Don't cancel your trip-- The dog food is considered an agricultural product. You'd be better off just going in with a minimal amout of dog food and then buying it in Canada. Yes, have all your dogs shots up to date and current veterinarian papers to prove your dog's good health. You can get a hunting rifle or shot gun in, but be prepare to do paperwork at the border crossing. The best thing to do would be to contact the Canadians and ask if you can download the permits and have them filled out in advance. If you want an easy crossing experience have all your paperwork in order and whatever you do, don't cop an attitude. Always be polite, and never ever try to hide anything. You can bet that if you declare your legal shotgun they will look for more. I'm not sure where you plan on crossing, but the smaller crossings with less traffic will save you hours of downtime. I myself used to cross into Canada two and sometimes three times a week in a commercial vehicle and every so often in our personal rig. The Canadian Border folks are, in general, a friendly group. I'd be more concerned with getting back into the lower 48. US customs officials can be a real PITA if you are, too friendly, too obnoxious, cop an attitude, or are not the correct skin color. To make things ever so much easier, have you considered not bothering with any weapons? Bear spray, common pepper spray and large knives are considered a weapon at border crossings. When we go up, I'll not be taking any weapons and I'll purchase bear spray in Canada when we get there and stash it in the trailer. There is a ton of scientifically gathered data on how much more effective bear spray works over guns. A shotgun would just make the bear very angry. Good luck !