My partner owns two 6/7 year old collies crossed with possibly a husky/alsation. They are brothers from the same litter and unspayed. Since I've come on the scene there have been a few behavioural changes as the dogs adapt. The "top" dog (Sam) has decided to adopt me in preference to my partner (much to her consternation!), the other dog (Finn) is starting to assert itself a little more. Sometimes there is conflict (growling) between them over who can be closest to me, and if I give Finn any attention, Sam watches like a hawk and is clearly unhappy about it. While Sam has a history of occasionally fighting with other dogs - notably labradors, it seems to have got worse recently. Both dogs are well exercised and well loved, with lots of attention. When I exercise them I tend to use my bike, and have so far managed to control both dogs fairly well, avoiding other dogs where possible, and generally giving both dogs little time to think about distrations - so for example, they no longer chase deer. However, I walked them with my partner the other week, and while we were playing ball with them, Sam suddenly ignored both of us and started to glare at a dog 100 yards away across the field. We gave it repeated warnings to leave it alone - the other dog then approached in a friendly way - my partner shooed it away while I kept Sam away. However, we thought the situation was resolved, but the other dog turned back and came up to Finn to sniff him at which point Sam just went for him and I had to grab him and haul him off. Fortunately no harm was done to the other dog, but I fear it's only a matter of time. Since then, he seems to be growling at pretty much every dog that comes near. We're thinking of making him wear a muzzle to be safe -it's the "kindest" one we could find, but we don't see this as a long-term solution. I don't know if it's connected, but another thing that Sam does is that he is very demanding (physically) for attention, but if he stops getting it, he simply leaves the room and goes to sulk in the bedroom, usually coming back 20 mins later. So if we're watching the TV in the evening, while Finn is happy to lie next to us, Sam insists on it either being all about him, or he goes away. It's weird because when he's happy, he's really really happy and loving - he'll shower you with licks in the morning (while Finn, while happy to receive attention, doesn't give much back lol), but he goes into a sulk quite easily if he doesn't get his way. Any recommendations??