm around someone, he will see that you are ok and there is no need to help. This is why being the alpha member works well.
The following site is helpful in helping owners train their dog. Be sure and click on the link to the page on obedience at the bottom. and links on subsequent pages leading to detailed instructions.
Training works best if you train at least 30 minutes a day (two 15 minute sessions). I would start making your dog work via the Nothing in life is free program (NILF). It is outlined below.
It will be helpful if you can find someone the dog reacts to who can help you once you have your dog listening to commands consistently. What you will do is have your dog on the leash. You will have your helper off in the distance. Your helper will gradually move a bit closer to you preferably walking past your position in the distance. As long as your dog ignores them, you can give your dog praise and a treat. The second you see her fixate on the helper or show any other sign of aggression (hair standing up, etc.) give your dog a correction by giving a short tug and a firm low toned "NO". It shouldn't take your dog long to realize you will not tolerate the aggression and that if he ignores the person, he gets treats. Once this happens you can repeat the training moving the helper closer until he is no longer trying to lunge at the helper. You will need to practice this when you and your dog are walking as well. You will likely need several helpers over time.
You can also have people he knows work with you as well. If he doesn't bark at them, give him a treat. Get him used to the idea of getting a treat when people he doesn't live with come close. I've even had some clients have one new person come with a group of 2-3 family members so the dog is more at ease when training.
Another way to help him get used to people is to sit a little away from the fence line of a school. If he is calm with all the children coming in and out of the school, give the treat. If he starts to lunge, give a tug to get his attention on you and a firm low toned NO. It usually doesn't take a dog long to realize that not barking and lunging is to their advantage. Hot dog slivers are great treats because the oil coats your hand and the dog continues to pay Attention to you rather than people. Many people try a less smelly treat but the dog ends up not wanting them as much as hot dogs. You can also but one hotdog into 30 or 40 paper thin treats that won't fill him up too.
The BAT method might be helpful as well. Read more on this here:
Let's address the coming to you now. He should come to you when called regardless of any distractions. Many dogs don't come when called because they have learned that the only time they are called is when fun time is over. People call their dogs to them to make them come inside or to stop chasing prey (cats) or to be put on leash (end of free running time) or even crated. The only association they have with the come command is negative.
Additionally, dogs find chase to be a highly amusing game and have learned that if they get close to a human, the human might chase them. They love a good game. So what you need to do is make coming to you more pleasurable.
The easiest way is to reward your dog with small tiny treats and praise whenever your dog comes to you when you give the command. Do this even when the dog wants to come to you. After a few treats, the dog will associate coming to you with getting treats and praise. Outside, you will want to use a long lead. Do not drag your dog to you, but say the command and if the dog doesn't come, give the leash a short tug. Start with short distances and gradually extend the distance as your dog becomes more familiar with the command. Over time, you will reduce the treats and increase the praise until praise is the only reward. Another thing to remember is to never call a dog to you to discipline it, go to the dog. During training I don't call a dog to me unless it is going to be pleasant for the dog. I usually don't have much of a problem since the dogs quickly learn that I have thinly sliced hot dog treats just waiting for them to obey me.
I alway recommend starting inside since most dogs are more than willing to come when inside. You can even have a helper and both call the dog to them in turn rewarding the dog for coming to you.
It is going to take some time but most people see improvement in just a couple of weeks of working with their dogs but they are trying most of the things I suggest at the same time and spending a lot of time working with their dogs.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer positively so I am compensated for my time.