These laboratories cannot move without being able to fight. You need to feed them with more bones, less croquettes and meat.
Dogs face bears all the time, usually with a package of five or more and dogs are still killed.
Dogs are bear dogs and generally run a hundred or less.
Labs are retrievers that don't specifically hunt dogs like fighting a bear.
Now, if a bear or a lion tries to invade the barn camp in its area, that lab could probably handle it, but that is not the same as "taking a bear or a cougar" in a timely manner.
Obviously they could not be chained or in a kennel they would have exercised and know their territory.
They may be able to handle even sows or coyete or wolf packs, but it is very dangerous with only two dogs and no man with a gun. Even a hammer.
You need to protect dogs, they work very hard to protect and serve us.