This dog’s name was Leo and he was depicted in Stonhenge’s The Dogs Of Great Britain, America, And Other Countries (circa 1880).
Stonehenge (John Henry Walsh) argues contends that there are three types of Newfoundland: The “true” Newfoundland, the “loosely made” Large Labrador, and the St. John’s water dog. The first is the large black Newfoundland type. The “Large Labrador” is what we’d call a Landseer, and the St. John’s water dog.
Leo is supposed to be a true Newfoundland, but he looks very much more like a modern retriever. He was probably a bit larger than the typical retriever, but he would have been able to have been registered as a retriever, as could his progeny.
Stonehenge makes the dubious argument that “pure” Newfoundlands on Newfoundland never exceed 26 inches in height, but when puppies those “pure” strains are bred in England, they become giants. Such a claim is quite.
In that same section, Stonehenge says the big Newfoundland were being bred with mastiffs, and the St. John’s water dog was bred with the setters in that same section.
So it is doubtful the giant size evolved on Newfoundland or that the nutrition in England would have been so much better that it could account for the size discrepancy. Newfoundland’s Grand Banks were producing high quality nutrition in the form of fish and other sea food that was being exported around the world. The US made a point to negotiate access to the Grand Banks as part of the treaty that ended our War of Independence. Dogs likely were well-fed and well-cared for, simply because they were such as asset to the fisherman and other settlers. If anything, the quality of nutrition would have decreased in England, simply because even middle class people would have had less access to the same amounts of good quality protein.
It is more likely that hybridization with mastiffs accounted for the increased size, and I note that Stonehenge appears to be exaggerating how large the big Newfoundland was. The average weight of a Newfoundland was 85 to 100 pounds in 1900.
This Landseer-colored Newfoundland was actually painted by Landseer. It is retrieving a European rabbit.
Unless a Night of the Lepus situation had happened when this painting was made, there is no way this Newfoundland was a giant dog. The proportions of the rabbit to dog suggest that the dog was more in the 80 to 100 pound range. A big dog, but not a giant.
It is very likely that all of these Newfoundlands contributed to the development of the retrievers, but the St. John’s water dog is the most important.