Tendons and ligaments are essential soft tissue structures that support movement and stability in the horse. Tendons are strap-like, elastic structures that connect muscles to bones, while ligaments connect bone to bone or, in certain cases, bone to tendon. Though most tendons are short and rarely injured, the long tendons of the limbs—especially the flexor tendons—are prone to injury during strenuous exercise or trauma. Ligament injuries, similarly, can result from excessive force on joints, trauma, or abnormal movement.
Flexor Tendons: Structure and Location
The flexor tendons include the superficial digital flexor tendon (SDFT) and the deep digital flexor tendon (DDFT). These tendons run down the back of the limb from the knee or hock to the foot. The SDFT attaches to the pastern, while the DDFT inserts onto the back of the pedal bone. These tendons pass through fluid-filled sheaths—such as the carpal sheath (at the knee), tarsal sheath (at the hock), and digital sheath (at the fetlock/pastern region). Annular ligaments help maintain their position in areas with high joint movement.
Tendons are composed of longitudinal bundles of fibres, but they have a poor blood supply compared to muscle, which contributes to slow healing.
Ligament Structure and Function
Ligaments provide support and alignment to joints, often running along either side—hence the term “collateral” in many ligament names. Some ligaments, such as the inferior check ligament, attach bone to tendon. Common ligament injuries in horses include:
- Suspensory ligament desmitis
- Collateral ligaments of the coffin, fetlock, and hock joints
- Palmar annular ligament of the fetlock
- Accessory (check) ligament of the deep flexor tendon
- Meniscal and cruciate ligaments of the stifle
Causes of Injury
Both tendon and ligament injuries most commonly occur due to overexertion during exercise. Risk factors include lack of fitness, fast work, jumping & movement on uneven ground. Sudden trauma—whether blunt or sharp—can also lead to bruising, rupture, or laceration. Infections involving tendon sheaths are particularly dangerous and potentially life-threatening.
Ligament injuries can also result from abnormal or excessive joint forces, such as sharp turns at speed, and may cause varying degrees of lameness or joint instability in severe cases.
Signs of Injury
Tendon and ligament injuries typically present with heat, swelling and pain. Mild sprains may not cause lameness, whilst severe injuries may lead to dropped fetlocks, toe-pointing, and difficulty walking. Ligament injuries may also present as joint instability and/or pain.
Infection in a tendon sheath (as with joint infections) will cause marked lameness even at a walk and requires immediate veterinary attention.
Diagnosis
Initial diagnosis involves a clinical examination to identify swelling, heat & and pain on palpation. However, the full extent of tendon or ligament damage cannot be determined solely by touch.
In acute cases, an ultrasound scan approximately one-week post-injury helps assess fibre damage. In more complex/chronic injuries, a full lameness investigation including nerve blocks, radiography & ultrasound may be required. For injuries within the foot an MRI is required for definitive diagnosis.
Treatment and Management
Initial treatment in the first 10–14 days is similar for both tendon and ligament injuries and includes:
- Box rest
- Ice application or cold hosing 2–3 times daily
- Bandaging to support the limb
- Anti-inflammatory drugs, such as phenylbutazone (‘Bute’), to reduce swelling and pain
The aim of this phase is to reduce inflammation and prevent further injury.
After the acute phase, a controlled exercise program is critical. Usually beginning with in-hand walking, exercise is gradually increased every 1–2 weeks over approximately three months. The specifics of a rehab programme are very individual but full recovery often requires 6–12 months for tendon injuries and 9 months or more for ligament injuries.
Controlled exercise helps newly formed tendon and ligament fibres align correctly, improving the quality and strength of the repair. Repeat ultrasound scans guide the progression of exercise and indicate when to introduce trot or canter work.
In some cases, horses may not return to full competition and might require a lower-intensity role to reduce the risk of re-injury.
Advanced Treatment Options
Though no treatment guarantees full recovery, other therapies such as stem cells or platelet rish plasma aim to enhance healing quality and reduce re-injury risk. Your vet will advise if any of these treatments are appropriate.
Shockwave Therapy
Extracorporeal shockwave therapy (ESWT) delivers focused physical shockwaves (not electrical) to stimulate healing in damaged tendons, ligaments, or bone. Typically repeated every 7–10 days for up to four sessions, ESWT can improve blood flow, reduce pain, and encourage tissue regeneration.
Surgical Options
Surgery may be indicated in specific cases such as:
- Tendon lacerations or septic tendon sheaths may require repair or debridement under general anaesthesia.
- In proximal suspensory desmitis, a lateral plantar nerve neurectomy and fasciotomy may relieve pain and improve function.
- In some cases of repeated SDFT injury, the accessory ligament may be cut to reduce tension—though this can increase the risk of suspensory ligament injury, so it is not routinely performed.
Conclusion
Tendon and ligament injuries in horses require prompt diagnosis, careful treatment, and long-term rehabilitation. While full recovery can take months and may not always result in a return to full work, modern therapies like stem cell injections, PRP, and shockwave therapy are improving outcomes. Working closely with a veterinarian and following a tailored recovery plan offers the best chance for a successful return to health.