Dr Annie Bevin MA Vet MB MRCVS discusses the increasingly common problem of kissing spines and its relationship to saddle fitting and the horse’s way of going.
Recently I have been pondering the large amount of claims that we are seeing for kissing spines, or more correctly overriding dorsal spinous processes. Nearly everyone will know someone whose unfortunate horse has been diagnosed with this condition; some responding to medication, a lot requiring surgical intervention, and some unfortunately never returning to the original level of performance.
When I qualified over thirty years ago this condition was never even contemplated because we did not have the powerful x-ray machines that we have today, nobody was able to visualise the horse’s spine, so any horses exhibiting symptoms such as refusing to jump, bucking, stiffness and reluctance to be saddled up just had a course of bute, or if they were lucky a visit from the “back man” ( and if they were extremely lucky indeed this would be a qualified osteopath, chiropractor or physiotherapist!)
Having said that we just did not see that many horses exhibiting these symptoms. Horses cannot suddenly have evolved to have close dorsal spinal processes, so there must be other factors in play here. I personally think that although our management strategies have changed, these may in fact be for the better, it was more usual than not for horses to be stabled for 23 hours a day, with just one hour out of the stable. Nowadays we do make more effort to provide turnout or at least some time on a horse walker in order for them to have some down time. Saddles have, on the other hand changed out of all recognition.
Modern saddles have been designed for optimum performance for horse and rider, putting the rider in the correct position for whatever discipline they choose. There is absolutely no doubt that when fitted correctly performance is enhanced. There are so many factors involved in the fitting of these saddles though, that if something goes amiss there is a huge knock on effect. I remember learning about saddle fitting for my Pony Club “B “ test in 1977: Two factors- you had to get 3 fingers under the pommel and see daylight under it when the rider was on top! The saddles in those “days of yore” were the old fashioned hunting type- they numbed your bottom but fitted virtually any horse- so what was going on? In my opinion it was because of the way that the weight was distributed. Those saddles were bigger, with larger panels so the weight of the rider was spread over a larger area. For the horse to be comfortable the muscles on top of the spine have to be able to move freely without any rubbing or excess of pressure. The maximum pressure, not to cause tissue damage has been found to be lb’s per square inch, so the larger the panel, the more the weight of the rider is distributed. Western saddles, Australian Stock saddles and Military saddles are good examples of weight distribution, in the case of the latter spreading the 15 stone of a Household Cavalry Trooper in Full Military Regalia over the back of relatively small Irish Horse.
The anatomy of the horse also comes into play, as does the way it carries itself and indeed the way it is ridden when considering the pressure on the horses back. In basic simple terms I like to think of the spine as a row of cotton reels on a thread with a tape along the top which represents the supra spinous ligament. This extends into the thick nucal ligament which runs along the top of the neck. This can be imagined as a thicker rod and at the front end is a weight, or the head.
When the head is in the correct position the tape (ligament) tightens thus stabilising the spine. Ligaments, which hold bone to bone are much stronger than the muscles which move them. The muscles over lying the spine run from vertebra to vertebra and assist their small amount of movement. Horses are prey animals and have a reflex to hollow their backs in anticipation of running away when attacked by a predator; in this position the supra spinous ligament is slack and consequently the back not stabilised.
If the horse is tense, short or in pain, it will hollow its back and the muscles will be forced to stabilise the spine and support the rider’s weight, which leads to muscle spasm and more pain, more hollowing and a vicious circle ensues. As the horse hollows those dorsal spinous processes will consequently move closer together and more pain results. Should there be insufficient clearance over the spine and the DSPs are close anyway the horse would be in agony. So then what is important when fitting the modern day saddle? The saddle must be level on the horse, the panels must be as large as possible and in contact with the horses back, but wide enough to be clear of the spine. An easy way to check this is to lightly dust the saddle with talcum powder and carefully place it on a slightly moistened horse’s back. Girth it up, then carefully remove the saddle. The area of contact will be clearly marked on the back. I usually double check by reversing the process. This is a quick and low tech way of establishing where pressure might occur, there are commercially available saddle pads used by some saddle fitters which give more accurate readings, and are also used in saddle design and development.
It is also vitally important that the shoulder blade (scapula) is free to move. The points of the saddle should not restrict its rotation backwards as the front leg moves forward. In order to check this, it should be possible to slide your hand under the points, with a rider on top. Using the other hand, gently pull the fore leg outwards. If your fingers get crushed- the saddle is too tight! The saddle should not move from side to side when the horse moves, this can happen due to uneven muscling over the back, or sometime due to low grade, undiagnosed hind limb lameness. Overall it is important to remember that your horse changes shape throughout the year and for peak performance it is vital that the saddle be checked regularly by a qualified person and that your athletic horse receives the best veterinary and physical therapy attention.
Correct saddle fitting and schooling will not prevent the worse cases of kissing spines, but in my opinion, the less severe cases which develop slowly over a period of time could well be helped considerably, worth a thought?
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