Also referred to as windgalls, windpuffs are palpable bumps that contain fluid and form on the the lower legs of horses. [1] They most commonly present on the sides and rear of the fetlock joint. [1]

Windpuffs develop due to the accumulation of fluid within the digital sheath, which envelops and protects both the Deep Digital Flexor Tendon (DDFT) and the Superficial Digital Flexor Tendon (SDFT). [2]

Although windpuffs are not typically associated with lameness or soreness, they may develop in conjunction with an injury. [6] It is important to investigate windpuffs for underlying causes that could affect the horse’s mobility and athletic career.

Factors that contribute to the formation of windpuffs include poor conformation, hoof imbalances, and strenuous activity on hard or deep terrain. [4] Injuries to ligaments, tendons, the fetlock joint capsule, or articular cartilage within the joint can also contribute to windpuffs. [4]

Windpuffs in Horses

Windpuffs (windgalls) are palpable lumps caused by swelling on the lower legs of horses. They may be present on one or more legs and can affect both the front and hind limbs. [1]

Although they are generally considered harmless and are often seen in perfectly sound horses, it’s important to understand their causes, symptoms, and management options.

Windpuffs can be categorized into two main types:

  • Idiopathic: Windpuffs that have an unknown cause and typically don’t cause a problem other than being a cosmetic imperfection. [6]
  • Pathologic: Windpuffs that are triggered by diseases or underlying conditions. [6]

Development of Windpuffs

Windpuffs are caused by an accumulation of fluid at the rear of the fetlock joint in the Digital Flexor Tendon Sheath (DDFTS). [3]

The DDFTS is a protective structure that houses both the Deep Digital Flexor Tendon (DDFT) and the Superficial Digital Flexor Tendon (SDFT). These tendons run along the back of the horse’s lower legs.

The DDFT is positioned close to the fetlock joint, while the SDFT is slightly higher up the leg and inserts in the mid-pastern region of both the front and hind legs.

The digital sheath surrounds both of these tendons and is lined with a synovial membrane. This membrane is responsible for producing synovial fluid, which facilitates the smooth movement of the tendons over the fetlock joint. [3]

When the tendon sheath becomes damaged or inflamed, the production of synovial fluid increases, causing the tendon sheath to swell and distend outwards. [3] Swelling can extend from the mid-cannon bone to the mid-pastern region at the back of the fetlock.

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Types of Windpuffs

Accumulated synovial fluid can produce noticeable bulges (“windpuffs”) on the sides and back of the fetlock in areas where the tendon sheath is not constrained by other structures. These swellings can take on one of two forms:

  • Articular windpuff: Characterized by an enlargement of the fetlock joint capsule [3][4]
  • Non-articular windpuff: Also referred to as a tendinous windpuff, this form involves swelling of the digital flexor tendon sheath. [4][5]

Although windpuffs may not be a sign of injury, it is common for them to develop when there is a repair process occurring in the fetlock joint. [8]

Windpuffs can manifest in a single leg, both front legs, both hind legs, or all four legs. [3]

Idiopathic Windpuffs

The most common type of windpuffs is idiopathic, meaning their underlying cause is unknown. Typically, idiopathic windpuffs occur on both sides of the tendon and are symmetrical in both hind limbs. [6]

Idiopathic windpuffs often persist chronically, meaning they affect the horse for a long period of time. However, their presence can be exacerbated following exercise due to increased stress on the tendons. [9]

Some horses may have an anatomical predisposition to forming windpuffs due to their conformation. For example, horses with club feet are prone to developing windpuffs.

Idiopathic windpuffs are not associated with lameness, as this condition is unrelated to any underlying injury.

Inflammatory Windpuffs

It’s important to distinguish between windpuffs, benign soft and cool swelling around the fetlock joint, and swelling from fetlock joint inflammation. [8] Swelling can occur in both the fetlock joint and the digital sheath simultaneously.

Inflammatory windpuffs involve swelling often accompanied by heat, pain, and potential lameness. These enlarged windpuffs could indicate an underlying injury.

An inflammatory tendinous windpuff typically affects one leg more prominently than the others. It is often accompanied by some lameness, although it may be subtle. [6]

Windpuffs and lameness can develop in conjunction with tendon injuries or ligament injuries. In particular, injuries to the digital flexor tendons or nearby ligaments can lead to windpuffs. Injuries that cause adhesions within the tendon sheath can also lead to windpuffs.

Inflammatory windpuffs can also arise due to lameness in another limb, causing increased pressure on the opposing leg due to chronic hyperextension of the fetlock joint.