Capped Hock / Calcaneal Bursitis

Capped hock, also known as calcaneal bursitis, is a common condition in horses characterized by swelling at the point of the hock caused by inflammation of the subcutaneous bursa overlying the calcaneus bone. This superficial bursa serves as a protective cushion between the prominent tuber calcanei (point of hock) and the overlying skin, reducing friction and absorbing impact during normal movement. When this bursa becomes inflamed through trauma, it distends with fluid and creates the characteristic rounded swelling that gives capped hock its descriptive name, altering the normal sharp contour of the hock point.

Capped hock affects horses of all breeds, ages, and disciplines, though its prevalence is strongly influenced by housing conditions, individual behavior, and management practices. The condition is encountered frequently in equine practice, and most horse owners with extensive experience will encounter horses with visible hock enlargement from current or previous capped hock episodes. Certain populations face elevated risk, including horses that kick stall walls, horses housed on inadequate bedding, and horses transported in trailers where they may contact walls or partitions.

The clinical significance of capped hock is primarily cosmetic rather than functional in most cases. The affected bursa lies superficial to rather than within the hock joint, meaning that uncomplicated capped hock does not directly impair joint function or cause lameness. Horses with even substantial capped hock swelling typically continue normal activities without apparent discomfort or movement restriction. However, the visible blemish at this prominent location concerns many owners, particularly those with show horses where conformation judging or visual presentation matters. Large swellings may also interfere with boot or bandage fit in the hock region.

Prognosis for capped hock is generally favorable for maintaining soundness and function, though cosmetic outcomes depend considerably on the chronicity of the condition and success of preventive measures. Early intervention addressing the traumatic cause often allows significant improvement, while chronic cases with established fibrous tissue typically result in permanent enlargement. Understanding the traumatic etiology of capped hock enables targeted prevention strategies and realistic treatment expectations.

The primary cause of capped hock is direct trauma to the point of the hock from contact with hard surfaces. The most common scenario involves horses kicking stall walls, barn structures, or trailer partitions, with each impact causing compression and injury to the tissues over the calcaneus. Repeated trauma from lying on hard surfaces with inadequate bedding also contributes significantly, as the prominent point of hock contacts the ground during recumbency. Falling or scrambling on hard surfaces, slipping in trailers, and collisions with fixed objects all can initiate capped hock development. Some horses traumatize their hocks by pawing backward or by habitually standing with their hocks pressed against walls or posts.

Genetic factors do not directly cause capped hock, as this is an acquired traumatic condition rather than an inherited disease. However, certain anatomical characteristics may influence susceptibility. Horses with particularly prominent, sharply defined calcaneal tuberosities have more exposed bony points vulnerable to external trauma. Individuals with conformation that positions the hocks closer to walls when standing in stalls may experience more frequent contact. Behavioral tendencies that lead to kicking, weaving, or restless stall behavior have both inherited and environmental components. While these predisposing factors may run in families, the capped hock itself results from environmental interactions rather than genetic programming.

Environmental and management factors are the primary determinants of capped hock development and represent the most important targets for prevention and treatment. Inadequate stall bedding fails to cushion the hock during recumbency, allowing repeated trauma with each lying episode. Stall design that places kick walls too close to standing horses or that lacks adequate padding invites trauma from kicking behavior. Narrow stalls forcing horses into awkward positions when lying down increase hock contact with walls. Trailer design and padding significantly influence capped hock risk during transport, particularly for horses that lie down or become unsettled during travel. Turnout areas with hard, frozen, or rocky ground can contribute to trauma.

Risk factors for capped hock include behavioral patterns, housing conditions, and situational exposures. Horses with kicking habits face dramatically elevated risk, with some individuals developing capped hock within days of beginning to kick. Horses that lie down frequently or for extended periods have increased exposure to bedding-related trauma. Young horses not yet accustomed to confinement may exhibit more stall-directed behaviors including kicking. Horses recovering from illness or injury that spend increased time recumbent face elevated risk. Trailer transport, particularly long-distance journeys, creates opportunities for trauma-inducing contact with partitions and walls.

The pathophysiology of capped hock involves inflammatory responses to mechanical tissue injury. Initial trauma causes rupture of small blood vessels, tissue disruption, and release of inflammatory mediators that increase vascular permeability and fluid accumulation. The bursal membrane responds by increasing synovial fluid production, distending the bursal cavity and creating visible swelling. Repeated trauma before healing occurs perpetuates the inflammatory cycle and prevents resolution. Over time, chronic inflammation leads to thickening of bursal walls, organization of cavity contents into fibrous tissue, and permanent structural changes that persist even after trauma cessation.

Early warning signs of developing capped hock may be subtle and require careful observation to detect. Initial indicators include slight puffiness or altered contour at the point of the hock, visible when viewing the hindleg from the side or rear. The normally sharp, well-defined point of hock may appear slightly rounded or softened. Hair coat over the calcaneus may show evidence of friction, appearing roughened, worn, or disturbed compared to surrounding areas. Mild warmth may be palpable before visible swelling becomes prominent. Horses may show subtle behavior changes such as reluctance to kick or contact the area, though many horses show no behavioral indicators whatsoever.

The characteristic symptom of established capped hock is a discrete, rounded swelling at the point of the hock, located directly over the calcaneal tuberosity. The swelling varies considerably in size, from barely perceptible bumps to substantial masses the size of a small apple or larger. In acute cases, the swelling is typically soft and fluctuant, reflecting fluid accumulation within the bursal cavity. The overlying skin remains intact and mobile unless complicated by wounds or chronic scarring. Palpation of uncomplicated aseptic capped hock elicits minimal pain response in most cases. The swelling may be unilateral or bilateral depending on the trauma pattern, with wall-kickers often affecting only the limb used for kicking while bedding-related cases may affect both hocks.

Behavioral changes directly attributable to uncomplicated capped hock are typically minimal to absent. The vast majority of horses with capped hock continue normal activities without apparent discomfort or reluctance. Unlike conditions affecting the hock joint itself, capped hock does not cause lameness in routine presentations. Some horses with large or actively inflamed swellings may show subtle hesitation during movement that extends the hock fully, but this is uncommon. Horses with infected capped hock demonstrate more significant behavioral changes including lameness, reluctance to bear weight normally, and depression.

Physical signs vary with the stage and nature of the capped hock. Acute presentations show soft, fluctuant swelling with possible warmth and mild sensitivity to firm palpation. Subacute cases demonstrate mixture of fluid and organizing tissue, with variable consistency across different portions of the swelling. Chronic capped hock characteristically becomes firm and fibrous, having lost the soft fluctuance of acute fluid accumulation. The overlying skin may thicken with chronic capped hock, developing a callus-like quality from repeated friction. Large swellings may make the hock appear asymmetric or unbalanced in comparison to the opposite limb or to normal hock conformation.

Symptom progression follows patterns determined by whether the inciting trauma is eliminated. Continuing trauma allows acute swelling to evolve into chronic, organized fibrous masses with permanently altered hock contour. Without trauma elimination, swellings often enlarge progressively as each new episode of inflammation adds to the accumulating mass. If trauma is eliminated early in the process, significant resolution is possible, with acute fluid accumulation potentially resolving substantially or completely. However, once fibrous organization has occurred, the structural changes are largely irreversible, leaving permanent cosmetic blemishes of variable size.

Emergency symptoms requiring immediate veterinary attention include signs suggesting septic (infected) capped hock or significant skin compromise. Infected capped hock presents with severe swelling, marked heat, substantial pain on palpation, and potentially drainage of purulent material. Systemic signs including fever, depression, and reduced appetite often accompany severe infection. Any wound directly over or communicating with the hock swelling requires urgent evaluation due to infection risk. Rapidly progressive swelling extending beyond the local bursal area suggests spreading infection. Though septic capped hock is less common than aseptic forms, its potential severity warrants awareness and prompt response to suggestive symptoms.

Physical examination provides definitive diagnosis of capped hock in straightforward cases based on the characteristic location, appearance, and palpation findings. Visual inspection reveals the discrete swelling at the point of hock, positioned directly over the calcaneal tuberosity. Comparison with the opposite hock helps appreciate the degree of enlargement when only one limb is affected. Palpation characterizes the consistency of the swelling, ranging from soft and fluctuant in acute fluid-filled cases to firm and organized in chronic presentations. The swelling moves freely with the overlying skin rather than being fixed to underlying bone. Pain response during palpation is typically minimal in uncomplicated aseptic cases, while infected capped hock elicits marked pain.

Diagnostic tests beyond physical examination are usually unnecessary for typical capped hock but may be valuable in specific circumstances. Ultrasound examination provides detailed characterization of bursal contents, differentiating simple fluid accumulation from organized fibrous tissue and identifying internal septation or loculation. Aspiration (centesis) of fluid from acute cases allows assessment of fluid character; normal bursal fluid is clear and slightly viscous, while infected fluid appears turbid, discolored, or purulent. Laboratory analysis of aspirated fluid, including cytology, protein content, and bacterial culture, helps diagnose or exclude septic bursitis. Radiography can evaluate the underlying calcaneus for fractures, periosteal reactions, or other bony abnormalities that might accompany or complicate the bursal swelling.

Advanced diagnostic imaging is rarely required for capped hock diagnosis but may assist with treatment planning or evaluation of complex cases. Ultrasound remains the most valuable modality for soft tissue assessment, enabling visualization of bursal wall architecture, cavity dimensions, content characterization, and relationships to adjacent structures. Contrast bursography can delineate the extent of the bursal cavity and identify any communication with the tarsal sheath or hock joint, which would significantly affect prognosis and treatment. MRI provides comprehensive evaluation when available but is generally unnecessary for this superficial condition unless concurrent deep structural pathology is suspected.

Differential diagnosis for swelling at the point of hock includes various conditions that may produce similar-appearing enlargement. Hock joint effusion or tarsal osteoarthritis causes swelling of the joint capsule, located more distally and medially than the subcutaneous bursa affected in capped hock, and typically causes lameness. Tarsal sheath distension (thoroughpin) produces swelling medially and laterally at the proximal hock but in a different location than capped hock. Abscesses following local infection present with more pronounced heat, pain, and potentially draining tracts. Hematomas from acute trauma may mimic acute capped hock. The characteristic location directly over the point of hock and typical history of trauma or management factors support capped hock diagnosis.

Initial treatment for capped hock must address the inciting trauma while managing the inflammatory response already established. Identification and elimination of the traumatic source is the most critical intervention. For horses that kick walls, solutions include padding kick areas, installing anti-kicking devices, addressing behavioral causes of kicking, or relocating the horse to housing less conducive to kicking. For bedding-related capped hock, dramatically increasing bedding depth and improving bedding quality throughout the stall prevents ongoing trauma during recumbency. Trailer modifications including padding and adequate space prevent transport-related trauma. Without addressing the cause, other treatments provide only temporary benefit.

Medical management of capped hock includes approaches targeting inflammation reduction and fluid resorption. Cold therapy applied to acute swellings helps reduce active inflammation and may limit fluid accumulation. Anti-inflammatory medications, both topical applications and systemic non-steroidal anti-inflammatory drugs, address the inflammatory component. Pressure bandaging when anatomically feasible helps limit fluid accumulation, though the hock's conformation makes effective bandaging challenging. Sweating wraps using osmotic agents such as DMSO or commercial sweating preparations can temporarily reduce swelling but provide only short-term cosmetic improvement. Aspiration of bursal fluid combined with intralesional corticosteroid injection may provide more lasting benefit by reducing inflammation directly within the bursa.

Protective equipment can help prevent continued trauma to affected hocks while other treatments are employed. Hock boots or wraps provide padding that protects the calcaneal area from wall contact during kicking or from ground contact during recumbency. Various designs are available including neoprene sleeves, quilted wraps, and hard-shell protectors. Proper fit is essential—equipment too tight may cause additional problems, while loose-fitting protection fails to prevent trauma adequately. Some horses require acclimation periods to accept wearing hock protection. Continued use may be necessary indefinitely for horses with persistent kicking behaviors or housing situations that cannot be modified.

Surgical treatment is reserved for chronic, refractory capped hock that fails conservative management or for cases where cosmetic outcome is paramount and owners are willing to accept surgical risks. Surgical options include drainage and lavage of the bursal cavity, injection of caustic substances intended to cause scarring and cavity obliteration, and complete surgical excision of the bursa. Bursectomy can provide definitive treatment but carries risks including wound healing complications at this motion-intensive location, seroma formation, and recurrence if causative factors persist. The decision for surgery must weigh realistic cosmetic expectations against procedural risks and costs.

Supportive care measures significantly influence capped hock outcomes regardless of which primary treatments are employed. Deep, cushioning bedding throughout the stall prevents trauma during recumbency. Padding of stall walls and elimination of kicking opportunities reduces trauma from behavioral sources. Turnout on soft footing provides relief from stall confinement while avoiding hard ground trauma. Attention to any behavioral factors contributing to kicking or stall-directed behavior addresses underlying causes. Management of any pain or anxiety that might promote restless behavior can reduce trauma risk.

Treatment decisions for capped hock should consider the stage of the condition, the identifiable causes, the horse's intended use, and realistic cosmetic expectations. Acute cases often respond well to environmental modifications combined with conservative medical management. Chronic, organized capped hock is unlikely to resolve cosmetically regardless of treatment intensity, though preventing further progression remains valuable. Show horses with significant cosmetic concerns may pursue more aggressive treatment approaches. Pleasure horses with stable, non-progressive swellings may require only ongoing preventive management. Veterinary guidance helps match treatment intensity to achievable outcomes.

Recovery timelines for capped hock depend substantially on the chronicity at treatment initiation and the success of trauma prevention measures. Acute capped hock treated promptly with environmental modifications and conservative care may show significant improvement within two to four weeks, with potential for substantial or complete resolution in uncomplicated cases. Subacute cases with beginning tissue organization may improve over four to eight weeks but typically retain some residual enlargement. Chronic capped hock with well-established fibrous tissue shows minimal resolution of the mass itself despite treatment, though preventing further enlargement remains achievable. Surgical cases require additional healing time of six to twelve weeks depending on the procedure performed.

Post-treatment care and monitoring focus on maintaining protective measures while tracking response to intervention. Daily assessment of the hock should note changes in swelling size, consistency, temperature, and any sensitivity to palpation. Environmental modifications addressing the traumatic cause must be maintained consistently rather than abandoned once initial improvement occurs. Protective hock boots or wraps should continue until confident the traumatic source is eliminated. Photographic documentation at regular intervals provides objective tracking of progress or changes. Any sign of increasing swelling, heat, pain, or drainage warrants prompt veterinary reassessment.

Prognostic factors for capped hock outcomes include duration of the condition before treatment, extent of fibrous organization, identifiability and correctability of the traumatic cause, and compliance with management recommendations. Horses treated within weeks of capped hock onset, before significant tissue organization, have the best prognosis for substantial resolution. Those with chronic, organized masses face more limited cosmetic improvement but can expect prevention of further enlargement. Cases where the traumatic source is clearly identified and successfully eliminated carry better prognoses than those where trauma cannot be prevented. Rigorous owner compliance with ongoing preventive measures significantly improves long-term outcomes.

Long-term outlook for horses with capped hock is excellent for soundness and function, with variable cosmetic outcomes. Capped hock does not cause lameness or impair athletic performance in typical uncomplicated cases, allowing horses to continue all intended activities regardless of visible swelling. The cosmetic blemish from chronic capped hock, while potentially significant for show horses, does not affect quality of life or comfort. Once stabilized with appropriate management, most horses require only ongoing preventive attention rather than active treatment. Periodic veterinary assessment confirms stability and provides opportunity to adjust prevention strategies as needed.

Management practices represent the foundation of capped hock prevention, with attention to housing conditions and behavioral management most important. Providing deeply bedded stalls with soft, cushioning material protects hocks from trauma during recumbency. Recommended bedding depths of at least six to eight inches of shavings, straw, or similar material maintain protective value throughout the cleaning cycle. Rubber stall mats beneath bedding provide additional cushioning. Addressing kicking behavior through behavioral modification, increased exercise, improved socialization, or environmental enrichment reduces trauma from this common cause. Stall walls should be smooth without protruding objects, and padding of kick walls may be necessary for horses prone to kicking.

Nutritional factors have minimal direct relationship to capped hock prevention, as this condition results from mechanical trauma rather than nutritional deficiency. However, maintaining appropriate body condition supports general tissue resilience. Very thin horses with prominent bony structures may be more susceptible to hock trauma due to lack of natural cushioning. Adequate protein intake supports tissue maintenance and healing capacity. Weight management prevents complications that might affect lying behavior or cause increased time recumbent. Overall nutritional health contributes to the body's ability to recover from minor trauma before clinical capped hock develops.

Exercise and turnout influence capped hock risk through effects on behavior and housing exposure. Adequate exercise and turnout reduce stall-directed behaviors including kicking, pawing, and restlessness that contribute to capped hock development. Horses with appropriate mental stimulation and physical activity exhibit fewer stereotypic behaviors that can cause self-injury. Turnout on soft pasture provides relief from stall confinement while generally presenting less hock trauma risk than hard stall surfaces. However, frozen, rocky, or excessively hard turnout ground can itself cause trauma, requiring attention to pasture conditions seasonally.

Environmental factors beyond bedding significantly impact capped hock risk. Stall design should position walls to minimize contact during normal standing and lying positions. Kick walls should be either padded or positioned far enough from standing horses to reduce impact force when kicking occurs. Trailer design and padding protect hocks during transport, with adequate space and appropriate partition materials reducing trauma risk. Turnout areas should be free from hazards that could cause direct injury to hocks including sharp posts, wire, and rocky ground. Careful evaluation of housing and turnout areas identifies specific trauma risks amenable to modification.

Behavioral management plays a crucial role in preventing capped hock in horses with kicking tendencies. Identification of triggers for kicking behavior—feeding time excitement, neighbor interactions, boredom, anxiety—enables targeted interventions. Increased exercise and turnout often reduces stall-directed behaviors. Environmental enrichment including stall toys, mirrors, and varied management routines may decrease boredom-related kicking. For some horses, relocation to different stall positions, different neighbors, or different housing arrangements resolves kicking behavior. Anti-kicking devices that provide aversive consequences for kicking can modify behavior, though addressing underlying causes is preferable when possible.

Daily management adjustments for horses with capped hock history focus on maintaining protective measures while monitoring for changes. Morning assessments should evaluate hock appearance before activity, noting any changes in swelling size or character. Bedding condition should be checked daily, with additions made promptly when depth becomes inadequate. Horses wearing protective hock boots should have equipment inspected for proper fit, cleanliness, and condition. Grooming provides opportunity for hands-on evaluation of the hock region. Evening routines should ensure bedding is adequately prepared and any protective equipment properly applied before the horse's primary rest period. Consistent attention to these details prevents the lapses that often lead to capped hock recurrence.

Housing and turnout considerations for horses with capped hock balance protection from trauma with normal activity and lifestyle. Stalls must maintain consistently deep, cushioning bedding regardless of cleaning schedules or supply issues. Rubber matting beneath bedding provides additional protection, particularly for horses known to lie frequently. Wall padding or increased distance from kick walls protects horses with kicking histories. Turnout on appropriate footing—soft ground free from rocks, frozen areas, or other hazards—reduces trauma risk while providing beneficial exercise and mental stimulation. Shelter areas in pastures should have soft footing where horses commonly rest. Horses with active or recurrent capped hock may benefit from strategic stalling versus turnout decisions based on conditions.

Exercise modifications for horses with capped hock are generally unnecessary, as uncomplicated capped hock does not affect movement or athletic function. Horses with stable, aseptic capped hock can continue all normal activities without restriction. Exercise equipment such as hock boots worn during work is unnecessary for capped hock management, as trauma occurs during rest rather than activity. The exception involves horses with actively inflamed or infected capped hock, which may benefit from reduced activity while acute conditions resolve. Normal athletic use does not worsen or exacerbate typical capped hock.

Monitoring and ongoing care for horses with capped hock history requires consistent attention to detect changes and prevent recurrence. Regular visual assessment and palpation identifies any changes in size, consistency, temperature, or sensitivity. Photographic documentation at monthly or quarterly intervals provides objective tracking of stability or progression. Bedding quality and protective equipment maintenance must continue indefinitely for susceptible horses. Periodic veterinary examination confirms stability and allows adjustment of management approaches. Any significant change in the character of existing capped hock, including sudden enlargement, increased heat, pain, or drainage, warrants prompt professional evaluation.

Quality of life and use considerations for horses with capped hock recognize that this condition is compatible with full, normal function in virtually all cases. The cosmetic blemish, while visible and potentially significant for show horses, does not affect comfort, soundness, or athletic ability. Horses with capped hock compete successfully in performance disciplines where judging does not emphasize such blemishes. Halter, conformation, and breed showing may be affected by visible hock enlargement, requiring owners to weigh cosmetic treatment intensity against showing goals. Pleasure horses require only routine preventive attention without impact on activities or quality of life.

Capped hock affects horses of all breeds, with individual risk determined primarily by management, behavior, and housing factors rather than breed-specific susceptibility. However, certain breed-associated characteristics may influence the likelihood of developing capped hock. Breeds with particularly prominent, angular hock conformation such as some Thoroughbred and Warmblood lines have more exposed bony points potentially vulnerable to trauma. Draft breeds with substantial body mass may experience greater ground contact pressure when lying on inadequate bedding, though their typically heavier bone and thicker skin may provide some offsetting protection. Hot-blooded breeds or individual horses with reactive temperaments may be more prone to kicking behaviors that cause capped hock.

Use patterns and management practices associated with different disciplines influence capped hock risk regardless of breed. Racehorses housed in track stabling may encounter variable bedding conditions and smaller stalls that increase trauma exposure. Show horses of all breeds spending significant time in show stabling may face inadequate bedding at unfamiliar venues. Sport horses in intensive training programs alternating between stall rest and athletic demands encounter varied housing conditions. Trail horses and pleasure horses with consistent home management may face lower risk than those frequently traveling to different facilities. The common thread is management quality rather than breed—horses of any breed with appropriate bedding and housing rarely develop capped hock.

Genetic testing for capped hock susceptibility does not exist, as this condition results from environmental trauma rather than inherited genetic factors. While conformational traits and behavioral tendencies may have heritable components, these do not constitute genetic disease predisposing to capped hock. Breeding decisions should not be influenced by capped hock history in breeding stock, as the condition reflects management rather than genetics. When evaluating horses for purchase, capped hock indicates previous housing or management conditions rather than ongoing health problems or heritable defects. Future prevention through appropriate management is the focus rather than genetic concerns.

Capped hock may co-occur with or be confused with several related conditions affecting the hock region. Capped elbow (shoe boil) often develops in horses with the same management factors predisposing to capped hock, as both result from inadequate bedding and trauma during recumbency. Curb, involving the plantar tarsal ligament, produces swelling at the back of the hock but lower than the point of hock affected in capped hock. Thoroughpin, distension of the tarsal sheath, creates swelling that appears to pass from medial to lateral sides of the hock rather than at the point. Bog spavin involves the hock joint itself and presents as puffy swelling at the front of the hock. Understanding the anatomical distinctions between these conditions enables appropriate diagnosis.

Several conditions produce swelling that may initially resemble capped hock on casual examination. Hematomas following acute trauma create fluctuant swelling that may mimic acute capped hock but often show characteristic color changes and typically resolve more completely without treatment. Abscesses at the point of hock present with more pronounced heat, pain, and potentially draining tracts compared to aseptic capped hock. Calcaneal fractures can cause swelling at the point of hock accompanied by significant lameness, requiring radiographic evaluation for diagnosis. Cellulitis of the hock region causes diffuse swelling extending beyond the discrete mass of capped hock.

Potential complications of capped hock include several conditions warranting monitoring and appropriate management. Secondary infection converting aseptic bursitis to septic bursitis represents the most serious complication, particularly when wounds provide bacterial access to the bursal cavity. Skin breakdown over large, chronic swellings can occur, especially with continued trauma. Progressive enlargement despite management efforts indicates ongoing trauma requiring more aggressive prevention. Chronic bursal distension may cause permanent stretching of overlying tissues and skin changes. Recognition of these potential complications emphasizes the importance of appropriate management and monitoring for all horses diagnosed with capped hock.