Move after every kill and you will remain undetected, even by dogs. You could also use a sniper rifle and Kill the dog first. I prefer to take out the dogs first and then I circle the encampment while picking off the guards one by one.
I found an outpost with like 8 dogs and 2 or 3 guards and I just shot one dog with an arrow which caused the other ones to sniff around it's corpse. One grenade and a couple arrows later I had the outpost and 1500 xp :P.
...do you mean to get the 1500xp for taking a base? You just have to be not DETECTED. You, as in, not scene. You can be heard. I normally just take a 50 cal and snipe everyone from a hill as they run around screaming trying to figure out where its coming from. You don't have to get stealth kills, lol.