A team from Dundee University found that saddles designed to stop spinal injuries in riders also have the reverse affect on horses, in turn causing them more back problems.
The researchers have now called for further work for a saddle to be designed which protects riders and horses.
The study, led by Professor Rami Abboud and Dr Graeme Nicol, in the University's Institute of Motion Analysis and Research, examined how the flocking (cushioning) material of a saddle affected the pressure on humans and animals.
Pressure recordings were carried out on a saddle fitted with wool, the most common flocking material, and compared to those taken from one with air-filled panels.
It was previously known that wool-flocking can cause back pain for horses but the results show that, while air-flocking reduces the pressure exerted on the horse, it increases the pressure on the rider at the same time.
Both flocking materials were tested using two pressure mats to record the pressures firstly being exerted onto the horse and secondly onto the rider.
All riders said they preferred the wool flocking, citing a variety of reasons.