biting 2.5-year-old German Shepherd bites 3.5-year-old peekapoo

[PeterDibble]

We have a 3  1/2-year-old female peekapoo and a 2 1/2-year-old male German Shepherd, both neutered. (Also a very old female cocker spaniel, neutered, but she's probably not directly involved in this issue.)

They're both generally good dogs though not well enough trained and they seem to enjoy the shelter at home time. They also, generally, get along fine.

The German Shepherd's main behavioral issue is that when he gets bored he becomes an insufferable pest. But, that's not my problem here. The problem is that, sometimes, often for no reason I can see, he attacks the peekapoo. He grabs her by the neck tight enough that she has trouble barking. He's never actually hurt her, though he certainly could. There's usually no obvious cause. For instance the peekapoo will chase the German Shepherd away from her food and he's fine with that. She'll eat his dog food, and he's fine with that too. Most recently she was maybe 50 ft away from him peeing in the grass and he ran over and grabbed her by the neck. He's not well enough trained to listen when he is really intent on something like this, so we can't just tell him to drop or come or leave it. He still thinks of commands as strong suggestions. We're working on that. Sometimes he bites the peekapoo when she is barking annoyingly at deer in the backyard. Maybe he can tell that it's bugging me. But him attacking her while she was peeing in the grass stretches the idea that he's being an enforcer for me. He has heard me scold her for peeing in the house, but I like her to pee in the grass!

The peekapoo, by the way, is not intimidated. She stands her ground.

Another thing. They usually get along fine. Sometimes you'll find them curled up on the same mat, asleep.

My questions are, why do you think he's doing this, and what is the most effective way to get him to stop?

[JMFS]

17 hours ago, PeterDibble said:

The peekapoo, by the way, is not intimidated. She stands her ground.

Typical small dog, lol.

Momo exhibits similar behavior with our cat, Monkey.  I cannot scold the Monkey in front of Mo or he'll go after poor Monks.  He doesn't go for a full on bite, but he'll do a tooth pinch, which is irritatingly painful, or a nose punch and woe betide the cat if he runs because then the prey drive kicks in.  Interesting that your GSD took after the peekapoo from such a distance - puzzling to be sure!  She was just peeing, not barking or making sudden movements? 

When Gertie stops listening to me in the yard I'll put her on a 50 ft lead so I can more easily correct the undesirable behavior.  For your peekapoo's safety that may be an option to consider.  These bites aren't breaking the skin, are they?  How quickly does he release?