My dog attacks small dogs. How do I stop this aggressive behavior?

I am very sorry to hear about Bandit. This is a scary situation if Bandit is truly giving no warning prior to his aggressive outbursts. There may be subtle changes in his behavior that are difficult to pick up on without having observed aggressive dogs in the past. Neutering may help decrease his aggression toward other dogs but truly with unpredictable aggression like this a consultation with a veterinary behaviorist is recommended. They can discuss Bandit with you in depth, examine him and observe him in different situations and come up with a training plan to help you manage him (or they may advise he not be around other dogs if they feel his behavior is too unpredictable). I would talk to Bandit's veterinarian to find out about veterinary behaviorists in your area.

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.

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.

Some dogs can be aggressive towards other dogs regardless of their upbringing. I recommend walking Sammy on a leash with a basket muzzle. Take treats with you on your box and when you see another dog have him sit until the other dog passes. Then give him a treat and praise him for being a good boy. This will take time in order for him to concentrate and focus on you rather than the other dog but with consistency he should start to focus on you and the treat. You can also look into hiring a dog trainer to help you train Sammy with his aggression towards other dogs. It is important to remember that this is not necessarily a consequence of how you raised him and may just be the way he is. Some dogs are never OK with other dogs.

This is a very dangerous situation and depending on the trigger for the aggresion neutering may or may not help. I would not recommend this without an individual visit from a certified behaviorist to explore the triggers and patterns of behavior. Please ensure he is not unsupervised, particularly around children until he can be fully assessed

First, neutering Freckles can help. I do recommend having that done. Then I would put him in with a professional behavioral expert for training. I never recommend owners work on aggressive issues by themselves due to safety issues. Your vet can make a referral to one for you. Best of luck.

Neutering can sometimes help with interdog aggression, so if you plan on keeping them both, having them neutered may help. If they are constantly fighting with each other, it may also be time to bring in a professional who can view the situation in person and help formulate a training plan to get the dogs OK around each other. You may need to keep them completely separated and slowly introduce them in a neutral location such as on a walk, and then only have short monitored sessions until they can be trusted around each other. However, if one dog is lunging and growling before even being introduced, seeking professional help is best.