The new system, Freedom Fence, is a refined descendant of the original Invisible Fence, invented in the United States more than 20 years ago by a dog-lover who was appalled by the number of animals killed and maimed on highways. Because the vogue in America was very much for open-plan gardens (or 'yards'), and it was either not allowed or not done to surround one's property with traditional fences, he devised an electronic barrier in the form of a buried wire carrying a radio signal which transmitted a small shock, via a collar-borne receiver, to any dog venturing too close.
To see the Freedom Fence working, I visited the village of Taston, in Oxfordshire, home of David Rogers, the entrepreneur who has set up a company to market the new system.
His own dogs - Jamie, a 10-year-old pedigree yellow labrador, and Poppy, a shaggy black creature, part golden retriever, part collie, aged four - were as glad as he to demonstrate their mastery of space-age technology.
Until a month ago they lived in a conventional kennel and wired-in run; but, although generally amenable and well-behaved, they blackened their reputation by barking a good deal and persistently jumping up on visiting cars with other dogs on board. Now, after the installation of a Freedom Fence, their lives have changed entirely.
Not many dogs can be as fortunate in their accommodation. Behind their owner's farmhouse the land rises gently in a shallow grassland valley, and they now have the run of six whole acres in which to dig, chase rabbits, sunbathe and generally fulfil themselves. Their territory, graced by several large ash trees, has a stream running down the middle and includes a spinney with a commanding view of the house's drive, so that the denizens can keep an eye on comings and goings. At the centre of the domain is a kennel, in which the dogs sleep at night, but of other physical containment there is no sign.
What keeps them in is a 3,000ft perimeter of wire, buried two inches below ground, which sends out a low-frequency radio signal. Each dog wears a collar fitted with a matchbox-sized receiver: if it approaches within 10ft of the wire, it receives an audible warning - a trill, like a feeble telephone bell - and then, if it goes any closer, a sharp nip of electric shock.
The cost of the whole installation - a far larger one than most owners would contemplate - was about pounds 500, a fraction of the expense of a chain-link fence.
Having heard that I would get no lunch until I had experienced a shock myself, I grasped a spare collar in one hand and advanced on the invisible barrier . . . until with a yell I flung the receiver away. 'Shock' was the word - though as much in the sense of a surprise as of a physical jolt. It was an unpleasant needling, but not violent.
Yet the point is that dogs are extremely quick to learn where their new boundaries lie, and, once they have them worked out, do not even cross the bell- line, let alone risk getting what the sales brochure describes as a 'correction'. Thereafter, the psychological barrier suffices to contain them, and many owners switch off the shock element of the system, leaving only the bleep in action.
Training is carried out by placing little white flags along the bell-line, taking a dog up to them on a lead, and then, when the warning sounds, encouraging it to turn back and come away. Poppy, a sensitive character, mastered the system in two days and needed no more than a couple of shocks to work out the form.
Jamie, being older, took longer. In the words of his owner, 'it was like asking a 70- year-old suddenly to master a computer'. Nevertheless, he, too, managed it - and according to Mr Rogers, 'both dogs' level of contentment went up tremendously'.
Certainly, when I visited them, they seemed as happy as could be. Ambling down the valley to meet us, they greeted us with a proprietorial air. Yet when encouraged to move close to the perimeter wire, they politely declined.
Watching them, I was troubled by the memory of an incident in the shooting field years ago. An incurably wild spaniel, in full cry after a hare, failed to notice that its quarry had slipped through the big mesh of a pig-wire fence. The dog struck the barrier head-on at about 30 knots, was flung bodily backwards at least five yards, picked itself up and continued the charge, this time clearing the barrier with a flying jump.
What would happen, I wondered, if a rabbit crossed the buried wire at full tilt? Mr Rogers admitted he was not sure, but felt confident that the dogs would not go after it.
Idyllic as their surroundings seemed, there was (and is) one major snag: they cannot be persuaded to leave their sanctuary. Mr Rogers's aim is to take them in and out through a small garden gate - and, once their radio-collars are off, they can of course go through it, over the buried wire, without warning bleep or shock.
But they, not knowing this, have so far refused all overtures: a course of careful education, with ostentatious doffing of radio-collars and putting-on of leads, is going to be needed to persuade them that this is a safe exit.
In spite of this drawback, Mr Rogers is convinced that, in social terms, the system has arrived at the right moment. In the old days, especially in the country, people tended to let their dogs wander at will, hunting and bitching; but now, in the era of wardens, higher standards of control and responsibility are expected. I can see that an electronic fence would be ideal for people with medium or large gardens who have to go off to work every day and do not want to leave a dog confined to the house. Furnished with personal receiver and dog door, Fido can roam the grounds at will - and if the postman carelessly leaves the garden gate open, it could not matter less.
All the same, it gave me a curious feeling to see Jamie and Poppy at large in their green valley: somehow they seemed more like cattle than dogs, out there on their own in the middle of the country.
It all depends on how you treat your own dogs. My two labradors live indoors, full members of the family. As I write this, the pair of them are both hull-down in the armchairs on either side of the wood-burning stove. If I wished to relax, I should have no alternative but to lie on the floor between them.
They, I suspect, would be outraged if suddenly put out to live in one of the paddocks . . . and yet, the Freedom Fence being highly adaptable, we could undoubtedly fashion an enclosure which included part of the garden or orchard, and so enable us, especially in summer, to leave doors open without worrying. At a suitable moment I shall canvass their views on the subject.
The Freedom Fence is marketed by Petsafe, Priory Lane, Burford, Oxfordshire OX18 4SG (0608 811433, fax 0608 811030).