HELP!!!! 2 Male Aggressive, 10 month old Shih Tzu dogs.?

[joe c]

When I walk my 2 ten month old shih tzu dogs from the same litter they fight with every dog in sight. Then when then have to move away the slightly bigger one attacks the other one. I have taken then to a behaviour therapist and a dog trainer but they have been no help as they want them trained separately - when this is set up with then neither dog exhibits aggressive behaviour towards the dogs they bring with them - its as if they know is a set up! anyway when I try to walk the each on their own they still are aggressive, however, they do require to be walked together most time especially as they go on holiday with me. Please can anyone give positive advice??? drowning then is not an option which was suggested when I had them down at Loch Lomond!!! Also I have been told that an Electric collar is not a good idea. I've tried using
the air canister pet controller to no avail. Quite frankly each one 'looses it' when they see a dog big or small. HELP