I have a ~17 year old black cat, breed unknown, who has been kept as an indoor cat since she was 18-24 months old. We have suspected a number of health problems for the last two years, and took her to the vet, who believes her kidney function is reduced. Unfortunately, we do not have the funds to pay the high cost for the treatment he recommended.
Two nights ago she began escaping from the house by clawing open the dryer vent, and has done so a total of five times. We have increased the complexity of the dryer vent seal each time to deter further escape.
Each time she's gotten out she simply finds a place to sit, and doesn't move until we go collect her and bring her back indoors. Once brought back inside, she doesn't make any effort to leave again for 3-5 hours. On two occasions she has been extremely cold, and will only move slowly when brought back inside.
I believe this may be end-of-life behavior for the cat, however my mother disagrees and has been resistant to taking the cat back to the vet. Is there a likely explanation for this changed behavior?