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Fractures of the Shoulder in Horses

By

Marcus J. Head

, BVetMed, Rossdales Equine Hospital and Diagnostic Centre

Last full review/revision Sep 2015 | Content last modified Oct 2015

Serious trauma can result in fracture to any part of the shoulder region. However, the main sites affected are the supraglenoid tuberosity of the scapula (which serves as the origin of the biceps brachii muscle), the mid to distal scapula, and the proximal humeral metaphysis.

Supraglenoid tuberosity fractures, if complete, invariably displace in a craniodistal direction, because of the pull of the biceps. Large fractures can be surgically repaired. However, this is not easy, because the fragments are often difficult to reduce and the implants are both difficult to place and prone to failure during recovery from anesthesia or during convalescence. Smaller fragments can be removed, but the involvement of the biceps tendon of origin has to be resected. Very large fragments can involve the joint surface. Cases usually present with severe lameness and a history of trauma (eg, a fall during jumping or collision with a fixed object). On manipulation, there is often a sense of disarticulation between the lower limb and shoulder as the biceps is disrupted. Crepitus may be felt. In most cases, because the inciting cause is significant trauma, other signs such as soft-tissue abrasions or swelling will pinpoint the shoulder as the site of pain. Radiographs will reveal the fracture, and ultrasonography can be very useful to assess the biceps tendon. Management varies and depends on intended use, age, size of fragment, size of horse, etc. The prognosis for restoration of normal function is guarded. The size of the fragment, degree of displacement, presence/absence of articular involvement, degree of biceps disruption, and intended use of the horse are probably the most important prognostic factors.

Mid to distal scapula fractures occur through trauma or, in racehorses, as stress fractures associated with cumulative cyclical fatigue. Trauma can result in complete or (presumably because of the flexibility of the bone, especially in foals) incomplete fractures. Radiographs rarely help, because of the difficulty in obtaining diagnostic images of the area. Ultrasonography can accurately assess the integrity of the bone surface and is the technique of choice. Scintigraphy can also detect the injuries. Comminuted fractures can occur, and the prognosis worsens with increased complexity of the fracture. Simple, nondisplaced, or minimally displaced fractures usually heal well with rest alone.

Ultrasonography can be used to monitor healing. Stress fractures are almost always incomplete and heal very well, carrying an excellent prognosis for return to training. Very rarely, scapula fractures manifest as severe, unstable, comminuted injuries necessitating euthanasia on humane grounds. The clinical appearance is key to making a decision in these circumstances; although painful, scapula fractures with a good prognosis cause no observable limb instability.

Deltoid tuberosity fractures are seen infrequently. They are usually the result of trauma, often a kick from another horse, and may involve a wound and variable amounts of infection within the injury. Lesion-oriented oblique radiographs and ultrasonography define these injuries, and affected horses usually recover fully with rest alone, although surgical debridement of infected bone may be required in rare cases.

Stress fractures affect the proximal humerus also, almost exclusively in the caudal metaphyseal region. They are an uncommon but important cause of lameness in racehorses (the craniodistal metaphysis of the humerus is also affected, see Fractures of the Shoulder in Horses). The typical history is one of sudden onset, often moderate to marked lameness closely associated with recent exercise, in an animal usually but not always in faster work. Lameness is usually transient, and the horse generally becomes sound within a short time (days to a week). If exercise resumes, lameness recurs. Localization is difficult; many are detected after the lower limb has been eliminated as the source of pain, or with scintigraphy. Radiographs can identify periosteal and endosteal new bone at the site of injury. Recovery is usually uncomplicated and complete with a few weeks’ rest. Prolonged confinement may be counterproductive, and light exercise (walking only) may be introduced surprisingly quickly once the initial painful period has subsided. The injury remains evident on radiographs long after the bone is strong enough to withstand exercise, but a gradual smoothing and resolution of the callus will be seen as remodelling proceeds. Undetected humeral stress fractures can result in failure of the bone during exercise and complete breakdown, necessitating euthanasia.

OTHER TOPICS IN THIS CHAPTER

Lameness in Horses
Overview of Lameness in Horses
The Lameness Examination in Horses
Imaging Techniques in Equine Lameness
Arthroscopy in Equine Lameness
Regional Anesthesia in Equine Lameness
Disorders of the Foot in Horses
Osseous Cyst-like Lesions in the Distal Phalanx in Horses
Bruised Sole and Corns in Horses
Canker in Horses
Fracture of Navicular Bone in Horses
Fracture of Distal Phalanx in Horses
Keratoma in Horses
Laminitis in Horses
Navicular Disease in Horses
Pedal Osteitis in Horses
Puncture Wounds of the Foot in Horses
Pyramidal Disease in Horses
Quittor in Horses
Quarter Crack in Horses
Scratches in Horses
White Line Disease in Horses
Sheared Heels in Horses
Sidebone in Horses
Thrush in Horses
Disorders of the Pastern and Fetlock
Fractures of the First and Second Phalanx in Horses
Fractures of the Proximal Sesamoid Bones in Horses
Osteoarthritis of the Proximal Interphalangeal Joint in Horses
Palmar/Plantar Metacarpal/Metatarsal Nonadaptive Bone Remodeling in Horses
Sesamoiditis in Horses
Chronic Proliferative Synovitis in Horses
Digital Sheath Tenosynovitis in Horses
Disorders of the Metacarpus in Horses
Tendinitis in Horses
Suspensory Desmitis in Horses
Inferior Check Desmitis in Horses
Bucked Shins in Horses
Exostoses of the Second and Fourth Metacarpal Bones in Horses
Fractures of the Small Metacarpal (Splint) Bones in Horses
Fracture of the Third Metacarpal (Cannon) Bone in Horses
Disorders of the Carpus in Horses
Fracture of the Carpal Bones in Horses
Subchondral Bone Disease of the Third Carpal Bone in Horses
Tearing of the Medial Palmar Intercarpal Ligament in Horses
Osteoarthritis of the Carpus in Horses
Distal Radial Exostosis and Osteochondroma of the Distal Radius in Horses
Carpal Hygroma in Horses
Rupture of the Common Digital Extensor Tendon in Horses
Disorders of the Shoulder in Horses
Developmental Diseases of the Shoulder in Horses
Fractures of the Shoulder in Horses
Bicipital Bursitis in Horses
Infection of the Shoulder in Horses
Suprascapular Neuropathy in Horses
Osteoarthritis of the Shoulder in Horses
Disorders of the Elbow in Horses
Developmental Orthopedic Disease in the Elbow of Horses
Fractures of the Elbow in Horses
Osteoarthritis of the Elbow in Horses
Collateral Ligament Injury in the Elbow of Horses
Disorders of the Metatarsus in Horses
Bucked Shins/Dorsal Cortical Fractures of the Third Metatarsal Bone in Horses
Exostoses of the Metatarsal Bones in Horses
Diaphyseal Fracture of the Third Metatarsal Bone in Horses
Incomplete Longitudinal Fractures of the Plantar Aspect of the Third Metatarsal Bone in Horses
Focal Bone Reaction and Avulsion Fractures of the Third Metatarsal Bone in Horses
Fractures of the Second and Fourth Metatarsal Bones in Horses
Enostosis-like Lesions of the Third Metatarsal Bone in Horses
Disorders of the Tarsus in Horses
Failure of Ossification of the Distal Tarsal Bones in Horses
Osteoarthritis of the Distal Tarsal Joints in Horses
Osteoarthritis of the Talocalcaneal Joint in Horses
Osteoarthritis of the Tarsocrural Joint in Horses
Synovitis/Capsulitis of the Tarsocrural Joint in Horses
Osteochondrosis of the Tarsocrural Joint in Horses
Osteitis of the Calcaneus in Horses
Fractures of the Distal Tarsal Bones in Horses
Fracture of the Talus in Horses
Fracture of the Fibular Tarsal Bone (Calcaneus) in Horses
Fracture of the Lateral Malleolus of the Tibia in Horses
Tarsal Joint Luxation in Horses
Desmitis of the Collateral Ligaments of the Tarsus in Horses
Rupture of the Fibularis (Peroneus) Tertius in Horses
Stringhalt
Curb in Horses
Disorders of the Tarsal Sheath in Horses
False Thoroughpin in Horses
Luxation of the Superficial Digital Flexor Tendon from the Tuber Calcanei in Horses
Gastrocnemius Tendinitis in Horses
Calcaneal Bursitis in Horses
Capped Hock
Disorders of the Stifle in Horses
Osteochondrosis of the Stifle in Horses
Subchondral Cystic Lesions in Horses
Meniscus and Meniscal Ligament Injuries in Horses
Cranial and Caudal Cruciate Ligament Injuries in Horses
Collateral Ligament Injuries in Horses
Intermittent Upward Fixation of the Patella and Delayed Patella Release in Horses
Fragmentation of the Patella in Horses
Patellar Luxation in Horses
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Musculoskeletal Disorders in Large Animals
A seven-year-old Quarter horse gelding presents with a 1-week history of mild lameness. During the examination, the horse raises his head as he places weight on his left forelimb and drops it when placing weight on the right forelimb. Which limb is most likely affected in this horse?
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