Pastern Arthritis / High Ringbone

Pastern arthritis, commonly known as high ringbone, is a degenerative joint condition affecting the proximal interphalangeal joint located between the long pastern bone (first phalanx) and the short pastern bone (second phalanx) in horses. This condition is characterized by progressive destruction of the articular cartilage surfaces, formation of new bone around the joint margins, and eventual loss of normal joint function. The term ringbone derives from the characteristic ring of new bone formation that develops around the affected joint as the disease progresses. High ringbone specifically affects the pastern joint, distinguishing it from low ringbone which affects the coffin joint lower in the foot.

Pastern arthritis occurs with significant frequency in the equine population, affecting horses across all breeds and disciplines though certain groups face elevated risk. The condition most commonly develops in mature working horses subjected to repetitive concussive forces and joint stress over years of athletic use. Horses with conformational predispositions, particularly those with upright pasterns, toed-out or toed-in stance, or asymmetric hooves, experience accelerated wear on the pastern joint surfaces. Both front and hind limbs can be affected, though front limb involvement is more common due to the higher percentage of body weight borne by the forelimbs.

The impact of high ringbone on equine health and performance ranges from mild stiffness to severe, career-ending lameness depending on disease progression and the demands placed on the horse. Early cases may present as intermittent lameness that improves with rest and anti-inflammatory medication. As cartilage damage progresses and new bone formation increases, lameness becomes more consistent and severe. The joint gradually loses range of motion as periarticular bone proliferation encircles the joint capsule. Eventually, the diseased joint may naturally fuse, which paradoxically can resolve lameness by eliminating painful joint motion once fusion is complete.

Treatment options for pastern arthritis range from conservative medical management to surgical joint fusion, with approach determined by disease severity, horse's intended use, and owner goals. Early cases often respond well to anti-inflammatory medications, intra-articular therapies, and management modifications that reduce joint stress. Advanced cases may benefit from surgical arthrodesis (fusion) which accelerates the natural fusion process and resolves pain by eliminating motion at the diseased joint. Early detection and intervention provide the best opportunity to slow disease progression and maintain comfort and function for extended periods.

The primary causes of pastern arthritis include repetitive biomechanical stress, direct traumatic injury, and abnormal loading patterns that exceed the joint's capacity for maintenance and repair. The pastern joint experiences tremendous forces during locomotion as it absorbs concussion from impact with the ground and manages the transition of forces between the limb and the hoof. Years of repetitive loading cycles create cumulative wear on articular cartilage surfaces that eventually exceeds the tissue's regenerative capacity. Direct trauma from kicks, striking obstacles, or interference injuries can initiate acute joint damage that progresses to chronic arthritis. Abnormal limb mechanics due to conformational defects or improper trimming and shoeing concentrate stress on specific joint regions, accelerating localized cartilage degeneration.

Genetic and conformational predisposition plays a substantial role in pastern arthritis development, with certain structural characteristics increasing joint stress and wear patterns. Horses with upright pastern conformation experience increased concussive forces through the joint due to reduced shock absorption compared to horses with more sloped pasterns. Toed-out or toed-in stance creates asymmetric loading that concentrates stress on one side of the joint, leading to accelerated regional cartilage wear. Horses with mismatched hoof angles between front and rear, or between left and right limbs, experience altered biomechanics that may predispose to joint disease. While specific genes have not been identified, familial patterns of ringbone suggest heritable conformational traits contribute to susceptibility.

Environmental and management factors significantly influence pastern arthritis development and progression through their effects on joint loading and recovery. Working on hard surfaces dramatically increases concussive forces transmitted through the pastern joint, accelerating cartilage wear compared to softer footing. Improper or neglected hoof care allows imbalances to develop that alter joint mechanics and stress distribution. Inadequate conditioning before demanding work subjects unprepared joint tissues to forces they cannot tolerate. Working horses when lame accelerates joint damage by forcing abnormal weight distribution onto affected structures. Obesity increases mechanical loading on all weight-bearing joints throughout the horse's life.

Risk factors for pastern arthritis development include age, athletic use intensity, conformational characteristics, and hoof care quality. Older horses with decades of accumulated joint stress face highest risk, though young horses with poor conformation or experiencing traumatic injury can develop the condition. High-level athletic use, particularly in disciplines involving repetitive jumping, hard stops, or high-speed work on firm surfaces, increases risk. Poor or inconsistent farriery that allows hoof imbalances to develop or persist contributes substantially to abnormal joint loading. Previous pastern joint injury, even if apparently healed, may initiate degenerative changes that progress over time.

The pathophysiology of high ringbone begins with cartilage damage that triggers inflammatory cascades and aberrant repair responses within the joint. Healthy articular cartilage provides a smooth, nearly frictionless surface that distributes loads across the joint. When cartilage becomes damaged through trauma or wear, the damaged tissue releases enzymes and inflammatory mediators that degrade surrounding healthy cartilage. The body's repair attempt involves new bone formation around joint margins, creating osteophytes that gradually encircle the joint. Subchondral bone beneath damaged cartilage becomes sclerotic and remodeled. Progressive cartilage loss leads to bone-on-bone contact, causing severe pain until natural or surgical fusion eliminates motion at the diseased joint.

Early warning signs of pastern arthritis are often subtle and may be attributed to minor stiffness or routine soreness rather than developing joint disease. Horses may demonstrate mild lameness that improves significantly with warm-up, reflecting the characteristic pattern of osteoarthritis where joints are stiffest after rest. Owners might notice slight hesitation or shortening of stride that is not consistently present. Some horses show mild reluctance to engage in activities requiring significant pastern flexion, such as walking downhill or transitioning between gaits. Behavioral changes including mild resistance to work or subtle changes in attitude may indicate developing discomfort. Because horses naturally hide pain, these early indicators frequently go unrecognized until more obvious symptoms develop.

Common symptoms of established pastern arthritis include moderate to severe lameness that typically worsens with exercise rather than improving with warm-up as occurs in early stages. The lameness often presents as a shortened, choppy stride with reduced flexion of the affected limb during the swing phase. Horses commonly demonstrate reluctance to flex the pastern fully when walking downhill or stepping over obstacles. Weight shifting when standing, favoring the unaffected limbs, indicates chronic discomfort. The degree of lameness may fluctuate with weather changes, exercise intensity, and medication use, but generally follows a progressive course worsening over months to years.

Behavioral changes accompanying pastern arthritis provide important diagnostic information for observant handlers. Affected horses may resist having the affected hoof lifted for cleaning or farrier work due to the forced pastern flexion this requires. Changes in stance including resting the affected limb more frequently or standing with unusual limb positioning suggest chronic discomfort. Reluctance to roll or lie down may develop as getting up requires significant pastern extension. General irritability, decreased willingness to work, and depression can result from ongoing pain. Some horses develop compensatory gait abnormalities attempting to minimize painful pastern motion.

Physical signs detectable on examination include visible swelling around the pastern joint that creates the characteristic ring-shaped appearance for which ringbone is named. Palpation reveals firm, bony enlargement around the joint margins rather than the soft tissue swelling of acute injury. Heat over the pastern region may be detectable, particularly during active inflammatory episodes. Reduced range of motion is often apparent when the pastern is manually flexed and extended. Pain responses to direct palpation over the affected joint and positive flexion tests help localize the problem. Crepitus or grinding sensations during joint manipulation suggest advanced cartilage damage with bone-on-bone contact.

Symptom progression in untreated pastern arthritis follows a generally worsening trajectory over months to years, though some horses experience periods of relative stability. Early intermittent lameness gradually becomes more consistent and severe as cartilage damage progresses. Visible bony enlargement around the joint increases as osteophyte formation continues. Range of motion progressively decreases as periarticular new bone encircles the joint capsule. Interestingly, some horses experience improvement in lameness if the joint proceeds to complete fusion, which eliminates painful motion by creating a solid bone bridge across the joint. The timeline for natural fusion is highly variable, often taking years if it occurs at all.

Emergency symptoms requiring immediate veterinary attention are uncommon with pastern arthritis but can occur in certain circumstances. Sudden severe lameness with acute swelling may indicate pathologic fracture through weakened bone or acute ligament injury superimposed on chronic joint disease. Signs of infection including fever, severe swelling, drainage, or systemic illness suggest possible septic arthritis that requires urgent treatment. Horses exhibiting extreme pain, refusing to bear weight, or demonstrating abnormal limb positioning should receive prompt veterinary evaluation. Any acute deterioration in a horse with known pastern arthritis warrants professional assessment to rule out complications requiring specific intervention.

Physical examination for suspected pastern arthritis begins with comprehensive lameness evaluation by a licensed equine veterinarian experienced in lower limb pathology. The examination includes observation of the horse at walk and trot on firm surfaces, circles in both directions, and evaluation of response to flexion tests. Palpation of the pastern region assesses for bony enlargement, heat, and pain responses to direct pressure over the joint. The veterinarian evaluates hoof balance, limb conformation, and any asymmetries that might contribute to abnormal joint loading. Comparison between affected and unaffected limbs helps characterize the degree of pathologic change. Hoof tester examination rules out concurrent foot problems that might compound or mimic pastern arthritis.

Diagnostic imaging, particularly radiography, provides definitive diagnosis of pastern arthritis and characterizes disease severity. Standard radiographic projections of the pastern region reveal characteristic changes including joint space narrowing, subchondral bone sclerosis, osteophyte formation at joint margins, and periarticular new bone production. Multiple views including lateral, dorsopalmar, and oblique projections ensure complete evaluation of all joint surfaces. Radiographs help determine disease stage, which guides treatment planning and prognostic discussions. Serial radiographs over time can document disease progression or response to treatment. The extent of radiographic changes often correlates with clinical severity, though exceptions occur.

Advanced diagnostic imaging provides additional information in selected cases where standard radiographs are insufficient or when evaluating treatment options. Nuclear scintigraphy (bone scan) can identify active bone remodeling before radiographic changes become apparent and may help identify additional affected sites. Computed tomography provides superior bone detail for surgical planning when arthrodesis is considered. Magnetic resonance imaging offers excellent soft tissue visualization that may identify concurrent ligament or tendon pathology. Ultrasound examination can evaluate periarticular soft tissue structures and identify joint effusion. Diagnostic anesthesia, blocking the pastern region to confirm the location of pain, may be performed before advanced imaging to ensure the pastern joint is the primary pain source.

Differential diagnosis for pastern region lameness includes numerous conditions affecting this anatomically complex area. Low ringbone affecting the coffin joint may be confused with high ringbone and requires careful radiographic differentiation. Pastern fractures, including chip fractures and stress fractures, can produce similar clinical presentations. Soft tissue injuries including pastern ligament strains and digital sheath pathology cause pastern region lameness without bony changes. Osselets affecting the fetlock region may produce lameness mistaken for pastern joint disease. Chronic heel pain from navicular syndrome or related conditions can create gait abnormalities resembling pastern arthritis. Thorough diagnostic evaluation ensures accurate diagnosis and appropriate treatment selection.

Emergency treatment is rarely required for pastern arthritis given its chronic progressive nature, but acute flare-ups may need immediate management. When significant lameness develops suddenly or known cases experience dramatic worsening, immediate rest and anti-inflammatory medication help control pain and inflammation. Cold therapy applied to the pastern region reduces swelling and provides comfort during acute episodes. Protective bandaging may provide support and limit motion during painful periods. The horse should be confined to minimize weight-bearing stress while awaiting veterinary evaluation to rule out acute complications such as pathologic fracture or infection superimposed on chronic disease.

Medical management forms the mainstay of treatment for most horses with pastern arthritis, particularly in early to moderate disease stages. Systemic non-steroidal anti-inflammatory medications including phenylbutazone, firocoxib, and flunixin meglumine help control pain and inflammation. Intra-articular corticosteroid injections provide targeted anti-inflammatory effect that may slow disease progression and significantly improve comfort for weeks to months. Hyaluronic acid injections support joint health and may provide additional benefit alongside corticosteroids. Polysulfated glycosaminoglycan injections administered intramuscularly or intra-articularly support cartilage health. Corrective farriery addressing any hoof imbalances reduces abnormal joint stress and may slow progression.

Surgical treatment through arthrodesis (joint fusion) becomes indicated for horses with advanced disease that no longer responds adequately to medical management. Surgical fusion accelerates the natural fusion process by debriding remaining cartilage and stimulating bone healing across the joint. Various surgical techniques exist including drilling across the joint to promote fusion, plate fixation for rigid stabilization, or combinations of approaches. The pastern joint tolerates fusion better than more mobile joints because normal gait requires only limited motion at this level. Surgical fusion eliminates pain by eliminating motion, though recovery requires several months of strict rest followed by gradual rehabilitation.

Supportive care during treatment encompasses multiple aspects of comprehensive case management. Controlled exercise programs appropriate to disease stage and treatment approach help maintain fitness without exceeding joint tolerance. Therapeutic shoeing modifications including rocker-toe shoes or shoes with enhanced heel support may improve comfort and facilitate movement. Physical therapy modalities including therapeutic ultrasound and cold laser therapy may provide additional symptom relief. Nutritional support through joint supplements containing glucosamine, chondroitin sulfate, and omega-3 fatty acids supports cartilage health. Weight management prevents excess loading on affected joints.

Rehabilitation following surgical arthrodesis requires patience and strict adherence to veterinarian-prescribed protocols over several months. Initial strict stall rest typically spans eight to twelve weeks while bone healing occurs across the fused joint. Serial radiographs monitor fusion progress and guide rehabilitation advancement. Hand-walking begins once early fusion is confirmed, gradually increasing in duration. Small paddock turnout follows, with progression to larger areas as fusion matures. Return to work typically requires four to six months post-surgery, with full soundness sometimes requiring a year or longer. Some horses return to athletic careers following successful fusion, while others are suitable only for lighter work.

Treatment decision factors influencing therapeutic approach include disease severity, horse's intended use, age, response to medical management, and owner goals and resources. Early disease generally responds well to medical management combined with appropriate farriery and exercise modifications. Advanced disease with significant bony changes may require surgical fusion for satisfactory outcomes. Young sport horses with severe disease may benefit most from early surgical intervention to enable return to athletic careers. Older pleasure horses may be managed comfortably with ongoing medical therapy without pursuing surgery. Financial considerations including surgical costs, extended rehabilitation, and uncertain outcomes influence many owner decisions.

Recovery timeline for pastern arthritis depends significantly on treatment approach, with medical management providing ongoing symptom control and surgical fusion requiring extended healing periods. Horses managed medically may show improvement within days to weeks of initiating treatment, though underlying disease continues to progress despite symptom relief. Individual responses to intra-articular therapy vary substantially, with some horses experiencing months of improved comfort after single injections while others require frequent treatment. Surgical arthrodesis typically requires four to six months minimum before return to work, with complete bone healing and adaptation sometimes requiring a year or longer.

Post-treatment care and monitoring requirements differ based on treatment approach and individual response. Medical management necessitates ongoing monitoring for treatment response, medication adjustments, and disease progression. Regular veterinary examinations, typically every three to six months for actively managed cases, assess current status and guide therapy modifications. Horses following surgical arthrodesis require strict adherence to prescribed rest periods and serial radiographic evaluation to monitor fusion progress. Daily observation for changes in lameness, swelling, or behavior enables early detection of problems requiring intervention. Maintenance of proper hoof balance through regular farriery supports treatment success regardless of approach.

Prognosis factors influencing outcomes include disease severity at treatment initiation, presence of concurrent pathology, treatment approach selection, and intended use level. Early-stage disease treated with appropriate medical management may remain controlled for years, allowing continued athletic use. Advanced disease with extensive bony changes carries more guarded prognosis, though surgical fusion can provide excellent outcomes when successful. Horses with concurrent conditions affecting other limbs may struggle with rehabilitation as they cannot effectively rest the surgically treated limb. Horses intended to return to high-level competition face more challenging recovery than those destined for pleasure use.

Long-term soundness outlook varies considerably based on individual circumstances and treatment success. Many horses with appropriately managed pastern arthritis continue working for years with ongoing maintenance therapy. Surgical fusion, when successful, can restore excellent soundness for continued athletic careers, though the fused joint creates subtle gait alterations. Some horses require progressive activity modifications as disease advances despite treatment. Natural fusion occurring without surgery occasionally produces satisfactory soundness, though the process is unpredictable and prolonged. Horses unable to achieve comfortable working soundness can often live comfortably as retired pasture companions with appropriate management.

Management practices designed to prevent pastern arthritis focus on reducing cumulative joint stress while maintaining musculoskeletal health throughout the horse's life. Implementing appropriate warm-up routines before demanding exercise prepares joint tissues for loading. Varying work surfaces to avoid exclusive use of hard footing reduces repetitive concussive stress. Limiting training intensity and duration to levels appropriate for the horse's current fitness prevents overloading unprepared tissues. Allowing adequate rest and recovery time between demanding work sessions supports tissue maintenance and repair. Monitoring horses for early signs of pastern discomfort enables intervention before significant damage accumulates.

Nutritional prevention strategies support joint health through appropriate dietary management and targeted supplementation. Maintaining ideal body condition prevents excess mechanical loading on weight-bearing joints throughout life. Providing balanced nutrition with adequate vitamins and minerals supports normal tissue maintenance. Joint supplements containing glucosamine, chondroitin sulfate, and omega-3 fatty acids may provide protective effects, though scientific evidence remains mixed. Ensuring adequate high-quality forage forms the dietary foundation that supports overall health including musculoskeletal wellness. Avoiding nutritional deficiencies that might impair tissue repair capacity helps maintain joint resilience.

Exercise and conditioning programs designed to develop balanced musculoskeletal support help protect the pastern joint from excessive stress. Progressive conditioning allows gradual adaptation of joint tissues to increasing demands rather than sudden overload. Varied exercise including walking, trotting, and cantering on different footings develops well-rounded tissue strength. Core strengthening through hillwork and ground exercises improves overall body mechanics that affect lower limb loading. Avoiding repetitive patterns that concentrate stress on specific structures helps prevent wear patterns. Maintaining fitness during rest periods prevents deconditioning that leaves tissues vulnerable when work resumes.

Environmental factors significantly influence pastern joint stress, with footing quality representing a particularly important modifiable variable. Working on well-maintained arena surfaces with appropriate cushion reduces concussive loading compared to hard packed surfaces. Avoiding frozen ground, which provides no shock absorption, protects lower limb joints. Ensuring turnout areas are free of holes and hazards prevents traumatic injuries that can initiate arthritis. Providing adequate shelter and dry footing in living areas supports hoof and lower limb health. Attention to environmental conditions that affect joint stress helps preserve joint health over time.

Regular professional hoof care represents perhaps the most important preventive measure for pastern arthritis by maintaining proper limb mechanics and force distribution. Consistent farriery every six to eight weeks prevents hoof imbalances from developing. Addressing any conformational abnormalities through appropriate trimming and shoeing minimizes asymmetric joint loading. Maintaining appropriate hoof-pastern axis alignment reduces stress concentration at the pastern joint. Regular farrier communication ensures hoof care goals align with the horse's athletic use and any developing concerns. Documentation of hoof measurements over time enables early detection of changes that might affect joint health.

Daily management adjustments for horses living with pastern arthritis require thoughtful attention to minimize joint stress while maintaining appropriate activity and quality of life. Morning routines should allow extra time for stiff joints to loosen before demanding activities. Observing horses during daily activities for changes in gait, stance, or behavior provides early warning of worsening symptoms requiring intervention. Consistent medication schedules for horses on ongoing anti-inflammatory therapy maintain steady symptom control. Regular monitoring of hoof balance between farrier visits helps detect developing imbalances early. Daily inspection of affected pasterns for changes in swelling or heat enables prompt response to flare-ups.

Housing and turnout considerations balance the benefits of movement with protection from reinjury or symptom exacerbation. Consistent turnout on safe, level footing supports joint health through natural low-impact movement. Avoiding turnout situations with significant hill terrain reduces painful pastern loading during up and downhill travel. Providing shelter allows horses to escape weather extremes that often affect arthritic joint comfort. Appropriate stall footing with adequate bedding depth reduces standing stress on affected joints. For horses with significant disease, turnout companions should be carefully selected to avoid rough play that might stress painful joints.

Exercise modifications for horses with pastern arthritis typically involve reduced intensity and careful attention to footing and terrain. Working on soft, consistent arena surfaces reduces concussive loading compared to varied outdoor footing. Avoiding work on hard or frozen ground protects affected joints from excessive impact. Reducing jumping demands, either by lowering heights or eliminating jumping entirely, significantly decreases pastern stress in sport horses. Trail riding on relatively level terrain may remain comfortable when arena work becomes problematic. Consistent light work often maintains better soundness than alternating extended rest periods with demanding exercise sessions.

Monitoring and ongoing care protocols help maintain optimal comfort and detect disease progression requiring treatment adjustments. Regular veterinary examinations every six to twelve months for horses with managed pastern arthritis assess current status and treatment effectiveness. Owner monitoring should include daily attention to lameness severity, pastern region changes, and response to current management. Documentation of symptom patterns including relationship to weather, exercise, and medication helps optimize treatment protocols. Periodic radiographic evaluation may be recommended to assess disease progression and guide prognosis discussions. Maintenance farriery every six weeks ensures continued optimal hoof balance.

Quality of life and use considerations guide realistic expectations and humane decision-making for horses with pastern arthritis. Many horses with well-managed disease enjoy comfortable lives with appropriate activity modifications, maintaining soundness for pleasure riding or light work. Some horses compete successfully at reduced levels with careful management and owner acceptance of limitations. Retirement from athletic careers becomes appropriate when joint damage precludes comfortable work at any level. Pasture soundness, allowing comfortable turnout without work demands, provides acceptable quality of life for many horses whose joints cannot tolerate ridden exercise. Regular assessment of individual comfort ensures management decisions prioritize equine welfare above human ambitions or expectations.

High-risk breeds for pastern arthritis include those commonly used in disciplines that place significant stress on the lower limb joints and those with conformational characteristics predisposing to abnormal pastern loading. Quarter Horses and Paint Horses engaged in Western performance disciplines including reining, cutting, and barrel racing experience high pastern stress from athletic demands involving rapid stops and directional changes. Thoroughbreds and Warmbloods used in jumping disciplines face repetitive loading cycles during takeoff and landing that accumulate over competitive careers. Standardbred harness racers experience significant pastern stress from pacing or trotting at speed. Draft breeds face high loads due to their substantial body weight, though their typically slower work may provide some protection. Any breed with conformational tendencies toward upright pasterns faces elevated risk due to reduced shock absorption.

Use and discipline considerations significantly influence pastern arthritis risk regardless of breed. Jumping disciplines including show jumping, eventing, and hunter competition create high pastern loads during takeoff and landing phases. Reining and cutting horses experience extreme lower limb stress during sliding stops, spins, and rapid directional changes. Barrel racing combines speed, tight turns, and uneven footing in a combination that stresses pastern joints significantly. Dressage horses performing collected work experience sustained lower limb engagement that accumulates over training years. Even pleasure horses can develop pastern arthritis if worked extensively on hard surfaces or without attention to proper hoof care and conditioning. Trail horses navigating uneven terrain face variable loading patterns that may stress pastern joints.

Conformational evaluation and breeding recommendations can help reduce pastern arthritis incidence in predisposed populations. Selecting breeding stock with moderate pastern angles that provide adequate shock absorption while maintaining strength reduces offspring risk. Avoiding breeding horses with extremely upright pasterns, significant offset (toed-in or toed-out) stance, or limb asymmetries helps prevent transmission of high-risk conformation. Pre-purchase examinations should carefully evaluate pastern conformation and any existing radiographic changes that might indicate developing or established disease. Early identification of conformational risk factors enables proactive management including appropriate farriery and activity selection that may help prevent clinical disease development.

Commonly co-occurring conditions with pastern arthritis reflect the biomechanical relationships between structures in the lower limb and shared risk factors for degenerative disease. Low ringbone affecting the coffin joint frequently develops alongside high ringbone, as both conditions share similar causative factors and conformational predispositions. Navicular syndrome and related heel pain conditions may coexist with pastern arthritis, particularly in horses with upright conformation affecting both areas. Fetlock osteoarthritis often develops in the same horses affected by pastern arthritis due to shared loading patterns and systemic factors. Suspensory ligament desmitis may occur in horses overloading soft tissue structures while protecting arthritic joints. Hoof imbalances contributing to pastern arthritis often affect multiple lower limb structures simultaneously.

Conditions with similar symptoms requiring differentiation from pastern arthritis include various causes of lower limb lameness that may produce comparable clinical presentations. Low ringbone causes similar bony enlargement and lameness but affects the coffin joint rather than the pastern joint, requiring careful radiographic differentiation. Pastern fractures including stress fractures and chip fractures can cause pastern region lameness with different treatment implications. Soft tissue injuries affecting the pastern region including ligament strains and tenosynovitis may mimic early pastern arthritis before bony changes develop. Foot problems including abscesses, bruises, and navicular disease can cause lameness that might be confused with pastern joint pathology. Thorough diagnostic evaluation by an experienced equine veterinarian ensures accurate diagnosis.

Potential complications of pastern arthritis and its treatment include both disease progression and treatment-related risks. Pathologic fracture through weakened, remodeled bone represents a rare but serious complication of advanced disease. Progressive lameness despite treatment occurs when disease continues to worsen beyond the capacity of medical management to control symptoms. Complications of surgical arthrodesis, though relatively uncommon, may include infection, implant failure, or incomplete fusion requiring revision surgery. Contralateral limb problems may develop as horses chronically overload the opposite limb to protect the affected pastern. Secondary behavioral and welfare concerns arise when chronic pain from advanced disease is inadequately controlled.