A person can end up in the kooky end of the Internet very easily if one begins searching info on how to feed dogs and cats. Animal feeds aren't regulated in the same way as human foods are, so getting reliable information about commercial pet foods isn't that easy.
Marion Nestle, author of a Food Politics blog, wrote a book titled "Feed Your Pet Right" in which she and her co-author describe the science of pet nutrition and survey the pet food industry. They pretty much describe all commercial pet foods to be "healthy" for your pet and explain the different prices as being based on marketing, not quality. Nestle wrote another book titled "Pet Food Politics: The Chihuahua in the Coal Mine" about pet food recalls. In the Feed Your Pet Right book she gives some recipes for making your own pet foods at home. If you choose to make your own pet food, getting the nutrition right is important. This isn't a bad place to start if you want reliable answers to your pet food questions.
Otherwise, there are plenty of Internet sites that monitor and rate commercial pet foods. Each seems to have its own agenda (for example, some insist only "muscle meat" and no byproducts should be in the food, which sounds tasty to us humans, but some important-to-your-pet nutrients can be found in the less-apetizing parts of the animal, so ... ???). In my experience, my pets' taste-buds don't seem to correspond with the ratings. Getting my pets to eat at all is pretty important to me, so I do take their preferences into consideration.
It is true that there are lots of very passionate people describing special pet diets all over the internet and they can be aggressive, dispensing their advice with a large serving of guilt. If you encounter these, look for some sound science to back up their claims before you get sucked into their cult. I found a lot of "it is common sense that feral/wild dogs/cats eat x, so that's what you should feed your pet" type claims, which are only backed up with more "obvious" "observations" and endless amounts of emphatic but circular prose, and zero recommendations to give your cats live birds and mice (for example) ... included with these are the "ethical" arguments in favor of vegetarian/vegan diets for pets ... but this is not necessarily science. I remember reading one blog by a vegan who fed her new kitten only off of her own plate ... of course her cat died of malnutrition soon enough, and she did post about feeling "guilty", but she also considered herself worthy of another try with another cat. Sigh.
I also ran into some very, very annoying marketing when shopping for pet foods at pet super store chains. There are people haunting the sales floors of these stores who work for pet food companies and will try any tactic to get you to buy their brand of pet food and just won't leave you alone until you put some of their food into your cart ... I have been offered a lot of misinformation by these marketers (like that canola is a corn product). They all promise smaller, drier, less smelly poop if your pet is fed their product. Now I refuse to shop at stores that allow this kind of un-informed yet high-pressure marketing.
What do I do? I still buy a highly-rated and more expensive commercial pet food brand at the local feed store. And my pets eat it happily enough and are all healthy. Maybe some day I'll start making my own pet foods at home ...
