Here is a problem with expired food or with food exposed to air – it’s poisonous. The nutrients degrade and more importantly the fats go rancid. It’s definitely BAD for the dog.
I don’t know whether or not inhalation of the odor would be an issue to a person; theoretically you smell by exposure to “particles” so I’d say potentially yes.
I understand that your roommate’s finances might call for budgeting but this is a very bad way of saving money. I’m surprised the dog is still alive. There are affordable dog foods out there which don’t have to be past expiration date not to break bank. And leaving food in the bowl upt to a few weeks is just crazy.
I use ol Roy and my dogs seem to really love it!
I use Hill’s too, but not the science diet, one of the prescription diets.
If you want the best you should go online and research feeding your dog a raw or “BARF” diet – this is the most biologically appropriate diet for almost any dog. Once you find local sources for the raw meat and raw bones required by the diet, and get both you and your dog comfortable feeding raw it will cost less than what you might spend on a premium prepared kibble or canned food.
But, it may not fit with your lifestyle — many people can’t stand the thought of handling raw meat, gathering the supplies, and making sure food is defrosted each day for the dog’s meal(s). It is easier to buy a bag or can of commercially prepared dog food. And some dogs have health issues or damaged teeth that can not tolerate a raw diet.
So, the way to pick the best dog food you can afford, you need to find a good pet store (one that does not sell puppies!) and locate the grain-free selection of dog foods (either kibble or canned, which ever you prefer to feed). Then start reading the labels. You want a grain-free product that has real meat as the first 2 (or even better 3) ingredients. Real meat will read: beef, lamb, turkey, elk, bison, salmon meal, whitefish meal, etc. Meals are the entire animal ground up and dried — which is a good thing when it comes to fish!
Do not buy anything that lists ‘by-products’ in the ingredients. By-products can be nothing more than ground up chicken feathers — not a good source of protein no matter what the commercial producers say!
You may pay more for this very good dog food, but your dog will eat less of it per meal to maintain an ideal weight over foods that contain grains.