There is a medical term that takes its name from Sir Arthur Conan Doyle’s 1902 novel The Hound of the Baskervilles, originally serialised in the Strand magazine. The Baskerville effect is a statistical observation, recorded among superstitious communities, suggesting that fatalities from heart attacks are directly increased by extreme fear or stress.

What could be more frightening than the thought of a ghostly hound roaming the moor and seeking vengeance for the sins of a dastardly baronet who chased a young woman to her death? In Ken Ludwig’s Baskerville, staged at Liverpool Playhouse, Sir Charles Baskerville – scion of a great family – stands in the garden of a gothic house in Devon then steps through iron gates and on to the moor. Fog swirls around him and the gigantic hound appears as a looming shadow. The audience scream, and the man thuds to the floor, apparently dead of fright.

Liverpool Playhouse has a habit of scaring us silly at Christmas, most notably with Melly Still’s flawed but fascinating staging of Shirley Jackson’s psychological shocker The Haunting of Hill House. But the only danger with Loveday Ingram’s production of Baskerville is that you might die laughing. Or at least the cast might: on the night I saw it, there was more corpsing than corpses, which actually rather upped the enjoyment levels. Part of the appeal of the great but rather egotistical and pompous Sherlock Holmes is that we can admire him and laugh at him at the same time.

Sherlock Holmes comedies are clearly in fashion this year, and are being done with a cut-price elan. While Liverpool have five actors playing more than 20 characters, at the tiny Jermyn Street theatre in London three performers take on 14 roles to put the hell hound on a leash in a revival of Steve Canny and John Nicholson’s The Hound of the Baskervilles, directed by Lotte Wakeham. The play first bounded across the stage at West Yorkshire Playhouse a decade ago before briefly transferring to the West End. Canny and Nicholson’s show, originally created for comedy theatre troupe Peepolykus, uses the idea of a play within a play. An actor, Shaun (Shaun Chambers), is cast as both the victim Sir Charles and potential victim Sir Henry, leaving him so scared that he keeps fainting. Is it an example of the Baskerville effect?

Drawing on the concept that made Patrick Barlow’s stage version of The 39 Steps such a success, the play continually draws attention to its shortage of actors and resources, rather than trying to hide it. A significant amount of the show’s pleasure is drawn from the virtuosity and quick-change skills of the performers.

In Liverpool, there is a brilliantly handled moment towards the end of the production where Edward Harrison plays both Charles Baskerville and Inspector Lestrade at the same time, swapping between the two from line to line and beat to beat. Concentrating on the comedy means rather interesting little insights sometimes appear, most notably in the Jermyn Street version in which the Holmes and Watson bromance is under constant scrutiny. At one point in Liverpool’s Baskerville, Watson has fainted on the moor and thinks his hand is being stroked by a nurse, only to be horrified to discover that it is Holmes.

The Liverpool production almost certainly gets the better balance between shivers and thrills, but then they have the bigger smoke machine and have called on the skills of Simon Daw for the set, costume and video design – which gives us a glimpse of Sir Hugo’s dreadful deed in animated form.

But not to be outdone, Wakeham brings verve to the Jermyn Street production by cleverly staging Watson and Henry’s journey from London to Paddington as a silent movie. It’s one of the highlights of the show, as is the post-interval quick-fire reprise of all that has come before, to ensure we stay on top of a knotty plot.

Neither of these shows is a substitute for reading the novel (perhaps Conan Doyle’s most satisfying Holmes mystery), but both come from a place of love and admiration for the original. They are performed with evident pleasure and real skill by Shaun Chambers, Max Hutchinson and Simon Kane in London, and Bessie Carter, Edward Harrison, Ryan Pope, Patrick Robinson and Jay Taylor in Liverpool. In both cases the curtain call will make you howl.

• Baskerville is at Liverpool Playhouse until 13 January. Box office: 0151-709 4776. The Hound of the Baskervilles is at Jermyn Street theatre, London, until 13 January. Box office: 020-7287 2875.