Musculoskeletal Injury and Illness Patterns in British Eventing Horses: A Descriptive Study.

There has been little investigation into the health patterns of the eventing horse population outside veterinary clinics. To target health problems in the eventing horse population, it is important to determine the relative impact of different health problems. The objectives were to describe the prevalence and patterns of lameness/illness in registered British eventing horses. An online survey was released for all horses registered with British eventing in 2018. Data were collated and descriptive analyses undertaken. A total of 1677 surveys were completed, among which 49.4% reported a previous lameness/musculoskeletal problem, 26% being in the previous six months. The most frequently reported musculoskeletal problems were in the foot (421), joints (382), wounds (340), back (333), ligament (205), tendon (213), bones (140) and muscles (135). The most frequent non-musculoskeletal problems related to the skin (183), gastric ulceration (173), colic (145) and infection (88). Injuries to the hoof sole/muscles/tendons were most frequently sustained in competition, suspensory ligament/splint bone/stifle/tarsal injuries were more frequently sustained in training and abscess/foot penetration at rest. DDFT injuries were most frequently out of training for >12 months, SDFT/stifle/suspensory ligament for <12 months, tendon sheath/splint bone for <3 months and tarsal/sole bruising/abscess for <2 weeks. A greater understanding of injuries/illnesses frequently sustained could be useful for veterinarians working with event horses.

Lesion Distribution in the Metacarpophalangeal and Metatarsophalangeal Region of 341 Horses Using Standing Magnetic Resonance Imaging.

Pain localised to the metacarpophalangeal (MCP) and metatarsophalangeal (MTP) region represents a frequent cause of lameness in sport horses, and standing magnetic resonance imaging (MRI) of these regions is increasingly being acquired. This multicentre retrospective study describes the ranges of abnormalities identified on standing MRI of the MCP/MTP region and compares patterns of abnormalities between forelimbs, hindlimbs and different sports disciplines. In total, 341 MRI reports were reviewed. Subchondral bone plate irregularities, condylar and proximal phalanx pathologies were frequently identified with subchondral bone defect, sclerosis and increased intensity on STIR images often described. Medial pathology was frequently identified in the forelimbs, and more lateral pathology was reported in the hindlimbs, which could potentially reflect differences in the loading patterns. Significant differences in MRI findings were found between different sports activities, with MCP/MTP bone pathology occurring more frequently in MRI reports from race and endurance horses and MCP/MTP soft tissue injuries being reported more frequently in dressage and show-jumping horses, particularly in the suspensory apparatus, including the distal sesamoidean ligaments. The findings of this study identify patterns of MCP/MTP abnormalities detected using standing MRI, with differences seen between forelimbs and hindlimbs and between different sports disciplines.

Histological and Histopathological Features of the Third Metacarpal/Tarsal Parasagittal Groove and Proximal Phalanx Sagittal Groove in Thoroughbred Horses with Racing History.

Information regarding the histopathology of the proximal phalanx (P1) sagittal groove in racehorses is limited. Twenty-nine cadaver limbs from nine Thoroughbred racehorses in racing/race-training underwent histological examination. Histological specimens of the third metacarpal/metatarsal (MC3/MT3) parasagittal grooves and P1 sagittal grooves were graded for histopathological findings in hyaline cartilage (HC), calcified cartilage (CC), and subchondral plate and trabecular bone (SCB/TB) regions. Histopathological grades were compared between (1) fissure and non-fissure locations observed in a previous study and (2) dorsal, middle, and palmar/plantar aspects. (1) HC, CC, and SCB/TB grades were more severe in fissure than non-fissure locations in the MC3/MT3 parasagittal groove (p < 0.001). SCB/TB grades were more severe in fissure than non-fissure locations in the P1 sagittal groove (p < 0.001). (2) HC, CC, and SCB/TB grades including SCB collapse were more severe in the palmar/plantar than the middle aspect of the MC3/MT3 parasagittal groove (p < 0.001). SCB/TB grades including SCB collapse were more severe in the dorsal and middle than the palmar/plantar aspect of the P1 sagittal groove (p < 0.001). Histopathology in the SCB/TB region including bone fatigue injury was related to fissure locations, the palmar/plantar MC3/MT3 parasagittal groove, and the dorsal P1 sagittal groove.

Comparison of cone-beam and fan-beam computed tomography and low-field magnetic resonance imaging for detection of proximal phalanx dorsoproximal osteochondral defects.

BACKGROUND: Dorsoproximal osteochondral defects commonly affect the proximal phalanx, but information about diagnosis on computed tomography (CT) and magnetic resonance imaging (MRI) is limited. OBJECTIVES: To assess CT and MRI diagnoses of osteochondral defects, describe the lesions and compare sensitivity and specificity of the modalities using macroscopic pathology as gold standard. STUDY DESIGN: Cross-sectional study. METHODS: Thirty-five equine cadaver limbs underwent standing cone-beam CT (CBCT), fan-beam CT (FBCT), low-field MRI and pathological examination. CT and MR images were examined for proximal phalanx dorsomedial and dorsolateral eminence osteochondral defects. Defect dimensions were measured. Imaging diagnoses and measurements were compared with macroscopic examination. RESULTS: Fifty-six defects were seen over 70 potential locations. On CBCT and FBCT, osteochondral defects appeared as subchondral irregularity/saucer-shaped defects. On MRI, osteochondral defects were a combination of articular cartilage defect on dorsal images and subchondral flattening/irregularity on sagittal images. Subchondral thickening and osseous short tau inversion recovery hyperintensity were found concurrent with osteochondral defects. Compared with pathological examination, the sensitivity and specificity of diagnosis were 86% (95% confidence interval [95% CI] 75%-93%) and 64% (95% CI 38%-85%) for FBCT; 64% (95% CI 51%-76%) and 71% (95% CI 46%-90%) for CBCT; and 52% (95% CI 39%-65%) and 71% (95% CI 46%-90%) for MRI. Sensitivity of all modalities increased with defect size. Macroscopic defect dimensions were strongly correlated with CBCT (r = 0.76, p < 0.001) and moderately correlated with FBCT and MRI (r = 0.65, p < 0.001). Macroscopic measurements were significantly greater than all imaging modality dimensions (p < 0.001), potentially because macroscopy included articular cartilage pathology. MAIN LIMITATIONS: Influence of motion artefact could not be assessed. CONCLUSIONS: Osteochondral defects could be visualised using both CT and MRI with sensitivity increasing with defect size. Diagnostic performance was best using FBCT, followed by CBCT then MRI, but CBCT-measured defect size best correlated with macroscopic examination. MRI provided useful information on fluid signal associated with defects, which could represent active pathology.

Comparison of cone-beam and fan-beam computed tomography and low-field magnetic resonance imaging for detection of palmar/plantar osteochondral disease in Thoroughbred horses.

BACKGROUND: Palmar/plantar osteochondral disease (POD) of the metacarpal/tarsal condyles is a common pathological finding in racehorses. OBJECTIVE: To compare diagnoses, imaging details, and measurements of POD lesions between cone-beam computed tomography CT (CBCT), fan-beam CT (FBCT), and low-field magnetic resonance imaging (MRI) using macroscopic pathology as a gold standard. STUDY DESIGN: Cross-sectional study. METHODS: Thirty-five cadaver limbs from 10 horses underwent CBCT, FBCT, MRI, and macroscopic examination. CT and MR images were examined for presence of POD, imaging details of POD, and measurements of POD dimensions and areas. Imaging diagnoses, details, and measurements were compared with macroscopic examination and between modalities. RESULTS: Forty-eight POD lesions were seen over 70 condyles. Compared with macroscopic examination the sensitivity and specificity of diagnosis were 95.8% (CI95 = 88%-99%) and 63.6% (CI95 = 43%-81%) for FBCT, 85.4% (CI95 = 74%-94%) and 81.8% (CI95 = 63%-94%) for CBCT, and 69.0% (CI95 = 54%-82%) and 71.4% (CI95 = 46%-90%) for MRI. Inter-modality agreement on diagnosis was moderate between CBCT and FBCT (κ = 0.56, p < 0.001). POD was identified on CT as hypoattenuating lesions with surrounding hyperattenuation and on MRI as either T1W, T2*W, T2W, and STIR hyperintense lesions or T1W and T2*W heterogeneous hypointense lesions with surrounding hypointensity. Agreement on imaging details between CBCT and FBCT was substantial for subchondral irregularity (κ = 0.61, p < 0.001). Macroscopic POD width strongly correlated with MRI (r = 0.81, p < 0.001) and CBCT (r = 0.79, p < 0.001) and moderately correlated with FBCT (r = 0.69, p < 0.001). Macroscopic POD width was greater than all imaging modality (p < 0.001). MAIN LIMITATIONS: Effect of motion artefact in live horse imaging could not be assessed. CONCLUSIONS: All imaging modalities were able to detect POD lesions, but underestimated lesion size. The CT systems were more sensitive, but the differing patterns of signal intensity may suggest that MRI can detect changes associated with POD pathological status or severity. The image features observed by CBCT and FBCT were similar.

Three-Dimensional Imaging and Histopathological Features of Third Metacarpal/Tarsal Parasagittal Groove and Proximal Phalanx Sagittal Groove Fissures in Thoroughbred Horses.

Fissure in the third metacarpal/tarsal parasagittal groove and proximal phalanx sagittal groove is a potential prodromal pathology of fracture; therefore, early identification and characterisation of fissures using non-invasive imaging could be of clinical value. Thirty-three equine cadaver limbs underwent standing cone-beam (CB) computed tomography (CT), fan-beam (FB) CT, low-field magnetic resonance imaging (MRI), and macro/histo-pathological examination. Imaging diagnoses of fissures were compared to microscopic examination. Imaging features of fissures were described. Histopathological findings were scored and compared between locations with and without fissures on CT. Microscopic examination identified 114/291 locations with fissures. The diagnostic sensitivity and specificity were 88.5% and 61.3% for CBCT, 84.1% and 72.3% for FBCT, and 43.6% and 85.2% for MRI. Four types of imaging features of fissures were characterised on CT: (1) CBCT/FBCT hypoattenuating linear defects, (2) CBCT/FBCT striated hypoattenuated lines, (3) CBCT/FBCT subchondral irregularity, and (4) CBCT striated hypoattenuating lines and FBCT subchondral irregularity. Fissures on MRI appeared as subchondral bone hypo-/hyperintense defects. Microscopic scores of subchondral bone sclerosis, microcracks, and collapse were significantly higher in locations with CT-identified fissures. All imaging modalities were able to identify fissures. Fissures identified on CT were associated with histopathology of fatigue injuries.

Identification of Heterotopic Mineralization and Adjacent Pathology in the Equine Fetlock Region by Low-Field Magnetic Resonance Imaging, Cone-Beam and Fan-Beam Computed Tomography.

Heterotopic mineralization in equine distal limbs has been considered an incidental finding and little is known about its imaging features. The study aimed to identify heterotopic mineralization and adjacent pathology in the fetlock region with cone-beam (CB) computed tomography (CT), fan-beam (FB) CT, and low-field magnetic resonance imaging (MRI). Images from 12 equine cadaver limbs were examined for heterotopic mineralization and adjacent pathology and verified by macro-examination. Retrospective review of the CBCT/MR images from 2 standing horses was also included. CBCT and FBCT identified twelve mineralization's with homogeneous hyperattenuation: oblique-sesamoidean-ligament (5) without macroscopic abnormality; deep-digital-flexor-tendon (1) and suspensory-branch (6) with macroscopic abnormalities. MRI failed to identify all mineralization's, but detected suspensory branch splitting, and T2 and STIR hyperintensity in 4 suspensory-branches and 3 oblique-sesamoidean-ligaments. Macro-examination found corresponding disruption/splitting and discoloration. All modalities identified 7 ossified fragments showing cortical/trabecular pattern: capsular (1), palmar sagittal ridge (1), proximal phalanx (2) without macroscopic abnormality, and proximal sesamoid bones (3). On MRI, fragments were most identifiable on T1 images. All abaxial avulsions had suspensory-branch splitting on T1 images with T2 and STIR hyperintensity. Macro-examination showed ligament disruption/splitting and discoloration. Suspensory-branch/intersesamoidean ligament mineralization's were identified by CBCT in standing cases; 1 had associated T2 hyperintensity. Both CT systems were generally superior in identifying heterotopic mineralization's than MRI, while MRI provided information on soft tissue pathology related to the lesions, which may be important for management.

Effect of Ground and Raised Poles on Kinematics of the Walk.

Walking over poles is a commonly employed training and rehabilitation tool and it is crucial to understand its effect on equine locomotion, particularly joint range of motion (ROM). The study aimed to compare the effect of ground poles (GP) and raised poles (RP) on limb kinematics and poll, wither and pelvic ROM at walk. It was hypothesized that walking over poles would increase joint ROM but have no effect on poll, wither and pelvic ROM compared to no poles (NP). Forty-one horses were walked in-hand over NP, GP (10 cm) and RP (26 cm) in a crossover design. Limb kinematics were determined via two-dimensional motion capture (240 Hz). Poll, wither, tubera sacrale, and left/right tuber coxae ROM were determined by inertial motion units (100 Hz). Multivariable mixed effects linear regression analyses were carried out. Walking over poles increased limb joint ROM, through increased swing flexion, compared to NP. There was a greater effect over RP compared to GP. Significant reductions in craniocaudal ROM of the wither, tuber coxae and tuber sacrale were observed over GP and RP. Mediolateral ROM of tuber coxae and tuber sacrale increased over GP and RP and was greatest over RP. Wither ROM was increased over RP only. Set-up and height of the poles used here may not extrapolate to other scenarios. Walking over poles appears to be effective at increasing joint ROM via an increase in mid swing flexion, without vertical excursion of the trunk, compared to normal locomotion, which supports the use of poles for rehabilitation.

Magnetic Resonance Imaging Findings in the Proximal Metacarpal Region of 359 Horses and Proximal Metatarsal Region of 64 Horses Acquired Under Standing Sedation.

Standing magnetic resonance (MR) images of proximal metacarpal/metatarsal regions are increasingly being acquired. This study aimed at describing ranges of abnormalities detected in sport/racehorses, using retrospective evaluation of magnetic resonance imaging (MRI) reports from horses with lameness isolated to proximal metacarpal/metatarsal regions with images acquired standing. It was hypothesized that MRI features are different between metacarpal and metatarsal regions and between horses doing different sports. Reports from 359 forelimbs and 64 hindlimbs were included. Palmar/plantar metacarpal/metatarsal bone injury and suspensory desmopathy, which often occurred concurrently, were most frequently reported. Third metacarpal abnormalities were more likely at palmar/medial locations, including cortical (86.4%) and trabecular (38.2%) pathology with frequent thickening, irregularity, and periosteal/endosteal abnormalities. Fluid signal was reported in cortical (38.7%) and trabecular (22.6%) bone. Medial intermetacarpal articulation abnormalities were more frequently reported (52.5%) than lateral. Suspensory ligament pathology was reported in 83.8% forelimbs, frequently with cortical (74.1%) or trabecular (32.9%) pathology. Tarsal-joint abnormalities were significantly more likely than carpal-joint abnormalities. Third metatarsal cortical (57.8%) and trabecular (20.3%) pathology was most frequently plantar, but significantly more likely to be dorsal than forelimbs. Metatarsal fluid signal was significantly less likely than metacarpal. Lateral intermetatarsal articulation pathology (23.4%) was more frequent than medial; medial was significantly more likely in forelimbs. Suspensory ligament abnormalities were reported in 64.1% hindlimbs, 39.1% having concurrent cortical pathology. Metacarpal fluid signal was significantly more likely in endurance/racehorses than dressage/show jumping horses. Dressage was overrepresented in hindlimb suspensory origin pathology. These findings indicate different pathology patterns between forelimb/hindlimb and between different sports and may be useful for MRI interpretation.

Standing low-field MRI of the equine proximal metacarpal/metatarsal region is considered useful for diagnosing primary bone pathology and makes a positive contribution to case management: A prospective survey study.

High-field MRI of the proximal metacarpal/metatarsal region has been associated with great diagnostic potential and clinical reports of standing low-field MRI of the forelimb suggest the same. To better understand diagnostic outcomes with standing low-field MRI of the proximal suspensory region, a prospective survey study was conducted and users of a widely available system questioned on their experience, operating procedures, and interpretation of standing low-field MRI findings. Response data included scores on a modified Likert scale from which weighted ratings were calculated for statistical analyses. Depending on the question, responses were obtained from 17 to 29 of the 38 invited facilities. Users indicated that standing low-field MRI was most frequently performed in the face of equivocal diagnostic findings; compared to Sports horses, general purpose riding horses were thought less likely to have detectable abnormalities and standing low-field MRI was rated most useful for the detection of primary bone pathology in the proximal metacarpal region. Standing low-field MRI signal change involving both the suspensory ligament and adjacent bone concurrently was rated most relevant and abnormalities solely affecting the muscle/adipose tissue bundles least relevant for diagnosing suspensory ligament injury. Transverse scans and in decreasing order T1-weighted gradient echo, short-tau inversion recovery FSE, T2*-weighted gradient echo, and T2-weighted FSE sequences were most frequently acquired and judged most useful by the majority of users experienced in imaging of the target area. This survey supports the relevant impact of standing low-field MRI on clinical case management, particularly in the context of imaging the proximal metacarpal region.

Citrate occurs widely in healthy and pathological apatitic biomineral: mineralized articular cartilage, and intimal atherosclerotic plaque and apatitic kidney stones.

There is continuing debate about whether abundant citrate plays an active role in biomineralization of bone. Using solid state NMR dipolar dephasing, we examined another normally mineralized hard tissue, mineralized articular cartilage, as well as biocalcifications arising in pathological conditions, mineralized intimal atherosclerotic vascular plaque, and apatitic uroliths (urinary stones). Residual nondephasing ¹³C NMR signal at 76 ppm in the spectra of mineralized cartilage and vascular plaque indicates that a quaternary carbon atom resonates at this frequency, consistent with the presence of citrate. The presence, and as yet unproven possible mechanistic involvement, of citrate in tissue mineralization extends the compositional, structural, biogenetic, and cytological similarities between these tissues and bone itself. Out of 10 apatitic kidney stones, five contained NMR-detectable citrate. Finding citrate in a high proportion of uroliths may be significant in view of the use of citrate in urolithiasis therapy and prophylaxis. Citrate may be essential for normal biomineralization (e.g., of cartilage), play a modulatory role in vascular calcification which could be a target for therapeutic intervention, and drive the formation of apatitic rather than other calcific uroliths, including more therapeutically intractable forms of calcium phosphate.

Development of a quantitative multivariable radiographic method to evaluate anatomic changes associated with laminitis in the forefeet of donkeys.

OBJECTIVE: To establish and validate an objective method of radiographic diagnosis of anatomic changes in laminitic forefeet of donkeys on the basis of data from a comprehensive series of radiographic measurements. ANIMALS: 85 donkeys with and 85 without forelimb laminitis for baseline data determination; a cohort of 44 donkeys with and 18 without forelimb laminitis was used for validation analyses. PROCEDURES: For each donkey, lateromedial radiographic views of 1 weight-bearing forelimb were obtained; images from 11 laminitic and 2 nonlaminitic donkeys were excluded (motion artifact) from baseline data determination. Data from an a priori selection of 19 measurements of anatomic features of laminitic and nonlaminitic donkey feet were analyzed by use of a novel application of multivariate statistical techniques. The resultant diagnostic models were validated in a blinded manner with data from the separate cohort of laminitic and nonlaminitic donkeys. RESULTS: Data were modeled, and robust statistical rules were established for the diagnosis of anatomic changes within laminitic donkey forefeet. Component 1 scores ≤ -3.5 were indicative of extreme anatomic change, and scores from -2.0 to 0.0 denoted modest change. Nonlaminitic donkeys with a score from 0.5 to 1.0 should be considered as at risk for laminitis. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that the radiographic procedures evaluated can be used for the identification, assessment, and monitoring of anatomic changes associated with laminitis. Screening assessments by use of this method may enable early detection of mild anatomic change and identification of at-risk donkeys.

Lipids in biocalcification: contrasts and similarities between intimal and medial vascular calcification and bone by NMR.

Pathomechanisms underlying vascular calcification biogenesis are still incompletely understood. Biomineral from human atherosclerotic intimal plaques; human, equine, and bovine medial vascular calcifications; and human and equine bone was released from collagenous organic matrix by sodium hydroxide/sodium hypochlorite digestion. Solid-state (13)C NMR of intimal plaque mineral shows signals from cholesterol/cholesteryl esters and fatty acids. In contrast, in mineral from pure medial calcifications and bone mineral, fatty acid signals predominate. Refluxing (chloroform/methanol) intimal plaque calcifications removes the cholesterylic but not the fatty acyl signals. The lipid composition of this refluxed mineral now closely resembles that of the medial and bone mineral, which is unchanged by reflux. Thus, intimal and medial vascular calcifications and bone mineral have in common a pool of occluded mineral-entrained fatty acyl-rich lipids. This population of fatty acid may contain methyl-branched fatty acids, possibly representing lipoprotein particle remnants. Cell signaling and mechanistic parallels between physiological (orthotopic) and pathological (ectopic) calcification are also reflected thus in the NMR spectroscopic fingerprints of mineral-associated and mineral-entrained lipids. Additionally the atherosclerotic plaque mineral alone shows a significant independent pool of cholesterylic lipids. Colocalization of mineral and lipid may be coincidental, but it could also reflect an essential mechanistic component of biomineralization.

Medium-term outcome of titanium uncemented stems in revision total hip arthroplasty.

PURPOSE: To assess the medium-term outcome of titanium uncemented modular tapered stems in revision total hip arthroplasty (THA). METHODS: A questionnaire was mailed to 421 patients who underwent revision THA using a titanium uncemented modular tapered stem. 66 of whom underwent re-revision THA. The questionnaire was composed to reveal the Charnley classification, the modified 12-item Oxford hip score, and the Devane patient activity level. RESULTS: 323 (77%) of the patients responded. The mean follow-up time was 6.6 years. 12 patients underwent bilateral revision THA. The mean Oxford hip score was 35.7, compared to 35.8 for all-component revision at postoperative month 6 in the New Zealand Joint Registry. The median Oxford hip scores for the subgroups of the stem-only revision (n=92), all-component revision (n=215), and re-revision (n=16) were 38, 39.9, and 30, respectively. The difference was significant between all-component revision and re-revision (adjusted p=0.003), and between stem-only revision and re-revision (adjusted p=0.037). Regarding patient distribution according to the Charnley class and the Devane patient activity level, the difference was significant between the mean Oxford hip scores of Charnley classes B and C (adjusted p=0.017), and between the Devane patient activity levels of Charnley classes A and C (adjusted p=0.043). CONCLUSION: The medium-term outcome of revision THA using a titanium uncemented modular tapered stem was comparable to that reported for other stems.

The appearance of the equine metacarpophalangeal region on high-field vs. standing low-field magnetic resonance imaging.

The appearance of the equine metacarpophalangeal (MCP) joint on high-field (1.5 T) vs. low-field standing (0.27 T) magnetic resonance (MR) images was evaluated. Objectives were (1) to describe the MR appearance of anatomic structures of clinical interest on images of the equine MCP joint obtained from 20 equine cadaver limbs from horses without lameness using high-field and low-field systems, (2) to categorize the clarity of appearance of anatomic structures on low-field MR images in comparison to high-field images as a gold standard. We found that larger anatomic structures were visible with sharp margins on both high- and low-field images, smaller structures were less distinct on low-field images and therefore interpretation of smaller structures on low-field images must be done with care.

Histopathologic features of distal tarsal joint cartilage and subchondral bone in ridden and pasture-exercised horses.

OBJECTIVE: To determine whether histopathologic characteristics of the osteochondral units of equine distal tarsal joints were associated with exercise history in horses without lameness. SAMPLE POPULATION: 30 cadaver tarsi from horses without lameness and with known exercise history were separated into 3 groups: nonridden, pasture exercise (group P); low-intensity, ridden exercise (group L); and high-intensity, elite competition exercise (group E). PROCEDURES: Standardized sites from the centrodistal and tarsometatarsal joints under went histologic preparation. A grading system was adapted to describe location, depth, and shape of lesions; cellular arrangement; organization at cartilage and subchondral bone (SCB) junctions; and organization of SCB. A high score signified a more severe pathological change than a low score. Exercise groups were compared by calculation of Spearman rank correlations. RESULTS: In the centrodistal joint, lesions were present in groups L and E but only medially. Cellular arrangement scores were higher at the dorsomedial location in group P than in groups L and E. Groups L and E had higher scores than group P for the organization of the cartilage, SCB junctions, and SCB, with higher scores at the dorsomedial location. In the tarsometatarsal joint, lesions were evident across the whole joint surface, with more severe lesions located laterally in all 3 groups. Overall, group E had higher scores for cellular arrangement and SCB organization than groups P and L. CONCLUSIONS AND CLINICAL RELEVANCE: Ridden exercise may increase the risk of osteochondral lesions at distal tarsal sites predisposed to osteoarthritis relative to the risk with nonridden exercise.

External characteristics of the lateral aspect of the hoof differ between non-lame and lame horses.

During a pre-purchase examination (PPE) there is always a debate about how clinical findings of the hoof different from ideal should be interpreted in relation to future lameness risk and/or unsuitability of the horse for the potential purchaser. The objectives of this study were to describe and compare external angular measurements, linear ratios and hoof capsule characteristics of non-lame and lame feet. Photographs of feet from 300 horses with foot pain and 25 non-lame horses were analysed. Hoof wall, heel and coronary band angles and hoof wall length and height, weight-bearing length, coronary band length and height of the coronary band at dorsal and palmar locations were measured and expressed as linear ratios. Mean hoof wall, heel and coronary band angles were larger in lame compared with non-lame feet; only the ratio of dorsal to palmar coronary band heights and the shape of the coronary band were significantly different between lame and non-lame horses. Growth rings were divergent and horn tubules were non-parallel in lameness of >3 months. At a PPE, a larger ratio of dorsal to palmar coronary band heights in one limb may be indicative of previous lameness in that foot. Changes in coronary band shape and divergent growth rings and horn tubules would suggest a longer duration.

Magnetic resonance imaging features of serous atrophy of bone marrow fat in the distal limb of three horses.

Emaciated human patients have changes in the fat content in medullary bone that are consistent with serous atrophy of the bone marrow histologically. Serous atrophy has been identified at postmortem examination in horses; however, the magnetic resonance (MR) characteristics have not been documented. Herein we describe the abnormalities of the bone marrow and medullary bone detected by low-field and high-field MR imaging of the distal limbs of three emaciated horses. These low- and high-field MR imaging abnormalities are characterized by a decrease in signal intensity on T1-weighted images in combination with an increase in signal intensity on short tau inversion recovery images in all areas of trabecular bone in the distal limbs, in the absence of lameness. Serous atrophy was confirmed microscopically in two horses. Appreciating the sensitivity of MR imaging for detection of bone marrow changes may assist in assessment of fat atrophy in welfare cases where starvation is suspected.

How do features of dressage arenas influence training surface properties which are potentially associated with lameness?

Results from a previous study indicated that there are specific arena surface characteristics that are associated with an increased likelihood of lameness in dressage horses. It is important to understand what modifiable arena factors lead to these detrimental surface characteristics. The aim of this study was to describe the use of training surfaces and arenas for United Kingdom dressage horses and to investigate any relationships between arena/surface variables and detrimental surface characteristics. Data from a questionnaire returned by 22.5% of all 11,363 registered members of British Dressage were used for the study. Univariate and multivariable logistic regression models were developed with each of the previously identified surface characteristics as dependent variables. Respondents reported that the majority of arenas were privately owned, sized 20 × 40 m and had a sand and rubber surface. The results indicated that wax-coated and sand and rubber surfaces were associated with less detrimental surface properties than sand, sand and PVC, woodchips or grass. Woodchips were most strongly associated with the detrimental characteristic of slipping, and sand with tripping. The findings indicated that any arena surface should have a base, with limestone the recommended surface, and that crushed concrete was best avoided. This information supported previous studies in racehorses that indicated that surface maintenance is essential, especially when many horses are using an arena daily. Problems were less likely if an arena was privately owned.

Identification of risk factors for lameness in dressage horses.

The aim of this study was to describe the prevalence of illness and lameness at different anatomical sites in registered United Kingdom dressage horses and to identify risk factors for lameness. A questionnaire was sent to all 11,363 registered members of British Dressage in 2005, with one questionnaire assigned per horse. Four multivariable logistic regression models were developed for each section of the questionnaire. A final mixed effects logistic regression model was developed which combined the results from all prior models. Owners reported that 33% of horses had been lame at some time during their career, with 24% of these within the previous 2 years. A number of factors were associated with the occurrence of lameness in the last 2 years, including age, height, indoor arenas, horse-walkers, lunging (as protective), back problems, arenas that become deeper in wet conditions and sand-based arenas. These factors were included as variables in a final model to provide information for selection of horses, development of safer arenas and more effective training regimens to minimise the onset of lameness.