I'm with Hershel on why Vets push Iams and Hills foods. The thing that Iams and Hills do best isn't make pet food. The thing they do best is MARKETING to vets and consumers. As you noticed, the foods are "pushed". They sponsor trips to warm places in winter for vets too, sponsor vet school scholarships, give away free food to vets, pretty much suck up to and razzle dazzle them with their own "studies", and since most vets have no real nutrional training (it's getting slowly better, like with doctors, who were also generally ignorant about nutrition), they've pushed the food for decades. Secretly, many of them feed their own pets something else these days. I fell for it for years with that horrible Science Diet, till I started surfing the net and learning about animal nutrition. The net and places like Chazhound will be the undoing in the end I think. That's why researching and reading ingredients is the best way to go. The word "byproducts" in itself is scarey. It can mean entrails, beaks, hair, any old crap, literally. Would we eat something contained a mystery ingredient? That's what "byproducts" means. Close your eyes and imagine reading a label in a supermarket that says, "Meat" as first ingredient. What meat is that? Basically, if a manufacturer can't tell us exactly what is in their bag or can, why should we trust them just because they do neat commercials of people hugging puppies? Dogs and cats are carnivores. Feeding them corn and wheat and other grains as primary sources cannot possibly even come close to nature, not to mention potential allergies. Fillers are cheap and that is why a bag of Iams costs a good deal less than, say, a bag of Eagle Pack. But as with people, carbs cause weight gain as well. Commercial pet foods just don't have the healthy ingredients of premium foods. They are really clever about it too because some list a meat as first ingredient, and then the next four ingredients are sources of wheat and corn, soy, etc. "Complete and balanced" can pretty much mean anything today, just like when we see "all natural" on a product. Natural what?
I really think that unless we have a holistic vet we are really asking a vet to sell us the food they have or we are basically on our own to do the research. I was thrilled when my own vet of more than 20 years started selling Eagle Pack. I had been feeding it to my cats for years. I knew then that enough people had stopped buying Science Diet and he was getting the idea that just maybe he had better focus on nutrition more. As people get smarter, these commercial "premium" foods are going by the wayside. That's why some of them are already relegated to supermarket shelves. I predict that eventualy Science Diet will be on the supermarket shelves one day too.