Articulatio tarsi
The tarsus (hock) is a complex joint equivalent to the human ankle. It is composed of six tarsal bones (talus, calcaneus, central tarsal, third tarsal, first/second tarsal fused, and fourth tarsal) and contains four joint levels. The proximal intertarsal joint (tarsocrural) has the most motion. The calcaneus (point of hock) provides leverage for the gastrocnemius and superficial digital flexor. The tarsus is critical for propulsion and provides spring-like energy storage during movement. The reciprocal apparatus mechanically links hock and stifle so that they flex and extend together.
Origin: N/A (bone)
Insertion: N/A (bone)
Action: Critical for propulsion; provides spring-like energy storage during movement; the reciprocal apparatus mechanically links hock and stifle
Osteoarthritis of the distal tarsal joints (bone spavin) is a common cause of hindlimb lameness. Osteochondrosis of the tarsocrural joint is common in young horses. Diagnosis uses clinical examination, flexion tests, and radiographs. Relevant in evaluations of performance horses.
## Overview Bog spavin is the common term for effusion (excess synovial fluid) in the tarsocrural joint, the large uppermost joint of the hock. It appears as soft, fluctuant swellings on the front an
## Overview Osteochondritis dissecans of the hock is a developmental disease in which cartilage fails to ossify normally, most often at the distal intermediate ridge of the tibia. Young horses develo
## Overview Capped hock is distention of the subcutaneous bursa or formation of an acquired bursa over the point of the hock (tuber calcanei). It results from repetitive trauma such as kicking stall
## Overview Bone spavin is osteoarthritis (degenerative joint disease) of the distal tarsal joints, principally the distal intertarsal and tarsometatarsal joints. Repeated compression and rotation da
Chronic hock swelling or reduced hindlimb engagement should be evaluated. Correct shoeing and balanced work help manage many hock conditions.
## Overview Bog spavin is the common term for effusion (excess synovial fluid) in the tarsocrural joint, the large uppermost joint of the hock. It appears as soft, fluctuant swellings on the front and inner aspect of the hock that communicate when pressed. Lameness may be absent or mild; the swelling itself is often mainly a cosmetic concern unless an underlying joint disease is present. ## Causes Osteochondrosis or osteochondritis dissecans in young horses, osteoarthritis, trauma, poor conformation (straight or sickle hocks), and idiopathic synovitis are the main causes. Infection produces a more painful, acute form. ## Diagnosis The characteristic soft, ballotable swelling is usually diagnostic. Radiographs or ultrasound identify osteochondral fragments or other bone changes. Synovial fluid analysis rules out infection when lameness is significant. ## Treatment Idiopathic or mild cases often need only monitoring. Rest, anti-inflammatories, and corrective shoeing help when inflammation is present. Intra-articular corticosteroids or arthroscopic removal of fragments are used for more significant underlying disease. ## Recovery and Prognosis Prognosis is good when no major bone or cartilage damage exists. Chronic effusion related to poor conformation tends to recur. Cases with osteochondritis dissecans or advanced osteoarthritis have a more guarded athletic outlook. ## Prevention Selection for good hock conformation and appropriate management of young horses with osteochondrosis reduce incidence. Signs include: soft fluctuant swelling on the front and medial hock; fluid that shifts when pressed; variable or absent lameness; occasional heat
## Overview Osteochondritis dissecans of the hock is a developmental disease in which cartilage fails to ossify normally, most often at the distal intermediate ridge of the tibia. Young horses develop hock effusion (bog spavin) with or without lameness. Radiographs confirm the lesion, and arthroscopic removal has an excellent prognosis. ## Causes Disturbance of endochondral ossification during growth. ## Diagnosis Radiographs of the hock in a young horse with effusion. ## Treatment Arthroscopic fragment removal. Many horses are sound afterward and return to full athletic use. ## Recovery and Prognosis Excellent for most distal intermediate ridge lesions. ## Prevention Balanced growth management. Signs include: hock effusion (bog spavin) in a young horse; variable lameness; radiographic OCD lesion
## Overview Capped hock is distention of the subcutaneous bursa or formation of an acquired bursa over the point of the hock (tuber calcanei). It results from repetitive trauma such as kicking stall walls or trailer doors. The swelling is usually cosmetic and not associated with lameness unless infection or deeper synovial involvement occurs. ## Causes Repeated contusion or pressure is the primary cause. A single severe blow can also initiate the swelling. Penetrating wounds may introduce infection. ## Diagnosis The characteristic soft or firm enlargement exactly over the point of the hock is diagnostic. Ultrasound distinguishes simple bursal fluid from abscess or involvement of the calcaneal bursa. ## Treatment Protect the area from further trauma. Cold therapy, bandaging, and anti-inflammatories reduce acute swelling. Chronic fibrous enlargements often persist. Infected bursae require drainage and antibiotics. ## Recovery and Prognosis Prognosis for soundness is excellent when the swelling is purely subcutaneous. Cosmetic blemishes frequently remain. Septic cases have a more guarded outlook. ## Prevention Padding stall walls, using hock boots during transport, and addressing behavioral kicking reduce recurrence. Signs include: soft or firm swelling over the point of the hock; usually no lameness; heat in acute cases; possible draining tract if infected
## Overview Bone spavin is osteoarthritis (degenerative joint disease) of the distal tarsal joints, principally the distal intertarsal and tarsometatarsal joints. Repeated compression and rotation damage cartilage, narrow the joint spaces, and stimulate new bone formation. The result is progressive hind-limb lameness that is one of the most common causes of performance limitation in sport horses. ## Causes Repetitive concussion, conformational faults (straight or sickle hocks), and athletic activities that heavily load the hocks (jumping, dressage, western performance) are the main drivers. Mineral imbalances have been suggested but evidence is limited. ## Diagnosis History of gradual hind-limb lameness that may warm out of, positive flexion tests, and a characteristic “stabbing” or short stride are suggestive. Radiographs show joint-space narrowing, sclerosis, and periarticular new bone. Diagnostic analgesia of the distal tarsal joints confirms the source of pain. ## Treatment Non-steroidal anti-inflammatory drugs, intra-articular corticosteroids, corrective shoeing, and workload modification are first-line measures. Chemical or surgical arthrodesis (facilitated ankylosis) can be considered when medical management fails and the goal is pain-free fusion of the low-motion joints. ## Recovery and Prognosis Many horses remain useful with medical management. Complete fusion, whether spontaneous or surgical, can restore comfort. Advanced bilateral disease may ultimately limit athletic career length. ## Prevention Selection for good hock conformation, balanced shoeing, and sensible training progression reduce risk but cannot eliminate it in high-level athletes. Signs include: gradual hindlimb lameness; shortened stride or toe dragging; positive hock flexion test; bony enlargement on the medial lower hock in advanced cases; stiffness after rest
Osteoarthritis of the distal tarsal joints (bone spavin) is a common cause of hindlimb lameness. Osteochondrosis of the tarsocrural joint is common in young horses. Diagnosis uses clinical examination, flexion tests, and radiographs. Relevant in evaluations of performance horses.
Chronic hock swelling or reduced hindlimb engagement should be evaluated. Correct shoeing and balanced work help manage many hock conditions.
See the Tarsus (Hock) on our interactive 3D horse model. Open 3D Model