One in four dogs at Crufts is overweight, according to veterinary experts.
Researchers said that with canine obesity now a common medical disorder, it is "disappointing" that a quarter of show dogs are overweight.
The team from the University of Liverpool School of Veterinary Science suggested that, as humans tend to do with their own weight, owners may underestimate the true body condition of their pet.
They said owners' perception of their dogs' body shape may reflect that of society as a whole, with the condition of overweight dogs assumed to be normal.
If this were true, then images of dogs in the media - such as at Crufts - might influence owners' perceptions of optimal body shape, running the risk of normalising canine obesity, they said.
They analysed 960 dogs that came in fifth place or higher in different classes at the famous competition between 2001 and 2013 and found none were underweight, 708 (74%) were of ideal weight and 252 (26%) were overweight.
Their comparison of 14 obesity-prone breeds with 14 non-obesity-prone breeds found that basset hounds, labradors and pugs were most likely to be overweight.
Border terriers, boxers, Dobermanns, Hungarian vizslas, standard poodles and Rhodesian ridgebacks were the least likely.
Researchers said fewer show dogs are overweight than in the general pet population, but the fact that the Crufts dogs that were overweight did not appear to have been marked down for it was "disappointing".
They said that, as with people, obesity in dogs has been linked to orthopaedic problems, diabetes, respiratory disease and certain types of cancer, and it can also affects the quality and length of a dog’s life.
“These dogs showcase the ideal characteristics of the pedigree breed, and there is a danger that widespread media exposure might adversely influence owner perception of optimal body shape,” researchers said.
“Further effort is now required to educate owners, breeders and show judges so that they can all better recognise overweight condition, thus helping to prevent the development of obesity."
They added that the Kennel Club has recently introduced changes in policy for judging criteria, to emphasise characteristics that promote good health in dogs.
The research is published online in Veterinary Record.