Mineralization of the supraspinatus tendon in dogs

Mineralization of the supraspinatus tendon is proposed as a cause of forelimb lameness in dogs. A new radiographic position (cranioproximal-cranio-distal) is advanced to detect abnormalities of the craniomedial aspect of the proximal portion of the humerus. Four dogs had surgery to remove mineralized debris from the supraspinatus tendon insertion and have improved limb function. Two dogs were evaluated in depth, with no signs of relapse 2 to 4 years after surgery. Other dogs, without apparent forelimb lameness, have had mineralization detected by use of radiography, thus emphasizing the need for thorough forelimb evaluation before determining that the mineralization is indeed the cause of lameness.     

Mineralization of the supraspinatus tendon in dogs: a long-term follow-up

Mineralization of the supraspinatus tendon was diagnosed in 24 large-breed dogs as a probable cause for a chronic unilateral forelimb lameness. Owners of 12 dogs responded to a questionnaire survey evaluating the treatment that their dog had received which consisted of either surgical removal of the mineralization after failure of conservative treatment (operated group; n=9) or rest and nonsteroidal anti-inflammatory drugs (NSAIDs) (nonoperated group; n=3). In eight out of the 12 dogs, the mineralization was also present in the asymptomatic forelimb. Based on owner evaluation, the degree of lameness had decreased distinctly in both groups. Six dogs (four operated and two nonoperated) were reevaluated at Michigan State University Veterinary Teaching Hospital (MSU-VTH) and were without lameness except for one dog in the operated group. The mineralizations had reformed in all dogs in the operated group after a mean follow-up time of 5.1 years.     

Supraspinatus tendinosis associated with biceps brachii tendon displacement in a dog

A 4-year-old spayed female Australian Cattle Dog (Blue Heeler) was evaluated because of right forelimb lameness of 5 months' duration. Orthopedic evaluation revealed signs of pain localized to the cranial aspects of both shoulder joints. Via magnetic resonance imaging, the mass of the supraspinatus tendon insertion in both shoulder joints was increased, compared with findings in cadavers of clinically normal dogs; additional imaging procedures revealed that, compared with clinically normal tendons, the tendon had increased signal intensity that was consistent with increased fluid content. The increased supraspinatus tendon mass in each shoulder joint was associated with medial displacement of the biceps brachii tendon, which was more severe in the right limb. Arthroscopic evaluations of both shoulder joints revealed no abnormalities. The dog underwent surgery, and the abnormal parts of the tendons were resected. The most prominent finding on histologic examination of excised tissues was severe myxomatous degeneration. The lameness resolved, and at 22 months after surgery, the dog was reported to have had no recurrence of lameness. The clinical signs and histologic appearance of the tendons in this dog strongly resemble findings associated with tendinosis in humans. Decompression of the biceps brachii tendon may have contributed to the successful outcome after surgery in this dog. Supraspinatus tendinosis should be considered among the differential diagnoses in dogs with uni- or bilateral forelimb lameness.     

Surgical treatment of lumbosacral foraminal stenosis using a lateral approach in twenty dogs with degenerative lumbosacral stenosis

Objectives— To describe clinical signs, magnetic resonance imaging (MRI) and surgical findings using a lateral approach to the lumbosacral intervertebral foramen and to evaluate clinical outcomes in dogs with or without concurrent dorsal decompression and annulectomy.
Study Design— Retrospective study.
Animals— Dogs (n=20) with degenerative lumbosacral stenosis (DLSS).
Methods— Medical records (2002–2006) of dogs that had lumbosacral lateral foraminotomy alone or in combination with dorsal decompression were reviewed. Degree of dysfunction was assessed separately for each pelvic limb; dogs with unilateral signs were included in group A, those with bilateral signs in group B. Retrieved data were: signalment, history, neurologic status on admission, 3 days, 6 weeks, and 6 months postoperatively, duration of clinical signs, results of MRI, surgical site(s), intraoperative findings, and outcome.
Results— Based on the clinical and MRI findings unilateral foraminotomy was performed in 8 dogs, bilateral foraminotomy in 1 dog, unilateral foraminotomy with concurrent dorsal decompression in 7 dogs, and bilateral foraminotomy with concomitant dorsal decompression in 4 dogs. Surgery confirmed the presence of foraminal stenosis in all dogs, with osteophyte formation and soft tissue proliferations being the most common lesions. Outcome was good to excellent in 19 dogs and poor in 1 dog. Mean follow-up was 15.2 months (range, 6–42 months).
Conclusion— Lateral foraminotomy addresses compressive lesions within exit and middle zones of the lumbosacral foramen.
Clinical Relevance— Successful surgical management of DLSS is dependent on recognition and correction of each of the compressive lesions within the lumbosacral junction.     

Achilles Tendon Repair in Dogs Using the Semitendinosus Muscle: Surgical Technique and Short-Term Outcome in Five Dogs

Objective— To describe augmentation of primary Achilles tendon repair using suture with a semitendinosus muscle flap and report outcome in 5 dogs.
Study Design— Prospective clinical study.
Animals— Dogs (n=5) with Achilles tendon rupture (n=6).
Methods— After tendon repair with #2 polypropylene in a 3-loop pulley suture pattern, the lateral one-half of the semitendinosus muscle was transected from the ischium, rotated distally then sutured with #2 polypropylene to the calcaneus in a 3-loop pulley pattern. The epitenon was sutured to the muscle flap fascia with interrupted sutures. All dogs had a bivalved cast for 2 weeks then a cranial splint for 2–6 weeks. Lameness scores (0=stands and walks normally to 4=non-weight-bearing lameness, plantigrade stance on affected pelvic limb) were determined every 2–3 weeks postoperatively for 12 weeks. Outcome was determined from telephone questionnaire of owners.
Results— Four had lameness scores of 0, the 5th had a score of 1 at 12 weeks. Three owners were very satisfied with outcome. Minor complications included cast sores (2 dogs), infection (2), and acute swelling (1); 1 major complication occurred (infection resulting in reoperation).
Conclusions— Semitendinosus flap augmentation resulted in early return to function without prolonged postoperative immobilization. Three dogs returned to full work/activity after repair.
Clinical Relevance— Augmentation of primary Achilles tendon repair with a semitendinosus flap can be considered in dogs with chronic rupture but further investigation of the long-term outcome using this technique is needed.     

Treatment of dogs diagnosed with medial shoulder instability using radiofrequency-induced thermal capsulorrhaphy

OBJECTIVE: To report clinical findings and outcome in dogs diagnosed with medial shoulder instability (MSI) treated with radiofrequency-induced thermal capsulorrhaphy (RITC). STUDY DESIGN: Retrospective study. ANIMALS: Dogs (n=43) with MSI. METHODS: Medical records from consecutive cases with MSI based on orthopedic examination, palpation of shoulder abduction angles, and arthroscopic findings were used to determine clinical findings and long-term (> or = 1 year) outcome of RITC. RESULTS: Forty-three dogs met the criteria for inclusion; 2 dogs had bilateral MSI. The most common clinical findings were chronic unilateral weight-bearing lameness, large (> 45 degrees) shoulder abduction angles, and spinatus muscle atrophy in the affected limb. Mean preoperative abduction angle (50.7 degrees +/- 4.8 degrees) in affected shoulders was significantly larger than in the unaffected shoulders (32.5 degrees +/- 2.1 degrees). Mean postoperative abduction angle in affected shoulders was not significantly different from unaffected shoulders when measured immediately, 8, 16-20 weeks, and approximately 1 year after surgery. Follow-up evaluation ranged from 1 to 6.2 years. RITC treatment resulted in improved clinical function in 40 cases (93%) with 34 cases (79%) considered excellent; 3 cases (7%) were considered failures. CONCLUSIONS: RITC was a safe and effective method of treatment of MSI in most dogs studied. CLINICAL RELEVANCE: RITC can be considered as a viable option for surgical treatment of selected cases of MSI in dogs.     

Single ultrasound-guided platelet-rich plasma injection for treatment of supraspinatus tendinopathy in dogs

The effect of a single platelet-rich plasma injection for supraspinatus tendinopathy was assessed in 10 dogs. Subjective (owner-assessed) improvement in lameness and function were seen in 40% of dogs with improved tendon heterogeneity and echogenicity in 60%. There were no significant changes in gait reaction forces 6 wk after treatment.     

Patellar luxation in 70 large breed dogs

O bjectives : To report the signalment, history, clinical features, and outcome in dogs weighing greater than 15 kg, treated surgically and non-surgically for patellar luxation. Risk factors for the development of patellar luxation, postoperative complications, and outcome were evaluated.
M ethods : Details regarding signalment, bodyweight, breed, aetiology, unilateral or bilateral luxation, duration of lameness, grade of luxation, direction of luxation, grade of lameness at presentation, concomitant cranial cruciate ligament rupture, method of treatment, surgical technique, surgeon, and complications were obtained from the medical records. Outcome was graded as excellent, good, fair, or poor, according to the degree of lameness.
R esults : Seventy dogs (45 males and 25 females) were included. Thirty-five had bilateral luxations (105 limbs). Mean age was two years, and mean weight was 30 kg. The relative risk for Labrador retrievers was 3·3 (P<0·001). All luxations were developmental. Luxations were medial in 102 stifles and lateral in three. Fourteen stifles had concomitant cranial cruciate ligament rupture. As the grade of patellar luxation increased, so did the grade of lameness (P<0·001). Surgery was performed in 70 stifles, and outcome was excellent/good in 94 per cent and fair/poor in 6 per cent of stifles. Complications occurred in 29 per cent of stifles, and increasing bodyweight was found to be a risk factor (P=0·03). Thirty-five stifles were managed non-surgically, and outcome was excellent/good in 86 per cent and fair/poor in 14 per cent of stifles.
C linical S ignificance : In view of the potential risk of postoperative complications, all surgically treated cases of patellar luxation in large breed dogs should be managed with a femoral trochleoplasty, a tibial tuberosity transposition (stabilised with K-wires and a tension band wire), and soft tissue releasing and tightening procedures.     

Ossification of the infraspinatus tendon-bursa in 13 dogs

Ossification of the infraspinatus tendon-bursa was diagnosed in 13 labrador retrievers, 12 of which were lame in one thoracic limb and the other in both. They ranged in age from 28 to 121 months (mean 69.4 months). The lameness developed gradually and was progressive in 11 of the 14 affected joints. Scapular muscle atrophy and signs of pain on direct pressure over the infraspinatus tendon of insertion were key clinical signs. Caudocranial radiographs revealed multiple mineralised masses lateral to the proximal humerus or glenohumeral joint in 11 of the 26 joints and single masses in 12. An arthroscopic examination revealed concomitant ligament or tendon abnormalities in six of seven shoulders. The dogs were followed up from one to 55 months (mean 20 months). Of five shoulders treated with non-steroidal anti-inflammatory drugs (nsaids), one resolved, two improved and two were managed surgically. Of six shoulders treated by the injection of long-acting intra-articular corticosteroid (five before and one after surgery), three resolved, two improved and one was unchanged. Of six shoulders treated by the surgical resection of the infraspinatus tendon and bursa (three before and two after treatment with nsaids, and one after treatment with a long-acting intra-articular corticosteroid), four improved, one was unchanged and one was managed with an intra-articular long-acting corticosteroid. One shoulder was managed by restricted exercise and the lameness resolved. Histological examination of the excised tissues revealed heterotopic bone within the infraspinatus tendon and/or bursa.     

Ventral intraspinal cysts associated with the intervertebral disc: magnetic resonance imaging observations in seven dogs

Objective— To report clinical and diagnostic imaging features, and outcome after surgical treatment of ventral intraspinal cysts in dogs.
Study Design— Retrospective study.
Animals— Dogs (n=7) with ventral intraspinal cysts.
Methods— Clinical signs, magnetic resonance imaging (MRI) findings and surgical findings of 7 dogs and histologic findings (1 dog) with intraspinal cysts associated with the intervertebral disc were reviewed.
Results— Ventral intraspinal cyst is characterized by: (1) clinical signs indistinguishable from those of typical disc herniation; (2) an extradural, round to oval, mass lesion with low T1 and high T2 signal intensity on MRI, compatible with a liquid-containing cyst; (3) cyst is in close proximity to the intervertebral disc; and (4) MRI signs of disc degeneration. Although the exact cause is unknown, underlying minor disc injury may predispose to cyst formation.
Conclusion— Intraspinal cysts have clinical signs identical to those of disc herniation. Given the close proximity of the cyst to the corresponding disc and the similarity of MRI findings to discal cysts in humans, we propose the term "canine discal cyst" to describe this observation.
Clinical Relevance— Discal cysts should be considered in the differential choices for cystic extradural compressing lesions.     

Unusual muscle and tendon disorders of the forelimb in the dog

Five dogs with unusual muscle and tendon disorders of the forelimb are described. In one dog, mineralisation of the tendon of insertion of the supraspinatus muscle was treated surgically but lameness returned following the resumption of exercise. Of two cases of avulsion of the origin of the extensor carpi radialis muscle, one was successfully managed conservatively while the other needed surgical intervention to resolve the lameness. A single case of chronic avulsion/rupture of the tendon of insertion of the extensor carpi radialis muscle was successfully managed conservatively while a case of medial displacement of the biceps brachii tendon was surgically corrected by repair of the transverse humeral ligament. The aetiology, diagnosis and management of the above conditions is discussed.     

Desmitis of the distal digital annular ligament in seven horses: MRI diagnosis and surgical treatment

Objective— (1) To describe the clinical signs and abnormalities observed on magnetic resonance imaging (MRI) in 7 horses with desmitis of the distal digital annular ligament (DDAL); (2) to describe the normal magnetic resonance (MR) appearance and thickness of the DDAL in health; and (3) to describe a tenoscopic surgical technique for treating horses with desmitis of the DDAL.
Study Design— Retrospective study.
Animals— Horses (n=7) with desmitis of the DDAL.
Methods— MR examinations of 20 sound horses were reviewed to determine the normal appearance of the DDAL. Dimensions obtained from these images were compared with MR findings from 7 horses with DDAL desmitis. Desmitis of the DDAL was treated by tenoscopic surgery and outcome assessed.
Results— Horses with DDAL desmitis had lameness (grade 2–3 out of 5) that improved after a palmar digital nerve block. The affected DDAL was enlarged and had an abnormal signal on MR images of the feet. After tenoscopy and DDAL transection, 5 horses returned to athletic performance, including 2 horses that failed to respond to medical treatment and rest before surgery.
Conclusion— Primary desmitis of the DDAL is a cause of lameness in horses. Transection of the DDAL allowed 5 horses with this injury to return to athletic performance.
Clinical Relevance— DDAL desmitis should be included in the differential diagnoses of horses with lameness that improves after a palmar digital nerve block but have no abnormalities observed on radiographs of the feet. Tenoscopic surgical transection of the DDAL is an effective treatment for some horses.     

Magnetic Resonance Imaging Findings in Dogs with Confirmed Shoulder Pathology

Objective— To evaluate the diagnostic potential of magnetic resonance imaging (MRI) compared with a reference standard, arthroscopic and/or open surgery, in dogs with soft tissue shoulder pathology. Study Design— Retrospective study. Animals— Dogs (n=21). Methods— Magnetic resonance (MR) images were retrospectively evaluated in 21 dogs that had surgically identified soft tissue shoulder pathology. The musculotendinous units of the biceps, infraspinatus, teres minor, supraspinatus, subscapularis, and the medial and lateral glenohumeral ligaments (MGHL and LGHL) were graded as either normal or abnormal. Abnormal structures were further classified as being either inflamed, partially torn, or fully torn. Impingement of the biceps tendon was also evaluated. Results were reported in terms of agreement and concordance between MRI findings and surgical findings. Agreement was defined as the percentage of times MRI findings concurred with surgical findings with respect to a structure being either normal or abnormal. Concordance was defined as the percentage of times MRI concurred with the exact surgically assessed pathology when abnormality was identified. Results— The findings were biceps tendon: 90% agreement with 100% concordance; subscapularis: 95% agreement with 62% concordance; MGHL: 84% agreement with 83% concordance; LGHL: 88% agreement with 100% concordance; infraspinatus: 100% both agreement and concordance; biceps tendon impingement: 90% agreement with 100% concordance. Conclusions— Soft tissue abnormalities of the canine shoulder were readily identified on preoperative MR images. Clinical Relevance— MRI shows great potential as a diagnostic tool in the evaluation of canine shoulder disease.     

Evaluation of the prognostic value of positive-contrast shoulder arthrography for bilateral osteochondrosis lesions in dogs

To investigate whether arthrographic findings had any prognostic value with respect to treatment and outcome of bilateral osteochondrosis, shoulder arthrograms (n = 80) from 40 dogs with bilateral lesions were evaluated. Arthrography was performed, using 1.5 to 4 ml of a 25% solution of meglumine-sodium diatrizoate, with admixture of 0.2 mg of epinephrine. A shoulder with signs of pain and lameness was surgically treated. The contralateral shoulder was treated conservatively, and the final outcome was compared with the arthrographic findings. In 37 dogs, signs of lameness and pain were associated with a loose cartilage flap and, in 3, with a detached cartilage flap. In 2 dogs, admitted with bilateral lameness, a loose cartilage flap was detected in both shoulders. Of 12 dogs with a detectable loose cartilage flap in the contralateral shoulder joint, 6 became lame 2 to 4 months after initial surgical intervention and needed bilateral surgery. In the contralateral joint, development of thick articular cartilage over the subchondral defect or a detached cartilage flap lodged in the caudal pouch of the shoulder joint was a favorable prognostic sign. Such dogs had no signs of lameness on the contralateral side during a follow-up period that ranged from 1 to 7 years.     

Ability to work and owner satisfaction following surgical repair of common calcanean tendon injuries in working dogs in New Zealand

AIM: To report the long-term outcome (return to work and owner satisfaction) following surgical treatment of common calcanean tendon (Achilles tendon) injuries in working dogs in New Zealand. METHODS: Ten New Zealand Huntaway or Heading dogs (working Collies) with complete or partial tears of the common calcanean tendon, were treated using locking-loop suturing and casting, with (7) or without (3), a calcaneo-tibial screw. All dogs were actively in work on sheep or cattle farms at the time of injury, and return to work was the desired outcome. Ability to work and owner satisfaction were investigated using a telephone questionnaire at a mean followup interval of 14.6 months. RESULTS: Overall, 7/10 dogs returned to full or substantial levels of work. Post-operative complications occurred in two dogs that did not return to full or substantial levels of work. Moderate persistent lameness (score 3 on a scale of 0-5) was present in 2/7 dogs that returned to full or substantial levels of work, equating to a 71% good-to-excellent functional outcome within this group. Seven owners felt the financial investment in opting for surgical repair was worthwhile. A screw and cast method of rigid immobilisation was thought to be superior to casting alone. CONCLUSIONS: Surgical treatment of common calcanean tendon injury in working dogs carries a good prognosis if an appropriate tenorrhaphy technique is used and rigid immobilisation is achieved for 6 weeks. Care must be taken to limit post-operative complications. CLINICAL RELEVANCE: This study justifies the use of surgical repair of such injuries in the working dog even when return to work is the only acceptable outcome.     

Laser-Doppler Measurements of Spinal Cord Blood Flow Changes During Hemilaminectomy in Chondrodystrophic Dogs with Disk Extrusion

Objectives— (1) To assess spinal cord blood flow (SCBF) during surgical treatment of disk extrusion in dogs and (2) to investigate associations between SCBF, clinical signs, presurgical MRI images, and 24-hour surgical outcome.
Study Design— Cohort study.
Animals— Chondrodystrophic dogs with thoracolumbar disk extrusion (n=12).
Methods— Diagnosis was based on clinical signs and MRI findings, and confirmed at surgery. Regional SCBF was measured intraoperatively by laser-Doppler flowmetry before, immediately after surgical spinal cord decompression, and after 15 minutes of lavaging the lesion. Care was taken to ensure a standardized surgical procedure to minimize factors that could influence measurement readings.
Results— A significant increase in intraoperative SCBF was found in all dogs (Wilcoxon's signed-rank test; P =.05) immediately after spinal cord decompression and after 15 minutes. Changes in SCBF were not associated with duration of clinical signs; initial or 24-hour neurologic status; or degree of spinal cord compression assessed by MRI.
Conclusion— SCBF increases immediately after spinal cord decompression in dogs with disk herniation; however, increased SCBF was not associated with a diminished 24-hour neurologic status.
Clinical Relevance— An increase in SCBF does not appear to be either associated with the degree of spinal cord compression or of a magnitude sufficient to outweigh the benefit of surgical decompression by resulting in clinically relevant changes in 24-hour outcome.     

Pull-through technique for palmar digital neurectomy: forty-one horses (1998-2004)

Objectives— To report outcome of horses treated for navicular syndrome using a pull-through (PT) technique for palmar digital neurectomy (PDN).
Design— Retrospective study.
Animals— Horses (n=41) with navicular syndrome (NS).
Methods— Medical records (1998–2002) for horses that had NS and failed to respond to conservative management that had unilateral or bilateral forelimb, biaxial PDN were reviewed. Outcome for up to 6 years was obtained by telephone questionnaire or lameness examination. Survival analysis was used to assess time to recurrence of lameness.
Results— One year after PDN, 36 horses (88%) were free of lameness. Mean survival with no lameness after surgery was estimated at 4.14±0.33 years (median, 5 years).
Conclusions— PT–PDN technique resulted in soundness for 88% of horses for at least 1 year. PT–PDN was easily and quickly performed without specialized equipment, and had a low incidence of complications.
Clinical Relevance— The PT technique is an effective and viable alternative surgical method for PDN.     

PREVALENCE OF COMPUTED TOMOGRAPHIC SUBCHONDRAL BONE LESIONS IN THE SCAPULOHUMERAL JOINT OF 32 IMMATURE DOGS WITH THORACIC LIMB LAMENESS

Osteochondrosis is a common developmental abnormality affecting the subchondral bone of immature, large breed dogs. The purpose of this retrospective study was to describe CT lesions detected in scapulohumeral joints of 32 immature dogs undergoing CT for thoracic limb lameness. Eight dogs (14 scapulohumeral joints) had arthroscopy following imaging. Thirteen dogs (19 scapulohumeral joints) were found to have CT lesions, including 10 dogs (16 scapulohumeral joints) with subchondral bone lesions and 3 dogs with enthesopathy of the supraspinatus tendon. In one dog, subchondral bone lesions appeared as large oval defects within the mid‐aspect of the glenoid cavities, bilaterally. These lesions resembled osseous cyst‐like lesions commonly identified in the horse. This is the first report of such a presentation of a subchondral bone lesion in the glenoid cavity of a dog. In all dogs, small, focal, round or linear lucent defects were visible within the cortical bone at the junction of the greater tubercle and intertubercular groove. These structures were thought to represent vascular channels. Findings from this study support the use of CT as an adjunct modality for the identification and characterization of scapulohumeral subchondral bone lesions in immature dogs with thoracic limb lameness.     

ULTRASONOGRAPHIC EVALUATION OF THE CANINE SHOULDER

The aim of this study was to determine the normal ultrasonographic anatomy of the canine shoulder. Fourteen shoulders from 7 clinically normal mid-sized dogs were radiographed and imaged using high frequency ultrasound. Each shoulder was isolated postmortem, and the ultrasonographic and gross anatomy was studied during dissection. The ultrasonographic appearance of the shoulder specimens was similar to that found in the live dogs. Twenty-four shoulders isolated postmortem from 12 variably sized dogs were also used to characterize the normal ultrasound anatomy over a range of sizes. Important anatomic structures that could be consistently evaluated were the biceps tendon and bursa, the bicipital groove surface, the supraspinatous tendon, the infraspinatous tendon, the teres minor tendon, and the caudal aspect of the humeral head. Results of ultrasonographic examination of 4 dogs with shoulder lameness are described to illustrate some applications of canine shoulder ultrasonography in the evaluation of the canine shoulder. In these dogs, ultrasound was a valuable tool to evaluate effusion and synovial proliferation within the bicipital bursa, supraspinatous and biceps tendinitis, biceps tendon strain, and dystrophic calcification.     

Lameness associated with foot pain: results of magnetic resonance imaging in 199 horses (January 2001--December 2003) and response to treatment

REASONS FOR PERFORMING STUDY: The diagnosis of foot-related lameness often remains elusive and it can be difficult to offer rational treatment, or to predict outcome. OBJECTIVES: To describe the spectrum of injuries of the foot identified using magnetic resonance imaging (MRI), to determine their relative prevalence among MRI diagnoses and to establish the long-term results of treatment. METHODS: The MR images of horses examined from January 2001--December 2003 were reviewed. Horses were selected for MRI if the pain causing lameness was localised to the foot using perineural analgesia but any clinical, radiological or ultrasonographic abnormalities were insufficient to explain the degree of lameness. The clinical significance of lesions identified using MRI was determined with reference to the results of local analgesia, radiography, ultrasonography and nuclear scintigraphy. Follow-up information was obtained in January 2004 for horses which had been examined 6-36 months previously and the outcome classified as excellent (horse returned to full athletic function without recurrent lameness), moderate (sound, but only in light work), or poor (persistent or recurrent lameness). RESULTS: One hundred and ninety-nine horses underwent MRI examinations. Deep digital flexor (DDF) tendonitis was the most common injury (59%) with primary injury in 65 horses (33%) and a further 27 horses (14%) having lesions of the DDF tendon and navicular bone. Seventeen percent of horses had injuries to multiple structures, including 24 with DDF tendonitis. Desmitis of a collateral ligament (CL) of the distal interphalangeal (DIP) joint was the second most common injury (62 horses, 31%), with primary injuries in 30 horses (15%) and a further 32 horses (16%) that had CL desmitis in conjunction with other injuries. Prognosis was best for horses with traumatic injuries of the middle or distal phalanges, with 5 of 7 horses (71%) having an excellent outcome. Horses with primary lesions of the DDF tendon or CL of the DIP joint had excellent results in only 13 of 47 (28%) and 5 of 17 horses (29%), respectively. Horses with combined injuries of the DDF tendon and navicular bone, or primary navicular bone abnormalities, had a poor outcome, with the majority of horses suffering persistent lameness. CONCLUSIONS: A wide variety of lesions associated with foot pain were identified using MRI, a high proportion of which were primary soft tissue injuries with a guarded prognosis for return to full athletic function. POTENTIAL RELEVANCE: It is now possible to propose more rational treatment strategies for the variety of foot injuries identified using MRI than had previously been possible; however, further information concerning aetiopathogenesis of these injuries is needed to improve their management.