As photo references go, this one isn't going to be easy. It's a head on shot of a black dog, with no discernible light source. Another photo taken in late afternoon light was provided, so I'm going to try to recreate those colors on this reference
Here's the sketch on a black gessoed panel, complete with annoying glare.
The first layer of underpainting.
There's going to have to be a lot of subtle coloration done in those darks, otherwise he's going to look as flat as a blackboard.
More work will be done on him a bit later...Woe is me, I have to spend this absolutely gorgeous day outside catching up on gardening chores (picture me with the back of one hand pressed against my forehead, the other patting my heart) It's a dirty job, but someone has to do it. :-D