Sometimes a horse’s ridden performance changes without there being any obvious signs of what the underlying problem may be. Frequently this is due to low grade lameness which the horse effectively obscures by adapting its movement, most notably by stiffening the spine and often shortening the step length of each limb. The horse may alter the ‘neck frame’ either by positioning the head slightly behind the vertical position (so-called ‘behind the bit’ or ‘overbending’) or placing the head above the vertical position (‘above the bit’). Being ‘above the bit’ will inevitably result in slight extension (sinking) of the spine, which will have a secondary effect of restricting hindlimb movement, so the horse will lack hindlimb impulsion and engagement. This may progress to the horse altering its balance, so that it places increasing load on the forehand.
The change in head and neck position may alter rein tension and the ‘connection’ that the rider feels via the reins with the horse’s mouth. If the horse becomes overbent rein tension may reduce. If the horse becomes excessively on the forehand there may be a symmetrical increase in rein tension – the horse may ‘hang on the bit’. If the horse is ‘above the bit’ the rider may feel a loss of interaction with the horse’s mouth via the reins and bit.
Some horses adapt by creating an uneven rein tension, ‘leaning’ or ‘hanging’ on one rein, creating excessive rein tension on one side, which may result in the bit being pulled through to one side. Rider’s often blame themselves saying for example that they are right-handed, so stronger in their right hand, so that is why there is excessive tension or weight in their right hand via the rein. This is not generally the case! A pain-free horse should be able to turn easily to both the left and right. If the horse becomes more difficult to turn in one direction this is usually an adaptation to minimise discomfort.
With hindlimb lameness, even if subclinical (not obvious), the horse may feel more uncomfortable when the rider sits on one diagonal compared with the other. This means that the rider should be able to feel a difference when they sit on the left or right diagonal, whereas in a pain-free horse the horse should feel similar on the left and right diagonals.
The ‘stiffening’ of the horse’s spine (reduced range of motion) will result in less absorption of forces through the musculature of the back, so more forces will be generated through the rider’s trunk, which may induce a jarring sensation or discomfort in the rider’s back. A rider with ‘feel’ may appreciate less swing of the back behind the saddle (the lumbar region), or may feel that the horse ‘drops’ behind the saddle.
With low-grade forelimb lameness the signs may be episodic and only evident under specialised circumstances, for example when turning up the centre line off the left rein. The horse may start to stumble occasionally, especially on uneven ground.
All of these changes may be slow and insidious in onset, so challenging for a rider to recognise. A rider ideally needs to go through a weekly check list. Does my horse move as freely and willingly as before? Does the horse feel similar on the left and right reins? If I change diagonal, does the horse feel the same? Do I have symmetrical rein tension? Does the horse’s back swing up and down and from side to side?
There’s more to come in next month’s blog when we consider canter.
© Sue Palmer, The Horse Physio, 2021
Treating your horse with care, connection, curiosity and compassion