Hello completely new to raising chickens. I got 6 baby chick's from the feed store a week and a half ago. 3 buff orpingtons and 3 Americaunnas. They have been great since we got em. We have them inside a big tub with fresh food and water always available. I started taking them outside 4 days ago for about 30 mins in the morning when I clean their brooder tub. They have a 75 watt regular light bulb on one side of the tub because it's summer and outside is 95-100 and inside is usually 78. Normally they eat sleep poop wander around and repeat. Never any aggression except when I take them outside they fly and jump around on top each other which from my understanding is just them deciding pecking order. This evening I heard them chirping loudly so I went to check them out and there was one of the orps being chased around by one of the Americaunnas the orps butt was bleeding with a big area of feather fluff missing and the Americaunnas beak was all bloody! I first took the orp out and the Americaunna started pecking the other ones. So I took out the Americaunna and put the orp back in and the others started pecking the bloody spot. So I took her out again. I have separated the aggressor by itself and the bleeding orp by herself and the 4 others have been fine since. I'm not sure what to do! I mean do they have to be separated forever I've Google and many posts said once they make other chicks bleed they will always do this. Is this correct? Do I need to get rid of this chicken? When can I put the injured one back? Do I need to go get medicine for the wound? What could have caused this. The only thing different between tonight and any other night was my 6 yr old put the dogs night time kennel next to the tub. We have a little Chihuahua and a Doxie. Also When i took both chick's out the other 4 started pecking like crazy at a spot on the plastic tub. Help the feed store is closed tomorrow and not sure what to do or how to proceed thanks.