[theBCnut]

A major issue with seniors is kidney disease, so I would suggest a diet rich in moisture. At 13, she deserves to eat something she likes.

And as for the vets, they are not nutritionists, so they frequently suggest foods based on who pays for tons of research. And they frequently treat syptoms rather than look for causes. Holistic vets are much more likely to look for the cause of an issue and more likely to pay attention to optimal diet.