It seems to have been the final straw. After a few unfortunate run ins and an attack-2 big off leads dogs crowded him and started to growl and snarl at him. He was on lead, but so frightened he whimpered. When he saw some dogs yesterday he immediately started barking at them and ignored the chicken that I had. He didn't stop barking until they had gone past. He has been to dog training and was fine there. My sister's dog is very calm, but is too old to play and they just ignore each other. I'm not sure of the best way forward. Thanks.