They're telling me every time they have a symptom and the Vitamin A clears it up.
It should tell everyone else when it is almost entirely a problem that appears when grass disappears and hay gets old and miraculously disappears right after grass reappears in the spring.
Cattle do the same thing. They get fungus spots and lice and clear up as soon as the grass gets good. A good loose mineral with 150,000 to 200,000 units of Vitamin A per pound will also fix them (and make them breed back sooner, calve with fewer problems and make them drop their placenta hours earlier than when they are deficient.
By the way, we keep a loose mineral out year 'round that has that much Vitamin A in it.