What are the genre differences in the BBC show Sherlock's episode "Hounds of Baskerville" in comparison to Doyle's novel The Hound of the Baskervilles?

While there are obvious similarties in the plotline of both the TV show and Doyle's story, there are also some notable differences which don't necessarily mean that the TV show and the book are different genres. Perhaps the TV show has more horror elements in it in comparison to the book, which sticks to the classic adventure thriller genre.
In the story, Holmes and Watson go to Baskerville Hall to protect Sir Henry Baskerville from his fate to be murdered by a gruesome and bloodthirsty hound. In the show, John and Sherlock go to Sir Henry Knight's home to investigate his father's murder, which leads them to a military research base about genetic mutation in animals called Baskerville. In the novel, Stapleton kills Henry's uncle with his hound and tries to kill Henry, too, so that he could inherit Baskerville Hall; in the TV show, Dr. Frankland and a group of scientists develop a hallucinogenic drug, H.O.U.N.D., and Frankland murders Henry's father to shut him up, then scares and tries to harm Henry as well.