When Steven Lowe was admitted to a rehabilitation centre aged 26 for severe alcohol addiction, it was his last opportunity to conquer the problem before he drank himself to death. After 10 years of addiction, he says he expected rehab to throw him some tough challenges but he never thought that interacting with horses would be the key to turning his life around.

In the 50-acre woodland setting of Castle Craig in the Scottish Borders, Lowe undertook an initial eight-week detox and was then put on an extended recovery programme, where he was introduced to the pioneering treatment option of equine therapy.

Devised in America and new to Britain, it involves controlled interaction, and role-playing, with horses (though not riding), where patients must coax the horses to do certain tasks. Being able to control these large, powerful animals helps to build self-esteem and modify addictive behaviour.

The success of equine therapy adds to the increasing body of international evidence that interacting with animals has a positive effect on health conditions.

Lowe says he never expected horses to be his salvation. "I'd never been in contact with horses before and I did have some fear of being around them at first but what I learned about myself from even the first session with them was absolutely incredible. I walked away stunned by the experience.

"The point of this for me was that if I could learn to control a horse I could learn to control other things in my life. It gave me a better insight into myself and how I could solve personal problems without resorting to alcohol."

That was something he says he failed at miserably before he went to Castle Craig. Having grown up in East Kilbride, Lowe experienced some personal traumas in his early teens and ended up homeless. He started drinking as a way of coping.

"It was quite frightening living on the streets of Glasgow," he says. "I used alcohol to get me through the day and if I couldn't get alcohol then I used drugs as well."

While he had tried other detox programmes, the addiction still spiralled out of control.

"In the six months before I came here, I'd hit rock bottom. I was drinking at least a bottle of vodka a day and I ended up one night curled up in a corner of a friend's flat, hugging an empty bottle and feeling such a sense of despair. I was at the stage where I didn't care if I drank myself to death or not."

Lowe felt that outcome was imminent if he didn't get help and a community worker encouraged him to get a referral to Castle Craig, which now takes the majority of its patients through the NHS.

The recovery programme at the hospital has different treatments on offer, mainly for alcohol and drug addiction, including the equine therapy, run by keen horsewoman and therapist Aureol Gillan, who has endured her own terrifying battle with alcohol and was also treated at the hospital 15 years ago.

Gillan, 52, says she probably wouldn't be alive today if she hadn't gone into rehabilitation when she did and it inspired her to become an addiction therapist herself. She has worked ever since at Castle Craig.

Three years ago, Gillan set up the equine therapy programme, with some of her own horses, after studying what is known as equine-assisted therapy in Utah, America. From the beginning she says the results were outstanding across the board. "The recovery programme here is about helping patients to learn new coping skills. Equine therapy helps patients to become more aware of their behaviour. It gives them experiential learning.

"Some patients are afraid of the horses to start with and it's a real achievement just to be able to work with them because you can't force a horse to do anything it doesn't want to do," she says.

Gillan has eight horses - from a feisty mule to a 17-hands gentle giant called Ivan - which are used in role-playing exercises "as a metaphor for certain situations".

One exercise in particular, where a circle is created in the field to represent a treatment centre, has proved tremendously valuable. The horses represent patients, and the real patients represent relatives. The object is to coax the horses into the circle without touching them, relying on ingenuity and perseverance.

As Steven Lowe explains: "The exercise has a lot to do with patience and it gave me great insight into what it must be like for people's families trying to get loved ones into places like this to save their lives. It made me think about my dad and all the worry he's had with me over the years.

"Horses also represented things I was afraid to confront before because they are so big and dominating. It helped me to build up my self-esteem because that's something that's completely diminished by addiction. I couldn't look people in the eye before because I was so ashamed of some of the things I'd done and what I'd become."

Apart from the effectiveness of the role-playing, Gillan has no doubt about the therapeutic power of horses. "Horses are very sensitive to people and they're very honest. They pick up on our moods and behaviours."

For Lowe, just being around horses satisfied a deep, emotional need. "It was the first time I'd built a real relationship with any other creature. I trust the horses and I don't trust people easily. Horses don't judge you."

A growing band of international researchers is slowly beginning to understand the healing power of animals, but we may only be scratching the surface with our current knowledge. Elizabeth Ormerod, a vet and also chair of the Society for Companion Animal Studies (SCAS), a charity which fosters the human/animal bond, says: "Studies show that when you interact with an animal your blood pressure drops, feel-good hormones such as serotonin increase, the stress hormone cortisol decreases. Physiological things take place and they can be measured."

Helene Mauchlen, development officer for the British Horse Society in Scotland, has no doubt that horses have a healing gift and "can sense if someone is in trouble mentally". That's something Elizabeth Ormerod also believes. "Certain animals, such as dogs, cats and horses, are often gentle when they are around people who are fragile. You see that with organisations like Riding for the Disabled. "There is enormous potential for animals to restore and maintain human health and I don't think we've really begun to tap into that fully yet."

Animal magnetism There are around seven million domestic dogs in Britain and nine million cats. Florence Nightingale was one of the first people to advocate the benefits of companion animals for the chronically sick. Dogs are now being trained to anticipate the onset of conditions such as epileptic fits in owners. A study in America showed that older people made fewer demands on health services when they had pets. Further research shows that those who own a cat and spend quality time with it could reduce their risk of heart attacks and stroke by a third. Another international study has shown human/pet interaction can even impact favourably on the level of bad fats in the bloodstream. Numerous health benefits have been attributed to swimming with dolphins. A study published in the British Medical Journal in 2005 compared 15 depressed people who swam in Honduras with dolphins to 15 depressed people in the same area who didn't and found that symptoms improved more among the first group. Although the findings of subsequent studies on the benefits of this therapy have been equivocal, it remains very popular. The researchers, Professor Michael Reveley and Dr Christian Antonioli of Leicester University, said: "The effects exerted by the animals were significantly greater than those of just the natural setting. The emotions raised by the interaction may explain the mammals' healing properties." Cats are said to be so sensitive to human behaviour that when kept in hospices can tell when patients are near death and will keep vigil over them. James Macdonald, a former firefighter from Glasgow, is a trustee for Canine Concern Trust Scotland and has been involved in its Therapet scheme for 20 years. Volunteers take different breeds of dog, and occasionally cats, into hospitals, care homes and schools to lift morale or to act as an adjunct to various therapies.

He says: "It's been a common experience that people will talk to dogs long before they'll talk to other humans. The dogs make patients do things, whether it's talking or laughing, or reaching out to them with their hands. I've seen it with psychiatric patients who are not bothered with anything and you put a dog with them and they will have a conversation with it."

He believes animals can help humans to modify their moods and behaviour, something that he has observed particularly with children suffering from autism and ADD.