I have 3 dogs. A 7 y/o English Springer Spaniel, a 6 y/o Basset Hound (adopted < 3 years ago), and a terrier mix puppy going on 1.
The puppy doesn't like eating in front of the Springer because the Springer will eat his food if a human isn't looking. Sometimes he'll growl at the Springer and even show his teeth. Twice now, the Springer has lunged at the puppy in retaliation/show of dominance/whatever. Obviously, the puppy is in serious danger, so I need to figure out how to get the puppy to be less protective of his food (stop growling, threatening, etc.) and for the Springer to actually leave the puppy alone when eating. The Springer DOES try to steal his food, so the puppy has good reason to be protective, and from those two altercations he also has good reason to be scared of the Springer. Both times the puppy kind of whined a little and gravitated toward a human for protection, because he got the sense what was coming, which makes me think the Springer is the clear aggresor, even though the puppy is the one who started growling and making threats. The Springer also gave this look to the puppy that was pretty scary right before. I don't know if the puppy is responding to the Springer's aggression or vice versa.
It escalted to not just over food, but now over toys. We've had the Springer the longest, who is basically my mom's dog. The puppy is basically my dad's dog. My dad coddles the puppy, which I think causes problems between the three. They all fight for affection, but that's totally normal. They usually get along fine; I even walk them all together (not easy). I just don't know what to do to prevent the Springer and the puppy from fighting, and I don't want to just "let them work it out" because the puppy could get hurt. If you have advice on how to handle this, I would very grateful.
P.S. The basset hound is super pacifist and sleeps all the time anyway. He's not involved in the fighting at all.