Having to put a pet down and grief

I'm very good about staying distracted from... everything.  Either through the magic of ADD or the myriad of things I can do on my phone coughredditcough combined with earbuds (youtube, podcasts, etc), i can stay mildly distracted from the world unless i want to be.  or sometimes not.

We have 2 poodles, well, a black poodle and a white maltee-poo.  And Charlie, the poodle, his health has been going downhill for a while.  Not fast, but he's been getting older and having more and more nagging health problems.  And we've come to the point that it's time.  He's on the precipice of the slope getting harder.

As a Buddhist, I should endeavor to never take life.  But something I've been wrestling with is, do I generate more negative karma by allowing him to suffer, or do I generate more by putting him to sleep?  I've secretly been hoping that he'd just... not wake up one morning, passing in his sleep painlessly and, yes, guilt free for me in a way.  When do I know it's time so that I don't steal any of his good days and only keep him from the worst days?

It's Thursday.  Final goodbye is 415.  I still hope I'm not stealing time from him.  I want him to be happy, I want him to feel better, I don't want him to stop being at my feet as I sleep every night.  I don't want to say goodbye.

And I can't distract myself from all this.  I won't be able to.  Even typing this out isn't helping, at least not yet.

I'm going to give his face a hair cut, not that the poor boy can see anymore.  I want him in his Sunday Best when I bury him, you know?  I'm going to keep the last toy he has, not that he's been able to play chase in a long time.  I miss his better days and I'm going to miss his lazy older days.