all our cats are going for injection boosters soon. They are all different ages but the oldest one is a siamese of 13. She was 13 in January. (her birthday is 3 days after mine btw)

She is very fit, agile, healthy, a great cat and more lively than all the others who are younger than her. She eats well, plays, just a great cat.

Do you think it worth having blood work done to check for anything re kidneys starting to fail as I know this happens to many cats as they get older?

There is no sign of anything being wrong with Katie, she isn't drinking any more than usual or anything. Just trying to be sensible.

I've been invited to get my older cat this test, from age 7, she is now 8. She drinks more water than she used to, and I have raised this with the vet, but as she points out, the cat is now on a prescribed dry diet (for weight control), and she spends a fair amount of time indoors, with central heating on for much of the year (hence need for weight control, partly!).

She's due her annual check up next week, and I'm in two minds. I totally understand why you are thinking about this, but in some ways I think it's mainly a money spinner for the vet, certainly when they have only just become senior. But you never know, I guess. Yours is a fair bit older, and though apperently fit, it's maybe worth a thought?

Wazzy, she will drink more under the conditions you are mentioning, this is normal.

Yeah, the vet said that to me when I asked her, but she seems to be really guzzling at the mo. Though the other cat seems to prefer her sister's water dish to her own for some reason as well which might be why it empties so fast