Equine Pastern Dermatitis: Causes, Signs & Treatments

Every horse owner knows how worrying and frustrating it is when their horse goes lame. Lameness is one of the most common health issues in horses and can have many different causes. Understanding the most common causes of lameness can help you respond appropriately and work effectively with your vet to get your horse back to work. This guide covers the main causes of lameness in horses, how to identify them, and what to do when your horse becomes lame.

What Is Lameness in Horses?

Lameness is broadly defined as any alteration in the horse’s normal gait caused by pain, mechanical restriction, or neurological dysfunction. It most commonly affects the forelimbs and can range from a barely detectable shortening of stride to an inability to bear weight on an affected leg. The degree of lameness is usually graded on a scale of 0 (sound) to 5 (non-weight-bearing), which helps to assess severity and monitor progress.

Common Causes of Lameness in Horses

Hoof Problems

A large proportion of equine lameness originates in the foot. Common hoof-related causes include:

• Laminitis: Inflammation of the laminae within the hoof capsule, which can be extremely painful and in severe cases leads to rotation or sinking of the pedal bone. It is associated with dietary causes, metabolic conditions (such as Equine Metabolic Syndrome and PPID/Cushing’s disease), and other systemic illness.
• Hoof abscess: A localised bacterial infection within the hoof, typically causing sudden, severe lameness that resolves quickly once the abscess drains. One of the most common causes of acute lameness in horses.
• Navicular disease (Palmar foot pain): A chronic condition affecting the navicular bone and associated structures in the back of the foot, causing low-grade, intermittent forelimb lameness.
• White line disease: Bacterial/fungal infection of the white line of the hoof.
• Thrush: Bacterial infection of the frog, often associated with wet or dirty conditions.

Joint Disease

• Osteoarthritis: Degenerative joint disease commonly affects older horses and those in hard work. The hock and fetlock joints are commonly affected.
• Osteochondrosis (OCD): A developmental condition affecting young horses, causing cartilage and bone abnormalities, particularly in the stifle, hock, and fetlock.

Soft Tissue Injuries

• Tendon injuries: Injury to the superficial or deep digital flexor tendons is common, particularly in sport horses. Tendon injuries can be subtle (detectable only on ultrasound) or severe (causing marked swelling and lameness).
• Ligament injuries: The suspensory ligament and its branches are commonly injured, as are the collateral ligaments of the joints.
• Muscle strains: Though less common as a primary cause of lameness, muscle soreness can affect movement and performance.

Neurological Causes

Conditions such as equine protozoal myeloencephalitis (EPM) or cervical vertebral malformation (wobbler syndrome) can cause ataxia and abnormal movement that may be confused with or accompany lameness.

What to Do When Your Horse Is Lame

If your horse is lame, rest them and call your vet. Avoid lunging or working the horse until the cause has been identified, as this can worsen many conditions. The vet will perform a lameness examination, which typically involves trot-up and flexion tests, nerve blocks (to localise the source of pain), and diagnostic imaging (X-ray, ultrasound, or MRI) as needed. Early diagnosis and appropriate management give the best chance of a full or satisfactory recovery.