I have collars that I bought via the Vet....breakaway, which is important. I keep them almost to the point of falling off, and seem to have no problems. Maybe you should chip the cat rather than use a collar. I think it is a tad expensive to have the chip inserted, but well worth it if you have no other alternative. Maybe you could remove the collar at night? Or times when you think the cat would be more likely to escape! Let us know how it turns out for you! And Good Luck.

Gotta love those cats and their special needs!