BRITAIN’S obesity problem is now starting to affect our horses.

Human love of junk food and overeating is putting extra strain on the backs of an animal that might have carried knights into combat but is suffering through a 21st century addiction to too many carbs and calories.

Research published in the Journal of Veterinary Behaviour has revealed that a third of horse riders are too heavy for their mounts, putting the animals at risk of bad backs, arthritis and lameness. A study of 152 horses found that just one in 20 riders is within optimum weight range.

As well as damaging the animal’s health, overweight riders can cause behavioural problems such as bucking, rearing and disobedience.

Julian Marczak, chairman of the Association of British Riding Schools, said: “A horse’s back is precious. The combination of a heavy rider and an incorrect saddle fitting is enough to put a horse out of work and you can turn a sweet-natured horse into a cranky one overnight.”

Julie Davies Bennetts, who owns Malvern Riding School in Malvern, agrees.

“With the greatest respect people need to understand that proprietors of riding schools and equestrian centres should have due concern for their horses,” said Julie.

“All reputable riding schools should ask potential clients for their weight and height so that they can put them on a horse which is suitable for them and can save any embarrassment.

“Our maximum weight limit is 13-and-a-half stone because that’s what my horses can cope with.”

People think that horses are such big animals they must be all right to carry heavy weights, said Dr Hayley Randle, the equitation scientist who led the research.

But the health impact on the horse can be quite extreme, quite quickly. And some owners are unaware of potential injuries.

Keith Chandler, president of the British Equine Veterinary Association, says a proportion of back and leg injuries he treats at his Scottish practice are caused by obese riders.

“Overweight riders tend to be people at the lower end of the professional spectrum, happy hackers or pleasure riders,” he said. “We see people on horses clearly unsuitable for them.”

Guidelines in Dr Randle’s research state that the optimum rider is less than 10 per cent of the weight of their mount, with the average stable horse weighing 500kg to 600gk. This means a rider should weight 9.4 stone.

But since horses have been lugging heavy loads for centuries – armour, carriages and caravans – you would have thought they would be used to it by now.

Large riders should look at heavier breeds like a half shire or weight-carrying cob. Whatever the breed, a rider’s weight is a sensitive subject. Mr Marczak agreed it is one of the most embarrassing things to bring up.

“But what’s more important? Saving someone’s blushes or saving the horse’s back?”