Loki laughed bitterly. "The only one of my children I've seen at all in centuries is Sleipnir and he's well cared for by Odin. Besides do you really think he'll give a damn about me, if we no longer share a blood connection?"

Actually Sleipnir probably would. He was no more intelligent than any other horse so the concept of exchanging a person's blood was not something that'd ever occur to him. It didn't matter, though, because the one deciding who Sleipnir associated with was Odin and there was no hiding something as big as this from him.