Usually it stems from Gus' lack of initiative. I get chews when I bring home work or want to give them a treat. Cotton dives right in to enjoy hers. Gus eyes his and walks away to lie down near Cotton. And eyes HER chew. It took me some time to figure this out. Once she has the end good and soft, he stands up and yips at her. It's a totally different voice from his normal booming bark. It's a nagging voice is what it is. As in "I want that one, give me that one, I saw it first". Frequently, she turns her head and ignores him. Sometimes she doesn't budge and ignores him. Once in a great while, she leaves the room and ignores him. You can see the common thread.
This is when Gus stares at me, willing me to intervene. Like below. I don't and Cotton finishes, gets a drink of water and all is quiet.
Until now. Cotton apparently had had enough. She finished her chew, went to get some water (I know this because she is a loud drinker, and splashes water back over her feet so even if I didn't hear her, I would see the evidence on the bathroom floor). I digress.
On this night, Cotton decided she would show Gus what happened to dogs who didn't enjoy their chews. She returned and applied herself to Gus' chew, the ignored chew lying on the living room floor. She blatantly brought it into the room where I was and lay down to gnaw again.
Gus was indignant. Even if he didn't want to chew it, she shouldn't because it was his. He stared at her.
As you can see, she stopped chewing. And Gus took his chew and went off to chew it, full of righteous indignation.
I swear I saw Cotton grin.