Originally proposed by brief Hammer cohort Kenneth Hyman, this film was planned to be the first in a series of many Sherlock Holmes films starring Peter Cushing, produced by Hammer Films. The audience disapproved of a Hammer film without any monsters and failed to turn up. The planned series was then dropped.
The hound they used was a real dog called Colonel. On the set before the hound attacks Christopher Lee's character Sir Henry Baskerville, they could not get Colonel to jump on Lee, so they started to 'prod' him into action. Lee gave up and suddenly, Colonel lunged on him and bit right through one of his arms.