Are you feeding your dogs any organ meats such as kidneys and liver? Although they are very good sources of protein, excessive consumption often leads to a condition known as Hypervitaminosis A or Vitamin A Toxicity.
Moderation is still the best way to go because these organ meats are very high in Vitamin A.
I remembered an article I read a few years back that cat food can be toxic to dogs. Cat food is very high in protein and fats which can predispose acute pancreatitis. It is also for this reason that dog owners should exercise caution in giving their pets fatty foods such as ham and bacon during mealtime.
Apple seeds should be avoided, so if you give them an apple, core it first. There are great sites out there that detail bad foods for dogs. Do a simple google search: "can dogs eat ... blah blah" ... and you'll find many answers.
And keep those with big paws away from kitchen counters. Of course, this doesn't apply to beagles, but my lab discovered the drippings from the George Foreman Grill sometimes back, and we've had to put in a baby gate to keep her out as a result. :}