Casey went home with his new mom last night. Though I'm a bit sad that he's gone, I'm mostly relieved, and so is Chai. When he was here, she didn't try to compete with him for toys or bones - he just took them over. But as soon as he left last night, I threw her her sheepie toy, and she happily chewed on it for awhile. She hasn't played with that since before he got here in Feb! And this morning she's out in the yard chewing the marrow out of a fresh bone.
Yesterday I tried a different approach to get her to use her cart for a longer period of time. I put her in it BEFORE we went through the gate into the park. I knew she'd have to walk around to pee and poop. That's what she did, and then she just kept going! She seemed so comfortable I went back to the car for her frisbee (which I'd stopped throwing for her months ago). I tossed it, and she ran so fast and enthusiastically that she did a somersault in her cart! Oh no! She looked worried, laying on her side, tangled up in the contraption. But I pulled her upright, and she was off and running again. What a truly satisfying day. One of the other dog parkers kept commenting on how happy she looked. This is what I've been hoping for - that she'd realize that she can run and do the things she used to do and have a sense of freedom. I hope it goes this well the next time we go to the park, which will probably be tomorrow.