Kissing Spines / Overriding Dorsal Spinous Processes

Kissing spines, clinically known as overriding or impinging dorsal spinous processes, represents one of the most common causes of back pain and poor performance in sport horses, occurring when the bony projections extending upward from the vertebrae come into abnormally close contact or actually touch and rub against each other. The dorsal spinous processes are the tall, fin-like extensions of bone that project dorsally from each thoracic and lumbar vertebra, normally separated by adequate space that allows free movement during normal spinal flexion and extension. When these processes become too close together, touch, or override each other, the resulting bone-on-bone contact creates inflammation, pain, and potentially progressive bone remodeling that significantly impacts the horse's comfort and athletic performance.

Kissing spines affects horses across virtually all disciplines but is most commonly diagnosed in sport horses engaged in dressage, show jumping, eventing, and other activities requiring significant collection, engagement, and back mobility. The condition occurs most frequently in the thoracolumbar region, typically between the 13th thoracic and 18th thoracic vertebrae, which corresponds to the area directly under the saddle and rider where mechanical stress is concentrated. Studies have demonstrated radiographic evidence of kissing spines in a surprisingly high percentage of horses, though the correlation between radiographic findings and clinical signs is not always straightforward, as some horses with significant imaging changes show minimal symptoms while others with mild changes experience substantial performance impacts.

The impact of kissing spines on equine health and performance can range from subtle performance decline to severe back pain rendering the horse unsuitable for any ridden work. Affected horses commonly display resistance to collection, reluctance to round the back, difficulty with lead changes, behavioral problems under saddle, and sometimes overt signs of discomfort including bucking, rearing, or refusal to work. The condition can significantly affect quality of life, as horses may experience chronic pain during activities that were previously performed comfortably. Early recognition of subtle performance changes allows intervention before severe degeneration and secondary problems develop.

Treatability of kissing spines has improved substantially with advances in both medical management and surgical techniques over the past two decades. Conservative management incorporating rest, anti-inflammatory medications, targeted rehabilitation exercises, and modifications to tack and riding approach helps many horses return to comfortable work. For cases not responding adequately to medical management, several surgical options including interspinous ligament desmotomy, partial spinous process resection, and newer minimally invasive techniques offer alternatives with generally favorable success rates. Early intervention and comprehensive rehabilitation programs significantly improve outcomes regardless of treatment approach selected.

The primary causes of kissing spines involve a combination of conformational predisposition, developmental factors, and acquired influences that bring the dorsal spinous processes into abnormal proximity. Congenital or developmental factors may result in spinous processes that are naturally closer together than average, longer than typical, or angled in ways that predispose to impingement during normal spinal movement. Some horses appear to be born with spine configurations that place them at higher risk, with clinical signs developing once training demands and rider weight stress the back sufficiently. The interaction between inherited spinal anatomy and mechanical stress from athletic use creates conditions for kissing spines development.

Genetic and breed predisposition to kissing spines appears significant based on clinical observations, though specific genetic markers have not been definitively identified. Thoroughbreds show high incidence rates, possibly related to their relatively long backs and athletic use patterns. Warmbloods demonstrate significant kissing spines prevalence, potentially reflecting breeding selection for movement characteristics that influence spinal conformation. Certain bloodlines within breeds may demonstrate familial clustering of kissing spines cases, suggesting hereditary components to spinal anatomy and susceptibility. Research continues to investigate genetic contributions to this condition.

Environmental and management factors significantly influence whether horses with anatomical predisposition actually develop clinical kissing spines. Training methods that encourage excessive hollowing of the back or fail to develop appropriate core musculature may accelerate impingement progression. Saddle fit issues creating focal pressure points alter spinal mechanics and stress distribution. Rider skill and balance affect how force is transmitted through the horse's back during work. Poor conditioning programs that fail to develop supportive musculature leave the spine vulnerable to mechanical stress. Starting horses in intensive training before skeletal maturation completes may initiate problems that worsen over time.

Risk factors for developing clinical kissing spines include conformational characteristics, use patterns, and management practices. Horses with naturally short backs may have spinous processes more closely spaced from birth. Activities requiring significant collection and engagement, including dressage and jumping, place particular demands on thoracolumbar flexibility that stress the spinous processes. Horses carrying heavier riders relative to their body size experience increased spinal loading. Previous back injuries or muscle atrophy may alter spinal mechanics and predispose to impingement. Age-related changes in spinal flexibility and muscle support can unmask previously subclinical anatomical variations.

The pathophysiology of kissing spines involves progressive bone remodeling in response to abnormal mechanical contact between adjacent spinous processes. Initial impingement creates periosteal inflammation at contact points, producing pain and triggering bone's adaptive response. Over time, continued contact results in sclerosis, where bone becomes denser and harder at pressure points. Progressive changes may include new bone formation, cyst development within spinous processes, and loss of the normal interspinous ligament. Secondary muscle spasm and atrophy in surrounding epaxial musculature both result from and contribute to the ongoing problem. Without intervention, a self-perpetuating cycle of pain, muscle dysfunction, and structural change progressively worsens the condition.

Early warning signs of kissing spines are frequently subtle and easily attributed to training issues, saddle fit problems, or behavioral causes, making vigilant observation essential for timely recognition. Affected horses may show subtle reluctance to engage the hindquarters or round the back during work, manifesting as reduced quality of movement rather than overt lameness. Gradual decline in performance scores, particularly in dressage movements requiring collection and engagement, sometimes provides the first indication that a physical problem exists. Some horses develop subtle behavioral changes under saddle including increased tension, resistance to aids, or loss of previously established skills. Handlers familiar with individual horses often recognize that something is wrong before specific signs can be identified.

Common symptoms of established kissing spines reflect the horse's attempts to protect the painful back region during work and daily activities. Resistance to being saddled, including attempts to move away, ears back, or tightening of facial muscles when the girth is fastened, commonly indicates back pain. Reluctance to flex the spine, whether during ridden work or in-hand stretching exercises, demonstrates discomfort with movements that compress the spinous processes. Difficulty maintaining consistent rhythm and tempo, particularly at canter, reflects the horse's struggle to move normally while protecting painful structures. Cold-backed behavior when first mounted that may persist longer than normal or fail to resolve with warm-up suggests ongoing back discomfort.

Behavioral changes associated with kissing spines often represent dramatic departures from previously established patterns and may be misinterpreted as training or attitude problems. Bucking, particularly during transitions or when asked to round the frame, represents an attempt to escape pain caused by these movements. Rearing may occur when horses are pressed to perform movements they find painful. Refusal to jump or rushing fences can indicate back pain making the bascule uncomfortable. Teeth grinding, tail swishing, and general irritability under saddle reflect ongoing discomfort. Some horses become dangerous to ride as they escalate defensive behaviors in response to persistent pain.

Physical signs observable during examination include muscle asymmetry and atrophy in the back region, particularly the epaxial muscles running alongside the spine. Palpation of the back may reveal pain responses when pressure is applied over affected spinous processes, though sensitivity varies between individuals. Muscle spasm may be palpable as taut, hard areas in muscles that should be soft and supple. Reduced range of motion in spinal flexion and extension tests indicates mechanical restriction or pain-related guarding. Some horses show altered hoof wear patterns reflecting compensatory movement changes aimed at protecting the back.

Symptom progression in untreated kissing spines typically follows a worsening trajectory as structural changes advance and secondary problems accumulate. Initial subtle performance issues gradually become more pronounced as bone remodeling increases impingement severity. Behavioral problems may escalate from mild resistance to dangerous defense reactions as horses become increasingly desperate to escape pain. Secondary muscle atrophy progresses, reducing the muscular support available to stabilize and protect the spine. Compensatory movement patterns may produce secondary lameness issues in other body regions. Quality of life deteriorates as affected horses experience chronic discomfort during activities that once brought no distress.

Emergency symptoms specifically related to kissing spines are rare, as this condition typically presents as a chronic progressive problem rather than an acute crisis. However, several situations warrant urgent veterinary attention. Sudden severe back pain with inability or extreme reluctance to move may indicate acute inflammation or fracture of an affected spinous process. Development of neurological signs including ataxia, weakness, or abnormal stance suggests possible spinal cord involvement requiring immediate evaluation. Dangerous behavior under saddle posing risk of serious injury to horse or rider demands immediate professional assessment to rule out treatable pain sources. Any horse exhibiting severe back pain should be rested and examined promptly to determine appropriate management.

Physical examination for suspected kissing spines begins with careful observation of posture, muscle development, and overall body condition before hands-on assessment. The veterinarian evaluates back symmetry, looking for areas of muscle atrophy or hypertrophy that might indicate compensation patterns. Systematic palpation proceeds along the spine, noting any pain responses, muscle tension, or heat that localizes problem areas. Range of motion testing evaluates spinal flexibility through ventroflexion, extension, and lateral bending, noting any restrictions or pain responses. Under-saddle evaluation when safe to perform may reveal gait abnormalities, resistance to certain movements, or behavioral responses correlating with specific exercises that stress the back.

Radiographic imaging provides essential information for diagnosing kissing spines and characterizing the severity and extent of involvement. Lateral radiographs of the thoracolumbar spine reveal the relationship between adjacent spinous processes, showing narrowing of interspinous spaces, contact between processes, bone sclerosis at contact points, and remodeling changes. Multiple overlapping views are necessary to evaluate the entire at-risk region thoroughly. Radiographic scoring systems have been developed to grade severity based on specific changes observed. However, interpretation requires clinical correlation, as some horses with significant radiographic changes show minimal clinical signs while others with mild imaging changes experience substantial symptoms.

Advanced diagnostic modalities provide additional information valuable for treatment planning and prognostication. Nuclear scintigraphy identifies areas of active bone metabolism, helping distinguish clinically significant lesions from incidental findings and identifying the most problematic locations in horses with multiple affected sites. Ultrasonography evaluates interspinous ligaments and surrounding soft tissues, providing information about ligament integrity and inflammation. Diagnostic anesthesia, injecting local anesthetic around specific spinous processes, helps confirm that identified lesions are actually causing clinical signs when the horse improves following injection. This information proves particularly valuable when deciding whether surgical intervention is warranted.

Differential diagnosis for horses presenting with back pain and performance problems includes numerous conditions requiring systematic evaluation to distinguish from kissing spines. Primary muscle disorders including myositis and muscle strain produce back pain without bony involvement. Sacroiliac joint disease causes hindquarter and back pain that may mimic kissing spines presentations. Vertebral facet joint arthritis produces spinal pain from different structures than spinous processes. Soft tissue injuries to supraspinous or interspinous ligaments may occur independently or alongside kissing spines. Lameness from limb sources may manifest as apparent back pain through compensatory movement changes. Thorough diagnostic workup including appropriate imaging distinguishes between these various conditions and identifies cases where multiple problems coexist.

Emergency treatment is rarely required for kissing spines given its chronic progressive nature, but acute severe back pain warrants immediate management with rest and anti-inflammatory medications while diagnostic workup proceeds. Affected horses should be removed from work to prevent exacerbation of inflammation and allow initial acute pain to subside. Non-steroidal anti-inflammatory drugs including phenylbutazone provide pain relief and reduce inflammation. Muscle relaxants may help address secondary muscle spasm contributing to discomfort. Stall rest with hand-walking maintains some movement while preventing activities that stress the painful area. Ice application over affected regions may provide temporary comfort during acute flare-ups.

Medical management represents the first-line treatment approach for most horses diagnosed with kissing spines and succeeds in returning many to comfortable work. Systemic anti-inflammatory medications manage pain during initial stabilization and acute phases. Local injection of corticosteroids into interspinous spaces directly targets inflammation at affected sites, often providing significant improvement lasting weeks to months. Mesotherapy, injection of medications into the mesoderm layer of the skin overlying affected areas, has proponents who report good results. Shockwave therapy applied to the back may provide pain relief and potentially stimulate healing. Acupuncture and chiropractic treatments offer additional modalities some owners and veterinarians incorporate into management programs.

Surgical options for kissing spines have expanded and refined substantially, offering effective treatment for cases not adequately managed through conservative approaches. Interspinous ligament desmotomy involves cutting the ligaments between affected spinous processes, allowing them to spread apart and reducing impingement. Partial spinous process resection, also called ostectomy, surgically removes portions of the bony processes to create space and eliminate bone-on-bone contact. Minimally invasive techniques including endoscopic-assisted approaches reduce surgical trauma and recovery time compared to traditional open procedures. Success rates for surgical treatment generally range from 70 to 90 percent improvement, though outcomes vary based on case selection and rehabilitation compliance.

Supportive care during kissing spines treatment addresses multiple factors influencing outcome. Saddle fit evaluation and optimization ensures equipment is not contributing to or exacerbating the problem. Weight management maintains appropriate body condition, avoiding excess weight that increases spinal loading. Core strengthening exercises performed correctly help develop muscular support protecting the spine. Proper warm-up protocols prepare the back for work and reduce risk of acute flare-ups. Mental health support through appropriate turnout, socialization, and environmental enrichment maintains psychological wellbeing during modified activity periods.

Rehabilitation following both medical and surgical kissing spines treatment proves essential for optimal outcomes and often determines success as much as the primary intervention. Physical therapy programs incorporating specific exercises to improve back flexibility and strengthen supporting musculature rebuild the functional capacity needed for return to athletic work. Ground work exercises including backing, transitions, and pole work encourage proper back engagement. Under-saddle rehabilitation proceeds gradually, emphasizing correct posture and movement patterns rather than frame or collection demands. Swimming or water treadmill work provides cardiovascular conditioning while reducing spinal loading. Rehabilitation typically requires three to six months for medically managed cases and six to twelve months following surgery.

Treatment decision factors guiding approach selection include severity of radiographic and clinical findings, response to initial conservative management, athletic demands, and economic considerations. Horses with mild to moderate findings often respond well to conservative management and targeted rehabilitation. Cases with severe bone changes or inadequate response to medical treatment over reasonable timeframes become surgical candidates. Intended use influences treatment intensity, with high-performance horses potentially benefiting from more aggressive intervention while pleasure horses may remain comfortable with conservative management. Owner commitment to extended rehabilitation influences success regardless of treatment approach chosen.

Recovery timelines for kissing spines treatment vary substantially based on treatment approach, case severity, and rehabilitation quality. Medical management with injection therapy may provide improvement within one to two weeks, though optimal response often develops over four to eight weeks as inflammation subsides and rehabilitation exercises strengthen supporting structures. Surgical cases typically require eight to twelve weeks of initial healing before gradual return to work begins, with full recovery to previous athletic levels requiring six to twelve months in most cases. Some horses achieve dramatic rapid improvement while others require extended rehabilitation programs before returning to comfort.

Post-treatment care and monitoring requirements emphasize rehabilitation exercise compliance and systematic progression of activity. Following injection therapy, horses typically receive two to four weeks of reduced work before gradual return to full activity with appropriate exercises. Post-surgical care involves initial stall rest followed by hand-walking, progressing to lunging, and eventually ridden work according to specific protocols established by the treating veterinarian and rehabilitation team. Regular veterinary reassessment at intervals determined by the treatment team tracks progress and guides advancement. Owner observation of comfort levels during daily activities and work provides valuable information guiding management decisions.

Prognosis factors determining outcome include initial severity, treatment response, rehabilitation quality, and intended future use. Horses with mild to moderate kissing spines and good response to conservative management carry favorable prognoses for return to previous athletic levels. Surgical outcomes depend on case selection, surgical technique, and post-operative rehabilitation adherence. Horses intended for less demanding activities such as light pleasure riding generally have better prognoses than those expected to return to upper-level competition. Development of secondary problems including chronic muscle dysfunction or behavioral patterns established during painful periods may persist beyond resolution of primary pathology.

Long-term soundness outlook for horses treated for kissing spines is generally favorable, though many require ongoing management modifications to maintain comfort. Medical management often requires periodic repeated treatments, whether injection therapy at intervals of months to years or ongoing medication use during heavy training periods. Surgically treated horses may achieve more permanent resolution but still benefit from attention to predisposing factors including saddle fit and training approaches. Many horses return to high-level competition following appropriate treatment and rehabilitation. Some horses find their optimal outcomes in less demanding careers that better accommodate their individual limitations. Lifelong attention to back health through appropriate conditioning, equipment selection, and prompt attention to any recurrence of symptoms optimizes long-term success.

Management practices aimed at preventing kissing spines or minimizing its impact focus on optimizing back health through all aspects of horse care and training. Correct saddle fit assessed regularly by qualified professionals ensures equipment supports rather than hinders normal spinal function. Balanced rider position and effective riding technique transmit aids smoothly without creating abnormal focal stresses on the back. Appropriate matching of rider weight to horse size prevents excessive loading on spinal structures. Regular professional evaluation of back health identifies developing problems before they become established. Avoidance of excessive or premature collection demands allows muscular support to develop alongside flexibility expectations.

Nutritional considerations for spinal health focus primarily on supporting overall musculoskeletal wellness and maintaining appropriate body condition. Adequate protein intake supports muscle development needed for back stabilization. Mineral balance including calcium and phosphorus maintains bone integrity. Anti-inflammatory properties of omega-3 fatty acids may provide some protective benefit. Avoiding excessive weight gain reduces mechanical stress on all skeletal structures including the spine. Growing horses benefit from nutritional programs supporting appropriate skeletal development without encouraging excessive growth rates.

Exercise and conditioning programs designed to develop strong, flexible backs may reduce kissing spines risk or severity in predisposed horses. Core strengthening exercises including transitions, backing, and work over varied terrain develop the epaxial muscles supporting the spine. Progressive training that builds flexibility alongside strength prepares the back for collected work demands. Warm-up routines that mobilize the spine before demanding work prepare structures for exercise stress. Varied training including trail riding, hill work, and different disciplines prevents repetitive stress accumulation. Recognition that different horses require different conditioning programs based on individual conformation enables personalized approaches.

Environmental and equipment factors influence spinal health throughout the horse's life and career. Turnout allowing free movement supports natural back mobility and muscle development. Surface quality for work areas influences how forces are transmitted through the body during exercise. Trailer design and travel management affect back comfort during transport. Housing that allows adequate movement prevents stiffness that might exacerbate subclinical spinal issues. Regular assessment of all equipment contacting the back, including saddles, pads, and blankets, prevents pressure-related problems.

Breeding considerations for kissing spines prevention remain somewhat speculative given limited understanding of genetic contributions. Selection against horses with known kissing spines in breeding programs may reduce incidence in offspring, though the condition's development often requires environmental triggers acting on genetic predisposition. Evaluation of potential breeding animals for back conformation and spinal spacing may provide useful information. Documentation of kissing spines incidence within breeding programs enables informed decisions about genetic management. Research into hereditary components continues with hope of eventually identifying genetic markers enabling selection against predisposition.

Daily management adjustments for horses diagnosed with kissing spines incorporate practices supporting back comfort throughout all routine activities. Grooming approaches avoid excessive pressure over sensitive areas while still maintaining coat and skin health. Blanketing selection and fit ensures no pressure points develop over the spine. Feeding management may position hay and feed at heights encouraging comfortable back positions rather than extreme flexion or extension. Observation during daily handling notes any changes in comfort, movement quality, or attitude that might indicate flare-ups or improvement. Documentation of daily observations provides information supporting ongoing management decisions.

Housing and turnout considerations for horses with kissing spines balance activity benefits against potential risks of uncontrolled exuberant behavior. Regular turnout allowing free movement promotes natural back mobility and psychological wellbeing. Turnout group composition avoids highly playful companions likely to incite running or rough play that might exacerbate spinal stress. Footing in turnout areas maintained to prevent deep or uneven conditions that alter movement patterns. Shelter access protects against weather conditions that might cause muscle tension. Stall design provides adequate space for comfortable lying down and rising without awkward positioning.

Exercise modifications for horses with kissing spines history emphasize appropriate work supporting back health while avoiding activities that trigger symptoms. Longer warm-up periods prepare the back for work demands and reduce risk of acute episodes. Working initially in longer, lower frames before requesting collection minimizes early compression of spinous processes. Incorporation of stretching exercises including carrot stretches improves back flexibility. Modification or elimination of movements that consistently produce discomfort respects individual limitations. Some horses require permanent exclusions of certain activities while others return to full work following successful treatment.

Monitoring and ongoing care for horses living with kissing spines requires consistent attention to indicators of comfort and function. Regular assessment by owners familiar with individual normal patterns identifies subtle changes warranting veterinary evaluation. Periodic veterinary reexamination, typically annually for stable cases, assesses current status and guides any management modifications. Reassessment of saddle fit as horse musculature changes ensures equipment continues to support rather than hinder back health. Communication between owners, trainers, veterinarians, and other professionals involved in the horse's care coordinates comprehensive management.

Quality of life and use considerations guide long-term planning for horses with kissing spines based on individual response to treatment and ongoing needs. Many horses with well-managed kissing spines enjoy excellent quality of life continuing athletic careers at various levels. Assessment of comfort indicators during work and rest determines whether current management adequately addresses individual needs. Modification of expectations to match individual capability ensures horses are not asked to perform beyond their comfortable limits. Some horses may require transition to less demanding activities or retirement from ridden work to maintain acceptable quality of life. Regular honest evaluation ensures welfare remains the primary consideration in all management decisions.

High-risk breeds for kissing spines include several commonly used sport horse types, though the condition occurs across essentially all breeds to varying degrees. Thoroughbreds demonstrate high incidence rates in multiple studies, possibly related to their relatively long backs and the athletic demands of racing and sport horse careers. Warmbloods, particularly those bred for dressage with emphasis on collected movement capacity, show substantial kissing spines prevalence. Quarter Horses experience kissing spines less frequently than Thoroughbreds and Warmbloods but are not immune. Arabians and Arabian crosses may develop the condition, though perhaps less commonly than some other types. Draft breeds and draft crosses show lower incidence, possibly related to their generally shorter, more compact backs.

Use and discipline considerations significantly influence clinical kissing spines development and recognition. Dressage horses face particular risk given the collection, engagement, and spinal flexibility demands of their discipline, with kissing spines ranking among the most common diagnoses in performance-limited dressage horses. Show jumpers experience kissing spines related to the bascule demands of jumping and the cumulative impact of landing forces. Eventers encounter combined stresses from all three phases. Hunter horses in competitive programs face similar risks to jumpers. Pleasure and trail horses may develop kissing spines but often at lower rates and with less clinical significance given their reduced athletic demands. Racing Thoroughbreds may develop kissing spines that becomes clinically significant only when transitioned to second careers requiring different back use.

Genetic testing and breeding recommendations for kissing spines remain limited by current scientific understanding of hereditary contributions. No specific genetic tests identify kissing spines predisposition in horses at present. Selection of breeding stock based on back conformation evaluation may provide some guidance, though the relationship between visible conformation and internal spinal anatomy is imprecise. Documentation of kissing spines within bloodlines enables informed breeding decisions for producers concerned about the condition. Breeding horses with known kissing spines warrants consideration of the possible hereditary component, particularly when offspring are intended for careers placing high demands on back function. Research into genetic markers for spinal conformation may eventually enable more precise selection strategies.

Commonly co-occurring conditions with kissing spines include various musculoskeletal problems that may develop secondary to or alongside spinal pathology. Sacroiliac joint dysfunction frequently accompanies kissing spines, whether as a contributing cause, a consequence of compensatory movement, or a concurrent problem. Hindlimb lameness issues may develop as horses alter movement patterns to protect painful backs. Fore limb problems including navicular syndrome and heel pain may similarly result from compensatory changes. Muscle pathology including chronic tension, spasm, and atrophy develops in the epaxial and other muscles as secondary consequences of back pain. Gastric ulcers develop at high rates in horses experiencing chronic pain and stress.

Conditions with similar symptoms that must be differentiated from kissing spines include multiple sources of back pain and poor performance. Vertebral facet joint arthritis produces back pain through different structures and may require different treatment approaches. Sacroiliac joint disease causes hindquarter and back discomfort that overlaps significantly with kissing spines presentations. Soft tissue injuries to supraspinous and interspinous ligaments may occur independently of bony changes. Primary muscle disorders including myositis and tying up produce back pain without skeletal involvement. Referred pain from lameness elsewhere may manifest as apparent back sensitivity. Thorough diagnostic workup distinguishes between these conditions, though multiple problems frequently coexist.

Potential complications of kissing spines and its treatment warrant consideration in management planning. Progressive bone remodeling may continue despite treatment, potentially requiring additional interventions over time. Surgical complications including infection, delayed healing, or inadequate improvement occur in a minority of cases. Chronic pain syndromes may persist even after anatomical problems are addressed, particularly when pain has been present for extended periods before treatment. Secondary problems in other body regions developed during compensatory phases may persist after back pain is resolved. Behavioral patterns established during painful periods sometimes continue as learned responses requiring specific training approaches to modify even after physical comfort is restored.