If riboflavin deficiency gets bad enough in animals, they grow too little, become unhealthy, and they may die. Dogs with bad riboflavin deficiency do not grow well, their skins become sore and their hair may fall out. Their eyes become cloudy, their insides may bleed, they become weak, they cannot move or even stand properly. In the end they lie down and die. All this is very much like what one might see in humans with riboflavin deficiency, but we seldom see such things except where people are very poor and starving. Still, millions of people in rich countries do not understand the need to eat the right foods or are too poor. They might have quite such bad signs of riboflavin deficiency, but still have what we call "sub-clinical" symptoms, not bad enough to send them to hospital, but bad enough to make them unhealthy and to stop children from growing properly and becoming healthy.