There is nothing new about leading animals by the head: the Incas had headcollars for their llamas 1000 years ago, in Ancient Egypt they were used for leading camels and riders have guided their horses by the head for over 4000 years.

I am Dr Roger Mugford, the animal psychologist from the UK who invented the HALTI principle nearly 25 years ago. Leafing through old photographs from a dead but not forgotten uncle who served in Belgium during World War One, I found old pictures of cart dogs with uncomfortable-looking leather harnesses and headcollars. In Switzerland, I found a simple figure-of-eight headcollar that was traditionally used to train Bernese Mountain Dogs as cart dogs.

I happened upon the HALTI because I am a horseman and farmer, and regularly manage carthorses, bulls and sheep with various designs of headcollars. I also suffer from back problems, so it was natural that when confronted with giant breeds of dog like an Irish Wolfhound called Ben, I should tinker with straps to create the first British design of canine headcollar: the HALTI.

The HALTI has been acclaimed world-wide as the most effective design of headcollar, which naturally follows the contours of most dogs' faces. Only sometimes do problems arise when fitting the HALTI to short nosed breeds like Pugs or Boxers, alternatively to the elegant, particularly long noses of Borzois. Nevertheless, for 98% of dogs, HALTI is the perfect fit.

Just as HALTI was born out of my professional interest in behaviour modification of difficult or disturbed dogs, so it is also the equipment of choice for dealing with an aggressive dog. The particular advantage of HALTI over other designs of headcollars is that it has a unique on-off muzzle-closing effect: when the dog struggles to lunge forward or attack, its jaws are closed by the rising ring under his chin. When he is relaxed or friendly, he can reopen his mouth. At all times that the dog is behaving well he can pant easy, loll his tongue and be just like your dog when free.

Beware of some designs of canine headcollars that are overly restrictive, whose fitting instructions unkindly emphasise that you should have a tight fit around your dog's muzzle and neck. This can impose intolerable pressures upon the underlying soft tissues of his head and neck, with a likelihood of damage to the delicate glands and nerves around the eye orbit and on the pressure-sensitive areas behind the ears and upper spine.

HALTI has been rigorously tested over the years by veterinarians and orthopaedic specialists who confirm that HALTI transfers the physical load of a heavy dog to the most resilient structures of the head, converting unwanted forward motion (pulling) into a gentle turning action.