Poor performance, subtle lameness, or changes in your horse’s way of going can be frustrating and worrying. One common but often misunderstood cause of these problems is proximal suspensory desmitis (PSD). This condition affects the suspensory ligament near its origin and can occur in either the front legs or hind legs, with important differences between the two.

Understanding how PSD presents, how it is diagnosed, and what treatment options are available can help horse owners recognise problems early and improve outcomes.

What Is the Suspensory Ligament?

The suspensory ligament is a strong structure that runs down the back of the cannon bone and plays a major role in supporting the fetlock during movement. It acts like a spring, absorbing impact and helping the horse move efficiently.

The ligament can be divided into:

• The proximal (upper) part, close to the knee or hock
• The main body
• The branches, which attach near the fetlock

Proximal suspensory desmitis refers to injury and inflammation at the top portion of the ligament, where it attaches to the cannon bone.

PSD in the Forelimbs

How It Commonly Presents

PSD in the front legs often causes:

• Sudden or intermittent lameness
• Lameness that may come and go
• Worse performance on soft ground or when circling
• ‘A feeling to the rider that “something isn’t right,” even if it’s hard to see from the ground

In some horses, both front legs may be affected, leading to a loss of action rather than obvious lameness.

There may be sensitivity when pressure is applied over the ligament.

Foot balance is very important, as poor hoof conformation can increase strain on the suspensory ligament.

Diagnosis of Forelimb PSD

Diagnosis usually involves a combination of:

• Lameness examination
• Nerve blocks to localise the source of pain
• Ultrasound, which is the most important single diagnostic tool

Ultrasound allows the veterinarian to assess:

• Enlargement of the ligament
• Changes in fibre pattern
• Areas of reduced density (damage)
• Chronic scarring or mineralisation

X-rays are often normal in early cases but may show bone changes in long-standing injuries.

Treatment and Prognosis (Forelimbs)

The outlook for front-limb PSD is generally good, especially when caught early.

Most horses respond well to:

• Strict rest initially
• Local and systemic anti-inflammatory therapy
• Local injection of Ortho-biologic (PPR or Stem Cells)
• Gradual, controlled return to exercise over several months
• Shockwave therapy
• Corrective farriery to improve foot balance

Many horses return to full work with no recurrence, provided rehabilitation is not rushed.

PSD in the Hindlimbs

How Hindlimb PSD Differs

PSD in the hind legs can be more challenging and often has a poorer long-term outlook.

Common signs include:

• Subtle or gradual onset of lameness
• Shortened stride or “toe dragging”
• Reduced hindlimb engagement
• Difficulty maintaining impulsion
• Poor performance rather than obvious lameness.

In many cases, both hind legs are affected, making the problem even harder to recognise.

Certain conformations, such as straight hocks or over-extended fetlocks, increase the risk of hindlimb PSD.

Why Hindlimb PSD Can Be More Serious

Unlike the forelimb, the hindlimb suspensory ligament sits in a tight anatomical space. When it becomes swollen, it can compress nearby nerves, contributing to ongoing pain. This is sometimes described as a “compartment-type syndrome”, which helps explain why rest alone is often less successful.

Diagnosing Hindlimb PSD

As with forelimb PSD, ultrasound is essential. X-rays may show bone changes near the ligament’s attachment, but these findings must be interpreted carefully, as similar changes can be seen in sound horses. Advanced imaging such as MRI are sometimes indicated.

Treatment Options for Hindlimb PSD

Unfortunately, hindlimb PSD is more difficult to treat, especially when it has been present for several weeks or months. Management options include the same as described for the forelimb, and in selected cases, surgical options such as fasciotomy or neurectomy may be considered, particularly when nerve compression is contributing to pain. Early diagnosis significantly improves the chances of success.

Why Early Assessment Matters

PSD often starts subtly. Many horses are initially labelled as “lazy,” “stiff,” or “not quite right,” especially when lameness is mild or bilateral. Delayed diagnosis can allow the condition to become chronic and harder to manage.

If your horse shows:

• Ongoing performance issues
• Subtle or inconsistent lameness
• Reduced impulsion or engagement
• Poor response to rest alone

A thorough lameness work-up is strongly recommended.

Final Thoughts

Proximal suspensory desmitis is a common but complex cause of lameness in sport horses. While forelimb PSD often carries a good prognosis with appropriate management, hindlimb PSD can be more challenging.

Accurate diagnosis, realistic rehabilitation timelines, and attention to hoof balance are all key factors in achieving the best possible outcome for your horse.

Best Regards,
Dr. Augie
DVM, MANZCVS (eq sport medicine)
Equine Veterinarian at Perth Equine Hospital
(08) 9479 1800
au***@*********************om.au
www.perthequinehospital.com.au

References
Dyson, S. (2000). Proximal Suspensory Desmitis in the Forelimb and the Hindlimb. Proceedings of the American Association of Equine Practitioners.
Dyson, S. (1994). Proximal suspensory desmitis in the hindlimb. British Veterinary Journal, 150, 279–291.
Dyson, S. (1998). The suspensory apparatus. In Equine Diagnostic Ultrasonography.