I like a bit of horror. In the stable our dog was delighted to eat some vaginal blood of a cow. You must have a strong stomach to look at the pictures.

If there is a pond of dark red blood in the vagina of the cow, then that cow has probably been cowardly. This blood is from the uterus of the cow. In the case of a cowardly cow, as a result of cyclical changes, there is a widening of the blood vessels in the uterine wall.
source