'Period pain'! I am wondering if this is a male vet...? Being in heat is NOT like a human having a period and cramps (especially not at the very end of a heat cycle!). The blood they discharge is not like the full clearing of the womb of the unused lining in women when they do not become pregnant during their cycle -- this wholesale ejection of the womb lining is what brings on the period pain cramps that some women get. On the contrary in a dog, the bleeding is very slight, has pheromones to attract male dogs and dogs can mount and impregnate a bitch while she is still spotting blood.