The reason you don't see horses that are completely white is because they usually die from megacolon or the complete lack of a digestive system. There is a gene called the Lethal White gene, and it causes so many devastating problems. It usually occurs when two homozygous paints are bred together, usually overos(tobianos don't seem to have this problem). Sometimes the foal will carry the lethal white gene, and if bred, will pass it on, creating a lethal white baby. But usually they will just exhibit the gene and will die very quickly. It is definately not a fun thing because the foals are usually born without an anus and the rest of the large intestine. Very sad.


Sometimes high white rats can get megacolon. Their colon just keeps distending with hard, compacted feces, and they end up dying from malnurition and failure to thrive. It usually occurs when the rat first becomes weaned and starts eating solid foods, but can occur even while the baby is nursing, or even 6 months down the road... Some have lived up to a year with this condition, usually from having daily enemas, and a special high calorie diet. I haven't really heard of too many mice getting it, so it must not be too common.

Ok, I think that is quite long enough, LoL. I guess I tend to write books when I get going...