The disease I think you are asking about is caused by a fungus/mold type spore, which causes the animal to be hyper sensitive to light, they can recover from this if kept in a shed or barn away from light for a long period, and fed good clean forage, and grain supliments. There is also a genetic dz called protoporphyria, which is rare but happens in Limousin and Herefords, carriers can sometimes be affected, homozygous carriers typicaly die, but your best bet is to cull any carriers, you can identify them through DNA tests, all Limousin AI sires must be tested for this trait. There are not many still in herds today that have this trait.
