...my ancient dog

My dog is 13 1/2 years old. When Katie was 8 years old she fell in love with Dalmatians, and this was even before the newer movie came out. She loved Dalmatians. So, she saved her money, and in 1995 we brought Chasse Lady Firefighter home. Yes, she was Katie's dog, but...eventually it was obvious that she was my dog. Chasse means Hunter in French but the name doesn't fit her personality. She is a wimp. But a tough wimp. I never expected her to live this long. She's been hit by a car and almost died of shock, and has been shot with a blowgun dart (back in her wandering days). And I really thought she would be gone by the time I sold the house and moved into the apartment. But she's still here. And we have a problem. Occasional accidents on the carpet turned into regular accidents on the carpet turned into daily accidents on the carpet. I've tried limiting her water during the day and penning her in the kitchen (she can get through whatever I put up). I always potty her twice in the mornings--once as soon as I'm up, and again just before I leave, and try to get home quickly after school. But today I left for one hour to go grocery shopping. One hour. I pottied her before I left...and came home to another puddle on the carpet. And I feel awful. I feel like a bad person because I'm ready for Chasse to go to doggie heaven. This has to be stressful on her too...once trained she rarely had accidents in the house.