Okay, equate abortion to murder and I can stick with you, equate it to slavery and you've lost me.
How can you have the legal right to kill someone(thing) unless you own it? I can take my cats down to the vet tomorrow and have them killed. I can even shoot them myself in the back yard. I own them and I have every legal right to kill them, even if my only reason for doing so is the inconvenience their claws are causing to my new sofa.
The acceptance of a right to kill is an acceptance of ownership. The concept of murder means NOT having the right to kill. Even when killing a burglar in self-defense, you're going to have to explain to the sheriff at least.