A beautiful brown collie, painted contre-jour. Contre-jour lighting is a type of backlighting where you place the subject right in front of the light. In French the phrase literally means “against the day”. Wikipedia talks about it only in terms of photography, but painters have known about the impact of contre-jour for far longer.
Most cameras tend to turn the subject into a silhouette when photographing contre-jour, but painters can choose whether to add details or not.
Here is a lovely example from 1884 by John Atkinson Grimshaw, where he plays it both ways for maximum dramatic impact: