I always wanted Sabes to be Wolverine's dad too, but now that that's been axed, I think the Dog angle is the best. Besides making sense logically, as I've said before, it would add a dimension to Sabertooth that writers could explore. Because the character has been growing stale over the past few years. He worked great back when Logan actually adhered to his sense of honor and actually tried to keep his berserker rages in check, because Sabertooth served to show readers what a Wolverine with no boundaries might be like. Now that Wolverine basically never tries to control his rages and just carves up everyone when he gets in fights, Sabertooth has kind of lost that symbolic place in Wolverine lore.
Making Sabes Dog could add an interesting side to Sabes. Now all the things he's done are cast in a little different light. Part of Sabes rage towards Wolverine would obviously come from the jealousy Sabes still feels from always getting the short end of the stick as kids.
One angle that I would explore (if I ever got to be a comic writer) would be to show that Sabertooth's actions are actually a form a brotherly love. Since Sabes had such a warped childhood, the only way he can express his affection for Wolverine is in a violent way. All the things he's done to Wolverine, the attacks, murders of his girlfriends, ect. was actually to make Wolverine tougher so he could make it through the world. And in his warped mind, he's not torturing his little brother, he's actually looking out for him by doing all this.
