The charity has been contacted recently by several people who have rescued horses from the meat trade in France. Some have asked about rehoming their rescue horse as they are unable to cope with medical or behavioural problems.
The Horse Trust is asking horse lovers to stop buying from many websites that allow people to buy horses destined for slaughter and to consider rehoming a British horse instead.
"These websites are profit-making ventures and by buying these horses people are encouraging the horse-meat trade," said Paul Jepson, chief executive of The Horse Trust.
"You may be saving one horse, but your money will fund the breeding of many more horses for the horse-meat trade.
"It's a very risky buying a horse unseen from a website as you have no idea what the horse is like - it could have behavioural issues and be too much to handle, or it could be permanently lame, so you could be taking on a horse that you will never be able to ride," he said.
"With the credit crunch, there are thousands of horses in the UK that need a new home. If people feel they have the time, money and long-term commitment to look after a horse, we would advise them to contact their local equine rehoming centre."
The Horse Trust is also concerned about the risk of an imported horse transmitting an infectious disease to local horses and advises anyone buying a horse unseen to ensure a thorough and independent vet check is carried out first.
"Most of the slaughter horses that are rescued only have basic vet checks and may have minor issues such as lice or ticks, or more serious issues, such as an infectious disease.
"We are particularly worried about the risk of Equine Infectious Anaemia virus being brought into the UK, after the recent outbreak in France." he said.
Wendy Farrington, 55, from Ivinghoe, Buckinghamshire contacted The Horse Trust earlier this year after her 18-year-old goddaughter purchased two foals destined for slaughter from a website for £1000.
"She came across the website when she was surfing the internet and felt sorry for the horses," said Wendy. "I tried to advise her not to - I think there are so many horses in this country that need rescuing and by buying the horses you're supporting the horse-meat trade."
Another woman that contacted The Horse Trust had purchased a pony for its meat price from a fattening farm in France, but asked if the charity could rehome it as she did not have the knowledge or skills to cope with the pony's behavioural problems.
The Horse Trust has information and advice on buying a horse at www.horsetrust.org.uk. Potential horse owners can also get individual advice by emailing The Horse Trust via the contact form on its website.