This sounds really horrible, but it's only the wording - it doesn't fill me with joy to be asking a question like this:

How do I convince my dad that it's time to put the family dog down?

We've got three of them - 2 Jack Russells and a Terrier (all great dogs) - and the oldest one is pretty much on the home straight. She's thirteen (old for a Jack), has had at least two strokes in the last year, struggles to walk in a straight line, is having trouble with her "lady bits" and has gone completely deaf.

It's obviously obvious that there's something seriously wrong with her, but my dad is in almost total denial. Understandable - first dog we got after his mum died, so she means a lot to him for personal reasons, like. I guess she helped him through the process of grieving in some way. Of course, none of us want to see her go, but it seems to me that it's crueller to keep her alive just to cheer us up. It kind of hurts your heart to see her the way she is (I'm sure you'll know what I mean if you've ever had a pet you felt a lot of affection for).

Now, my dad has made - and cancelled - three appointments with the vet in the last month, so I know that he knows that the vet will most likely advise putting her to sleep (a horrible euphemism, IMO). Every time we broach the subject he pretty much goes stone silent and won't talk to anyone for hours afterwards. But like I said...keeping a pet alive just to make yourself feel better, even tho the pet must be in near-constant agony...seems to me there's something a little selfish in that. I dunno. I'm confused, a little depressed at having to face the truth, etc...

...so, anyway, what to do? Or to be more precise, how to do what I know and you probably know has to be done?