Ohhhhhh Rowan!!!!
You did the right thing. With our Bailey, a 13-year-old collie with pancreatitis, I called the vet and then canceled more than a dozen times because she'd rally around when I started getting her into the van for her final vet visit. In hindsight, I should have spared her that last year of being blind and deaf (we think) and increasingly unable to climb the step to get in and out of the house. We waited for the final stage: she couldn't stand, couldn't eat or drink, but she'd still look at us and give a wag, as if to say "I will never leave you unless you force me to." So we took her to the vet and finally, finally, Bailey's infirmity ended. Like her brother, she wouldn't give up the ghost on her own. Years ago my dad had a Dalmation who languished for three weeks before he resorted to having her put down. They will not leave us - they force us to make that dreaded decision for them. I feel your pain and all of us at @dpet and #dailypetphotography mourn the loss of Rowan along with you.
Because of you.... Rowan, you big, beautiful, sweet, fluffy white puffball, you inspired a poem that dog lovers everywhere will want to share. (Get your name on it, get it copyrighted.)