What to feed mature (senior) dogs? (lab, terrier, rottweiler, clean)

[cheesenugget]

My dog is 7 years and I wanted to start planning her diet, preventative care, etc. We just came back from the vet. All her blood work was fine. Her teeth has slight tartar but no need for cleaning at this time. When it comes to diet, I am on the fence on what to do.

Currently my dog is on American Journey (Chewy.com brand) or Wellness Core mixed with Merrick canned. She gets plenty of veggies every day when I prepare dinner. She is on joint supplements and salmon oil.

I read many articles written by other vets stating that the trend is leading towards MORE protein, not less, for older dogs. My neighbor recently lost their 14 year old Rottweiler to stomach cancer. Otherwise, his organs were fine. They fed him strictly regular adult Wellness Core kibble (they don't carry senior diets in the Core line). The dogs I had in the past in my country lived up to 8-10 years died from old age, also lab mixes, eating human food. My husband's18 year old terrier mix also ate human food and died from surgery complication.

Many, including my vet, who advocates the senior dog diet because of less protein (easier on the kidneys), more fiber (to help with pooping) and less calories due to slow metabolism and preventing weight gain. My vet says the older they get, the less protein they need. He also told me to stop feeding canned because it contributes to the tartar on her teeth (That is the same argument made to feed kibble to cats which turns out to be false).

Pebbles is at a good weight, she is still very active (lab mix) and like I said, she gets her extra fiber from the veggies we give her.

What do you feed your senior dogs? What brand do you recommend?