Yet the Leonberger, a German watchdog crossed from a St Bernard and a Newfoundland, may be the guide dog of the 21st century.
The dog, which was bred to pull carts and drag drowning people from water, is being put through its paces by the charity, Guide Dogs for the Blind.
It is one of several unusual breeds - including poodles and Bernese mountain dogs - being trained by the organisation to add to its standard supply of labradors and retrievers.
The charity is putting several unorthodox breeds to the test in the hope of spotting undiscovered talent - and giving blind people more variety in the dogs they choose.
Australian shepherds, Bouvier des Flandres, boxers and even rottweilers have taken part in the organisation's rigorous educational programme.
Several have qualified in the past year, including a number of standard poodles - and several more are due to start training soon. The poodle is proving an ideal dog for people with asthma or allergies to dog hair because it does not moult. But owners have special instructions to take the dogs for a regular haircut.
"They don't have poodle show cuts. But the people who take them have to go to the poodle parlour regularly and get the dogs clipped," said a senior guide-dog trainer.
Senior staff from the charity have surreptitiously been scouting round Cruft's dog show for talented animals they can take on as puppies or young adults. But they are wary of breeding them until a type has a proven track record. In the past, a dalmatian was successfully trained, though the breed is regarded as rather boisterous.
"We haven't eliminated anything. We wander round Cruft's and say, 'Maybe we should give that a go'," said Neil Ewart, Breeding Centre manager, who is in charge of choosing suitable dogs. "Some day we might discover another perfect breed. It does us all good to see something different like the Leonberger occasionally. They are huge. Leonbergers are obsessed with water: they jump in."
Labradors and retrievers - and a cross between the two - are still regarded as the ideal guide dog (1,200 are bred by the charity each year with 4,500 working on the street) but some blind people have been calling for more individual companions.
Leonbergers are being allocated to tall men who want a big, unusual dog and do not mind chatting about it to the public. They are regarded as too strong for women and too much of an attention magnet for shy people.
The breed has also been excluded from work in big cities because it is too large to go on buses (it knocks people down if it turns around), the owners have also been advised to try to keep the dogs away from ponds, streams and beaches.
One Leonberger puppy, named Elsa, has recently started work after finishing a two-year training course.
Another puppy, called Faith, is in a "puppy walker" foster home undergoing a year's training. Another Leonberger puppy, now being weaned, is set to start work by the end of the year.
The dogs spend a year getting used to unusual situations and sounds, including busy roads, trains, markets and shops while under the care of volunteer "puppy walkers". They are taught basic commands such as "up up" (keep going), "forward", "leave", and "busy" (go to the lavatory).
Anne Hope, a Birmingham volunteer, has trained three Leonbergers over the past year. She is now educating Faith, which is already as big as an adult labrador.
"I was asked, 'Do you want a challenge,' and I said yes," said Anne Hope. "I didn't know the Leonberger breed at all. They are a lot more energetic than normal dogs. They want to go a mile a minute but have to learn to go at a sensible pace and not bounce around. They learn very, very quickly. We have to introduce them to several different situations. They have no brakes. I have been knocked over when they have been out free running in the fields."
MOVE OVER, LABRADORS - THESE MAY BE THE NEW DOGS FOR THE BLIND
Bouvier des Flandres: a medium-sized Belgian working dog originally used for herding cattle. It has a coarse curly coat, floppy ears, a beard and a square face. This rugged, powerful dog comes in dark grey, fawn and black. It is regarded as intelligent, calm and sensitive.
Australian Shepherd: despite its name, does not originate from down under, but originates from the Basque sheepdogs of Spain. It looks like a border collie with no tail, but is stockier with a patchy coat. It has an even disposition and is never shy or aggressive. It can turn its intelligent mind to tracking and herding.
Bernese Mountain Dog: originally used to herd sheep and cattle, this large shaggy dog was introduced to Switzerland by the Romans, whose mastiff-style dogs bred with the Swiss sheepdogs. It is sleek and elegant, ideally black with a white nose and white chest. It is typically 25 to 27 inches high.
Leonberger: a very big dog reaching up to 32 inches tall, with an equable, self-confident temperament. Originating in the German town of Leonberg, it was produced from crossing St Bernards with Newfoundlands. It is either tan or "conker" coloured, and has a slightly wavy coat with a prominent mane across the throat and chest. It usually has a black nose and ears, and was originally bred for its appearance, to pull carts and for water rescue.
Boxer: a self-assured and fearless animal with traces of Great Dane and bulldog in its blood. It was first seen in its present form in the late 1800s and originates from Germany. It is typically 22 inches tall, and tan and black with a stocky figure. Regarded as "a guarding breed of a high order", it is intelligent and can be stubborn.
Rottweiler: a very strong and imposing dog introduced into Britain in 1936. It came from Germany, where it was used to guard livestock, and is the descendant of animals taken to Germany by the Romans. Although it has a reputation as a ferocious guard dog, it is not by nature nervous or aggressive.
Standard Poodle: bred as a duck-retrieving dog in the marshes of Germany. It is over 15 inches high, with a curly coat. It is often clipped in many different styles. It is a jovial dog by nature, is even-tempered and devoted to its owners, but is too often dismissed as a clown.