I came across this draft gelding today who has a very dull coat and appears to be having some issues shedding out (as evident by the large clumps of hair still remaining). I am unsure of his age but I would estimate him to be probably 13+ years. The owner claims they have de-wormed him frequently, but with what I do not yet know. He is used as a work horse but can't seem to keep up with the others and fatigues more easily.
I understand that the issue could be a number of things: nutritional, skin health, and/or parasites. What are you thoughts on this issue?