As I have stated on a few posts, we are taking/rehoming my FILs Havanese in a few weeks when we move. When we lived there the dog was happy, content and sociable when off lead with other dogs. Never a problem. In the last year (so since all the upheaval/being moved constantly/no stability) he has become snappy with other dogs, especially with other small dogs. A dog will approach him, bit of sniffing which goes OK, then Harvey's body will go a bit stiff and then he will snap/snarl (usually when other dog is sniffing his willy!). The other dog usually buggers off then, and we have not had any fights or bites thankfully.
With bigger dogs he tends to sniff them, they let him and then they have a running/chasing game.
I would like some strategies and ideas in place to help me deal with this when he comes to live with us. Not letting him off lead seems a bit drastic as nothing has actually happened, but on the other hand I don't want to take chances.