When we brought Bella home, our cat would disappear for 1-2 days at a time. We could not find her. There's only so many places she could hide in our house. I looked everywhere 5 times. It was bizarre. She also wasn't eating much, and lost a little weight.
The vet recommended we try this:
It seemed to work, but it could be a coincidence.
In addition, I've been putting these on her since we brought Bella home, otherwise she would have sliced Bella up by now:
Bella wants to be friends with the cat, but not the other way around. Our 55 lb dog would be no match for the 10 lb cat if they ever got into it. Bella has never shown any aggression toward the cat. Just the normal chase her because she wants to play stuff.