
mabe he has a water infection ...fill his bowl and note how much he has drunk in the day
dogs that are fed dry do tend to drink a lot more than food such as naturediet
you mention
older dog ...what age is he??
you have to be careful with kidneys in older dogs as my old boy use to get infections occasionally
but if his urine is strong and you are concerned catch a morning pee on a saucer and take it to the vets for tests.
Roni