[yorkietalkjilly]

He is fearful and anxious around other dogs and using his biting and aggressive ways to warn them off. You have to take a deep breath and calm yourself when another dog approaches and do your thing yourself to re-direct his attention and keep him busy while the other dog goes by, rather than both of you worrying about how he's going to react. He reads your anxiety about his anxiety and reacts to that as well as his own anxieties - so calm yourself a bit and he'll be calmer, too. Next, I'd start distracting him when another dog approaches by crossing to the other side of the road or stepping off the path for now, getting out luscious - high-value, loud-smelling food like a piece of freshly boiled chicken and put that in front of his nose and walk him in a tight circle with that food just ahead of his nose as the other dog passes. If he stayed focused on the food for the most part and didn't aggress as the other dog went past, he gets the food. If not, put the treat back in the treat pouch and continue your walk, ignoring him. Do this every time a dog approaches and walks past.

For the time being, distracting this fearful guy with something he really, really wants every time a dog that worries him comes near will start to retrain his brain that actually the other dog isn't going to hurt him as nothing bad happens as it goes by and he gets rewarded with good food when he doesn't growl or bite at the other dog as it goes by. The tight-circle walking will also serve to keep him worried about running into you and he'll have to concentrate on his footing, your legs and feet and that food - not the other dog. Next you could try using a squeaky toy or chewie to distract him as another dog comes by. If you keep this up and do it every time you walk him for the next couple of months, he should begin to develop a better attitude and far less fear.