When I had a indoor cat, I had a large 4-door vanity in my bathroom. I fitted a hard plastic cat door -- too small for a big GSD head to fit in, in the 4th door of the vanity. I put the litter box on the other end so the cat would have to go in their to potty.
It worked good, kept the dogs out of the poop.
But when I redid my bathroom, that vanity went, so no more indoor cats. Bad for the asthma anyway.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC