Equine Musculoskeletal Disorders: Diagnosis and Treatment

Musculoskeletal disorders in horses encompass a wide range of conditions affecting bones, joints, muscles, tendons, and ligaments. This article provides veterinarians, veterinary students, and horse owners with diagnostic and treatment guidance for conditions including osteoarthritis, back pain, muscle disorders, fractures, and tendonitis. The focus is on practical diagnostic imaging approaches, treatment options, and management decisions supported by current evidence.

At a Glance

Diagnostic Imaging in Equine Musculoskeletal Disease

Radiography

Radiography remains the first-line imaging modality for evaluating equine musculoskeletal disorders. It provides assessment of bone structure, joint spaces, and fracture detection. Standard views for specific regions include weight-bearing and flexed projections for the distal limb, and oblique views for the proximal limb and spine. The Merck Veterinary Manual provides guidance on radiographic interpretation for common conditions such as osteoarthritis, subchondral bone cysts, and fractures [4].

Limitations of radiography include poor soft tissue contrast and inability to detect early cartilage damage. Radiographic changes in osteoarthritis, such as osteophyte formation and joint space narrowing, appear late in the disease process. For early diagnosis, advanced imaging modalities are required. When radiographs fail to explain the degree of lameness observed, the clinician should proceed to ultrasound or MRI instead of concluding the absence of pathology.

Ultrasound

Ultrasound is essential for evaluating soft tissue structures including tendons, ligaments, and muscles. It allows dynamic assessment during weight-bearing and non-weight-bearing positions. Tendonitis appears as hypoechoic or anechoic areas within the tendon substance, with loss of normal fiber alignment. The AAEP provides resources on ultrasound techniques for tendon and ligament evaluation in the horse [1].

Ultrasound is also useful for guided injections into joints, tendon sheaths, and bursae. It improves accuracy of medication delivery and reduces the risk of iatrogenic injury. For back pain evaluation, ultrasound can assess the supraspinous ligament, interspinous spaces, and epaxial muscles. The clinician should record cross-sectional area measurements and echogenicity scores for serial comparison during rehabilitation.

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) provides superior soft tissue contrast and is the gold standard for diagnosing early osteoarthritis, cartilage defects, and subchondral bone pathology. It is particularly valuable for the foot and proximal limb regions where radiography and ultrasound have limitations. The ACVIM offers guidelines on the use of MRI in equine practice [3].

MRI requires general anesthesia or heavy sedation and is expensive. Availability is limited to referral centers. Despite these limitations, MRI has improved diagnostic accuracy for conditions such as navicular syndrome, proximal suspensory desmitis, and stifle pathology. The decision to pursue MRI should be based on failure to localize the source of lameness with nerve blocks or when surgical intervention depends on precise characterization of soft tissue lesions.

Computed Tomography

Computed tomography (CT) is useful for complex fractures, particularly in the distal limb and skull. It provides three-dimensional reconstruction and better bone detail than radiography. CT is increasingly available at equine referral hospitals and is performed under general anesthesia. For articular fractures where fragment size and displacement determine surgical approach, CT provides superior preoperative planning information compared to radiography alone.

Osteoarthritis

Diagnosis

Osteoarthritis is a progressive degenerative joint disease characterized by cartilage loss, synovitis, and subchondral bone changes. Diagnosis is based on clinical examination, lameness evaluation, and imaging findings. The Merck Veterinary Manual describes osteoarthritis as a common cause of lameness in horses, particularly in performance animals [4].

Clinical signs include joint effusion, reduced range of motion, pain on flexion, and lameness that worsens with exercise. Radiographic findings include osteophyte formation, joint space narrowing, subchondral bone sclerosis, and cyst formation. However, radiographs may be normal in early disease. The clinician should document the grade of lameness using the AAEP scale (0 to 5) and record response to flexion tests for each affected joint.

Medical Treatment

Non-steroidal anti-inflammatory drugs (NSAIDs) are the mainstay of medical management for osteoarthritis. A 2022 review in the Equine Veterinary Journal discusses the use of NSAIDs in equine orthopaedics, including their efficacy and safety considerations [7]. Phenylbutazone and flunixin meglumine are commonly used, but long-term use carries risks of gastrointestinal ulceration and renal toxicity. The clinician should prescribe the lowest effective dose for the shortest duration and advise owners to monitor for signs of adverse effects including reduced appetite, colic, or diarrhea.

Intra-articular therapies include corticosteroids, hyaluronic acid, and polysulfated glycosaminoglycans. Corticosteroids provide rapid anti-inflammatory effects but may have chondrotoxic effects with repeated use. A 2022 review in the Journal of Equine Veterinary Science discusses intra-articular 2.5% polyacrylamide hydrogel as a new concept in osteoarthritis medication [8]. This synthetic gel provides long-term lubrication and pain relief without the risks associated with corticosteroids. The clinician should consider the number of previous intra-articular injections and the interval between treatments when selecting therapy.

Regenerative Therapies

Regenerative therapies for osteoarthritis include platelet-rich plasma (PRP), mesenchymal stem cells (MSCs), and autologous protein solution. A 2025 systematic review in Animals evaluates the clinical and experimental evidence for PRP in equine osteoarthritis [9]. PRP contains growth factors that may reduce inflammation and promote tissue healing. The clinician should consider the preparation method, platelet concentration, and activation protocol when selecting PRP products.

A 2023 review in Frontiers in Veterinary Science discusses strategies to enhance MSC-based acellular therapies for equine osteoarthritis [6]. MSCs have immunomodulatory and anti-inflammatory properties, but their efficacy depends on cell source, preparation, and delivery method. A 2024 systematic review in Cureus evaluates gold-induced cytokine (GOLDIC) therapy for osteoarthritis management, though this evidence is from human studies [10]. The clinician should discuss the experimental nature of some regenerative therapies and the variability in evidence quality with owners.

Surgical Treatment

Surgical options for osteoarthritis include arthroscopic debridement, osteochondral fragment removal, and joint lavage. For advanced disease, arthrodesis (joint fusion) may be considered for low-motion joints such as the pastern and hock. Surgical intervention is indicated when medical management fails to control pain and lameness. The clinician should refer horses requiring surgical treatment to a board-certified equine surgeon at a referral center.

Tendonitis and Desmitis

Diagnosis

Tendonitis and desmitis are common causes of lameness in performance horses. The superficial digital flexor tendon (SDFT) is most frequently affected. Diagnosis is based on clinical examination, palpation, and ultrasound. The AAEP provides guidelines for tendon and ligament evaluation [1].

Clinical signs include heat, swelling, pain on palpation, and lameness. Ultrasound reveals hypoechoic or anechoic areas within the tendon, loss of fiber alignment, and increased cross-sectional area. Chronic lesions may show hyperechoic areas representing fibrosis. The clinician should record the percentage of cross-sectional area affected, the length of the lesion, and the echogenicity score for monitoring progression.

Conservative Treatment

Conservative management includes controlled exercise, cold therapy, and anti-inflammatory medications. The initial phase involves stall rest with hand walking, progressing to controlled turnout and gradual return to work. NSAIDs are used for pain control but do not promote tendon healing. The clinician should provide a written rehabilitation protocol with specific timelines for each phase and criteria for progression based on ultrasound findings.

Regenerative Therapies

Regenerative therapies for tendonitis include PRP, MSCs, and amnion allografts. A 2022 study in BMC Veterinary Research reports outcomes following local injection of a liquid amnion allograft for treatment of equine tendonitis or desmitis in 100 cases [12]. Amnion allografts provide growth factors and anti-inflammatory cytokines that may improve healing. The clinician should discuss the evidence level for each therapy and the expected outcomes with owners.

A 2013 randomized controlled trial in Stem Cell Research and Therapy evaluates equine tendonitis therapy using MSCs and platelet concentrates [14]. The study found improved tendon healing with MSC therapy compared to controls. A 2016 study in Semina Ciencias Agrarias discusses adipose tissue as a source of MSCs for equine tendinitis treatment [13]. The clinician should consider the cell source, preparation method, and timing of injection when selecting MSC therapy.

A 2021 study in Frontiers in Veterinary Science evaluates autologous protein solution injection for treatment of superficial digital flexor tendonitis in an equine model [15]. Autologous protein solution contains concentrated growth factors and anti-inflammatory cytokines. The clinician should monitor for adverse reactions including injection site swelling or infection following regenerative therapy.

Surgical Treatment

Surgical options for tendonitis include tendon splitting, desmotomy, and tenoscopy. Tendon splitting is used for core lesions to promote drainage and healing. Desmotomy is performed for chronic desmitis of the accessory ligament of the SDFT. Tenoscopy allows minimally invasive evaluation and treatment of tendon sheath lesions. Surgical intervention is indicated when conservative and regenerative therapies fail to produce improvement after 3 to 6 months.

Back Pain

Diagnosis

Back pain is a common cause of poor performance in horses. Diagnosis is challenging due to the complex anatomy and overlapping clinical signs. The Merck Veterinary Manual discusses back pain evaluation, including palpation, range of motion assessment, and imaging [4].

Clinical signs include resistance to saddling, bucking, poor jumping performance, and behavioral changes. Palpation reveals muscle spasm, pain over the thoracolumbar spine, and reduced flexibility. Radiography can detect vertebral fractures, osteoarthritis of the articular processes, and kissing spines. The clinician should perform a systematic palpation of the epaxial muscles, supraspinous ligament, and spinous processes, recording areas of pain or muscle spasm.

Ultrasound is useful for evaluating the supraspinous ligament, interspinous spaces, and epaxial muscles. MRI provides detailed assessment of the intervertebral discs, nerve roots, and soft tissues. The clinician should consider referral for MRI when radiography and ultrasound fail to identify the source of back pain.

Treatment

Treatment of back pain depends on the underlying cause. For muscular pain, rest, massage, and controlled exercise are beneficial. NSAIDs and muscle relaxants provide symptomatic relief. Chiropractic manipulation and acupuncture may be helpful for some horses. The clinician should document the response to each treatment modality and adjust the plan accordingly.

For kissing spines (impinging dorsal spinous processes), treatment includes rest, anti-inflammatory medications, and corticosteroid injections between the affected spinous processes. Surgical options include interspinous ligament desmotomy or partial ostectomy of the spinous processes. The clinician should discuss the prognosis for return to athletic function with owners, as outcomes vary depending on the severity and location of impingement.

For osteoarthritis of the articular processes, intra-articular corticosteroid injections provide pain relief. Rehabilitation includes controlled exercise and gradual return to work. The clinician should monitor for progression of osteoarthritis and adjust treatment as needed.

Muscle Disorders

Diagnosis

Muscle disorders in horses include exertional rhabdomyolysis, polysaccharide storage myopathy (PSSM), and myotonia. Diagnosis is based on clinical signs, blood chemistry, and muscle biopsy. The Merck Veterinary Manual provides information on equine muscle disorders [4].

Clinical signs of exertional rhabdomyolysis include stiffness, sweating, reluctance to move, and dark urine. Blood chemistry reveals elevated creatine kinase (CK) and aspartate aminotransferase (AST). PSSM is characterized by recurrent episodes of exertional rhabdomyolysis and abnormal glycogen storage in muscle fibers. The clinician should collect blood samples for CK and AST measurement within 4 to 6 hours of the episode for accurate assessment.

Myotonia is a rare condition characterized by delayed muscle relaxation after contraction. Diagnosis is confirmed by electromyography and muscle biopsy. The clinician should refer suspected cases to a veterinary neurologist for specialized testing.

Treatment

Treatment of exertional rhabdomyolysis includes rest, fluid therapy, and NSAIDs. Severe cases require intravenous fluids and electrolyte supplementation. Dietary management includes reducing starch intake and increasing fat and fiber. The clinician should provide a written dietary plan and exercise protocol for affected horses.

For PSSM, dietary management is the mainstay of treatment. A low-starch, high-fat diet reduces the frequency and severity of episodes. Controlled exercise is important for maintaining muscle health. The clinician should monitor CK and AST levels periodically to assess response to dietary changes.

Fractures

Diagnosis

Fractures in horses range from minor chip fractures to catastrophic long bone fractures. Diagnosis is based on clinical examination and radiography. The Merck Veterinary Manual discusses fracture evaluation and management [4].

Clinical signs include acute severe lameness, swelling, instability, and crepitus. Radiography confirms the diagnosis and guides treatment decisions. CT provides detailed assessment of complex fractures. The clinician should obtain at least two orthogonal views and additional oblique views as needed to fully characterize the fracture configuration.

Treatment

Treatment depends on fracture location, configuration, and the horse's intended use. Conservative management with stall rest is appropriate for non-displaced fractures of the distal limb. Surgical fixation with plates and screws is required for displaced fractures and those involving weight-bearing bones. The clinician should refer horses with displaced or articular fractures to a board-certified equine surgeon.

Internal fixation techniques include dynamic compression plates, locking compression plates, and lag screw fixation. External coaptation with casts or splints is used for distal limb fractures. Arthrodesis may be necessary for fractures involving the pastern or hock joints. The clinician should discuss the prognosis for return to function and the risks of complications including implant failure and infection with owners.

Rehabilitation

Controlled Exercise Program

Rehabilitation is essential for successful recovery from musculoskeletal disorders. A controlled exercise program progresses from stall rest to hand walking, then to turnout, and finally to ridden work. The duration of each phase depends on the condition and response to treatment.

For tendonitis, the controlled exercise program typically lasts 6 to 12 months. Ultrasound monitoring guides the progression of exercise. The AAEP provides guidelines for rehabilitation after tendon and ligament injuries [1]. The clinician should provide a written rehabilitation protocol with specific timelines and criteria for progression at each phase.

Physical Therapy

Physical therapy modalities include cold therapy, heat therapy, massage, and therapeutic ultrasound. Cold therapy reduces inflammation and pain in acute injuries. Heat therapy promotes blood flow and tissue healing in chronic conditions. The clinician should instruct owners on proper application techniques and duration for each modality.

Therapeutic ultrasound provides deep heating and promotes tissue healing. Extracorporeal shock wave therapy is used for chronic tendonitis and desmitis. Laser therapy may reduce pain and inflammation. The clinician should document the type, frequency, and duration of each physical therapy modality used.

Regenerative Rehabilitation

Regenerative rehabilitation combines regenerative therapies with controlled exercise. PRP, MSCs, and amnion allografts are injected into the injured tissue, followed by a structured exercise program. A 2017 review in Operative Techniques in Sports Medicine discusses equine models for investigating MSC therapies in orthopaedic disease [16]. The clinician should monitor for adverse reactions and adjust the rehabilitation protocol based on serial imaging findings.

Common Failure Patterns

Incomplete Diagnosis

Failure to identify the primary cause of lameness leads to ineffective treatment. Common errors include relying solely on radiography without ultrasound or MRI, and failing to perform a thorough lameness examination. The AAEP provides guidelines for lameness evaluation [1]. The clinician should perform a systematic lameness examination including observation at walk and trot, flexion tests, and nerve blocks before proceeding to imaging.

Inadequate Rehabilitation

Premature return to work is a common cause of reinjury. Tendonitis and desmitis require prolonged rehabilitation, often 6 to 12 months. Owners may be reluctant to follow the controlled exercise program, leading to poor outcomes. The clinician should educate owners on the importance of adherence to the rehabilitation protocol and schedule regular rechecks to monitor progress.

Overuse of NSAIDs

Long-term NSAID use carries risks of gastrointestinal ulceration and renal toxicity. NSAIDs should be used at the lowest effective dose for the shortest duration. Alternatives such as intra-articular therapies and regenerative therapies should be considered for chronic conditions. The clinician should monitor renal function and gastrointestinal health in horses receiving long-term NSAID therapy.

Failure to Address Underlying Causes

Musculoskeletal disorders often have underlying causes such as poor conformation, improper shoeing, or inappropriate training. Addressing these factors is essential for long-term success. The Merck Veterinary Manual discusses the importance of preventive management [4]. The clinician should evaluate hoof balance, saddle fit, and training practices as part of the comprehensive assessment.

Welfare and Safety Context

Pain Management

Pain management is a welfare priority in equine musculoskeletal disorders. The World Organisation for Animal Health (WOAH) provides guidelines for animal health and welfare, including pain management in horses [5]. NSAIDs, intra-articular therapies, and regenerative therapies are used to control pain and improve quality of life. The clinician should assess pain using validated scoring systems and adjust treatment accordingly.

Withdrawal Periods

Horses treated with NSAIDs and other medications must observe withdrawal periods before slaughter for human consumption. Veterinarians must advise owners on appropriate withdrawal times based on the medications used. The AAEP provides resources on medication withdrawal times [1]. The clinician should document withdrawal periods in the medical record and provide written instructions to owners.

Regulatory Considerations

Regulatory considerations include the use of medications in competition horses. Many NSAIDs and intra-articular therapies are prohibited in competition. The ACVIM provides guidelines on medication use in performance horses [3]. The clinician should verify competition rules before prescribing medications and advise owners on permitted alternatives.

Professional Escalation Criteria

Urgent Escalation

Urgent escalation to a referral center is indicated for:

• Acute severe lameness with suspected fracture
• Open fractures or joint penetration
• Neurologic deficits
• Severe colic or systemic illness
• Failure to respond to initial treatment within 48 hours

The clinician should stabilize the horse before transport and provide referral center staff with a summary of findings and treatments administered.

Routine Escalation

Routine escalation is indicated for:

• Chronic lameness that does not respond to treatment
• Need for advanced imaging (MRI, CT)
• Surgical intervention
• Complex fractures
• Regenerative therapy

The clinician should provide referral center staff with complete medical records including lameness examination findings, imaging studies, and treatment history.

Records and Measurements

Lameness Examination Records

Standardized lameness examination records include:

• Grade of lameness (AAEP scale 0 to 5)
• Response to flexion tests
• Response to nerve blocks
• Imaging findings
• Treatment plan

The clinician should record the date, examiner, and conditions of the examination for each entry.

Imaging Records

Imaging records should include:

• Views obtained
• Findings
• Comparison with previous studies
• Recommendations for follow-up

The clinician should store digital images in a secure system and provide copies to owners and referral centers as needed.

Treatment Records

Treatment records should include:

• Medications used, dose, route, and frequency
• Response to treatment
• Adverse effects
• Withdrawal periods

The clinician should update treatment records at each recheck and communicate changes to owners in writing.

Practical Decision Framework for Selecting Musculoskeletal Therapies in Horses

Selecting the appropriate therapy for equine musculoskeletal disorders requires a systematic approach that integrates diagnostic findings, evidence quality, cost considerations, and expected outcomes. A structured decision framework helps clinicians avoid common errors such as over-reliance on a single treatment modality or failure to consider the stage of disease. This section provides a practical decision framework for selecting therapies across the major musculoskeletal conditions, with emphasis on matching treatment intensity to disease severity and intended use of the horse.

Decision Framework for Osteoarthritis Therapy Selection

Osteoarthritis management requires matching treatment to disease stage, joint affected, and performance demands. The clinician should classify osteoarthritis into early, moderate, and advanced stages based on clinical and imaging findings. Early osteoarthritis presents with mild lameness that resolves with rest, minimal radiographic changes, and normal or mildly reduced joint range of motion. Moderate osteoarthritis shows consistent lameness with work, radiographic evidence of osteophytes or joint space narrowing, and palpable joint effusion. Advanced osteoarthritis presents with persistent lameness at rest or with minimal exercise, marked radiographic changes including subchondral bone sclerosis and cyst formation, and reduced joint mobility.

For early osteoarthritis, first-line therapy includes systemic NSAIDs administered at the lowest effective dose for the shortest duration, combined with controlled exercise modification. The 2022 review in the Equine Veterinary Journal on NSAIDs in equine orthopaedics emphasizes the importance of using these medications judiciously to minimize adverse effects [7]. Intra-articular hyaluronic acid may be considered for joints that do not respond to systemic therapy alone. The clinician should document the lameness grade before and after a 7 to 14 day trial of NSAID therapy to assess response.

For moderate osteoarthritis, intra-articular therapies become the primary treatment modality. The clinician should select between corticosteroids, hyaluronic acid, polysulfated glycosaminoglycans, and polyacrylamide hydrogel based on the joint affected and the horse's intended use. A 2022 review in the Journal of Equine Veterinary Science discusses intra-articular 2.5% polyacrylamide hydrogel as a new concept in osteoarthritis medication, noting its potential for providing long-term lubrication without the chondrotoxic risks associated with repeated corticosteroid use [8]. For high-motion joints such as the stifle and fetlock, the clinician may prefer hyaluronic acid or polyacrylamide hydrogel over corticosteroids to minimize cartilage damage. For low-motion joints such as the hock, corticosteroids remain effective and carry lower risk.

For advanced osteoarthritis, regenerative therapies including platelet-rich plasma (PRP) and mesenchymal stem cells (MSCs) may be considered when conventional therapies fail. A 2025 systematic review in Animals evaluates the clinical and experimental evidence for PRP in equine osteoarthritis, noting variability in study quality and outcomes [9]. The clinician should discuss the experimental nature of these therapies and the lack of standardized protocols with owners. Surgical options including arthroscopic debridement and arthrodesis are reserved for cases where medical management fails to control pain and lameness. The clinician should refer horses requiring surgical intervention to a board-certified equine surgeon.

Decision Framework for Tendonitis Therapy Selection

Tendonitis therapy selection depends on lesion severity, chronicity, and the horse's athletic discipline. The clinician should classify tendonitis based on ultrasound findings into mild, moderate, and severe categories. Mild tendonitis shows less than 20 percent cross-sectional area involvement with minimal fiber disruption. Moderate tendonitis shows 20 to 50 percent cross-sectional area involvement with moderate fiber disruption. Severe tendonitis shows greater than 50 percent cross-sectional area involvement with complete fiber disruption or core lesion formation.

For mild tendonitis, conservative management with controlled exercise and cold therapy is appropriate. The clinician should prescribe a written rehabilitation protocol with specific timelines for each phase. Hand walking begins immediately and continues for 4 to 6 weeks, followed by gradual introduction of trotting if ultrasound shows improvement. NSAIDs are used for pain control during the first 7 to 14 days but do not promote tendon healing. The AAEP provides guidelines for rehabilitation after tendon and ligament injuries [1].

For moderate tendonitis, regenerative therapies should be considered in addition to controlled exercise. PRP is the most commonly used regenerative therapy for tendonitis and has the strongest evidence base. A 2013 randomized controlled trial in Stem Cell Research and Therapy evaluated equine tendonitis therapy using MSCs and platelet concentrates, finding improved tendon healing with MSC therapy compared to controls [14]. A 2022 study in BMC Veterinary Research reports outcomes following local injection of a liquid amnion allograft for treatment of equine tendonitis or desmitis in 100 cases, with favorable results [12]. The clinician should select the regenerative therapy based on availability, cost, and evidence quality. PRP is generally preferred for acute lesions, while MSCs may be more appropriate for chronic or recurrent lesions.

For severe tendonitis with core lesions, surgical intervention may be necessary. Tendon splitting allows drainage of the core lesion and promotes healing. The clinician should refer horses with severe tendonitis to a board-certified equine surgeon for evaluation. Postoperative rehabilitation is prolonged, typically lasting 9 to 12 months. The clinician should monitor ultrasound findings at 3-month intervals to guide exercise progression.

Decision Framework for Back Pain Therapy Selection

Back pain therapy selection depends on the underlying cause, which may include muscular pain, osteoarthritis of the articular processes, kissing spines, or vertebral fractures. The clinician should perform a systematic diagnostic workup including palpation, range of motion assessment, radiography, and ultrasound before selecting therapy.

For muscular back pain, first-line therapy includes rest, massage, and controlled exercise. NSAIDs and muscle relaxants provide symptomatic relief during the acute phase. The clinician should evaluate saddle fit and training practices as contributing factors. Chiropractic manipulation and acupuncture may be helpful for some horses, though evidence for these modalities is limited. The clinician should document the response to each treatment modality and adjust the plan accordingly.

For kissing spines (impinging dorsal spinous processes), treatment depends on the severity of impingement and clinical signs. Mild cases may respond to rest, anti-inflammatory medications, and corticosteroid injections between the affected spinous processes. Moderate to severe cases may require surgical intervention including interspinous ligament desmotomy or partial ostectomy of the spinous processes. The clinician should discuss the prognosis for return to athletic function with owners, as outcomes vary depending on the severity and location of impingement.

For osteoarthritis of the articular processes, intra-articular corticosteroid injections provide pain relief. The clinician should use ultrasound guidance to ensure accurate needle placement. Rehabilitation includes controlled exercise and gradual return to work. The clinician should monitor for progression of osteoarthritis and adjust treatment as needed.

Record System for Therapy Selection and Monitoring

A standardized record system for therapy selection and monitoring improves clinical decision-making and facilitates communication with owners and referral centers. The clinician should maintain a treatment log for each horse that includes the following elements:

• Date of diagnosis and condition classification
• Diagnostic findings including lameness grade, imaging results, and nerve block responses
• Treatment selected and rationale for selection
• Dose, route, and frequency of medications administered
• Response to treatment at specified intervals (7 days, 30 days, 90 days)
• Adverse effects observed
• Withdrawal periods for medications
• Rehabilitation protocol and progression criteria
• Date of next recheck

The clinician should use the AAEP lameness grading scale (0 to 5) for consistent documentation of lameness severity [1]. For ultrasound monitoring of tendonitis, the clinician should record cross-sectional area measurements, echogenicity scores, and percentage of fiber disruption at each recheck. For radiographic monitoring of osteoarthritis, the clinician should record the presence and severity of osteophytes, joint space narrowing, and subchondral bone changes.

Troubleshooting Common Treatment Failures

When a horse fails to respond to initial therapy, the clinician should systematically evaluate potential causes of treatment failure. Common failure patterns include incorrect diagnosis, inadequate treatment intensity, poor owner compliance, and progression of disease.

For incorrect diagnosis, the clinician should review the lameness examination findings and consider the need for additional diagnostic tests. If radiographs were normal but lameness persists, the clinician should proceed to ultrasound or MRI instead of concluding the absence of pathology. The ACVIM offers guidelines on the use of advanced imaging in equine practice [3].

For inadequate treatment intensity, the clinician should evaluate whether the selected therapy matches the disease severity. For example, a horse with moderate osteoarthritis may require intra-articular therapy instead of systemic NSAIDs alone. The clinician should also consider whether the rehabilitation protocol is appropriate for the condition being treated.

For poor owner compliance, the clinician should provide written instructions for medication administration, exercise restrictions, and recheck appointments. The clinician should schedule regular follow-up calls or visits to monitor progress and address owner concerns.

For progression of disease, the clinician should repeat diagnostic imaging to assess changes in the condition. If osteoarthritis has progressed from moderate to advanced, the clinician may need to consider regenerative therapies or surgical intervention. The clinician should discuss the prognosis and treatment options with owners and consider referral to a specialist if needed.

Welfare and Safety Considerations in Therapy Selection

The World Organisation for Animal Health (WOAH) provides guidelines for animal health and welfare, including pain management in horses [5]. The clinician should prioritize pain relief while minimizing the risks of adverse effects from medications. NSAIDs should be used at the lowest effective dose for the shortest duration, and the clinician should monitor for signs of gastrointestinal ulceration or renal toxicity.

Withdrawal periods for medications must be observed before horses are slaughtered for human consumption. The AAEP provides resources on medication withdrawal times [1]. The clinician should document withdrawal periods in the medical record and provide written instructions to owners.

Regulatory considerations include the use of medications in competition horses. Many NSAIDs and intra-articular therapies are prohibited in competition. The ACVIM provides guidelines on medication use in performance horses [3]. The clinician should verify competition rules before prescribing medications and advise owners on permitted alternatives.

Professional Escalation Criteria for Therapy Selection

The clinician should recognize when a case exceeds their expertise or available resources and requires referral to a specialist. Urgent escalation is indicated for horses with acute severe lameness, suspected fracture, open joint injuries, or neurologic deficits. The clinician should stabilize the horse before transport and provide referral center staff with a summary of findings and treatments administered.

Routine escalation is indicated for horses with chronic lameness that does not respond to initial therapy, need for advanced imaging (MRI, CT), surgical intervention, complex fractures, or regenerative therapy. The clinician should provide referral center staff with complete medical records including lameness examination findings, imaging studies, and treatment history.

The decision to escalate care should be based on the horse's welfare, the owner's expectations, and the clinician's assessment of their ability to provide appropriate care. The clinician should discuss the reasons for referral with owners and provide them with information about the referral center and expected costs.

Frequently Asked Questions

What is the most common cause of stifle lameness in horses?

Stifle lameness in horses is most commonly caused by osteoarthritis of the femorotibial and femoropatellar joints. Other causes include osteochondritis dissecans, subchondral bone cysts, and meniscal injuries. Diagnosis requires a thorough lameness examination, radiography, and often ultrasound or MRI. The Merck Veterinary Manual provides information on stifle conditions in horses [4]. The clinician should perform flexion tests of the stifle and hindlimb and use intra-articular nerve blocks to localize the source of pain.

How is a lameness examination performed in horses?

A lameness examination involves observing the horse at walk and trot on a hard surface, performing flexion tests, and using nerve blocks to localize the source of pain. The AAEP provides guidelines for lameness evaluation [1]. The horse is observed from the front, back, and sides to detect asymmetry in head nod, hip hike, and foot placement. The clinician should record the grade of lameness and response to each diagnostic test.

What causes back pain in horses?

Back pain in horses can be caused by muscular strain, osteoarthritis of the articular processes, kissing spines (impinging dorsal spinous processes), and vertebral fractures. Poor saddle fit, improper training, and conformational abnormalities contribute to back pain. The Merck Veterinary Manual discusses back pain evaluation and treatment [4]. The clinician should perform a systematic palpation of the back and recommend saddle fitting evaluation as part of the diagnostic workup.

Is osteoporosis a common condition in horses?

Osteoporosis is not a common clinical condition in horses. Horses more commonly develop osteoarthritis and subchondral bone cysts. Osteoporosis may occur in older horses or those with nutritional deficiencies, but it is rarely diagnosed as a primary cause of lameness. The Merck Veterinary Manual provides information on bone disorders in horses [4]. The clinician should consider other causes of lameness before pursuing a diagnosis of osteoporosis.

What is myotonia in horses?

Myotonia is a rare muscle disorder characterized by delayed muscle relaxation after contraction. It is caused by a genetic mutation affecting ion channels in muscle cells. Diagnosis is confirmed by electromyography and muscle biopsy. There is no specific treatment, but management focuses on avoiding triggers and maintaining muscle health. The Merck Veterinary Manual discusses myotonia in horses [4]. The clinician should refer suspected cases to a veterinary neurologist for specialized testing.

What are the treatment options for equine tendonitis?

Treatment options for equine tendonitis include conservative management with controlled exercise and anti-inflammatory medications, regenerative therapies such as PRP and MSCs, and surgical intervention for severe cases. A 2022 study in BMC Veterinary Research reports outcomes following local injection of a liquid amnion allograft for treatment of equine tendonitis [12]. Rehabilitation is essential for successful recovery. The clinician should discuss the evidence level for each therapy and the expected outcomes with owners.

How long does it take for a horse to recover from tendonitis?

Recovery from tendonitis typically takes 6 to 12 months, depending on the severity of the injury and the horse's response to treatment. A controlled exercise program is essential for successful recovery. Ultrasound monitoring guides the progression of exercise. The AAEP provides guidelines for rehabilitation after tendon and ligament injuries [1]. The clinician should provide a written rehabilitation protocol with specific timelines and criteria for progression.

What is the role of NSAIDs in equine orthopaedics?

NSAIDs are used for pain control and inflammation reduction in equine orthopaedics. A 2022 review in the Equine Veterinary Journal discusses the use of NSAIDs in equine orthopaedics [7]. Phenylbutazone and flunixin meglumine are commonly used, but long-term use carries risks of gastrointestinal ulceration and renal toxicity. NSAIDs should be used at the lowest effective dose for the shortest duration. The clinician should monitor for adverse effects and consider alternative therapies for chronic conditions.

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References and Further Reading

• aaep.org
• www.merckvetmanual.com
• www.acvim.org
• Merck Veterinary Manual. Merck Veterinary Manual.
• Animal Health and Welfare. World Organisation for Animal Health.
• Equine osteoarthritis: Strategies to enhance mesenchymal stromal cell-based acellular therapies.. Frontiers in veterinary science, 2023.
• Non-steroidal anti-inflammatory drugs in equine orthopaedics.. Equine veterinary journal, 2022.
• Intra-articular 2.5% polyacrylamide hydrogel, a new concept in the medication of equine osteoarthritis: A review.. Journal of equine veterinary science, 2022.
• Platelet-Rich Plasma in Equine Osteoarthritis: A Systematic Review of Clinical and Experimental Evidence.. Animals : an open access journal from MDPI, 2025.
• Gold-Induced Cytokine (GOLDIC) for the Management of Knee Osteoarthritis: A Systematic Review.. Cureus, 2024.
• Sheep Models in Translational Surgery.. European surgical research. Europaische chirurgische Forschung. Recherches chirurgicales europeennes, 2025.
• Outcome following local injection of a liquid amnion allograft for treatment of equine tendonitis or desmitis - 100 cases. BMC Veterinary Research, 2022.
• Adipose tissue as mesenchymal stem cells source in equine tendinitis treatment. Semina Ciencias Agrarias, 2016.
• Equine tendonitis therapy using mesenchymal stem cells and platelet concentrates: A randomized controlled trial. Stem Cell Research and Therapy, 2013.
• Evaluation of Autologous Protein Solution Injection for Treatment of Superficial Digital Flexor Tendonitis in an Equine Model. Frontiers in Veterinary Science, 2021.
• Equine Models for the Investigation of Mesenchymal Stem Cell Therapies in Orthopaedic Disease. Operative Techniques in Sports Medicine, 2017.

This article is educational and is not a substitute for veterinary diagnosis or treatment. Contact a veterinarian for advice about an individual animal.