I'm a label reader, and the ingredients in commercial dog foods disgusted me. I also watched my very first dog, a Brittany, decline in old age while being fed a Hill's product formulated for geriatric dogs prescribed by my vet. It contained ground peanut shells among other things I felt could not possibly be good for even a facultative carnivore, but I followed what I was told. My dog paid the price.
Then my aunt's dog started losing function in her rear legs and we took her to Iowa State's veterinary teaching hospital. There, the chief of neurology diagnosed her with spinal myelopathy and said there was no treatment. Brandy would continue to deteriorate with ascending paralysis until euthanasia would become necessary. Again, we followed what we were told, and that's exactly what happened.
Then I stumbled across an article describing Dr. Wendell Belfield's successful treatment of this same "fatal" condition. I read, and learned, and changed the way I fed and cared for my dogs.
By this time I was up to my eyeballs in Greyhound adoption and vice-president of GPA's Midwest Chapter. A Grade-A running Greyhound owned by a friend who was the chapter president started having problems just like my aunt's dog. He went to ISU and was diagnosed by the same board-certified neurologist with spinal myelopathy. My friend called me to say that Conway couldn't stand up by himself any more and they were going to put him down. I told her to start giving him high doses of vitamin C, and that I would take the dog and see if he could get better.
I called Dr. Belfield's office, and he was happy to advise a local vet on a treatment protocol. No vet would cooperate, so I tried a less-aggressive regimen involving oral vitamin C to bowel tolerance, other supplements, homeopathic support, chiropractic adjustments, and a raw diet. Long story short, Conway got better. He got back up, and except for some minor incoordination between his front and rear ends remained happily chasing tennis balls for the rest of his life. His breeder/racing owner saw how well he had recovered, and I gave Dr. Sharon Willoughby, his chiropractor, copies of both his and Brandy's patient files from ISU. He was also the star of a number of Dr. Willoughby's teaching seminars in Illinois.
Seeing how diet helped Conway convinced me that raw food was definitely the way to go for dogs. I don't feel qualified to address cat nutrition, because I've never successfully transitioned a cat to a completely raw diet. Their tendency to go into hepatic hyperlipidosis has always scared me off taking the hard line of not offering the commercial food the cat will eat to force them to eat the raw stuff they're refusing.
Fortunately, dogs aren't so fussy or stubborn, and generally love raw meat and bones. Most of my dogs' food is exactly that: raw meaty bones. Ten-pound bags of chicken hindquarters are a staple. Pork neck bones and pigs' feet are another favorite -- modern farming practices have made trichinosis a thing of the past. The rest of the diet is a glop of "green slime:" raw vegetables run through a juicer with the juice mixed back in. Sometimes we change it up with some canned mackerel, cooked but still better than dog food. None of my dogs like raw fish, unless they can hide it long enough to get nice and rank. Then they roll on it.
Harriet in particular likes to bury food, then dig it up and eat it later. Doesn't bother her in the least. I certainly don't encourage it, but canids are predator-scavengers, and a healthy dog can handle carrion just fine.
Once in a while, I throw in a multivitamin on general principles, half of one of the caplets I take myself. Everything my dogs ingest regularly is sold for human consumption. Which vitamin formula? Doesn't matter. What are the dietary proportions? Doesn't matter. Does every bite we eat have to be "complete and balanced for growth and maintenance?" Of course not. Same goes for dogs.
There are plenty of raw diet plans out there that are wonderfully complicated. I started out that way, and over time learned it wasn't necessary. Probably 95+% of what my dogs eat is raw meat and bones. The rest is green slime, or a blob of canned pumpkin if I don't have time to mess around with the juicer. Notice the total absence of grain products. I used to feed whole grains, but not any more. The dogs do far better without them.
Periodic fasting is also good for carnivores on a natural diet. They'll even fast themselves with absolutely no ill effects. One day every week or two on water only is a good cleanout.
Feeding raw may be a bit more expensive than quality dog food, but you'll more than make it up in vet bill savings.
There is way more information available on raw feeding than I can link to individually here. There are also lots of holistic vets around now with whom you don't have to play the "don't ask, don't tell" game.
I take a team approach with my animals' health, with holistic and conventional practitioners. My conventional small-animal vet once told me, "If an average client asks us about raw feeding, we'll advise against it since they're not going to take the time to do it right. Your dogs live longer, healthier lives than theirs do, so whatever you're doing, keep it up."
Works for me.