The ideal horse shoulder slopes approximately 45 to 50 degrees and the pastern angles typically follow that of the shoulder. The health and position of the shoulders affect all areas of the horse and its conformation. Too much shoulder slopes can lead to coon-foot. Too little, and the horse is predisposed to navicular disease.
The Equine Shoulder
Shoulder slope influences the horse's length of stride and overall balance while regulating the amount of shock absorbed during movement. Straight-shouldered horses possess short strides and offer rough rides while long, sloping shoulders assist in dispersing the concussion of the foot hitting the ground.
Reliable shoulder injury indications include pain, swelling, reluctance, muscle atrophy and lameness. Applying pressure to the shoulder area or pulling the shoulder forward, backward or away from the body without to flexing lower leg joints results in pain. Swelling occurs in the joint area, caused by broken down cartilage around the joint allowing bones to rub together. Upon elevating the leg, the injured horse reluctantly swings the leg in an outward arc to advance it rather than stepping up and forward. This motion can also indicate knee pain or injury. Chronic shoulder injuries cause chest and shoulder muscle atrophy and may affect the foot position.
Signs of Muscular Problems
Horses are not able to verbalise pain; however, they display a wide array of signs to alert us. Head tossing, lack of coordination, choppy strides, improper tracking and refusal to lead should set off alarms regarding muscle health. Riders may even notice a slipping saddle, girthing problems and general feeling "off" while riding.
The horse shoulder is a ball and socket joint comprised of the humerus and scapula. The large knob of the humerus fits into a cup at the lower edge of the scapula. Shoulder dysplasia occurs when the cup is flatter and shallower than normal. Dysplasia can lead to lameness and the need for surgical intervention. Shoulder arthritis is typically either a result of infection or of osteochondrosis dessicans. Septic or infectious arthritis in healthy adult horses usually develops rapidly, creating significant lameness, after receiving a puncture wound. Osteochondrosis dessicans is a developmental bone disease presenting abnormal transition zones between bone and cartilage. Cysts or cartilage secretions form, attach loosely, form flaps and break off into the joint. Soft tissue injuries are the most common cause of equine shoulder pain. Muscles and bones within the shoulder become inflamed or torn, causing pain. Injuries occur when the leg is behind the horse and the shoulder joint is trying to flex to bring it forward. Travelling uphill, moving on slippery ground or wearing ill-fitting shoes without appropriate traction pose the greatest risks for shoulder injuries. Harnessed horses pulling weight are in jeopardy of shoulder injury over than those ridden.
Diagnosis and Treatment
Proper diagnosis is essential to recovery. It is vital to remember there are instances where symptoms can be confused with the injury site. Misdiagnosis can lead to further, more serious injury. An equine sports therapist locates the underlying pain source and employs a series of massage strokes as relief.