geriatric dog

Question
You may not be able to help me and if not, that's OK.  My 11-year old lab-rott mix dog died 12/24.  He recently had some ear infections that was being treated by my vet (who's gone till Jan.).  Sat. he seemed fine.  It's been very difficult for him to walk, get up, stand for any length of time, etc.  However, he wasn't 'sick' at all until Sunday.  Sunday he wouldn't eat nor drink.  He was panting quite heavily so I tried to get a pain pill (for dogs) down him and he wouldn't even eat the pill wrapped in a slice of chicken.  Sunday night was more of the heavy breathing, his extremeties were cold to the touch.  I covered him with a blanket, but he shook it off after a while and went outside (I live in Phx, AZ).  He stayed outside until 5:00 AM when I went out to check on him.  I figured maybe he didn't come inside because he couldn't, so I helped him up and helped him into the house.  He died 15-20 minutes laters in my arms.  
My question is:  If he had eaten 'something' Saturday out of the cat litter box (either feces, the litter or a combo of both), would that have set something off in him (Chester) that caused him to die?  Sat. he came outside with me doing stuff in the yard and I pulled him away from the cat litter box.  I'm not even sure if he ate anything from there.  I've only had one other dog die of old age and I had to put him to sleep.  So, it could be that Chester died of natural old-age causes, but thought I better check, as I have another lab dog that if the cat feces/litter was a cause of death, I don't want it to happen again.
Thanks for you help, johna

Answer
I doubt seriously it was anything from the kitty litter box.Your dogs symptoms sound like organ failure. How was the ear infection diagnosed? What meds was he on for that? At eleven, it could've been a heart attack,. or a stroke. Although it does sound more like kidney failure or heart failure to me. Remember that you did all that you could. Being a loving, responsible caring pet owner is one of the FEW things in life that never ends well. At least your dog passed away in the arms of the person he loved the most, knowing he was secure and love. Loving a pet always ends in loss and death for the owners. thankfully you made sure it ended WELL for your dog in a loving, safe way. I'm so sorry for your loss
Cindi