As far as I know, Cycircled doesn't affect buffs? I'd say from your screen that you have custom borders around your buffs using Buffalo or something similar and use the standard Pitbull debuffs on your target, witch have the standard Blizzard border. The strange thing is, as it's your UI you should know better than I do
You can change the Border of Pitbul Buffs/Debuffs, by replacing the default Blizzard border.