In 2011 (iirc), our oldest dog, Becka, (a Jack Russell Terrier) was 13. We knew she would be winding down soon so my mom lined up and got a replacement puppy to help fill the eventual void.
The rest of 2011 passed and she continued living. 2012, she survived that too. However, in 2013, just a week or so (it was the day Stan Musial died) after she turned 15, I heard my mom screaming upstairs. I didn't think anything about it at first, but curiosity got the best of me and I slowly went up the stairs wondering if I really wanted to know. I found my mom huddled over Becka, who was lying prone on her side in the middle of the kitchen floor. There may have been some spilled urine too, but I don't remember. We thought she had just suffered a stroke. I heard from my mom that she suddenly toppled over on her side and began violently kicking her legs and having seizures. But that night about an hour after the incident, she got back up and started walking around again. Okay...
She had a few more attacks over the next month and began walking with a very pronounced limp. We put gates up to prevent her from climbing stairs (she rolled down the stairs several times) and she frequently tripped over her own legs. But she didn't appear to be in severe pain except for her arthritis that she'd had for years prior. Around the time of Valentine's Day, she had her most violent seizure yet and had diarrhea everywhere. My parents, sister, and I were not home because we were getting shots for our cat, but my other siblings saw it happen. It was also around that time that she stopped eating. We'd leave food out for her to freely eat what she pleased, but it just sat there and we couldn't encourage her to eat. A few days later, my parents made the decision. I didn't even know about it until I was physically in the car riding to the vet to put her down.
We didn't leave until evening. All through that day, we kept her gated up in the laundry room. She mostly just laid on her blanket by the gate watching us move around the kitchen. A few times, she even hobbled around by the gate looking at us trying to get our attention. When we left, my mom wrapped her in my favorite blanket from when I was a baby/toddler and she rode on my mom's lap. Normally, she'd be a nervous wreck in the car plastering her nose on the window and jumping around on the seats yelping. This time, she just laid still.
We got to the vet and found out she had been bleeding from her rectum. She just laid flat on her side on the examination table while the vet checked her out and gave her the lethal dose of euthanasia. After she was gone, I totally lost it. It didn't even seem real all throughout that day but the reality check caught up with me. After all, we'd had her since I can remember (I was maybe 20 months old when my mom got her after her first dog passed in December 1997) Once her body was all relaxed, yellow goo started oozing from her nose so my mom shoved everyone out of the room, including me. We think it was fluid from her lungs caused by cancer, which we didn't even know about before her passing. My parents and the vet wrapped her in a towel and put her body in a coffin that my dad made for her. We carried her box out to the van and I just sobbed through the whole ride. We had to stop at Shop n' Save on the way home. I was so beside myself that my mom told me to wait in the van, but something with me didn't sit right about sitting by myself in the van with the family dog's corpse sitting behind me. So then I went in Shop n' Save sulking around and sobbing and my mom finally told me to stop.
When we got home, I just went inside and closed myself in the basement. I could hear my younger sisters making jokes about her death and it was making me upset all over again. My mom and dad went off into the woods that night and buried her next to our dirt bike trail. It was maybe two or three days until I was over it entirely.
I do feel now though that I really wouldn't be too devastated if we lost our current dogs. Yes, it would probably be a bummer if they died, but I really don't care for dogs anymore and I can remember what life was like before they existed and I don't think my life would vary too much if they were gone, except for the fact that I wouldn't have to clean up after the messes and destruction that they cause.