Driving horses can be enjoyed at many different levels, from exploring countryside lanes in a pony and trap, to the ponies used in scurry driving around obstacle courses. At higher levels there are one, two or three day driving trials, using singles, pairs or four-in-hand which include a dressage section, a marathon to test speed and stamina, and an obstacle section using natural hazards such as water, gates and various other obstacles.
Driving is very different to other equestrian sports, with a vehicle and often more than one horse involved. Consequently a lot more control is needed over a group of horses being driven, than a single horse under saddle, and when accidents occur they can be extreme due to harness leathers becoming entangled around legs and feet.
The harness is going to be the major factor affecting the movement of the driving horse or pony. The overhead check rein should be fitted to allow the poll to be the highest point and the nose slightly in front of the vertical. When fitted too tightly it causes the nose to be extended too far set-forwards, as in "star gazing" or the head to be set to one side. Both these actions will cause tension to develop in the poll and upper neck, which will transfer along the underside neck muscles to the shoulders, where the horse will begin to show stiffness and restriction in extension of the forelegs.
When horses are pulling into collars they become more developed in the shoulders, this can cause problems in the lower neck and wither area. Traditionally, carriage horses are bred with upright pasterns in front, causing jarring from ground level into an upright shoulder, which compounds problems in the wither and shoulder area.
Foot balance is of prime importance in the driving horse, as bad shoeing or wearing studs can create an appearance of shoulder lameness and can cause sore shins by the inevitable concussion in front.
Driving horses do not have as much engagement from behind in their action due to the rider's legs not pushing them on, and although they do not have the added weight of a saddle and rider, and are not required to jump fences, their back problems will become apparent from the twists and turns of driving around the obstacle courses, and slipping on mud while cornering. It is the wheelers behind, rather than the leaders, of a four-in-hand group, which have more problems in competition, and accidents can result in legs through traces and horses in a panic with a carriage upside-down.
The overhead check rein can cause falls, especially on uneven grass tracks, when the horse would usually lower its head to assess foot placement. Some harness horses may run into each other, causing a collision, or may run out at corners taking the other horses with it.
Harness racing is another form of driving on tracks over a mile or more, usually taking place in Wales and Northern England. The Standardbred is the breed used, they can trot or pace at high speeds without breaking into canter.
Pacing uses hobbles or leg straps to encourage the movement of front and hind limbs on the same side, rather than in diagonal pairs as is the usual trot gait. Pacers will move with a rolling action as the weight is shifted from side to side, and boots are used to protect more parts of the horse's legs during racing. The overhead check rein is used to help control hard-pulling horses and to prevent a horse spooking at things on the ground in front of him. As with other driving horses this rein can cause falls on uneven grass tracks and will cause musculo-skeletal problems to develop at the poll and withers. These trotters and pacers must also stay in a straight-line to prevent collisions with others on the track or running out at the corners.
Chiropractically, driving horses will benefit from regular checks to treat problems in the poll and withers, caused by the overhead check rein, at the early stages before affecting their performance levels. Similarly pelvic problems, caused by tight cornering around obstacles or slips on mud, should be checked for regularly.
After a major accident while competing in driven classes the pony/horse should be assessed by the vet and, if its injuries were felt suitable for treatment, use a chiropractor.