The reason why Cudi is snapping is because he is frustrated. A lot of dogs will re-direct their frustration to other objects / animals when they get to the level where they have to find an outlet for thier frustration. It's the same thing with dogs who fence fight - one dog on one side, one dog on the other. They go at it like maniacs. But take both dogs out into society and they are quiet and friendly (but not always with eachother at that point).
Training helps. My GSD and my Golden are enemies. I have to keep them seperated 24/7. When my GSD is in the back yard and my Golden is in the outdoor run, they'll fence fight. They don't when I'm home...but I'm not always home. I noticed a big tree by the outdoor run had chunks missing out of it, high on the trunk. I finally figured out that my GSD and Golden would fence fight and then my GSD would take his frustration out on the tree. Bad idea. I don't want broken teeth.
So - I leave large rope toys - rubber jolly balls (for horses) and on a branch on the tree I have a large jolly ball tied off. Now when he gets frustrated he'll kill the ball or snatch a toy and shake it. Saves his teeth and the tree.
Hondo Von Dopplet L Bauernhof "Hondo"- GSD
Lilie's Tug McGraw "Tug" - Golden Retriever
Maggie - Mini Dachshund (Rescue)
Lonestar - Texas Blue Lacy
Funyon, Ashe, Soot - Barn Cats
Scooter /1/2 Arabian, Shadow, Katie / APHA