|Feed me, eh?|
Dry food will last longer than the expiration date listed and you can tell it's going bad when it starts to get pale/white (normally on the top layer). If the brand you buy lasts 12 months, and you use 1 bag a month then you should keep 13 bags on hand. When your current bag is low, go buy another one and put it into storage and take the closest expiration dated food out for consumption. Canned food lasts longer and I keep about 10 cases of that. A year supply of dry food ran me $600, the canned food ran me about $250 since I found it on sale.
I know it seems simple but many people I know say they have food and water and such for SHTF actually have nothing at all for the pets. Sure, your pets can eat rice and veggies just like you, but then you have to factor in how much they will eat and how that will divide your food storage supplies or how much you need to add for them. Water is something many people miss out on too, an average dog will use 1/2 gallon of water a day even if just lounging in your zombie bunker next the the artificial grass bathroom spot.
For those people like me who pour the open bag into a bin for easy feeding frenzy access, make sure you keep the bin clean or you can poison your dog if the old food pieces turn rancid in the bottom of the bin.