It’s hard to avoid sentimentality on the evening before putting down a beloved dog. Something there is that wants to explain, but all of us who’ve ever owned such a pet know what it’s like, which doesn’t bear repeating.
Sandy at this moment has no idea that she’s within her last 24 hours of life and, ironically, seems happy enough, having lain outside for most of the day because it’s cool, quite good dog weather. Nor does her friend, our other Belgian terrier Danny, understand he’s about to lose his best friend, and even if he could understand, he’d hardly comprehend why. Tomorrow at 1:15 pm we’ll walk Sandy the three blocks to the neighborhood vet and there say goodbye. Amazing, we don’t think she’ll be unable to walk the three blocks if we take our time, although she might have some pain in her hind quarters. Her back legs hardly work at all anymore, and she suffers when she tries to get up and cannot, legs splayed out under or behind her. It’s something no pet owner ever wants to see.
Danny will probably be jealous that Sandy’s getting a walk and he’s not. The three of us – Laurie, our daughter Jean, and I – will come back without her, sad of course, and Danny will think that Sandy’s just coming later; then, over a period of days, Danny will adjust to Sandy not being around (we hope), and soon he may recall her only in his dreams. Would that her owners be able to adjust as readily.
brucejberger 
This is incredibly sad. We have a dog, which of course I love. But he is our first and only years after getting him, I realized that with life we bought death as well.