Lily was able to get a better look at him once he did start to stand, which only drew a deeper line between 'this is Sirius' and 'this is a regular dog' and there was no way Sirius would ever look like this, at all. Her heart sank in one regard, but welled in another, as it might not be Sirius but the poor thing still needed some love and care. And she would give it to him.
"Oh no, mate, we're not walking home." She frowned. "Not sure you could, even if we tried. But the ride is going to be a little scary, so it's best you close your eyes."
She wrapped her arm around him, able to get it the entire way around him despite him being a large dog, covered his eyes with her hand and then grasped her wand with the arm around his body, Disapparating a moment later.