Equine Foot Disorders

Overview of Disorders of the Foot: The foot is a primary source of equine lameness, with conditions affecting both the internal bony/soft tissue structures and the hoof capsule itself. Internal disorders include navicular syndrome and distal phalanx fractures, while external hoof conditions include laminitis, canker, and hoof wall cracks.

Bruising of the Hoof Capsule

This condition involves the rupture of local capillaries resulting in tissue discoloration without a break in the epidermal tissue, often caused by blunt trauma or shear forces. Bruising in the angle of the sole is specifically referred to as "corns," while those in the sole are generally called "stone bruises". Because hemorrhage stays red and only becomes visible as the horn grows out, sensitivity to hoof testers is the primary indicator of an active problem. Treatment focuses on removing the inciting cause, rest, NSAIDs, and protective shoeing if the condition is recurrent due to thin soles or poor conformation.

Canker

A proliferative pododermatitic condition of the hoof characterized by abnormal, white, "crabmeat-like" horn that bleeds easily. It typically originates in the frog’s sulci and can rapidly spread to the sole, heel bulbs, and hoof wall. While its exact etiology is unknown, anaerobic bacteria and bovine papillomavirus are suspected agents. Successful management generally requires a combination of surgical debridement, chemical treatments (such as chlorine dioxide soaks), and topical medications like metronidazole or oxytetracycline.

Collateral Ligament (CL) Desmopathy of the DIP Joint

This is a common cause of lameness isolated to the foot, often resulting from injuries sustained during the stance phase of movement in a circle. Because most collateral ligaments lie deep to the hoof capsule, clinical signs are often non-specific and require advanced imaging for diagnosis. MRI is the gold standard for identification because radiography and ultrasonography have limited sensitivity for distal lesions. Treatment focuses on rest and potentially specialized shoeing with a wider branch on the injured side to reduce ligament strain.

Fractures of the Distal Phalanx

These common fractures of the third phalanx (pedal bone) result from concussive injury or direct trauma, such as kicking a wall. Horses typically show sensitivity to hoof testers, and lameness can be localized using palmar digital nerve blocks. Nonarticular fractures are managed conservatively with approximately six months of rest and hoof support (bar shoes or foot casts) to prevent expansion. Articular fractures involving the coffin joint generally have better outcomes with surgical lag screw fixation, though comminuted articular fractures carry a grave prognosis.

Fractures of the Navicular Bone

This condition is less frequent than pedal bone fractures and is usually secondary to concussive injury or pre-existing navicular degeneration. Diagnosis is primarily radiographic, though sulci must be packed with modeling compound to avoid gas artifacts that mimic fracture lines. Conservative treatment with heel elevation may be attempted, but many horses fail to improve, often resulting in a fibrous union. Surgical repair via lag screw is possible but requires advanced three-dimensional imaging like CT or MRI for planning.

Heel Bulb Lacerations

These injuries result from overreaching or contact with sharp objects and range from superficial skin breaks to deep wounds affecting bone or synovial structures. Thorough probing and synovial centesis are required to check for sepsis in the coffin joint, navicular bursa, or digital flexor tendon sheath. Because excessive skin motion in the heels can lead to slow healing and proud flesh, a foot cast is recommended for 2–3 weeks for all full-thickness lacerations.

Hoof Abscesses

Identified as the most common cause of acute, non-weight-bearing lameness, abscesses are focal accumulations of purulent exudate between the germinal and keratinized epithelium. Bacteria enter through defects like microcracks or white line separation, often exacerbated by environmental moisture changes. The primary treatment goal is establishing ventral drainage with a small hole, followed by bandaging with a medicated poultice. Recurrent abscesses in the same location warrant imaging to rule out underlying causes like keratomas or sequestra.

Hoof Cracks

Fissures in the hoof wall can be horizontal or vertical and are classified by their location, depth, and length. Vertical cracks are most common and usually result from hoof imbalances, conformational abnormalities, or poor wall quality. While partial-thickness cracks are often cosmetic, full-thickness cracks can cause instability and infection, necessitating debridement and stabilization. Correcting underlying hoof balance is essential for long-term management and efficient healing.

Hoof Imbalance

Imbalance can occur in the sagittal (front-to-back) or medial-to-lateral planes and often results from poor conformation or improper trimming and shoeing. Sagittal imbalances include "broken-forward" (upright/clubfoot) and "broken-back" (long-toe/low-heel) configurations. Diagnosis involves physical evaluation and weight-bearing radiographs (dorsopalmar and lateromedial views). While many imbalances can be corrected through farriery, drastic changes in sound horses can inadvertently induce lameness.

Keratomas

A benign epithelial tumor of the hoof capsule that can take cylindrical or spherical forms, potentially causing lysis of the underlying coffin bone. They often present as a change in the contour of the white line and are frequently associated with a history of recurrent foot abscesses in the same location. Radiography often shows a well-demarcated area of bony resorption. Surgical removal is the preferred treatment if the tumor causes lameness or persistent infection.

Laminitis

This catastrophic disease involves inflammation and separation of the hoof laminae, often caused by carbohydrate overload, endotoxemia, or endocrine dysfunction (PPID/EMS). The hallmark clinical signs are severe lameness, bounding digital pulses, and a typical posture where weight is shifted to the hindlimbs. Management is multifaceted, focusing on cryotherapy (most effective early), NSAIDs, supportive footing (dental impression material), and corrective farriery. The prognosis is guarded to poor if the coffin bone rotates or sinks.

Navicular Syndrome

A degenerative disease complex affecting the navicular bone, bursa, ligaments, or the deep digital flexor tendon. It is a leading cause of bilateral forelimb lameness in middle-aged horses, characterized by a shortened stride and stumbling. Diagnosis is typically supported by improvement after a palmar digital nerve block and imaging evidence of medullary sclerosis or vascular channel enlargement. Treatment is palliative and lifelong, involving corrective farriery (rolled toes), bisphosphonates, and intra-articular medications.

Osseous Cystlike Lesions (OCLLs) in the Distal Phalanx

These subchondral bone lesions are developmental in young horses and traumatic in older ones, primarily affecting the forefeet. They can be clinically silent or cause lameness that improves with nerve or joint blocks. While visible on radiographs, a rim of sclerosis is often present, and advanced imaging (CT/MRI) may be required for subtle cases. Treatment options include joint medication, surgical debridement, or packing the cysts with bone grafts or biologics.

Osteoarthritis of the DIP (Coffin) Joint

This condition can cause a range of signs from poor performance and shortened strides to severe lameness, often affecting the forelimbs. Physical signs may include joint effusion or dorsal fibrosis proximal to the coronary band. Diagnosis is confirmed by localizing pain via intra-articular anesthesia and radiographic evidence of bone proliferation at the joint margin. Management involves systemic NSAIDs, chondroprotectants, and intra-articular injections of steroids or biologics.

Pedal Osteitis

This is an inflammation of the distal phalanx thought to result from excessive concussive forces, particularly in horses with thin soles. Radiographic evaluation typically reveals loss of mineral at the solar margin or enlarged vascular channels. Because these radiographic changes may persist after lameness has resolved, advanced imaging like MRI or nuclear scintigraphy can help identify an active inflammatory process. Treatment includes rest, systemic NSAIDs, and protective shoeing.

Puncture Wounds of the Foot

These result from stepping on sharp objects and can infect various deep structures, including the coffin joint, navicular bursa, or digital flexor tendon sheath. It is critical to leave the object in the foot for radiography, if possible, to accurately determine the trajectory and structures involved. Treatment requires tetanus prophylaxis, ventral drainage, and systemic/local broad-spectrum antimicrobials. Prognosis is highly dependent on the depth and specific anatomical involvement.

Quittor

A chronic infection of the collateral cartilages of the foot, typically resulting from a prior wound in the area. Clinical signs include soft tissue swelling and purulent drainage over the affected cartilage. Diagnosis is confirmed via clinical signs, radiography, and contrast material injections into the tract. Treatment involves surgical debridement of the cartilage and aggressive antimicrobial therapy to prevent secondary sepsis of the nearby coffin joint.

Sequestra of the Distal Phalanx

These occur secondary to puncture wounds or deep subsolar abscesses, especially in horses with chronic laminitis. They should be suspected in any horse presenting with recurrent hoof abscesses in the same region. While identification on radiographs may require oblique views and frog sulci packing, advanced imaging (CT/MRI) is sometimes necessary. Treatment involves surgical debridement and removal, typically through the solar surface.

Sidebone

This refers to the ossification of the collateral cartilages of the distal phalanx, generally associated with concussive forces and common in heavy horses. It is rarely a primary cause of lameness and is usually an incidental finding on physical exams or radiographs. Extensive ossification can lead to a palpable lack of cartilage flexibility. Treatment is only necessary if lameness is present and involves rest, NSAIDs, and addressing hoof imbalances.

Thrush

A degenerative keratolytic condition of the frog frog's sulci thought to be caused by anaerobic bacteria. It presents with a distinct foul odor and thick black discharge from an overly soft frog. While predisposing factors include poor hygiene and lack of exercise, it can also occur in clean environments due to foot conformation. Management requires debridement of abnormal horn and applying disinfecting and hardening topical treatments.

White Line Disease

This is a progressive keratolytic condition affecting the deeper layers of the hoof wall, leading to a crumbling decomposition of the horn. It is insidious and often subclinical until cavitation is significant enough to cause wall separation or P3 displacement. Diagnosis is aided by percussion and radiographs taken in a horizontal plane to reveal radiolucent cavities. The most critical treatment aspect is the complete resection of undermined hoof wall to expose the area to air.

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