Wow, I'm a mess after reading that b/c this thread definitely hits close to home for me too. All of these posts really show the incredible bonds we develop with our pets. I personally believe it's b/c they are so loyal to us and are pure at heart. They obey and do not judge. They bring a different kind of joy to our lives that humans can't provide, so it can be really difficult when they're gone.
It's also only a matter of time before I'll have to put our 4.5 year labaradoodle (Timber) down as well. We came very close to losing him twice already. The 1st time came as a puppy after he got neutered b/c of complications from the anesthesia, but he rebounded after 2 weeks in ICU and a lot of TLC at home over the next several months. My wife and I were recently married when we got Timber and he was our first pet/kid. Nursing him back to health was really tough (feedings thru stomach tubes, expensive meds, constant monitoring, frequent checkups, etc.....) and there were numerous times where I thought he wouldn't wake up the next morning, but he ended up slowly getting better over time. Looking back, that experience ended up bringing my wife and I a lot closer. We found out that as long as we were always there for each other, we could overcome an awful lot of heartache.
This past April Timber's belly suddenly filled up with fluid and he was eventually diagnosed with both Liver and Kidney disease (which is a pretty lethal combo for dogs, let alone humans). The vet thought he might have a couple weeks at best, so again, we thought we were going to lose our best friend at a young age. After doing a lot of research, we decided to change his diet drastically and put him on a unique combo of food/supplements/medications/probiotics. I wanted to be proactive as much as I could instead of just sitting around and watching his health slowly decline. It's now 6 months later and I'm happy to report that he is back to being a pretty healthy and happy dog overall.....and subconsciously, I'm back to thinking Timber will be around for along time (although deep down I know that's not true).
Some good advice that our vet gave us was that once he can't (or doesn't want to) do 2 of his 3 favorite things, it's time to let him go b/c his quality of life isn't there anymore. We've done everything we could to give Timber a good life up to this point and he's rewarded us 10 fold from the joy he brings our family (we now have a 2 year old boy who absolutely loves Timber), but his time will come sooner than later and that will bring us immense sadness.
Best wishes with your pets and helping them pass on to the other side. There's no easy way to go about it, but you need to do what's right for the pet when it's time.