The plummet in puppy numbers has led to the Kennel Club placing the Sealyham on their Vulnerable Native Breed list alongside Welsh corgis, Dandie Dinmont terriers and Otterhounds.
Their popularity wasn't even boosted when a Sealyham named Efbe's Hidalgo At Goodspice won best in show at Crufts in 2009.
That means that some owners have had frozen Sealyham sperm sent in from the USA to make sure future puppies are healthy.
PUPPY LOVE: Tracy gets a cuddle from Cooper VERY RARE TERRIER: Tracy Titchmarsh and her Sealyham Terrier Cooper SEALYHAM FANS: From left, Liz Taylor, Cary Grant, Princess
The staggering decline in the Sealyham terrier's popularity has seen the number of puppies registered with the Kennel Club fall to fewer than 50 in the UK, prompting Country Life magazine to launch a campaign aimed at saving the breed.
Sam Richards, the endangered breed's international president, and owner of the dogs' ancestral home between Haverfordwest and Fishguard, said the Sealyham was an important part of Welsh heritage.
Latest figures show 49 Sealyham puppies were registered with it in the UK last year.
A Sealyham winning Best in Show at Crufts for the first time in 2009 failed to have an impact as the competition was not televised that year.
Janet Wonnacott, secretary of the Sealyham Terrier Club in Milford Haven, said the dogs make ideal family dogs.
Since docking dogs' tails was banned in 2007 interest in showing Sealyhams has waned.
Paul Keevil, formerly of the Kennel Club's vulnerable breed committee, said: "Traditionally, soon after Sealyhams were born, their tails were docked in half.
BEST OF FRIENDS: Alfred Hitchcock with one of his Sealyhams PICTURE: Hulton Archive/Getty Images
Humphrey Bogart, Elizabeth Taylor and Alfred Hitchcock all loved pampering their Sealyham terriers.
The Milford Haven-based secretary of the Sealyham Terrier Club, Janet Wonnacott, 66, has three - Silver, Star and Gracie.