Dog owners will soon be able to deploy sat-nav technology to track down a missing pet. A high-tech dog collar was previewed yesterday on the first day of the Crufts Show.

The lockable collar, on sale from July, is made of anticut material to deter thieves and sends texts to the owner’s mobile telephone if the dog crosses a preset boundary. The owner can log on to a website where, using the sat-nav technology of the collar, they can pinpoint the pet’s location.

The collar is not cheap at £200, but its makers, Retrieva, insist that it is worth it. Andrew Stuart, the company’s director, said: “Dog theft is out there but it’s not high on the list of police priorities, for obvious reasons. But for owners or families, if a dog gets lost it is a traumatic experience.”

About 23,000 pedigree dogs, including more than 1,160 from abroad, are expected to take part in the annual show, at the National Exhibition Centre in Birmingham. The event is recognised by Guinness World Records as the world’s largest dog show.

Organisers say that this year will be the second-largest show in Crufts’s 117 years, with only 27 fewer registered dogs than the largest show in 1991.

Over the next three days dogs will compete in more than 2,000 classes and ultimately for the title of Best in Show, which will be awarded on Sunday.

William Hill has closed betting on which breed would win amid talk of a mystery “superdog”. In only a few hours the odds on the winner coming from the “utility dog” category, which includes bulldogs, miniature poodles and Dalmatians, rather than the more traditionally favoured terrier, hound and working dog classes, were shortened from 13-2 to 1-2 after a flurry of large bets.

Rupert Adams, spokesman for William Hill, said: “There must be an exceptional dog out there that we have not heard about.”

Owners can put their dogs forward for additional competitions, such as the international obedience, agility and heelwork to music competition. Dog dance teams performed yesterday to the strains of theFlashdancetheme.

Some dogs are just there to show off. Scooby the dog posed at the PDSA Pet Fit Club stand yesterday to share her weight loss secrets. She had lost 5.5lb (2.5kg) after the fish and chips, curry, pizzas and ice-cream that her owner used to feed her were cut from her diet.

A PDSA spokeswoman said: “Now she enjoys a balanced diet and a healthy lifestyle, which has much improved her quality of life and will no doubt mean she’ll live a lot longer than she would have done if she had remained dangerously overweight.”

About 153,000 visitors are expected to attend Crufts this year. The whole event occupies almost 20 acres, including five halls, two pavilions and the main arena.

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