Our springer spaniel Bramble is nine now and her coat had gone properly dull over the last year or so. Lots of dry patches of fur left on the rugs, and the vet said it was nothing to worry about health-wise, just an older dog thing. We'd tried a couple of other things before with no luck.
Started her on Tailsome about two months back, one dropper mixed into her breakfast every morning. Took a good three or four weeks before I noticed anything, but her coat is definitely softer now when you run your hand along her back, and there's noticeably less fur collecting under the radiators. I wish I'd taken a before photo because the change crept up gradually and you only really notice it looking back.
Not a miracle fix and she still sheds, dogs shed, but there's a lot less of it about the house and she looks better for it. Would give it a proper couple of months before deciding either way.