Equine Muscle Lameness
The Unrecognized Injuries
E. Allan Buck 2010 ©
The Unrecognized Injuries
E. Allan Buck 2010 ©
Lameness: Is a departure from the normal gait in animals.
Lameness is most usually associated with injuries to the lower legs and/or hooves. Unfortunately for the horse, this confined diagnosis area actually places the horse at risk for long term extensive muscle injuries located in other regions of the body.
Hyperflexion is excessive and forceful flexion of a limb or other part and results in occurrences of muscle injuries arising in other regions of the body. Usually the region diagonally opposite to the original injury can sustain muscle injury, primarily as a result of over compensation of the original injury.
Improper contraction of muscles is usually the result that occurs when muscles are damaged. A contraction is a drawing together – a shortening or shrinkage. These contractions can be caused by muscle spasms wherein the increased muscular tension and shortness cannot be released voluntarily and prevents lengthening of the muscles involved.
The primary muscle injuries in the working/ridden horse are tetanic contractions which are sustained muscular contractions without intervals of relaxation. When tetanized, the contracting tension in the muscle remains constant in a steady state. This is the maximal contraction and causes rigidity of the muscle system within the region.
Cause and effect of the combination of rider, saddle and bridle used upon a horse has never been studied in a scientific research study. Individual localized studies have been done by independent researchers such as how bits move in the mouth, back pain studies, saddle pressure points, etc., however, a cumulative study has never been accomplished.
Externally induced tetanic contractions are not recognized nor widely discussed or researched in the equine world. Odd situation, as externally induced tetanic contractions alter gait movement, stride length, self carriage, and impulsion, which causes the horse to be unable to perform at its optimum and thus as in the case of dressage horses, actually unable to meet the stipulated descriptions which clarify how the horse shall appear performing the movements.
In the working/ridden horse, the most common area for externally induced tetanic contractions is the lumbar region, followed by the pelvic region, then followed by the shoulder, followed by the neck. Generally you will find that tetanic contractions do occur concurrently in the neck and shoulder area. The pelvic and lumbar regions are affected by different direct forces other than the neck and shoulders, however, tetanic contractions within the neck and shoulder areas do have an indirect impact upon the lumbar and pelvic regions. Externally induced tetanic contractions can exist within one localized region or these contractions can exist in conjunction with another region, such as left or right front diagonally to the right or left rear.
In the lumbar region, the area of the loins and point of the hip, the muscles are subject to numerous overstresses caused by the horse not rising the back. The muscles in this region that are directly affected are the thoracolumbar facia, the transverse abdominal muscles, costal retractor muscles, lumbar longissismus muscles, and the middle gluteal muscles.
The pelvic region consists of the sacral region [croup] and the gluteal region [hindquarters]. The muscles in this region that are directly affected are the sacral tuber, gluteal fascia, superfacial gluteal muscles, biceps femoris muscles, and the semitendinosus muscles.
These two regions manifest the gait and length of stride of the hindquarters. These two regions are also the rear component in the suspension bridge muscle support system for the back and torso regions. When even one muscle is affected by tetanic contraction, the entire back and hindquarters are directly affected. The result is more than one muscle will be in tetanic contraction, and this single muscle injury will directly impact surrounding muscle support systems until the entire region is locked down in tetanic contraction.
A prime example of the singular affect can be seen when one does palpate the region of the loin and proceeds to press down upon the longissimus muscle in a particular spot, most often the horse will move downward and away in order to not be affected by the palpation. If one continues the palpation and tries to go deeper, one will be met with rigidity of the longissimus and thoracolumbar facia muscles, and if one is able to work past this rigidity one may find the costal retractor and transverse abdominal muscles may also be affected.
These locations may not be affecting the rest of the hindquarter. However, as a result of these externally induced tetanic compressions, the sacral region will probably be affected. The gluteal region also may or may not be affected and palpation through the region will reveal tetanic compressions.
Externally induced tetanic contractions within the muscle structure of the hindquarters directly affect the length of stride and the gait of the hind legs. Therefore, under any rules governing the health and welfare of the horse, a horse with tetanic contractions that affect length of stride and gait must not be allowed to compete in sanction events.
Rider impact upon the forehand of the horse should be of paramount concern to any individual who truly stands for the health and welfare of the horse.
Where the rider places him or herself is a critical piece of the puzzle of constraints and restraints imposed upon the horse. The majority of working/ridden horses have the rider and saddle set forward close to or partially upon the withers of the horse. This places all of the weight of the rider and the saddle upon the forehand of the horse. Such weight is imposed upon the horse to its detriment, due to the fact that the horse carries 60% of its weight on the forehand. Adding the weight of the rider and saddle in the forward position loads the fulcrum in the front and the horse is not balanced. The forward placed saddle has a direct compression impact upon the muscle underlying the saddle and can cause these various muscles to have a externally induced tetanic contraction.
The back muscle structure of the horse is designed as a connector front to rear, a suspension bridge, as well as, the stringer for the muscles of the abdomen and torso. Placing the saddle forward actually impedes the operational function of the thoracic longissismus, the thoracic and cervical, the cranial dorsal serrate, the caudal dorsal serrate, latissimus dorsi muscles, and the thoracic part of trapezius muscles.
The fulcrum point for the horse is approximately at the 12th thoracic vertebrae. Place weight upon the back of the horse and the fulcrum will shift rearward in order to maintain the balance in the forward motion of the horse. The shift is usually rearward to the 17th and/or 18th thoracic vertebrae. Placement of the riders’ spine close to this location will not have a negative affect upon the lumbar vertebrae and thus the kidneys will not be in any danger.
End of Part One