You are going to want to check into any illnesses that the breed that you choose might be predisposed towards and factor that into possible long term medical costs. You can also add in yearly vaccinations, de-worming and vet check. To avoid heartworms, you will want them on a monthly heartworm preventative that could also be given with a flea and tick preventative. The heartworm alone would be any where from $8-12, but it is much cheaper than paying for the heartworm treatments should they get them. Depending on your situation, you might want to look into pet insurance. It would keep you from having to worry about paying full price if the dogs end up having any serious illness or emergency medical needs due to protecting your property. Another good point on the feed bill is that often times you can end up spending a bit more on a better quality food and reducing the amount of feed that you have to give them. The better foods pack more nutrients and less filler into each piece of kibble. The vet bills will depend on your location, some places are much cheaper than others. Food can depend on what you have available in your area, but I pay $48/30lb bag for a large breed dog that needs a diet without beef, chicken, pork, wheat or corn. I also feed half as much as my friend that gets the cheaper grocery store brands to her dogs.
