My dog suddenly attacks other dogs. How can I stop this behavior?

Poor Bandit! It does sound like he's very fearful of new people - this is a fairly common problem in dogs, and can be due to genetics, inadequate socialization as a puppy, and/or negative experiences with strangers in the past. The good news is, most dogs with this problem are able to improve tremendously with some help from a professional. I would recommend making an appointment with a veterinary behaviorist who can evaluate Bandit in person and help you put together a detailed treatment plan for him - this would normally include management recommendations to help keep him from being put in situations that are overwhelming for him, a training plan to teach him to associate new people with good things (usually treats!), and possibly also medication depending on the severity of his anxiety. It can be very challenging to try and do this on your own if you don't have any experience working on this problem, so I would definitely recommend having a behaviorist help you - especially since he does sometimes try to bite. You can search for a board-certified veterinary behaviorist in your area here: www.dacvb.org

I hate to hear this is happening. Unfortunately, it is very difficult to give advice without being able to observe the behavior. Canine aggression is a complex behavior as it can stem from dominance, possessiveness, fear, anxiety, resource guarding or a combination. Most people are not familiar with reading canine body language and training. Because of this, I recommend to work with a professional trainer. Researching on your own will also be helpful. Familiarizing yourself with canine body language and dog training can help you to recognize what your pet is trying to say. You can find many books written on the topic and there is a trainer named Victoria Stilwell who I think is particularly helpful. Neutering him may help but will not likely solve the problem. In general, neutered males are less aggressive than intact males. Best of luck.

Neutering him would be recommended however, at his age, it may or may not help. I suggest you work with a professional, in-home dog trainer. You need to find a way to actually correct the underlying reason for him trying to attack the smaller dog. You can also put a basket muzzle on him so that if he attacks the smaller dog he can't hurt him. This is not fixing the problem but you could use it as an adjunct to prevent injury. ( https://www.akc.org/expert-advice/training/dog-muzzles-about-when-why-and-how-to-use-one/ ) If you can't keep them separated then you may have to re-home him.

You should definitely have him neutered and getting professional help is a great idea. In the meantime, you could start teaching him the "look" command so you can use this command when you want him to focus on you instead of another dog.

Canine aggression is a complex behavior as it can stem from dominance, possessiveness, fear, anxiety, resource guarding or a combination. Most people are not familiar with reading canine body language and training. Because of this, I recommend to work with a professional trainer. Researching on your own will also be helpful. Familiarizing yourself with canine body language and dog training can help you to recognize what your pet is trying to say. You can find many books written on the topic and there is a trainer named Victoria Stilwell who I think is particularly helpful. Certainly male dogs who are not neutered are more prone to fighting and aggression. Neutering him may help but it will not likely solve all the problems. Best of luck.

I'm sorry that you're having this problem with Cssh! Aggression issues between dogs can be very complex, so without being able to actually meet him in person and observe his interactions with the other dogs, it's very difficult to say what might be causing this. Some dogs simply don't get along well with "new" dogs once they have grown out of their puppy stage - this could well be the case with your dog, since he's about 6-7 months old now. This isn't necessarily abnormal, but it may mean that your dog is not a good candidate for casual socializing with strange dogs. If you want to try and get a better idea of what may be causing Cssh's aggressive behavior and see if anything can be done to improve it, I would recommend making an appointment with a veterinary behaviorist - he/she can evaluate your dog in person and help you understand exactly what is happening. If needed, they can also help you put together a detailed plan to work on the problem. Your veterinarian should be able to find out where your nearest veterinary behaviorist is located, and set up a referral for you if you wish. In the meantime, I would recommend not allowing Cssh to interact with any dogs that he doesn't already know and like since there is a significant risk that he will continue to behave aggressively, which could cause injury to him or other dog.

Neutering can help with aggression, so I strongly recommend getting that done for Regan. But he also needs behavioral training as soon as possible. He needs an expert to work with him on his aggressive behaviors to prevent him from hurting another person. I never recommend owners work with aggressive dogs on their own, so speak to his vet about a recommendation to a professional behavioral expert. I would do this today. Best of luck.