[ Rowley / "Extraordinary Account of a Dog Killed by Swallowing a Poisonous Serpent" ]
This brief note, signed by "Wm. Rowley M. D. Saville Row, Nov. 8" appeared in the popular Gentleman's Magazine of November 1803. It regards the fate of a beloved spaniel that, shortly after being observed attacking a snake, died under great distress over a period of several days; an autopsy reveals the dog's stomach contained the head and part of the body of the snake. Dr. Rowley assumes the snake, still alive, darted into the dog's mouth, was swallowed, and fastened its fangs into the lining of dog's stomach, leading to the dog's death.
Here's what (little) this has to do with Newfoundlands:
About a week after [attacking the snake], the young spaniel dog went into the field again, accompanied with a large Newfoundland dog of the finest breed in England, who guards my house, garden, etc. (999)
Rowley also submitted the identical article to the Sporting Magazine, which published it in their January 1804 edition; Rowley had dated that article December 8, 1803.