Goats can get "Athlete's horn" -- the same fungal infection that people get. Trim off as much as you can then alternating days applying iodine and fungus ointment can clear this up, but just like with human athlete's foot, this can linger.
The main cause that I am aware of is lack of moisture. You can purchase some special moisturizer or you can just use human moisturizer to save money to rub on the horns.
Horn flaking can be caused by damage to the horns, abrasion, malnutrition, genetics and old age. Usually flaking does not start until the goat is several years old. This condition is not unique to goats.
Sometimes flaking of the horns can be normal but it would be best to check the goat's diet to rule out a vitamin or mineral deficiency. A lack of protein in the goat's diet may also cause flaking.
Kid goats' horns usually flake as a result of horn growth. Adult goats' horns flake for a variety of reasons: mineral deficiencies, horn damage, fungal infection, old age, etc.
