Staying calm is a good thing! Is your dog calm as well? Holding the collar tight can produce a problem if your dog feels trapped by the closeness of the other dogs approaching. A short leash is good and to keep moving is best, that's if the dogs do not mean any harm. If the dogs do mean harm, then you cannot move. For a dog - movement sets the game in motion sort of speak. It it all about space and movement and it must be assessed each second like a chess game. To keep other dogs at bay, I would carry an umbrella, and flash it open as a bluff, but make sure it doesn't scare your dog. That would mean that you would train your dog in the house, in the backyard and on the walk to associate the opening of the umbrella with a treat, and go very slowly with the opening of the umbrella and then build to the intensity that you will use during the threat of another dog. Some trainers carry treats, and throw the treats over the approaching dogs head, and some carry pepper spray to deter the dogs. I did hear about using the spray bottle with water and vinegar, but I don't know if my aim is any good and I would rather carry an umbrella. Sometimes a good loud yell at the dog while stomping your feet and keeping it up until they turn and move away may work. This isn't an easy question to answer. It depends on what your dog is doing and what the other dog is doing/acting like. Do they hesitate while coming closer, barking? I would see this as an interested dog, but not confident, watch him and keep moving in a calm manner. Perhaps the dog circles you and your dog, come head on, or from the rear? A dog that circles has entered your space, that tells me it has enough confidence to do so, but hasn't committed to engaging, this one I would say isn't that confident -- try a yell or the umbrella may work. The dog that comes from the rear is scared, but still has approached, this one I would keep moving as your eyes are watching for him to accelerate into confidence. Again, the yell and the umbrella. It's the dogs that come at you head on with stiffness in the body that scares me the most. I would not wait for this dog to get to your inner circle, you must be able to read this dog from far away, give it all you got,and I would use pepper spray. I have used pebbles and rocks from the ground or other objects within to throw at these types of dogs. If I knew that such a dog were in my area, I would think twice about walking there. I would get a DVD about canine body language so you would be able to make judgement calls. Dogwise.com has excellent books and DVDs that may help you understand this language and this will in turn help your dog. As you become more aware of body language, yours, your dogs and the approaching dog, you will be able to make decisions in the spur of the moment and change as fast as you can think. Bottom line is above all else, you must make sure that your dog is not going to do damage to the dogs, even though they are off leash. When out in public, your dog has to be on its best behavior or not out in public at all. For two or more dogs, I would keep my wits about me and keep moving in a small circle to watch both of them. It would be good if your dog knows how to move in the direction you want to go, and this comes with training exercises before you need them.