if he gets out of a collar have you thought of a harness and a police style lead they have two clips one for the head collar and one for the actual neck collar or harness?

It gives you more control as you have two points to control the dog with, they are very good

I guess i would more then likely muzzle him while out but carry on training, do classes e.t.c not everyone likes that tho But i guess it depends on how you can deal and control if happened again but i feel the same about my dogs being able to defend themselfs so its hard!

Saying that tho alot of friendly dogs dont like being jumped on and would react in a "bugger off" way to the other dog, Zeb does something and hes a soft lomen with everyone But some times he has enough of being jumped on and tells the other dog

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Owner to-
lots of rodents
2 monster dogs
1 slinky cat