Never done a critique on a deviation before, but here goes:
I have seen the animation to know full well the story behind the painting. The animation makes a very good point. The painting here, really captures the moment, like a second that one wishes would be forever. If realistic was what you aimed for, you succeeded. Like a photograph, the painting shows what the primary focus is, that being the mother wolf cradling her late pup before she is to die, which was all that she wants. A mother's love is a great example that humans and animals are much alike. The positions of the animals are very accurate, and the same goes with the detail of their fur. I can see how you took shading into account because of the grey in the snow. Bringing back to my point how this is much like a photograph, I like to think the trees are out-of-focus because of their lack of detail. As for the man in the background, he could have been more like a shadow if he's to be distant from the wolf.
It may be cliché now, seeing an animal die in the picture, but it really touches the heart of the viewer. I am saddened that wolves are killed for sport, and that the wolf mother gets fatally shot, but I do admire that her love gave her strength. In my opinion, the viewer will probably pick at the detail in the background, but will love the colouring and the animals.
I may have exaggerated, but I consider this among the very best.