It is a commonly held belief that nearly all horse and pony lameness starts in the front legs below the carpus (often incorrectly referred to as the knee which is in reality the stifle of the hind leg). There is of course the well-known saying "No foot, no horse" and there is no doubt that good farriery, which properly addresses the length of the toe as well as the balance of the foot, is essential if concussion resulting from the footfall is to be evenly directed to the hoof and on up the leg. However, as a result of using the Scenar device over the past 11 years or so to find and treat sports injuries in horses, I have come to the conclusion that (assuming the farriery is adequate) then nearly all slow onset lameness originates from much higher on the horse than previously recognised and migrates on into the tendons and ligaments of the lower foreleg or to the hind suspensory ligaments of the back legs.
If we go back to the evolutionary origins of the horse in the wild we can get a possible insight as to why this happens. As herbivores grazing in herds in the wild, horses would have been a prey animal for the larger carnivorous predators. From the predators’ perspective lame prey are the easiest to single out to chase and kill. It is therefore in the best interests of an individual horse to mask minor lameness issues and compensate through a slightly altered gait so that it continues to blend into the herd and minimise its chances of being singled out as the next dinner for a predator!
Horses have therefore instinctively developed an ability to compensate for minor lameness that eases the pressure on strained or injured structures, and spreads the excess pressure onto secondary structures within the same limb followed by a different or diagonal limb. Over time, the excess strain on these secondary structures takes its toll and the horse either finds another way to move to compensate for both the original and the compensatory strains or it is forced to show overt lameness. Eventually there is no further possibility to compensate and damaged structures then fail. Of course some horses are more stoical than others and different horses will demonstrate their lameness at different stages of the compensatory progression.
If we now consider the anatomy of the horse, the front legs are attached to the thorax by muscles that must not only move the horse but also act as a sling for the majority of the horse’s weight when standing still. There is no collar bone as humans have and so these muscles must be both strong and capable of great stamina. In human athletic performance of nearly any sport, the most common injuries are muscle strains and tears with ligaments and tendon injuries following behind. I believe it is therefore to be expected for horses to first have problems in their muscles that they compensate for elsewhere.
Tendons and ligaments of the lower leg take up the extra burden and the horse will very likely be showing the first signs of preferring a different leg or diagonal to take the major strains of work such as taking off and landing in jumping. There might be an almost imperceptible short-stride on the leg or other minor alterations in gait that only an experienced eye or well tuned-in rider will perceive at that time, or more commonly will recognise on hindsight should the minor stresses and strains progress to overt lameness.
The likelihood of this happening is increased in horses that are stabled. Horses that have evolved in nature to be constantly mobile and moving between grazing areas throughout the day whilst intermittently reacting to signs of danger through flight, will inevitably be more prone to muscle injuries when worked if kept relatively immobile in a stable for significant stretches of the day and night especially if they are not properly stretched and warmed up prior to exercise and are expected to carry the additional weight of a rider. Badly fitting, or inappropriate but well-fitting tack, will create additional stimuli that may tend to force a horse to work in an unbalanced manner. The same pressure to work incorrectly is frequently placed on horses and ponies by poor unbalanced dentistry even if overtly sharp points have been rasped.
Examining the whole horse
It is therefore essential when examining a horse for lameness, even if it is an obviously swollen tendon or joint, to examine the whole horse in order to work out why that horse was putting more strain through a particular leg that caused a tendon for example to tear. By approaching lameness of unknown origin and even obvious injuries in this manner, I have discovered that poor dentistry, muscle damage in a shoulder, chiropractic issues and farriery issues, have contributed to the more obvious tendon or ligament problem in a lower leg.
Lameness in the lower leg
From the veterinary perspective, it has been historically much easier to identify lameness below the carpus and stifle. Although whole horse bone scintigraphy and MRI are now available they are inevitably expensive and often equate to using a sledgehammer to crack a nut, ie. possible but rather OTT! Nerve blocks of the lower leg are easier to do and more easily interpreted, x-rays can be carried out with units that are carried in cars to the yard and ultrasound is also easier. Above these joints, lameness examination is much more tricky, carries greater risks and may require an injured horse going to a veterinary practice with welfare considerations surrounding that.
It follows however that if you mostly look below the carpus or stifle for whatever reason then it is not surprising that the overall impression is that this is where lameness usually begins. In my opinion, a gradual onset lameness that is obviously manifested in a tendon or ligament has probably been increasing in likelihood from a higher issue for a few months or maybe even longer. Even injuries that can be identified and related to a specific incident (eg. a horse putting a leg down a rabbit hole or running cross country on soft going) may have been an accident waiting to happen as a result of an ongoing downward spiral that created a weakness in these structures.
Hind leg lameness
Inflammation of the higher hind leg suspensory ligament is more often than not a symptom of other issues. It is relatively easy to find and diagnose in hind limb lameness because there can be multiple causes that all feed into this area. There might be one or more of these other issues ongoing that all need to be addressed and corrected if the horse or pony is to come right. Every horse I have treated with this condition has had other issues that once corrected have enabled all individuals to go back to the level of work or higher that they were previously achieving.
Unfortunately, many horses are being butchered and irreversible de-nerving operations to this area are masking the situation whilst seemingly making a lame horse sound although this is only "successful" in 70% of cases. This is a banned procedure at FEI level and the FEI need to find a way to detect which horses have had this procedure carried out and catch any cheats who continue to compete knowing they are in breach of regulations. It would be easy to make it legally compulsory for the operating veterinary surgeon to endorse the Passport with any surgical procedure and I see no reason why this couldn’t be retrospectively introduced.
Now that I have a mobile thermal imaging camera, I am seeing the higher issues that I have previously been finding using the Scenar device (which detects and treats problem areas using electrical impulses). The beauty of both these techniques together is that one confirms the other, and with Scenar I also have the ability to treat any high muscle issues in combination with treating any lower leg injuries to get the horse back in training in double quick time with a reduced risk of re-injury.
(In the first thermal imaging picture above you can see the increased temperature in the gluteal region shown by the white areas. Post Scenar treatment this area has reduced in size and intensity as seen in the second picture.)