Dog Tail Curled Under. Common symptoms of limber tail are obvious. There are many reasons that can cause a dog's tail to be limp, or held down.
This is similar to a sprain of the muscles. Sometimes a tail held in a neutral or low position just means the dog is incredibly relaxed — this even happens to dogs with curled tails like pugs, whose tails unravel and go straight when resting. You may then notice that the dog has a curled tail under his body.