Shinsoreness / Shin sore

Shin soreness, bucked shins, dorsal metacarpal disease, are all names for the condition particularly prevalent in racehorses especially thoroughbreds when first brought in to work. It is particularly severe in younger animals i.e. two year olds.

A horse brought into trackwork for the first time is immediately causing different stresses to its whole body and in particular the front aspects of the forelegs. The bones adapt to the new stress and commence to remodel as a reaction to the stress.

The main compressive force during the outstretched stride occurs up and down the front aspect of the leg, particularly in the cannon bone, fetlock, knee area but also right up to the shoulder.

In essence the reaction to this stress is to thicken the bone at the front, to enable the horse to better withstand these forces. It is a relatively slow process compared to the muscular and heart fitness which occurs also. If the training programme is too rapid or too forced the horse may be muscle-fit before being bone-fit. A long period of slow work is necessary before fast work should be commenced hence the importance of pre-training.

It is interesting to note that when German troops were made to march goose-step, a similar effect occurred, a human shin soreness, due to the unusual and individual forces set up in the bone by this particular, unnatural, marching style.

So the racehorse that is forced on too fast for its bone remodelling process becomes shinsore. In fact, many very fine fractures (microfractures) occur on the front of the cannon bone, and haemorrhages (or bleeding) can occur under the periosteum which is the thin skin like layer overlying the actual bone. A deposition of new bone occurs at the same site. The area is damaged, it may be swollen and will almost certainly be painful. The animal will be reluctant to run and particularly unwilling to stretch out.

Understanding this process is important in handling the shinsore youngster. Remember the two year old is still growing up as well as growing fit, and bone is still being laid down. The importance of adequate and balanced calcium and phosphorus in its diet is frequently forgotten at this stage. Providing Folactin to balance the minerals in the horse's grain based diet is of great significance in counteracting this problem.

Shinsoreness can cause an enforced spell and loss of time and potential earnings. If the trainer is aware of it and adapts the training programme before the shins get very painful he may be able to avoid completely spelling the horse. Mild blisters or counterirritants improve blood supply to the periosteum bone lining and help to heal damage caused by the haemorrhages. This gives pain relief in the milder cases. Upon return to work a controlled exercise
programme should be followed, exercise without a rider and slow galloping depending upon the severity of the condition.

The balance of amino acids in the diet of young growing horse is critical as well as the overall crude protein rating.  Power Formula provides the essential amino acids vital for strong, sound bone and it should be fed in conjunction with a suitable protein source.

Check the front surface of the cannon bones every day after training. With this regular regime of fingers pressing on the shins, the first sign of a slight pain response will warn the trainer, and the work should be reduced until his bones have "caught up".

A long period of rest certainly stops the shinsoreness, but also stops the remodelling so that when the horse returns to work he may well go shinsore again. So the answer is to ease up at the first sign then gradually reapply the pressure of training.

The very painful cases, however where acute inflammation is present, do need a spell so that micro-fractures can heal and inflammation be reduced.

For horses coming into work at pre-training a long period (120 days) of foundation will prepare them better for actual trackwork. The shoeing should be done to assure that long toes and low heels are not perpetuated since these delay the breakover of the foot and result in a longer compression period.

Finally consider the track surfaces before work. Hard tracks and wet tracks result in more impact and slide, and therefore a longer compression period of the front part of the bone.