I am growing increasingly fearful that some form of Mad Cow Disease (BSE) can be passed on to our pets because we still allow rendered proteins to be fed to chickens and some other animals. Even pet foods that are made with "human grade" meats can be suspect. There is growing evidence that Alzheimer's Disease is also caused by prions and some suspect that up to 1% of the cases of Alzheimer's are actually BSE, thus making the disease already present in Americans. This disease has already crossed the species barrier, what is to keep it from crossing to our pets?
I believe the FarMore raw dog products were certified organic at one time, but they appparently are not now (a supply problem?). The Newman's Own products have some organic ingredients and there are other products with some organic ingredients, but I imagine most commercial producers encounter the same supply and imbedded ingredient issues that the Muenster people have encountered. Supply and production economics, storage and distribution issues, shelf life concerns, consumer ignorance, and competition from low quality and/or low price products are problems for the well-intentioned producer. If the best quality products available are not good enough, and they may not be, the alternative is to home-prepare the pet food. The average mass marketed pet foods (not including Muenster and specialty brands) almost certainly have objectionable ingredients or ingredient sources, and there is the yet unresolved acrylamide issue with extruded products. It is ironic that the well-meaning but ignorant cat owner might be filling their pet with mercury and dioxin, and I wonder if the prevalence of contaminated fish products in pet food will increase as people reject/restrict those products for human consumption. I suppose the rapidly vanishing fish population will have some bearing on that. To the extent that government agricultural and food policy is detrimental to human health, it is even more suspect in the pet food arena.
The current thought is that BSE is not transmissible to dogs through food, but what will be the thought tomorrow? Part of the puzzle depends on whether ingestion of the affected body parts is a/the only mode of transmission and whether undiagnosed cases are occurring, either here or in the countries from which we import meat products/by-products. (I don't have a lot of confidence that Central/South American countries from which we import a lot of beef would diagnose or be quick to announce diagnosed cases of BSE.) There are documented cases of a feline version of BSE (FSE), and there is a similar disease in the wild elk population.
That said, how much and what type of protein do dogs require and can they be healthy on a vegetarian diet? Their digestive system is different than humans and while they eat vegetation in the wild it is usually from the stomachs of their prey and has been partially digested.
Canines apparently function quite well on a vegen diet, although I suppose there may be the occasional working dog situation where animal-based ingredients are helpful. I believe the average pet dog, as with the average pet dog owner, likely ingests too much protein. Nutrition-related disease/longevity conditions may not be obvious to the casual pet owner and to the casual vet, but they are more likely to be noticed by show participants and those with long-term breeding programs. I know some show people who think longevity began to be an issue when the high density dry food became the norm. There are plenty of non-meat canine diet recipes on the Web and in holistic books. Wild canines seem to take digestive tract contents first as a preference before they eat muscle tissue (for other than bite-sized voles and mice). Cats are another story, partly because of their taurine requirement. Cats can live well on a supplemented vegan diet if they will eat it, but palatability can be an issue. Beware of lactose intolerance issues, especially with adult animals.
I have no doubt that the "usual" pet food companies feed processed garbage to out pets. Does any pet food manufacturer guarantee organic meat with safe handling practices? Is there an organic vegetarian food manufactured for pets?