Hi Sarah,
This is actually a good thing. He sees other dogs as something positive and rewarding. The thing is that you say that you are struggling to keep him with you when there is another dog around, that is not something that should be tolerated and will only build because he ends up being rewarded for this behavior, since he pulls on the leash and gets whats he wants which is to meet the other dog.
Try training your dog to stay calm when there are other dogs around, and make sure that you don't let him meet the other dog. If your dog is overly excited, then move away from the other dog until he can handle himself, then reward and slowly approach.
Please let me know if I can be of more help or if you need clearer instructions.
This is actually a good thing. He sees other dogs as something positive and rewarding. The thing is that you say that you are struggling to keep him with you when there is another dog around, that is not something that should be tolerated and will only build because he ends up being rewarded for this behavior, since he pulls on the leash and gets whats he wants which is to meet the other dog.
Try training your dog to stay calm when there are other dogs around, and make sure that you don't let him meet the other dog. If your dog is overly excited, then move away from the other dog until he can handle himself, then reward and slowly approach.
Please let me know if I can be of more help or if you need clearer instructions.