We have had our 3yr old Vizsla Fletch now for 10weeks, he is getting on well and is a very loving dog. When we are out in our local rec where there are dogs off the lead he generally gets on with most of them fine but he has been quite aggressive towards a couple of dogs barking growling when they are sniffing him, we cant figure out what it is about certain dogs or which dogs he will or wont get on with, we always keep himon a 30ft lead so that we can meet the dog first before fletch then call him over and even the most friendly dogs he dislikes especially non-neuterd dogs? He also when in the house growls at noises he can hear from outside? He gets lots of exercise from cycling and running and alot of mental stimulating games but we struggle to get him to play retrieve with any toy we have brought his noise just takes over and he just wants to sniff around so a couple of throws of a toy and hes bored? any ideas?