When is a dog considered a "senior"?

[Sarah83]

I know a lot of people who don't like puppy food. They say it makes them grow faster than they would normally and can lead to bone/joint problems, especially in larger breeds. Never seen much said about senior food though.

Rupert is 7 years old and I've not changed his food to a senior food. He's doing fine on the adult food he's been on for the past few years so I see no need to change it. He's classed as senior now but he didn't get the memo

[Nettle]

My current oldest dog is 14 and still fed exactly the same BARF as the others. He is a very frail old dog now, but still as well as extreme old age allows. We have to feed the dog in front of us, not a dog picture on a sack or tin.

Heck, just realised the dog on my avatar - his daughter - is seven now! And "the puppy" is two