I've not had one run away from me yet, maybe because I give all mine loyal traits. Have you tried right-clicking on their icon to see where they are or called them home like regular Sims can? I enjoy watching my adventurous cats and dogs running round the neighbourhood with the right-click option when I let them out hunting etc.
My cat which is pampered and lazy has run away a few times but comes back in less than 24 hours - either when my sim has a new baby (4 babies ran away each time) or if there is a loud long party (the cat has a fear of the stereo which is normally kept off to keep it calm).
I had one cat that ran away constantly. It was a combination of factors I think. First I had two toddlers and three pets in the household so I didn't always keep on top of the pets' social needs. I was good at keeping them fed but remembering who'd been petted or played with that day, not so much. The older cat was not friendly to other cats, and the younger one would always run away if they had a fight. But I don't think a fight was involved every time. The older cat and the dog never ran away so traits must have been a factor also, but I don't remember what they all had. the runaway was an adopted stray while the others were CAS pets.
Now that the kids are older and all those pets have passed, the new pets get plenty of attention from the family on a regular basis just in case. the current cat goes wandering because of a certain trait but it never counts as running away and I can call her home whenever I want.
I don't know if it will work for everyone but whenever my pets try to runaway, I would pause the game and locate my pet, then Shift + click the pet and chose reset object (debug). It would stop them from running away temporarily then just make sure the pet is happy before it chooses to run away.
I had a sim with a dog who had the adventurers' trait. I think she ran away a lot because I never took her out for adventures I'm gonna try out a cat with lazy and aloof trait.
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Now that the kids are older and all those pets have passed, the new pets get plenty of attention from the family on a regular basis just in case. the current cat goes wandering because of a certain trait but it never counts as running away and I can call her home whenever I want.
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