Autologous platelet concentrates as a treatment for musculoskeletal lesions in five horses

Two horses with acute tendinopathy of a superficial digital flexor tendon (SDFT) and three horses with chronic proximal desmitis of the suspensory ligament (PDSL) were treated by injecting autologous concentrates of their platelets into the lesions. The lesions were monitored ultrasonographically and clinically. There were significant ultrasonographic and clinical improvements in the two horses with SDFT, but no ultrasonographic improvements in the horses with PDSL; however, they improved clinically and became less lame. All the horses had returned to their pre-injury level of performance by six months after the completion of the treatment, and none of them had suffered a recurrence after 20 months.     

Ultrasonographic assessment of the superficial digital flexor tendons of National Hunt racehorses in training over two racing seasons

Reasons for performing study: It is important to ascertain the prevalence of superficial digital flexor tendon (SDFT) injuries and to improve methods of predicting injury in National Hunt (NH) racehorses. Objectives: To establish: 1) the prevalence of SDFT tendinopathy in NH horses; 2) whether routine ultrasonography can be used to predict SDFT injuries; 3) whether previous tendinopathy predisposes to reinjury; 4) a normal range for the SDFT cross‐sectional area (CSA); and 5) the effects of gender, age, background (ex‐flat or exstore), limb, training and rest periods on SDFT CSA. Methods: Routine ultrasound assessment of the palmar metacarpal soft tissues of 263 NH racehorses was performed on up to 6 occasions over 2 NH racing seasons. Results: The prevalence of SDFT pathology detected using ultrasonography was 24% (n = 148), with a nonsignificant variation between yards of 10–40%. No changes in SDFT CSA or ultrasonographic appearance were detected prior to injury. Older horses had a significantly higher prevalence of SDFT pathology compared to younger horses, and horses with tendinopathy were more likely to suffer an acute injury compared to horses with no evidence of pathology. A reference range for normal CSA measurements was established as 77–139 mm² at level 4, from 142 horses with no ultrasonographic evidence of SDFT pathology. The CSA of normal horses did not vary significantly with age, limb or over 2 racing seasons, but did with sex and background. Conclusions: The study confirms that SDFT tendinopathy is common in NH horses, with substantial variation between training yards. Ultrasonography at 3 month intervals did not seem to predict acute SDFT injuries. Potential relevance: Variation in the prevalence of tendinopathy between yards suggests that training methods may influence injury rate. It was not possible to predict injury using routine ultrasonography and therefore other methods must be identified. A normal reference range for SDFT CSA is provided.     

Incomplete Tears of the Medial Calcaneal Insertion of the Superficial Digital Flexor Tendon of a Hind Limb in Three Horses

Twelve tarsi from six horses humanely destroyed for reasons unrelated to the study were dissected and measurements of the calcaneal insertions of the superficial digital flexor tendon (SDFT) were acquired. The medial calcaneal insertions of the SDFT ranged in length and thickness from 4.0 to 5.4 cm and 0.3 to 0.5 cm, respectively, and the lateral calcaneal insertions ranged in length and width from 4.0 to 6.3 cm and 0.3 to 0.5 cm, respectively. The calcaneal insertions of the SDFT of both hind limbs of six horses with no history or clinical signs of hind limb lameness and no palpable abnormality of the tarsi were examined ultrasonographically. The medial calcaneal insertion of the SDFT was of uniform echogenicity, thickest at the attachment to the SDFT, and smoothly tapering to its insertion on the plantaromedial aspects of the calcaneus. The lateral calcaneal insertion was less echogenic adjacent to the SDFT than the tendon itself but was of similar echogenicity toward the insertion on the plantarolateral aspect of the calcaneus. Three horses with full-thickness incomplete tears of the medial calcaneal insertion of the SDFT had variable enlargement of the calcaneal bursa, an unstable (n = 2) or stable (n = 1) SDFT and lameness. The presence of an extensive but incomplete full-thickness tear of the medial calcaneal insertion of the SDFT was determined ultrasonographically in all horses.     

Five cases of gastrocnemius tendinitis in the horse.

The normal gastrocnemius tendon may contain some muscular tissue proximally. This results in a patchy echogenicity ultrasonographically where it lies caudal or lateral to the superficial digital flexor tendon (SDFT). When it has assumed a position dorsal (cranial) to the SDFT the gastrocnemius tendon has a more uniform echogenicity and its margins are well defined. Five horses had lameness associated with lesions identified ultrasonographically in the gastrocnemius tendon in the latter region. Lameness ranged from mild to severe and was characterised by reduced hock flexion, lowered arc of foot flight, shortened length of the cranial phase of the stride and in some horses a reduced duration of weight bearing during the caudal phase of the stride. Lameness was variably accentuated by flexion of the proximal or distal limb joints of the lame limb. Perineural analgesia of the tibial and fibular nerves or the tibial nerve alone substantially improved the lameness. All horses remained lame 2-3 months after initial examination, with minimal change in the ultrasonographic appearance of the lesion(s).     

Recombinant equine growth hormone does not affect the in vitro biomechanical properties of equine superficial digital flexor tendon

OBJECTIVE: To evaluate the effect of recombinant equine growth hormone (rEGH) on the in vitro biomechanical properties of normal adult equine superficial digital flexor tendon (SDFT). STUDY DESIGN: Completely randomized design. SAMPLE POPULATION: Nine Standardbred horses, 6 to 9 years of age with ultrasonographically normal forelimb SDFT. METHODS: Six horses were administered intramuscular (IM) rEGH at 10 microg/kg/day for 1 week, and then 20 microg/kg/day for another 5 weeks; 3 horses (control subjects) were administered an equivalent daily volume of sterile water IM. Horses were killed at the end of the 6-week treatment period, and both forelimb SDFT were harvested and stored at -70 degrees C. In vitro biomechanical testing was performed under uniaxial tension. Results were analyzed using a general linear model of analysis of variance; significance was set at P <.05. RESULTS: There were no differences in cross-sectional area, maximal load at failure, yield load, ultimate and yield tensile strain, ultimate and yield tensile stress, or stiffness between tendons from control and treated horses. CONCLUSIONS: Administration of rEGH to adult Standardbred horses for 6 weeks had no detectable effect on the in vitro biomechanical properties of normal SDFT. CLINICAL RELEVANCE: Administration of rEGH does not modulate the in vitro biomechanical properties of SDFT from adult Standardbred horses.     

Outcome of medical treatment for horses with foot pain: 56 cases

Reasons for performing study: Currently, there are limited data regarding the long‐term outcome of horses with foot pain treated with corrective shoeing, rest and rehabilitation, and intrasynovial anti‐inflammatory medication to target lesions detected with MRI. Objective: To report the long‐term (≥12 months) outcome of horses with foot lesions following medical therapy. Hypotheses: 1) There is no association between clinical parameters considered and a poor response to therapy. 2) Horses with a deep digital flexor tendinopathy are less likely to respond to medical therapy than horses without a deep digital flexor tendinopathy. Methods: The medical records of horses with foot pain subjected to MRI examination and medical therapy (2005–2007) were evaluated retrospectively. Data collected included history, signalment, occupation, duration and severity of lameness at the time of MRI, radiological and MRI abnormalities. Number of treatments, complications and long‐term response to treatment were obtained by detailed telephone questionnaires. Association between clinical and MRI findings and long‐term lameness were investigated. Results: Frequent abnormal structures included the navicular bone, the deep digital flexor tendon, the navicular bursa and the distal interphalangeal joint. Thirty‐four of 56 horses (60.7%) failed to return to previous level of exercise due to persistent or recurrent lameness or owners' decision to decrease the horse's athletic level; however, 11 horses (32.3%) were being used for light riding. Prognosis for horses with concurrent deep digital flexor tendon, navicular bone and navicular bursa lesions was worse than horses with individual lesions. Deep digital flexor tendinopathy was strongly associated with persistent or recurrent lameness. Conclusions: Horses with multiple foot lesions managed with conservative therapy have a guarded prognosis for long‐term soundness. Deep digital flexor tendinopathies negatively influence prognosis.     

The effect of recombinant equine growth hormone on the biomechanical properties of healing superficial digital flexor tendons in horses

OBJECTIVE: To evaluate the effect of recombinant equine growth hormone (rEGH) on the in vitro biomechanical properties of healing superficial digital flexor tendon (SDFT) in horses. STUDY DESIGN: Completely randomized design. SAMPLE POPULATION: Twelve Standardbred horses, 3 to 7 years of age, with ultrasonographically normal forelimb SDFT. METHODS: One week after induction of collagenase (2,000 U) induced superficial flexor tendonitis, horses were randomly divided into groups of 6. One group was administered intramuscular rEGH (10 microg/kg/day for 1 week, then 20 microg/kg/day for 5 weeks), whereas the other group (control subjects) were administered an equivalent volume of saline (0.9% NaCl) solution. At the end of this 6-week treatment, horses were killed and one forelimb SDFT from each horse was harvested for biomechanical testing under uniaxial tension. Results were analyzed using an unpaired Student's t test; significance was set at P 相似文献   

Possible role of carpal hyperextension in superficial digital flexor tendinopathy

Reasons for performing study: The specific biomechanical circumstances that induce excessive superficial digital flexor tendon (SDFT) strain in horses are unknown. Hypothesis: Carpal joint hyperextension during axial limb loading during the middle of stance disproportionately enhances SDFT strains compared to suspensory ligament (SL) strains. Methods: Superficial digital flexor tendon and SL strains were measured in 7 cadaver limbs during in vitro loading that maintained carpal extension or allowed carpal hyperextension by constraining, or allowing rotation of, the radius during loading conditions that simulated the middle of stance at the walk. The effect of carpal hyperextension on SDFT and SL strains and joint angles was assessed using repeated measures ANOVA. Results: Limb loading generally resulted in higher SL strains than SDFT strains for both carpal extension and hyperextension loading conditions. Compared to carpal extension, carpal hyperextension resulted in increased strains in both the SDFT and the SL; however, a greater increase in strain was seen in the SDFT. On average, carpal hyperextension caused approximately 3° greater carpal extension, 1° greater metacarpophalangeal joint hyperextension, 1° greater proximal interphalangeal joint flexion and <1° greater distal interphalangeal joint flexion than did carpal extension. Conclusions and clinical relevance: Carpal joint hyperextension is likely to induce disproportionately higher strain in the SDFT than in the SL. Factors that affect carpal stability are likely to affect the risk for superficial digital flexor tendinopathy.     

The relationship between in vivo limb and in vitro tendon mechanics after injury: a potential novel clinical tool for monitoring tendon repair

Reasons for performing the study: Highly prevalent superficial digital flexor tendon (SDFT) injury results in compromised tendon function through fibrosis and high frequency of re‐injury due to altered biomechanical function. This study investigated the consequences of SDF tendinopathy on limb mechanics in relation to the mechanical properties of injured tendon. Objectives: To develop and validate a noninvasive in vivo assessment of tendon mechanics to investigate the effect of recent SDFT injury on limb stiffness index, providing an objective method to assess quality of healing. Hypotheses: Limb stiffness index would reduce as a consequence of SDFT injury and progressively increase during tendon healing and correlate with in vitro mechanical properties of the respective SDFTs. Methods: Kinematic analysis was performed at walk in 10 horses that had sustained career‐ending SDFT injury. Stiffness index was derived from limb force recorded via a series of force plates and measurement of change in metacarpophalangeal joint angle using 3D motion analysis software. Horses were subjected to euthanasia 7 months after injury, the SDFTs removed and subjected to nondestructive in vitro mechanical testing. Results: Limb stiffness index was reduced following SDFT injury in comparison with the contralateral limb and increased during the convalescent period, approximating that of the contralateral limb by 7 months post injury. There was a significant positive correlation between in vivo limb stiffness index and in vitro SDFT stiffness. Clinical relevance: The ability to assess and monitor SDFT mechanical competence through limb stiffness measurement techniques in horses recovering from SDFT injury and the possibility of corroborating this with functional tendon healing may permit a more objective and accurate assessment of optimal tendon repair in the horse. This technique may be a useful method for assessing the efficacy of treatment regimens for tendinopathy and could be utilised to predict time to safe return to performance or re‐injury.     

Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. 4. Morphometric, microscopic and biomechanical properties of the digital tendons of the forelimb

AIM: To determine the weight, volume, density and cross-sectional area (CSA) of the digital flexor tendons, common digital extensor tendon (CDET) and suspensory ligament (SL) of the forelimb of young Thoroughbred horses in early training, and to assess the response to a training programme of known parameters of superficial digital flexor tendon (SDFT) tissue at mid-metacarpal level. METHODS: The tendons of seven 2-year-old Thoroughbred horses in training were inspected, transected into segments of known length, and compared with those from seven untrained horses matched for age, sex and breed. The weight, volume, density and CSA of each segment, and the crimp angle, histological features, and biomechanical ultimate stress and stiffness of tendon samples from the mid-metacarpal region of the SDFT were determined. RESULTS: There was no macroscopic evidence of swelling or discolouration in any of the tendon segments or cut surfaces. The volumes of SDFT and CDET segments of horses in the trained group were significantly greater than those in the untrained group (p=0.036 and p=0.039, respectively). A greater increase in volume than weight resulted in a lower density in the SDFT but not CDET in trained compared with untrained horses (p=0.038). CSA of these two tendons was significantly greater in the trained group (p=0.002 and 0.036, respectively), the percentage increase being greater in the CDET than the SDFT. The number of tenocytes at four sites in the mid-metacarpal SDFT region was less in trained than untrained horses (p=0.025). There was no histological evidence of inflammation, and no difference in crimp angle between groups. There was no significant between-group difference in stiffness or ultimate stress of tendon strips. CONCLUSIONS: Volume and CSA of the SDFT and CDET were larger in trained than untrained horses. The SDFT was less dense in the trained group. Because no evidence of tendonitis was detected and training appeared to have no significant effect on crimp angle or biomechanical properties of tendon strips, the size and density changes were presumed to be adaptive and induced by the training. CLINICAL RELEVANCE: Although evident in this in vitro study, the detection of adaptive from initial pathological increase in size of the SDFT is likely to be difficult in vivo.     

Magic angle magnetic resonance imaging of diode laser induced and naturally occurring lesions in equine tendons

Magic angle magnetic resonance (MR) imaging consists of imaging tendons at 55° to the magnetic field. In people, magic angle MR imaging is valuable for detection of chronic tendon lesions and allows calculation of tendon T1 values. Increased T1 values occur in people with chronic tendinopathy. The T1 values of normal equine tendons have been reported but there are no available data for abnormal equine tendons. Twelve limbs were studied. Two limbs had diode laser tendon lesions induced postmortem, four limbs had diode laser tendon lesions induced in vivo and six limbs had naturally occurring tendon lesions. The limbs were imaged at 1.5 T using both conventional MR imaging and magic angle MR imaging. The post-mortem laser induced lesions were identified only with magic angle MR imaging. The in vivo induced lesions and naturally occurring lesions were identified with both techniques but had a different appearance with the two imaging techniques. Magic angle imaging was helpful at identifying lesions that were hypointense on conventional imaging. Increased T1 values were observed in all abnormal tendons and in several tendons with a subjectively normal MR appearance. The increased T1 value may reflect diffuse changes in the biochemical composition of tendons. Magic angle imaging has potential as a useful noninvasive tool to assess the changes of the extracellular tendon matrix using T1 values.     

Injuries of the calcaneal insertions of the superficial digital flexor tendon in 19 horses

Reasons for performing study: Injuries of the calcaneal insertions of the superficial digital flexor tendon and their relationship to displacement of the tendon from the calcaneus have not previously been reported. Objectives: To describe findings made on clinical cases with disruption of the calcaneal insertions of the superficial digital flexor tendon (SDFT) including observations on their role in horses with unstable subluxation of the tendon. To describe novel surgical techniques and the results of treatment. Hypotheses: Disruption of the calcaneal insertions of the SDFT is associated with lameness and distension of the calcaneal bursa. Unstable displacement of the SDFT from the calcaneus is a more complex injury than incomplete disruption of one of its calcaneal insertions. Methods: The case records and diagnostic images of horses with lesions involving the calcaneal insertions of the SDFT, which were confirmed by endoscopic evaluation of calcaneal bursa between 2005 and 2009, were reviewed. Results: Nineteen horses were identified including 7 that had unstable displacement of the tendon from the calcaneus. Following endoscopic surgery, 9 of 12 horses with stable tendons and 6 of 7 horses with unstable displaced SDFTs returned to work. Conclusion: Tearing of the calcaneal insertions of the SDFT is associated with lameness and distension of the calcaneal bursa; endoscopic removal of the torn tissue carries a good prognosis. Horses with unstable displacement of the tendon have also disruption of the tendon fibrocartilage cap. Removal of this results in stable subluxation and can return horses to athletic activity. Both lesions can be detected by preoperative ultrasonography. Potential relevance: Tearing of the calcaneal insertions of the SDFT should be included in the differential diagnoses of lame horses with distended calcaneal bursae. Tearing of the tendon fibrocartilage cap in horses with unstable displacement of the SDFT is a plausible explanation of the clinical features of the injury and explains previously unreliable results of reconstructive surgeries. Subtotal resection is a technically demanding technique but appears to offer an improved prognosis.     

Influence of topically applied cold treatment on core temperature and cell viability in equine superficial digital flexor tendons

OBJECTIVE: To determine rate and degree of cooling for the superficial digital flexor tendon (SDFT) during a standard cryotherapy application in horses and evaluate in vitro effects of cooling on survival of tendon cells. SAMPLE POPULATION: 6 limbs of 5 adult horses and cultured cells obtained from SDFT of 3 adult horses during necropsy. PROCEDURE: In vivo data were acquired by use of a thermocouple temperature probe inserted into the SDFT of a forelimb of each standing sedated horse. After baseline temperatures were recorded, a commercial compression splint with circulating coolant was placed on each selected limb, which was then exposed to cold treatment for 60 minutes. Temperatures were recorded at 30-second intervals. Mean minimum core temperature was calculated and used to design a protocol for in vitro cold treatment of cells. Specimens were obtained from the SDFT of horses during necropsy; tendon cells were cultured in suspension and exposed to 1-hour of cold treatment that mimicked the in vivo procedure. Viability of cells after cold treatment was compared with viability of cells maintained at body temperature. RESULTS: After 1 hour of cold treatment, SDFT core temperature was reduced by a mean of 21.8 degrees C, reaching a mean minimum temperature of 10 degrees C. Viability did not differ significantly between cold-treated and control cells. CONCLUSION AND CLINICAL RELEVANCE: Results indicated that topical application of cryotherapy significantly reduced core SDFT temperature in standing sedated horses. Temperatures achieved in vivo during cold treatment were not detrimental to the in vitro viability of tendon cells.     

Parameters influencing prevalence and outcome of tendonitis in Thoroughbred and Arabian racehorses

Flexor tendonitis and suspensory desmitis are among most prevalent musculoskeletal injuries observed in racehorses. The aim of this study was to determine which horse and race-related parameters can help to diminish the possibility of injury or--when injury has occurred--to evaluate the potential for the horse to continue a successful career after convalescence. Special attention was given to the comparison of Arabian and Thoroughbred racehorses. 187 horses with ultrasonographically visible lesions were included in the study. Following parameters were analyzed: structure (Superficial Digital Flexor Tendon [SDFT], Deep Digital Flexor Tendon [DDFT], Suspensory Ligament [SL]); percentage of cross sectional area increase; hypoechogenic lesion character; in horses with SDF tendonitis - tendonitis grade according to Genovese. This study showed that Thoroughbreds are more at risk of musculoskeletal problems than Arabian racehorses. In both breeds, the most frequent injuries concern SDFT, then SL. Over 95% of tendonitis concern forelimbs. In Thoroughbreds, the prevalence of tendonitis is higher in bigger horses, in males when compared to females and in fence/steeple racehorses when compared to flat track racehorses. The inside limb is more at risk of SDF tendonitis, when the external limb - of SL desmitis. Tendonitis severity increases with age and is greater in steeplechasers when compared to flat track racehorses. The outcome of tendonitis without hypoechogenic lesion is much better than that with hypoechogenic lesion. Evaluation of hypoechogenic lesion length is an easy and accurate prognosis tool, as the chances of returning to racing drop dramatically with lesions longer than 12 cm.     

Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. 3. In vivo ultrasonographic assessment of the cross-sectional area and echogenicity of the superficial digital flexor tendon

AIM: To determine if the superficial digital flexor tendon (SDFT) of young Thoroughbred horses changed in size and echogenicity in association with early race training. METHODS: Cross-sectional area (CSA) and echogenicity were determined ultrasonographically at five levels of the SDFT of the forelimbs of 2-year-old fillies (n=14), corresponding to 4, 8, 12, 16 and 20 cm distal to the accessory carpal bone (DACB). Measurements were made before and after a 13-week period in which a trained group of seven horses was compared with another group of seven untrained horses. RESULTS: Level below the accessory carpal bone had a significant effect on CSA and Level 8 was smaller than all other levels except Level 12, while Level 12 was smaller than Levels 4 and 20 but not different from Levels 8 and 16. There was a significant interaction between level and time due to effects observed at Level 8. The CSA at Level 8 measured pre-training was different from that of Levels 4 and 20 in both pre- and post-training groups (p<0.05), but when measured post-training was not different from any other measurement. There was also a significant interaction between treatment group and time. There was no difference between CSA for the untrained and trained groups at the pre-training observation (p=0.9), but post-training the CSA (pooled over all levels) in trained horses was significantly larger than that of the untrained horses both post-training (p=0.019) and pre-training (p=0.034), and was not different from the pre-training CSA recorded in the trained group (p=0.29). Treatment group had no effect on echogenicity (p=0.43), while echogenicity was less at the end of the trial in both trained and untrained horses (p<0.001). CONCLUSIONS: Early training for racing was associated with an increase in mean CSA of the SDFT. Other factors such as age and maturity may play a role in limiting this increase.     

Risk factors for superficial digital flexor tendinopathy in Thoroughbred racehorses in hurdle starts in the UK (2001-2009)

Reasons for performing study: Superficial digital flexor (SDF) tendinopathy is a common injury in Thoroughbred horses racing over hurdles. Identification of risk factors may allow the introduction of measures to minimise the incidence of this injury. Objective: To identify risk factors for SDF tendinopathy in Thoroughbred horses in hurdle races in the UK. Methods: Potential risk factors for SDF tendinopathy were studied between 1 January 2001 and 31 December 2009 using a retrospective cohort study design with 1031 case starts and 168,637 control starts. Potential risk factors were screened using univariable logistic regression prior to multivariable model building. Results: In the final multivariable model, 20 statistically significant risk factors were identified. Variables found to be associated with increased odds of SDF tendinopathy included: firmer going; increased horse age at first race; having had a previous SDFT injury; and racing in the summer compared to other seasons. Variables found to be associated with decreased odds included: being trained by a more successful trainer; and having raced more frequently in the preceding 9–12 months. Conclusions: This study identified multiple risk factors associated with SDF tendinopathy, some of which are difficult to explain with the current data source. Factors resulting in increased cumulative horse and tendon fatigue (increased years in racing; carrying increased weight; and racing over longer distances), firm ground, and the presence of previous tendon injury should be considered when attempting to reduce the likelihood of sustaining SDF tendinopathy. Potential relevance: The results will facilitate the development of strategies to improve the overall safety of horses in hurdle racing in the UK.     

Collateral desmitis of the distal interphalangeal joint in 18 horses (2001-2002)

REASONS FOR PERFORMING STUDY: There have been no previously published case series of horses examined using either scintigraphy or MRI to diagnose collateral ligament injuries not detectable using ultrasonography or radiography, nor have other concurrent soft tissue lesions been described. OBJECTIVES: To describe the clinical features of horses with desmitis of the collateral ligaments of the distal interphalangeal (DIP) joint and to evaluate the results of radiographic, ultrasonographic, scintigraphic and magnetic resonance imaging (MRI) examinations. METHODS: Horses were examined between January 2001 and January 2003 and were selected for inclusion in the study if there was unequivocal evidence of collateral desmitis of the DIP joint based on ultrasonography or MRI. Subject details, case history, results of clinical examination and responses to local analgesic techniques were reviewed. The results of radiographic, ultrasonographic, scintigraphic and MRI examinations were assessed. RESULTS: Eighteen horses were identified with desmitis of a collateral ligament of the DIP joint, 3 horses (Group 1) based on ultrasonography alone, 7 (Group II) with positive ultrasonographic and magnetic resonance images and 8 (Group III) with no lesion detectable using ultrasonography, but lesions identified using MRI. Seventeen horses had forelimb injuries and one a hindlimb injury. The medial collateral ligament was injured most frequently (13 horses). In the majority of horses, no localising clinical signs were seen. Lameness was invariably worse in circles compared with straight lines. Lameness was improved by palmar digital analgesia in 16 horses (87%), but only 6 were nonlame. Intra-articular analgesia of the DIP joint produced improvement in lameness in 6/15 horses (40%). In 16 horses, no radiographic abnormality related to the DIP joint or collateral ligament attachments was identified. Eight of 14 horses (57%) had focal, moderately or intensely increased radiopharmaceutical uptake (IRU) at the site of insertion of the injured collateral ligament on the distal phalanx. Alteration in size and signal in the injured collateral ligament was identified using MRI. In addition, 5 horses had abnormal mineralisation and fluid in the distal phalanx at the insertion of the ligament. Eleven horses had concurrent soft tissue injuries involving the deep digital flexor tendon, distal sesamoidean impar ligament, navicular bursa or collateral ligament of the navicular bone. CONCLUSIONS AND POTENTIAL RELEVANCE: Collateral desmitis of the DIP joint should be considered as a cause of foot lameness. Although some injuries are detectable ultrasonographically, false negative results occur. Focal IRU at the ligament insertion on the distal phalanx may be indicative of injury in some horses. MRI is useful for both characterisation of the injury and identification of any concurrent injuries. Further follow-up information is required to determine factors influencing prognosis.     

Platelet-Rich Plasma in the Treatment of Induced Tendinopathy in Horses: Histologic Evaluation

This study was carried out to evaluate the effect of platelet-rich plasma (PRP) on the treatment of tendinopathy induced in the superficial digital flexor tendon (TFDS) of horses, by using histologic evaluation. Six healthy crossbred geldings aged 8 to 15 years (12 ± 3) were used. The TFDS tendinopathy was provoked in both forelimbs, by intratendinous administration of 2.5 mg collagenase (2.5 mg/mL), and this procedure was considered as the beginning of the experimental phase. At 12 days after induction of the tendinopathy, the animals were subjected to the following treatments: (1) in the lesion caused in the right superficial digital flexor tendon (PRP-treated group), 2.5 mL PRP activated with calcium chloride at 0.0125 mol/L at concentrations from 320,000 to 500,000 platelets/μL, were injected; (2) in the tendinopathy of the left SDFT (control group), 2.5 mL 0.9% saline solution was administrated. Thirty-six days after the treatments, a biopsy of the injured area was performed for histologic evaluation. In both groups, the histologic analysis showed an increase in the fibroblastic density, as well as the presence of neovascularization, lymphocytes, and plasmocytes infiltrate and tissue organization at variable intensity. In the PRP-treated group, the SDFT was more organized, with the collagen fibers and fibroblasts being better arranged on the tendon matrix. The numbers of the fibroblasts and blood vessels did not differ between the groups. Histologic evaluation 36 days after tendinopathy showed that injuries under a single PRP treatment present a more uniform and organized tissue repair when compared with the control group.     

Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. 3. In vivo ultrasonographic assessment of the cross-sectional area and echogenicity of the superficial digital flexor tendon

AIM: To determine if the superficial digital flexor tendon (SDFT) of young Thoroughbred horses changed in size and echogenicity in association with early race training.

METHODS: Cross-sectional area (CSA) and echogenicity were determined ultrasonographically at five levels of the SDFT of the forelimbs of 2-year-old fillies (n=14), corresponding to 4, 8, 12, 16 and 20 cm distal to the accessory carpal bone (DACB). Measurements were made before and after a 13-week period in which a trained group of seven horses was compared with another group of seven untrained horses.

RESULTS: Level below the accessory carpal bone had a significant effect on CSA and Level 8 was smaller than all other levels except Level 12, while Level 12 was smaller than Levels 4 and 20 but not different from Levels 8 and 16. There was a significant interaction between level and time due to effects observed at Level 8. The CSA at Level 8 measured pre-training was different from that of Levels 4 and 20 in both pre- and post-training groups (p<0.05), but when measured post-training was not different from any other measurement. There was also a significant interaction between treatment group and time. There was no difference between CSA for the untrained and trained groups at the pre-training observation (p=0.9), but post-training the CSA (pooled over all levels) in trained horses was significantly larger than that of the untrained horses both post-training (p=0.019) and pre-training (p=0.034), and was not different from the pretraining CSA recorded in the trained group (p=0.29). Treatment group had no effect on echogenicity (p=0.43), while echogenicity was less at the end of the trial in both trained and untrained horses (p<0.001).

CONCLUSIONS: Early training for racing was associated with an increase in mean CSA of the SDFT. Other factors such as age and maturity may play a role in limiting this increase.     

Monitoring the fate of autologous and allogeneic mesenchymal progenitor cells injected into the superficial digital flexor tendon of horses: preliminary study

Autologous mesenchymal progenitor cells (MPCs) purified from bone marrow aspirates are being used in the treatment of superficial digital flexor tendon (SDFT) injuries in the horse with promising results. In this study the fate of autologous and allogeneic MPCs following injection into the SDFT was monitored by stable transfection of MPCs with green fluorescent protein (GFP). Small lesions were created manually in one forelimb SDFT of 2 horses and injected with autologous MPCs, allogeneic MPCs or bone marrow supernatant alone. Post mortem examinations performed after 10 or 34 days revealed GFP labelled cells located mainly within injected lesions, but with a small proportion integrated into the crimp pattern of adjacent healthy areas of tendon. Furthermore, there was no visible cell mediated immune response to allogeneic MPCs in either of the host horses.