When should I switch to senior food?

So my boyfriend and I are awaiting for a home check (may not be until September due to us moving) for a senior Italian Greyhound. We know that his top teeth have been removed and we have to get his bottom teeth removed so we know he's going to be solely on wet/soft food (will probably do a mix of wet food and like frozen patties melted into a soup like texture) but I have a few questions about that.

So he's ten years old. We're in the process of awaiting the questions to if he has any health issues like joints, eyes, etc. Once we find that out, I'm sure that will give us some more ideas.

With all of that being said, if he is not having any senior-related health issues, does he need to be on strictly wet food made for seniors or can he be on just regular adult wet food?

EDIT: But along with that, how much wet should I be feeding him? 1/4 of a can?