Lost mine (12 years old) in October last year, was signs of decline but put it down to age. Took her for a long walk on the Sunday, by the Tuesday she couldn’t get up the stairs, and vet said she could have chronic renal failure, tests for two days and they said nothing they could do so had to say goodbye which was so hard. Whole family was devastated, only saving grace was that it wasn’t drawn out so we know she didn’t suffer much.