I have very successfuly used Re-Borne, whole liquid bovine colostrum, on horses like your explaining. This product will help bloom out his coat and to help him increase his weight and lean muscle. Re-Borne is all natural and very easy to dispense on your horses food or in their mouth, actually horses love the taste of it. It will do a number of things; first it will give a boost to his immune system which will help with his bad hair coat. Second, because of the growth factors it will help to increase his appetite and promote lean muscle mass, and will not make him high. This is a great overall supplement due to the 4 main growth factors, proteins, anti-oxidants and all constituents from colostrum. This can be just a situational application or used everyday, depending on what your dealing with. I personally have had huge successes with the depleted type horse and using Re-Borne as a daily supplement to keep horses at their optimum health.