Investigation of the Reliability of Saddle Fitters to Determine the Position of the Last Thoracic Vertebra of Horses Using Palpation Techniques: A Pilot Study.

Published guidelines indicate an English saddle tree should not extend beyond the 18th thoracic vertebra (T18). The study aimed to assess reliability of saddle fitters (SFs) to identify the T18 spinous process (SP). Part 1 investigated agreement between T18 (T18SF) as identified by three SFs using palpation and a veterinary surgeon (VS) using radiography (T18VS) in seven horses. Saddle fitter 1 and SF2 palpated the lumbosacral joint and counted cranially six SPs, whereas SF3 followed the rib curvature toward the dorsal midline. In part 2, SF1 and SF2 identified T18 by counting cranially five SPs in seven horses on two occasions. Agreement between SFs and VS was assessed using t tests and Bland-Altman plots. Interrater and intrarater reliability were estimated using intraclass correlation coefficients. In part 1, SF1 and SF2 found T18SF 4.3 cm (±4.1 and 4.0 cm, respectively) cranial to T18VS. Mean difference between T18SF3 and T18VS was 0.1 ± 4.9 cm (95% CI: -9.5 cm, 9.6 cm, P = .976). When counting cranially five SPs, mean difference between T18SF1 and T18VS was -1.5 ± 3.4 cm (95% CI: -8.3 cm; 5.1 cm; P = .265) and T18SF2 and T18VS was -0.3 cm ± 4.5 cm (95% CI: -8.8 cm; 8.5 cm; P = .847). Interrater reliability was "good" (ICC = 0.798). Intrarater reliability was "excellent" for SF1 (ICC = 0.905) and "good" for SF2 (ICC = 0.847). Counting cranially five SPs from the lumbosacral joint, when coupled with observation of the rib position and curvature should ensure a saddle is not placed beyond T18.

Evaluation of the diagnostic accuracy of skeletal scintigraphy in lame and poorly performing sports horses.

Skeletal scintigraphy is an established imaging modality, however, its validity as a diagnostic test in lame or poorly performing sports horses has not been determined. The objective of this retrospective cross-sectional analytical study was to determine the accuracy of skeletal scintigraphy as an indiscriminate screening test in sports horses. All sports horses that underwent scintigraphic examination between March 2008 and December 2014 for which a definitive diagnosis was reached were included. Examinations were evaluated blindly. Characteristics of increased radiopharmaceutical uptake were recorded and subjectively categorized as possibly relevant or non-relevant. Kappa statistics were used to assess agreement between test results and final diagnosis. There were 1222 positive clinical diagnoses in 480 horses, of which 687 regions (56.4%) had no associated increased radiopharmaceutical uptake and 99 regions (8.1%) had non-relevant increased radiopharmaceutical uptake. The sensitivity of increased radiopharmaceutical uptake for identification of final diagnosis was low (43.8%) and specificity was high (94.0%). The agreement was fair (κ = 0.36). Relevance categorization improved the test; the sensitivity for final diagnosis was low (35.7%), specificity was high (98.9%), and the agreement was moderate (κ = 0.45). The agreements of increased radiopharmaceutical uptake and relevance categorization with final diagnosis were only substantial for feet (κ = 0.67 and κ = 0.66, respectively) and proximal aspect of the forelimb (elbow, shoulder, and scapula combined) (κ = 0.69 and 0.78, respectively). Scintigraphic examination is unlikely to lead to a full and correct diagnosis of the cause(s) of lameness or poor performance in sports horses when used as an isolated or indiscriminate screening tool.

Evaluation of the diagnostic accuracy of skeletal scintigraphy for the causes of front foot pain determined by magnetic resonance imaging.

There is good correlation between increased radiopharmaceutical uptake anywhere in the feet of sports or leisure horses and the presence of foot pain. However, low sensitivity of scintigraphy for identifying lesions contributing to foot pain as determined by magnetic resonance imaging (MRI) has been reported. The aim of this retrospective, cross-sectional, analytical study was to assess the accuracy of scintigraphy for identifying the cause(s) of foot pain, using MRI as the reference standard. Sports and leisure horses that underwent both skeletal scintigraphy and MRI of the front feet between March 2008 and December 2014 and for which a definitive diagnosis of the cause(s) of front foot pain was reached were included (121 feet of 70 horses). Imaging studies were evaluated retrospectively, blindly. Agreements between scintigraphic localization of increased radiopharmaceutical uptake and subjective categorization of lesions with MRI diagnosis were assessed using Kappa statistics (κ). Measures of diagnostic accuracy were calculated. Sensitivity of increased radiopharmaceutical uptake varied among regions (31.8-76.2%) but specificity was at least high for all (84.6-100%). Agreements between both scintigraphy measures and MRI diagnosis were substantial for the distal phalanx (palmar processes and body) (κ = 0.77 and κ = 0.74, respectively), and ungular cartilages and chondral ligaments (κ = 0.62, for both). When all regions were combined, agreements of increased radiopharmaceutical uptake (κ = 0.49) and relevance categorization (κ = 0.45) with MRI diagnosis were moderate. In conclusion, skeletal scintigraphy does not meet the minimum reliability level for a diagnostic test, but is reliable for identification of osseous trauma to the distal phalanx and ungular cartilages.

Use of high-field and low-field magnetic resonance imaging to describe the anatomy of the proximal portion of the tarsal region of nonlame horses.

OBJECTIVE To use high-field and low-field MRI to describe the anatomy of the proximal portion of the tarsal region (proximal tarsal region) of nonlame horses. SAMPLE 25 cadaveric equine tarsi. PROCEDURES The proximal portion of 1 tarsus from each of 25 nonlame horses with no history of tarsal lameness underwent high-field (1.5-T) and low-field (0.27-T) MRI. Resulting images were used to subjectively describe the anatomy of that region and obtain measurements of the collateral ligaments of the tarsocrural joint. RESULTS Long and short components of the lateral and medial collateral ligaments of the tarsocrural joint were identified. Various bundles of the short collateral ligaments were difficult to delineate on low-field images. Ligaments typically had low signal intensity in all sequences; however, multiple areas of increased signal intensity were identified at specific locations in most tarsi. This signal intensity was attributed to focal magic angle effect associated with orientation of collagen fibers within the ligaments at those locations. Subchondral bone of the distal aspect of the tibia was uniform in thickness, whereas that of the medial trochlear ridge of the talus was generally thicker than that of the lateral trochlear ridge. In most tarsi, subchondral bone of the talocalcaneal joint decreased in thickness from proximal to distal. CONCLUSIONS AND CLINICAL RELEVANCE Results generated in this study can be used as a reference for interpretation of MRI images of the proximal tarsal region in horses.

Radiographic characterization of ossification of the ungular cartilages in horses: 271 cases (2005-2012).

OBJECTIVE: To describe in detail the radiographic appearance of ossified ungular cartilages in horses and to evaluate the usefulness of a flexed dorsolateral-palmaromedial oblique (flexed oblique) radiographic view in evaluating the ungular cartilages. DESIGN: Retrospective case series. Sample-Radiographs of 1,255 front feet of horses. PROCEDURES: Ossification of the ungular cartilages was graded during evaluation of radiographs on a scale from 0 to 5; feet with cartilages with an ossification grade ≥ 2 were included (386 feet [271 horses]). The shape (straight, curved outward or inward, and dorsopalmar extension of ossification) was determined. The view on which abnormalities were best identified was documented. Abnormalities of the compact bone, radiopacity, trabecular architecture, compactospongious demarcation, and presence of radiolucent lines were recorded; grouped as modeling, adaptive changes, or both; compared with ossification grade, separate centers of ossification, mediolateral symmetry of ossification, shape, cartilage (medial or lateral), and foot (left or right); and tested for significant associations. RESULTS: Fractures (n = 35) were most common in feet with cartilages with an ossification grade of 4 (18) or 5 (17) and were best identified in flexed oblique images, compared with more commonly recommended images. Multivariable logistic regression showed a significant positive association of ossification grade with modeling or adaptive changes; feet with cartilages with an ossification grade of 4 (OR, 11.59; 95% CI, 6.52 to 20.60) or 5 (OR, 72.90; 95% CI, 25.32 to 209.90) were more likely than those with an ossification grade of 2 or 3 to have modeling or adaptive changes. Abnormally shaped cartilages were more likely to have modeling or adaptive changes, compared with normally shaped cartilages (OR, 4.90; 95% CI, 1.94 to 12.42). CONCLUSIONS AND CLINICAL RELEVANCE: Extensive ossification and the presence of inward or outward curvature as well as palmar curvature or a bulbous shape were significant risk factors for modelling and adaptive changes. Flexed oblique images provided clinically useful information, including detection of abnormal shape and fractures, that may not be evident on other currently recommended images. Such images are recommended for complete radiographic appraisal of ossified ungular cartilages of the foot in horses.

Magnetic resonance imaging characteristics of equine head disorders: 84 cases (2000-2013).

The equine head is an anatomically complex area, therefore advanced tomographic imaging techniques, such as computed tomography or magnetic resonance imaging (MRI), are often required for diagnosis and treatment planning. The purpose of this multicenter retrospective study was to describe MRI characteristics for a large sample of horses with head disorders. Horses imaged over a period of 13 years were recruited. Eighty-four horses met the inclusion criteria, having neurological (n = 65), sinonasal (n = 14), and soft tissue (n = 5) disorders. Magnetic resonance imaging accurately depicted the anatomy and allowed identification of the primary lesion and associated changes. There were good correlations between MRI findings and intraoperative or postmortem results. Magnetic resonance imaging showed the exact localization of the lesions, their size, and relation to surrounding structures. However, in the neurological group, there were 45 horses with no MRI abnormalities, 29 of which had a history of recurrent seizures, related to cryptogenic epilepsy. Magnetic resonance imaging was otherwise a valuable diagnostic tool, and can be used for studying a broad range of head disorders using either low-field or high-field magnets.

An investigation of risk factors for foot-related lameness in a United Kingdom referral population of horses.

Lameness relating to the foot of the horse is common, but the majority of information concerning risk factors for injury is anecdotal. The objectives of this study were to investigate risk factors for foot-related pain in a referral population of horses, with particular reference to injury/disease of the podotrochlear apparatus (PTA), by comparison with the remainder of the clinic population. It was hypothesised that there would be an increased risk of foot pain associated with breed, work discipline, age, height and bodyweight (BW). A retrospective study of all horses examined at a referral centre between 2001 and 2010 was performed using univariable and multivariable logistic regression analyses. There were 4618 horses investigated, 1132 of which had foot pain. There was increased risk of foot pain in multivariable analyses (all categories combined) in horses aged 6-9 and 10-15 years (OR = 1.60 and 1.72, respectively), compared with horses <6 years old, in show jumpers (OR = 1.44) compared with dressage horses, Thoroughbred cross-breeds (OR = 1.53) compared with Warmbloods and in horses with a BW:height ratio in the upper two quartiles (3.45-3.71 or >3.71; OR = 1.55 and 1.44, respectively), compared with the lowest quartile (<3.19). Racehorses had reduced risk for all types of foot pain combined (OR = 0.13) compared with dressage horses. Risk factors for PTA injury were age (10-15 years, OR = 2.12; >15 years, OR = 3.36, compared with <6 years old), BW:height ratio (>3.45-3.71 (OR = 2.75), >3.71 (OR = 2.06), compared with <3.19) and Thoroughbred cross-breed (OR = 1.73) compared with Warmbloods. Show jumpers had an increased risk of PTA and other injuries (OR = 2.29) when compared with dressage horses. Age, breed, work discipline and BW:height ratio influenced the risk of foot pain, but other factors probably also play a role.

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.

A veterinary review of endurance riding as an international competitive sport.

The popularity of competitive endurance riding is growing worldwide and this has led to considerable changes in the discipline (e.g., fitter and faster horses and different types of injuries), which create challenges to all involved in the sport, including veterinarians. During endurance competitions, horses are closely monitored by veterinarians throughout the ride, with the aim of removing from the competition animals whose welfare appears to be endangered. This close monitoring provides veterinarians with an insight into problems during competitions. However, there is a relatively small amount of clinically relevant, evidence-based data published on endurance horses, and this article reviews the evolution of the discipline, the published information on epidemiological data on endurance rides, the problems veterinarians face at competitions, and highlights those areas where research is warranted.

Radiographic and scintigraphic evaluation of the third carpal bone of control horses and horses with carpal lameness.

We compared the radiographic and scintigraphic findings in the third carpal bone of horses performing different work disciplines and investigated their relationship with lameness. Horses had undergone carpal radiography including acquisition of a dorsoproximal-dorsodistal oblique (DPr-DDiO) image of the distal row of carpal bones and/or scintigraphic examination of the carpi. Cause of lameness, breed, age, and work discipline were recorded. Increased opacity in the third carpal bone was graded, ratio of radiopharmaceutical uptake calculated objectively, and increased radiopharmaceutical uptake graded subjectively. Relationships between radiographic, scintigraphic, and clinical findings were assessed statistically. Increased opacity in the third carpal bone (P = 0.003) and ratio of radiopharmaceutical uptake (P = 0.015) were associated with the work discipline. Increased opacity in the third carpal bone was associated with both increased radiopharmaceutical uptake grade (P = 0.002; rs = 0.59) and ratio of radiopharmaceutical uptake (P = 0.013; rs = 0.46). Increased radiopharmaceutical uptake and increased opacity in the third carpal bone were not always observed concurrently. Lameness related to the middle carpal joint was associated with increased opacity (P < 0.001), ratio of radiopharmaceutical uptake (P = 0.037), and increased radiopharmaceutical uptake grade (P < 0.001). Radiographic and scintigraphic abnormalities were observed in horses performing all disciplines, indicating that high-speed exercise may not be the only factor determining the development of osseous disease in the third carpal bone. Both increased opacity and increased radiopharmaceutical uptake were more likely to be seen in horses with lameness related to the middle carpal joint than in horses with other sources of pain.

Lesions of the equine neck resulting in lameness or poor performance.

Lesions of the neck are an uncommon primary cause of pain resulting in either lameness or poor performance but should be considered if local analgesic techniques of the limbs fail to abolish lameness or if there are clinical signs directly referable to the neck such as pain, abnormal neck posture, stiffness, or patchy sweating. Accurate diagnosis requires careful clinical examination, exclusion of other causes of lameness or poor performance, and accurate interpretation of diagnostic imaging findings.

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.

Radiologic anatomic variation of the carpus in horses with carpal lameness and control horses.

Our purpose was to describe the variation of the radiologic appearance of the carpus of horses of different breeds, discipline, and gender with lameness related to the carpus and control horses, with particular reference to the ulnar carpal bone. Two hundred and eighty-six sets of carpal radiographs from 222 horses were analyzed. Breed, gender, discipline, and cause of lameness were recorded. Chi square tests were used to test for associations between radiologic findings and gender, breed and discipline, to test for associations between different radiologic findings, and to test for associations between radiologic findings and causes of lameness. Bonferroni correction was applied when necessary. The shape of the ulnar carpal bone and most of the anatomic variants, with the exception of the first carpal bone and a radiolucent area in the second carpal bone, were not breed or gender related. Radiolucent areas and associated fragments on the palmaromedial aspect of the ulnar carpal bone can be an incidental finding in horses from all disciplines.

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.

Effect of exercise on thicknesses of mature hyaline cartilage, calcified cartilage, and subchondral bone of equine tarsi.

OBJECTIVE-To investigate effects of exercise on hyaline cartilage (HC), calcified cartilage (CC), and subchondral bone (SCB) thickness patterns of equine tarsi. SAMPLE POPULATION-30 tarsi from cadavers of horses with known exercise history. PROCEDURES-Tarsi were assigned to 3 groups according to known exercise history as follows: pasture exercise only (PE tarsi), low-intensity general-purpose riding exercise (LE tarsi), and high-intensity elite competition riding exercise (EE tarsi). Osteochondral tissue from distal tarsal joints underwent histologic preparation. Hyaline cartilage, CC, and SCB thickness were measured at standard sites at medial, midline, and lateral locations across joints with a histomorphometric technique. RESULTS-HC, CC, and SCB thickness were significantly greater at all sites in EE tarsi, compared with PE tarsi; this was also true when LE tarsi were compared with PE tarsi. At specific sites, HC, CC, and SCB were significantly thicker in EE tarsi, compared with LE tarsi. Along the articular surface of the proximal aspect of the third metatarsal bone, SCB was thickest in EE tarsi and thinnest in LE tarsi; increases were greatest at sites previously reported to undergo peak strains and osteochondral damage. CONCLUSIONS AND CLINICAL RELEVANCE-Increased exercise was associated with increased HC, CC, and SCB thickness in mature horses. At sites that undergo high compressive strains, with a reported predisposition to osteoarthritic change, there was increased CC and SCB thickness. These results may provide insight into the interaction between adaptive response to exercise and pathological change.

Scintigraphic assessment of the metacarpophalangeal and metatarsophalangeal joints of horses with joint pain.

Our aims were to evaluate the pattern of radiopharmaceutical uptake in horses with lameness related to the metacarpophalangeal and/or metatarsophalangeal joint and compare the results with similar information from sound horses. It was hypothesized bthat there would be a difference in radiopharmaceutical uptake between the lame and contralateral limb in unilaterally lame horses and that there would be a difference between lame and sound horses. Nuclear scintigraphic images of 43 horses with forelimb lameness and 30 horses with hindlimb lameness were evaluated. In all horses lameness was improved by intraarticular analgesia of the joint, or by perineural analgesia of the palmar/plantar (at the junction of the proximal 3/4 and the distal 1/4 of the metacarpal/metatarsal regions) and palmar/plantar metacarpal/metatarsal nerves. All images were assessed subjectively and a quantitative image analysis was performed by drawing a vertical line profile through the center of each joint in the lateral images and using region of interest analysis in both lateral and dorsal/plantar images. Ratios of radiopharmaceutical uptake were compared for each region between lame and contralateral limbs in unilaterally lame horses and between lame and control horses. There was a significant difference in the ratio of radiopharmaceutical uptake in the proximal aspect of the proximal phalanx between lame and nonlame forelimbs in unilaterally lame horses and in both lame and contralateral limbs of lame horses compared with control horses for the regions of the distal aspect of the third metacarpal/metatarsal bone and the proximal sesamoid bones. However, the profile analysis was of limited clinical value.