Joint injections

During your horse's journey through their career, it is possible they may need some help to keep them moving with fluency. A comfortable and free-moving horse is more likely to produce their best on the racecourse, after all. Whilst in training, before leaving for the gallops, a horse will pass a senior member of staff, who will be constantly checking they are moving well, every time they leave the yard. They will naturally want to investigate and potentially improve the movement of any horses who look stiff in any way.

When horses are not moving as well as normal, the vet and the physiotherapist often become involved to detect any muscle soreness (which the physio will then treat). The vet may intervene if they feel the soreness is joint-related, which they can potentially improve. For diagnosis, the horse is likely to be walked and then trotted in a straight line before the vet, and then possibly in circles. Hard surfaces (e.g. a tarmac yard) are likely to make lameness more obvious, as working on soft sand in an arena has a cushioning effect on the lower limbs, which can shield some types of lameness from the vet.

The vet may then perform a 'flexion test'. The groom will hold the horse still while the vet lifts a specific leg up high towards the horse's body for around 15 seconds. The groom will then trot the horse away as soon as the vet releases the leg. The hope is that the horse's gait (movement pattern) will not be affected by the test, but if they are stiff on a specific leg, the vet could treat the joint (e.g. knee or fetlock) with a lubricating steroid.

In young horses, stiffness may be caused by inflammation or soft tissue swelling, but in older horses who have been racing for several years, there may be some arthritic changes in the joint. The vet must be meticulous when preparing the joint for injection, as there is always a small risk of allowing infection into the joint capsule by penetrating it with a foreign body (the hypodermic needle).

Corticosteroids are the most commonly used joint injection in racehorses, due to their efficiency and the fact that there is only a short withdrawal period before the horse can return to racing.

Corticosteroids are man-made versions of the hormone cortisol, which is produced naturally in the horse's body. When injected into a structure such as a joint, corticosteroids will escape into the horse's system to exert their influence throughout the horse's body. Although related chemically, they are different from anabolic steroids used to promote weight gain or muscle development (anabolic steroids are outlawed in many countries, including Britain). Corticosteroids are an anti-inflammatory drug which can have a rapid and significant effect on reduction of soreness. The reason horses are not treated routinely with this drug is that very high doses can promote laminitis* in exceptionally rare cases, hence the drug is used sparingly.

These injections often last a season, but may need repeating a year later, if the trainer once again notices the horse's movement is restricted. Corticosteroids are not only used in lower limbs, as horses' backs and quarters can also be injected, if stiffness is located in these areas. The chances are the vet may choose to x-ray or send the horse for an MRI scan to diagnose the location of the stiffness. In some cases, in more vulnerable locations (e.g. the spine), injections can placed using x-ray or MRI guidance, to ensure the injection is administered in a specific location.

Once the horse has received an injection, they will spend the next day or two on the horse-walker or just having a leg stretch, but can then return to normal canter work. The British Horseracing Authority have a mandatory 14-day 'stand down' period following an injection of corticosteroids, which means the horse cannot race for at least a fortnight after treatment. This period gives the horse time for the drug to take effect, which should improve their range of movement. This is the aim of the treatment, with the overall hope that performance on the track will be elevated to previous levels.

*Laminitis is a condition in which the tissues that attach the hoof wall to the pedal bone (the laminae) become inflamed. Whilst individual 'episodes' of laminitis can often be treated effectively, and careful management helps to reduce the risk of reoccurrence, a horse who has had laminitis before is always more at risk of an episode than one who has not. Laminitis, particularly when it recurs, can lead to rotation or sinking of the pedal bone within the hoof, which is incurable.