My poor little Thunder (mostly boarder collie) was just diagnosed with a thyroid problem and is now on meds. He too was losing hair and had a bad skin odor. No noticable weight gain however. Although it may not be life threatening it's a matter of the quality of life. Poor little guy was embarrassed and you could tell he was not a happy fella. Magic pills will do the trick and take your dog to the Dr at once if you even suspect something like this. Be aware. Be forwarned.