Dog behaviour. Problem approaching other dog's.?

i am dog sitting a dog right now that is quite reactive to other dogs when out walking .... he will lunge at them, growl, bark and basically wants to kill them ... when i see another dog coming i nonchalantly move his leash and him to the side there the other dog is not ... i shorten the leash but remaining calm and not stressed out about the approaching dog ... and i just keep walking ... i do not look at the other dogs or other dogs owner, i just keep walking ... if the he starts to freak out i still keep walking and if it really freaks out i step on his leash so he is pretty much immobilized and i just stand there until he mellows out ... and you have to wait until he mellows because if you just keep moving then the whole exercise was about his freaking and not him mellowing out ... the first time it took him almost 15 minutes to mellow out with me standing on his leash, he could not move ... i have been doing that for over a week now and he is much less reactive to dogs ... he can tolerate little dogs now but any dog that wants to go for him, it is on, we still working on that :O) considering your dog is familiar with other dogs and is okay with other dogs in most situations, you should not have too much trouble training the dog ... be sure you are not using a harness but a collar, and a martingale collar might be a good idea (tightens with pulling but does not choke) ...