Well, as threatened in the original submission, I'm proceeding with a vector tracing and color.
This is the sort of thing I really love – injecting and extrapolating detail where there was none before. Just small details like tapering the stroke widths/ends and so on.

[Update]
Well, I'm also now re-interpreting some things like the making both eartips not-frayed. I'm not quite decided which is better, so I still have the original lines hidden in a separate layer.
Seeing as how I'm strictly amateur and not working for any particular deadline, I'm taking the time to create 'behind the curtain' detail which will likely be mostly if not completely covered up by other elements – such as the base and inner curve of the left ear which will be obscured by the left paw