My 1 year old Shih Tzu gets agressive towards other dogs while on walks. This started around last November it has not been a constant thing. He went to puppy training classes from May - July last year had no problems with him there. He is fine with dogs he knows there are dogs around the area that he has seen regularly since he was a puppy and is well behaved with them it is just new dogs he gets agressive with. Usually we try to walk him at times where we know it will not be busy and if we do see another dog in the distance we use a clicker and give him a treat so he associates dogs with something positive but if there is a dog coming towards us we try to cross the road or turn around but he will not move he drops to the floor and lays down waiting for the dog and when the dog walks past he tries to lunge at the dog and starts barking like crazy we ignore him and wait until he has stopped barking to carry on the walk. But once he is in that zone you cannot distract him with anything his focus is just on the dog we have tried offering all sorts of treats and jumping up and down to get his attention but he won’t budge. He started going to doggy daycare in February once a week and he is totally fine there they asses all dogs and make sure they fit into the group and he really enjoys it there! At doggy daycare he is off lead as it is in an enclosed farm. We don’t not take him off the lead while we walk him as we are unsure how he will react if he sees another dog in the park. We use a long lead so he can run free and if we need to grab him we can but we went to a enclosed picnic area in a park and let him off the lead in there to practice recall and a lady with her dog came into the enclosed area to walk through and he ran straight to the dog and tried to attack. Any advice on how we can train him to stop the aggressive barking and lunging and maybe how we can get him to not take notice of dogs at all when he is on walks?