Before the Shoot (1849)
by
George William Horlor
Horlor (1823 - 1895) was a British painter known primarily for sporting and animal subjects.
detail from
Before the Shoot
Can I be 100% certain that the dog depicted in this work is a Landseer? Not quite 100% — especially since the horse in this painting is a pony, making the dog look larger than it otherwise would — but I very strongly suspect it is, given the range of appearance of "Newfoundland" dogs in the mid-19th Century, so I believe it merits inclusion here.