I am so sorry to hear of your Domino's illness. Is this stage 3 cancer or kidney failure diagnosis? You didn't say.
I think the best guideline for a 'hospice care at home' dog, is to run through a checklist every day of "Quality of Life" points.
Dogs will often show their pain by:
refusing to eat
not wishing to move or staying asleep
whining
Holding their bodies with a hunched back or their tails down or even between their legs.
Or more obvious things such as limping, yelping etc.
Generally "Quaility of Life" means they are able to:
Eat and drink fairly normally and keep food and liquids down.
Sleep okay even if their sleep is irregular or broken by needing to pee/poop etc
Go out for walks -even if those walks are very short, and they don't have the zest or energy they used to have when younger and fitter.
Pee and poop regularly.
Wag their tails and show affection, look fairly relaxed, and appreciate loved ones.
They are showing no signs of pain.
With an end-of-life dog, there are going to be changes. But if you can tick all those boxes, they are still getting a decent quality of life and the time hasn't come yet to leave life.
The list has to be considered every single day. Because with a 'hospice dog' changes can happen at any time.