Veterinary problems of endurance horses in England and Wales.

Several studies have shown that a considerable proportion of horses are eliminated from endurance rides due to lameness and metabolic problems. Limited information is available on specific veterinary issues in endurance horses and there are no descriptive data on veterinary problems in a large population of endurance horses. The aim of this study was to describe veterinary problems occurring in endurance horses in England and Wales, the regions of the United Kingdom where endurance rides are organised and regulated by Endurance Great Britain (Endurance GB). A comprehensive online self-completed questionnaire was used for data collection (30th December 2015-29th February 2016) All members of Endurance GB who were the main rider of one or more endurance horses were eligible to participate. From the target population of 1209 horses, 190 questionnaires were completed by riders, resulting in a 15.7% response rate. The most common rider-reported veterinary problem was lameness, affecting 152/190 (80.0%) of endurance horses at some point during their careers and 101/190 (53.2%) of horses in the previous 12 months. Detailed information on the most recent episode of lameness was available for 147 horses. Seventy-six percent of these lameness episodes (112/147) had been initially identified by a veterinarian, but only 52% of these lameness episodes were investigated further by a veterinarian, despite the high proportion of horses affected by lameness and the proportion of horses with recurrent lameness episodes. The second most common veterinary problem was thoracolumbar region pain, followed by non-specific cough, skin disease and colic. Education of endurance riders may improve the number, quality and timing of veterinary investigations, especially for lameness and thoracolumbar region pain.

Comparison of limb kinematics between collected and lengthened (medium/extended) trot in two groups of dressage horses on two different surfaces.

BACKGROUND: Dressage horses are often asked to work in lengthened paces during training and competition, but to date there is limited information about the biomechanics of dressage-specific paces. Preliminary work has shown increased fetlock extension in extended compared with collected paces, but further investigation of the kinematic differences between collected, medium and extended trot in dressage horses is warranted. OBJECTIVES: Investigation of the effect of collected vs. medium/extended trot on limb kinematics of dressage horses. STUDY DESIGN: Prospective kinematic evaluation. METHODS: Twenty clinically sound horses in active dressage training were used. Group 1: Ten young horses (≤6 years) were assessed at collected and medium trot and Group 2: Ten mature horses (≥9 years) were assessed at collected and extended trot. All horses were evaluated on two different surfaces. High speed motion capture (240 Hz) was used to determine kinematic variables. Fore- and hindlimb angles were measured at mid-stance. Descriptive statistics and mixed effect multilevel regression analyses were performed. RESULTS: Speed and stride length were reduced and stride duration increased at collected compared with medium/extended trot. Lengthened trot (medium/extended trot) was associated with increased fetlock extension in both the fore- and hindlimbs in both groups of horses. Changes were greater in mature horses compared with young horses. Shoulder and carpus angles were associated with forelimb fetlock angle. Hock angle was not significantly influenced by pace. Surface had no effect on fetlock or hock angles. MAIN LIMITATIONS: Only 2D motion analysis was carried out. Results may have differed in horses with more extreme gait characteristics. CONCLUSIONS: Medium/extended trot increases extension of the fore- and hindlimb fetlock joints compared with collected trot in both young and mature dressage horses, respectively.

Descriptive epidemiology and risk factors for eliminations from Fédération Equestre Internationale endurance rides due to lameness and metabolic reasons (2008-2011).

REASONS FOR PERFORMING THE STUDY: There is limited information on international endurance rides and on risk factors for eliminations. OBJECTIVES: To describe and compare the frequency of occurrence of elimination due to lameness and metabolic reasons from Fédération Equestre Internationale (FEI) endurance rides (≥100 km) during 2008-2011 in all countries and to assess risk factors for elimination due to lameness and metabolic reasons. STUDY DESIGN: Retrospective unmatched case-control study. METHODS: Data collected from the FEI website included the following: the country where the ride was held; the year; the result for each horse-rider combination; the number of entries in each class; whether the class was restricted to young riders; and the winning speed. Descriptive data were summarised, and univariable and multivariable logistic regression analyses were performed to assess risk factors for eliminations due to lameness and metabolic reasons. RESULTS: Between 2008 and 2011, there were 30,741 horse starts at FEI endurance rides of 100-160 km distance in 47 countries. Of all started horses, 30% were eliminated for lameness. Eliminations for metabolic reasons were recorded for 8.7% of all started horses. There was a large range of winning speeds amongst countries (10.2-29.5 km/h). Multivariable analysis revealed that the risk of elimination due to lameness was significantly associated with the country where the ride was held, the year, the distance of the ride and the number of entries. Elimination for metabolic reasons was significantly associated with the country where the ride was held, the year and the number of entries. CONCLUSIONS: Differences existed among elimination rates at FEI endurance rides in different countries (2008-2011). Lameness was the most common reason for elimination globally. POTENTIAL RELEVANCE: These results provide objective global data on endurance riding that can replace anecdotal information, which has been the base of opinions, decisions and regulations. The Summary is available in Chinese - see Supporting information.

Horse-, rider-, venue- and environment-related risk factors for elimination from Fédération Equestre Internationale endurance rides due to lameness and metabolic reasons.

REASONS FOR PERFORMING THE STUDY: There is limited information on risk factors for elimination from endurance rides. OBJECTIVES: To assess risk factors for elimination for lameness and metabolic reasons from Fédération Equestre Internationale (FEI) endurance rides of 80-160 km distance. STUDY DESIGN: Unmatched case-control. METHODS: Venue-, horse- and rider-related data were collected from the FEI website. Data on weather conditions and terrain were collected at the venue. Univariable and multivariable logistic regression analyses were used to assess risk factors for elimination for lameness and metabolic reasons, respectively. RESULTS: Multivariable logistic regression on 1435 horse starts revealed that the venue was significantly associated with elimination for lameness (P = 0.013). The horse's previous experience at a greater distance than the current ride (odds ratio [OR] = 0.82, 95% confidence interval [CI] 0.71-0.95, P = 0.008) and > 90 days elapsed since the last FEI ride (OR = 0.78, 95% CI 0.62-0.99, P = 0.044) significantly reduced the risk of elimination for lameness. In the multivariable model for elimination for metabolic reasons, the venue (P = 0.011), increasing number of started horses (OR = 1.008, 95% CI 1.00-1.01, P = 0.001) and deep sand or soil on the track (OR = 1.98, 95% CI 1.17-3.35, P = 0.001) significantly increased the risk of elimination for metabolic reasons. CONCLUSIONS: Reducing the frequency of racing may contribute to decreased risk of elimination for lameness. Competing in deep sand or soil may contribute to exhaustion, leading to elimination for metabolic reasons. Eliminations are likely to be the end result of a complex process, and not every aspect was or can be measured. Further studies with a larger number of horse starts and assessment of variables that could not be measured in this study may identify additional risk factors that can be modified.

The interrelationship of lameness, saddle slip and back shape in the general sports horse population.

REASONS FOR PERFORMING STUDY: Saddle slip is usually blamed on saddle fit, crooked riders or horse shape, but may reflect hindlimb lameness. There are no studies of the frequency of occurrence of saddle slip and risk factors within a tested sample population of the general sports horse population. OBJECTIVES: To quantify the frequency of saddle slip and to describe the association with lameness, thoracolumbar shape/symmetry, crooked riders and ill-fitting saddles. STUDY DESIGN: Nonrandom, cross-sectional survey using convenience sampling. METHODS: Five hundred and six sports horses in normal work were assessed prospectively. Thoracolumbar shape/symmetry were measured at predetermined sites; the presence of lameness (in hand and/or ridden) and saddle slip was recorded. Descriptive statistics, univariable and multiple logistic regression were performed to assess the relationship between horse-saddle-rider factors and saddle slip. RESULTS: The frequency of lameness, quadrilaterally reduced cranial phase of the stride or stiff, stilted canter was 45.7%, saddle slip 12.3%, left-right thoracolumbar shape asymmetries ≥ coefficient of variance of 8% (1.2 cm) 0.6%; and 103 of 276 riders (37.3%) sat crookedly. The saddle consistently slipped to one side in 24.4% of horses with hindlimb lameness alone, 45.5% of horses with concurrent hindlimb and forelimb lameness, compared with 5.4% with forelimb lameness, 17.4% with stiff, stilted canter, 20% with quadrilaterally reduced cranial phase of stride and 5.5% nonlame horses. Nineteen horses (30.6%) with saddle slip had no detectable hindlimb lameness; however, 14 had a gait abnormality, particularly in canter. Multivariable analysis revealed that saddle slip was significantly associated with hindlimb lameness and gait abnormalities (odds ratio [OR] = 52.62, 95% confidence interval [CI] 17.3-159.7), a saddle fitted with even contact and uniform flocking (OR = 15.49, 95% CI 1.9-125.5), riders sitting crookedly (OR = 6.32, 95% CI 2.9-13.7), a well-balanced saddle (OR = 3.05, 95% 1.4-6.9) and large back shape ratio at T18 (OR = 1.2, 95% 1.1-1.3). CONCLUSIONS: Many horses with hindlimb and/or forelimb lameness go unrecognised. Saddle slip may be a sign of hindlimb lameness. Education of the equestrian population to identify lameness and saddle slip is required. The Summary is available in Chinese - see Supporting information.

Riders' prediction of results at Fédération Equestre Internationale (FEI) endurance rides and sources of bias in questionnaires completed by riders.

Information acquired from endurance riders and its relationship with the results of the ride has not been investigated. The aims of this study were to assess associations between data provided by riders and data obtained from the Fédération Equestre Internationale (FEI) website at FEI endurance rides and to identify whether data provided by riders in pre- and post-ride questionnaires was subject to response and/or information bias. Variables were collected from the FEI website and from self-completed pre-ride and post-ride questionnaires at 20 FEI endurance rides in 2011 and 2012. Kappa statistics and Mann-Whitney U-tests were used to assess the relationship between FEI website and questionnaire data and between the riders' predictions and experiences. Univariable logistic regression was used to investigate association between completion of the ride and riders' predictions. Response bias was assessed using multi-level logistic regression models. At least one questionnaire was completed for 236 (18.8%) of 1254 competition starts included in the study. There was excellent agreement on signalment between questionnaire and FEI data, except for data on breed. There was moderate agreement between the mean speed category predicted by riders and reported in the official results. Riders with the aim of qualification or 'competition, achieving the best possible results' were less likely to complete the ride than riders aiming for 'training'. Female riders, riders competing in a young rider class, older riders, riders competing in rides of shorter distances and riders that had completed the distance of the study ride more than three times were associated with increased likelihood of completing the questionnaires. In conclusion, some riders' predictions were associated with the outcome of the ride. A larger study is needed to assess these variables as risk factors for eliminations. The response biases and the difficulties of data collection identified in this study can help when designing future studies.

Effect of a Pessoa training aid on temporal, linear and angular variables of the working trot.

Development of core muscle strength is important for training and during rehabilitation following injury. A Pessoa training aid (PTA) is a system of ropes and pulleys which is commonly used during equine training and rehabilitation, but there is limited information on its effectiveness. The objective of the study was to determine the effect of the PTA on the temporal, linear and angular kinematics of the working trot. Influence of testing order on effect of a PTA was assessed in four horses. Twelve riding horses were lunged at working trot on a 16 m diameter circle without (WO) and with a PTA (WP) that was set level with the shoulder. Objective measurements were carried out using high-speed motion capture (125 Hz) and inertial measurement units. Subjective video assessment was also undertaken. When a PTA was applied there was a significant reduction in speed, stride length, head angle (P<0.0001 for all) and lumbosacral angle at maximal hindlimb retraction (P=0.0028), but no effect on limb joint angles. The highest point of the horse was significantly different between conditions (WO, poll; WP, crest) (P=0.0010). Dorsoventral displacement of the middle of the back (P≤0.0001) and overall impression grade (P=0.0002) were significantly greater WP compared with WO. These findings indicated that a PTA may be beneficial for general training and rehabilitation as a method of improving posture, stimulating core muscle activation and improving overall way of going, without increasing the loading of forelimb and hindlimb structures. Further work is warranted to understand the mechanism which induces these changes.

An investigation of the relationship between hindlimb lameness and saddle slip.

REASONS FOR PERFORMING STUDY: We have observed saddle slip consistently to one side because of a crooked rider, an ill-fitting saddle, asymmetry in a horse's thoracolumbar shape and lameness. Currently, there are no objective data to permit assessment of the relative importance of each factor. OBJECTIVES: To document the frequency of occurrence of saddle slip in horses with hindlimb lameness compared with other horses. To describe the effect of lameness characteristics and grade, the abolition of lameness by diagnostic analgesia, breed, size, thoracolumbar shape and symmetry and the rider's weight. METHODS: One hundred and twenty-eight horses were assessed prospectively, and lameness and saddle slip were assigned a grade before and after diagnostic analgesia. The thoracolumbar shape and symmetry were measured objectively. In 3 horses, the force distribution and magnitude underneath the saddle were measured before and after diagnostic analgesia. RESULTS: The saddle consistently slipped to one side in 38 of 71 horses (54%) with hindlimb lameness, compared with one of 26 horses (4%) with forelimb lameness, none of 20 (0%) with back pain and/or sacroiliac joint region pain and none of 11 sound horses (0%). The association between saddle slip and hindlimb lameness was significant (Spearman's rank correlation coefficient, ρ = 0.548, P<0.001). Diagnostic analgesia abolishing the hindlimb lameness eliminated the saddle slip in 37 of 38 horses (97%). In 2 horses, the saddle continued to slip after resolution of lameness; one horse had bilateral forelimb lameness and the other horse had concurrent hindlimb and forelimb lameness. The saddle of both these horses was asymmetrically flocked. The saddle slipped to the side of the lamer hindlimb in most horses (32 of 37 [86%]). No horse with saddle slip had significant left-right asymmetry of the back at 4 predetermined sites. CONCLUSIONS AND CLINICAL RELEVANCE: Hindlimb lameness is an important factor in inducing saddle slip. Saddle slip may be an indicator of the presence of hindlimb lameness.

Diffusion of contrast medium after four different techniques for analgesia of the proximal metacarpal region: an in vivo and in vitro study.

REASONS FOR PERFORMING STUDY: There is limited information on potential diffusion of local anaesthetic solution after various diagnostic analgesic techniques of the proximal metacarpal region. OBJECTIVE: To document potential distribution of local anaesthetic solution following 4 techniques used for diagnostic analgesia of the proximal metacarpal region. METHODS: Radiodense contrast medium was injected around the lateral palmar or medial and lateral palmar metacarpal nerves in 8 mature horses, using 4 different techniques. Radiographs were obtained 0, 10 and 20 min after injection and were analysed subjectively. A mixture of radiodense contrast medium and methylene blue was injected into 4 cadaver limbs; the location of the contrast medium and dye was determined by radiography and dissection. RESULTS: Following perineural injection of the palmar metacarpal nerves, most of the contrast medium was distributed in an elongated pattern axial to the second and fourth metacarpal bones. The carpometacarpal joint was inadvertently penetrated in 4/8 limbs after injections of the palmar metacarpal nerves from medial and lateral approaches, and in 1/8 limbs when both injections were performed from the lateral approach. Following perineural injection of the lateral palmar nerve using a lateral approach, the contrast medium was diffusely distributed in all but one limb, in which the carpal sheath was inadvertently penetrated. In 5/8 limbs, following perineural injection of the lateral palmar nerve using a medial approach, the contrast medium diffused proximally to the distal third of the antebrachium. CONCLUSIONS AND POTENTIAL RELEVANCE: Inadvertent penetration of the carpometacarpal joint is common after perineural injection of the palmar metacarpal nerves, but less so if both palmar metacarpal nerves are injected using a lateral approach. Following injection of the lateral palmar nerve using a medial approach, the entire palmar aspect of the carpus may be desensitised.

Reliability of high- and low-field magnetic resonance imaging systems for detection of cartilage and bone lesions in the equine cadaver fetlock.

REASONS FOR PERFORMING STUDY: To determine the reliability of 2 magnetic resonance imaging (MRI) systems for detection of cartilage and bone lesions of the equine fetlock. OBJECTIVES: To test the hypotheses that lesions in cartilage, subchondral and trabecular bone of the equine fetlock verified using histopathology can be detected on high- and low-field MR images with a low incidence of false positive or negative results; that low-field images are less reliable than high-field images for detection of cartilage lesions; and that combining results of interpretation from different pulse sequences increases detection of cartilage lesions. METHODS: High- and low-field MRI was performed on 19 limbs from horses identified with fetlock lameness prior to euthanasia. Grading systems were used to score cartilage, subchondral and trabecular bone on MR images and histopathology. Sensitivity and specificity were calculated for images. RESULTS: High-field T2*-weighted gradient echo (T2*W-GRE) and low-field T2-weighted fast spin echo (T2W-FSE) images had high sensitivity but low specificity for detection of cartilage lesions. All pulse sequences had high sensitivity and low-moderate specificity for detection of subchondral bone lesions and moderate sensitivity and moderate-high specificity for detection of trabecular bone lesions (histopathology as gold standard). For detection of lesions of trabecular bone low-field T2*W-GRE images had higher sensitivity and specificity than T2W-FSE images. CONCLUSIONS: There is high likelihood of false positive results using high- or low-field MRI for detection of cartilage lesions and moderate-high likelihood of false positive results for detection of subchondral bone lesions compared with histopathology. Combining results of interpretation from different pulse sequences did not increase detection of cartilage lesions. MRI interpretation of trabecular bone was more reliable than cartilage or subchondral bone in both MR systems. POTENTIAL RELEVANCE: Independent interpretation of a variety of pulse sequences may maximise detection of cartilage and bone lesions in the fetlock. Clinicians should be aware of potential false positive and negative results.

Radiological anatomy of the donkey's foot: objective characterisation of the normal and laminitic donkey foot.

REASONS FOR PERFORMING STUDY: Anatomical change within a laminitic foot is of diagnostic and prognostic importance. A lateromedial radiograph represents the current 'gold standard' by which these changes are identified. Detection of anatomical change is dependent upon a priori knowledge of normality and subjective assessment alone may not identify modest change. Normal baseline data is, therefore, needed against which objective comparisons can be made. There is little information regarding the radiological anatomy of the donkey foot, hence an equine model has been widely adopted. However, descriptive accounts suggest fundamental anatomical differences between these 2 species. OBJECTIVES: To characterise objectively the radiological anatomy of normal donkey feet and define the nature and extent of anatomical change associated with laminitis. METHODS: The anatomy of the forefoot was quantified from lateromedial radiographs of 83 normal and 74 laminitic donkeys, using a computer based imaging system. Data were analysed using univariate and bivariate statistical methods. RESULTS: Baseline data were established that define the radiological characteristics of the anatomy of normal donkey feet. The key hoof, bone and weightbearing stance parameters of lateromedial radiographs have been evaluated. Laminitis was associated with significant rotation and distal displacement of the distal phalanx, increases in integument depth and morphometric change to the distal phalanx (P<0.05). CONCLUSIONS: This study challenges the validity of applying an equine model to the radiological anatomy of donkey feet. Hence, the diagnosis of anatomical change cannot be based on baseline data previously given for the horse and guidelines should be revised accordingly for the donkey. POTENTIAL RELEVANCE: This study provides an objective basis for the identification of anatomical change associated with laminitis in donkey feet.

An investigation of the relationships between angles and shapes of the hoof capsule and the distal phalanx.

REASONS FOR PERFORMING STUDY: There is little scientific evidence to support the premise that poor foot conformation predisposes to foot pain and lameness. OBJECTIVES: To determine relationships between external characteristics of the hoof capsule and angles of the distal phalanx; to determine variability in shape of the distal phalanx; and to investigate association between distal phalanx angles and the injury causing lameness. MATERIALS AND METHODS: Feet were documented photographically and radiographically. Linear and angle measurements were obtained for the hoof capsule and distal phalanx and compared statistically. Horses were categorised according to injury group, and angles and linear ratios were compared between groups. RESULTS: There was modest correlation between hoof wall and heel angles and angles of the distal phalanx. There was variation in shape of the distal phalanx. There was no significant association between injury type and angles of the distal phalanx, although there was a trend for the angle of the dorsal aspect of the distal phalanx with the horizontal to be smaller in horses with injuries of the podotrochlear apparatus or deep digital flexor tendon compared with other groups. CONCLUSIONS: There are variations in shape of the distal phalanx largely due to differences in orientation of the concave solar border and the solar border to the horizontal. Variations in shape of the distal phalanx were not accurately correlated with external characteristics of the hoof capsule. There were weak associations between injury groups and angles of the distal phalanx. CLINICAL RELEVANCE: Further work is required to elucidate risk factors for foot-related lameness.

Distribution of radiodense contrast medium after perineural injection of the palmar and palmar metacarpal nerves (low 4-point nerve block): an in vivo and ex vivo study in horses.

REASONS FOR PERFORMING STUDY: Evidence-based information is limited on distribution of local anaesthetic solution following perineural analgesia of the palmar (Pa) and palmar metacarpal (PaM) nerves in the distal aspect of the metacarpal (Mc) region ('low 4-point nerve block'). OBJECTIVES: To demonstrate the potential distribution of local anaesthetic solution after a low 4-point nerve block using a radiographic contrast model. METHODS: A radiodense contrast medium was injected subcutaneously over the medial or the lateral Pa nerve at the junction of the proximal three-quarters and distal quarter of the Mc region (Pa injection) and over the ipsilateral PaM nerve immediately distal to the distal aspect of the second or fourth Mc bones (PaM injection) in both forelimbs of 10 mature horses free from lameness. Radiographs were obtained 0, 10 and 20 min after injection and analysed subjectively and objectively. Methylene blue and a radiodense contrast medium were injected in 20 cadaver limbs using the same techniques. Radiographs were obtained and the limbs dissected. RESULTS: After 31/40 (77.5%) Pa injections, the pattern of the contrast medium suggested distribution in the neurovascular bundle. There was significant proximal diffusion with time, but the main contrast medium patch never progressed proximal to the mid-Mc region. The radiological appearance of 2 limbs suggested that contrast medium was present in the digital flexor tendon sheath (DFTS). After PaM injections, the contrast medium was distributed diffusely around the injection site in the majority of the limbs. In cadaver limbs, after Pa injections, the contrast medium and the dye were distributed in the neurovascular bundle in 8/20 (40%) limbs and in the DFTS in 6/20 (30%) of limbs. After PaM injections, the contrast and dye were distributed diffusely around the injection site in 9/20 (45%) limbs and showed diffuse and tubular distribution in 11/20 (55%) limbs. CONCLUSIONS AND POTENTIAL RELEVANCE: Proximal diffusion of local anaesthetic solution after a low 4-point nerve block is unlikely to be responsible for decreasing lameness caused by pain in the proximal Mc region. The DFTS may be penetrated inadvertently when performing a low 4-point nerve block.

Diffusion of contrast medium after perineural injection of the palmar nerves: an in vivo and in vitro study.

REASONS FOR PERFORMING STUDY: Proximal diffusion of local anaesthetic solution after perineural anaesthesia may lead to the desensitisation of structures other than those intended. However, there is no evidence-based study demonstrating the potential distribution and diffusion of local anaesthetic solution after perineural analgesia in the distal limb. OBJECTIVE: To document the potential diffusion of local anaesthetic solution using a radiopaque contrast model and to evaluate the influence of walking compared with confinement in a stable after injection. METHODS: Radiopaque contrast medium was injected subcutaneously over one palmar nerve at the base of the proximal sesamoid bones in 6 nonlame mature horses. Horses were assigned randomly to stand still or walk after injection. Radiographs were obtained 0, 5, 10, 15, 20 and 30 min after injection and were analysed to determine the distribution and diffusion of the contrast medium. RESULTS: In 89% of injections an elongated pattern of the contrast medium was observed suggesting distribution along the neurovascular bundle. After 49% of injections a fine radiopaque line extended proximally from the contrast 'patch', and in 25% of injections a line extended distally. There was significant proximal and distal diffusion with time when sequential radiographs of each limb were compared. The greatest diffusion occurred in the first 10 min. Walking did not significantly influence the extent of either proximal or distal diffusion. CONCLUSIONS AND POTENTIAL RELEVANCE: Significant proximal diffusion occurs in the first 10 min after perineural injection in the distal aspect of the limb and should be considered when interpreting nerve blocks. Distribution of local anaesthetic solution outside the fascia surrounding the neurovascular bundle or in lymphatic vessels may explain delayed or decreased effects.

Osseous abnormalities associated with collateral desmopathy of the distal interphalangeal joint: part 1.

REASONS FOR PERFORMING STUDY: Osseous abnormalities associated with collateral ligament (CL) injury of the distal interphalangeal (DIP) joint have been documented using magnetic resonance imaging (MRI) but there is currently limited information about the frequency of osseous pathology associated with CL injury. OBJECTIVES: To determine the frequency of occurrence of osseous abnormality coexistent with CL injury of the DIP joint and describe the distribution and character of osseous lesions; and to establish if there was an association between osseous abnormality and increased radiopharmaceutical uptake (IRU). HYPOTHESES: There would be a higher incidence of osseous abnormality at the insertion of an injured CL than at the origin; and a relationship between the presence of osseous abnormality and duration of lameness. MATERIALS AND METHODS: Magnetic resonance images of 313 feet of 289 horses with foot pain and a definitive diagnosis of collateral desmopathy of the DIP joint were analysed retrospectively for presence and type of osseous abnormality in the middle and distal phalanges. Scintigraphic images were examined and the presence of IRU in the middle or distal phalanges recorded. RESULTS: Osseous abnormalities were detected in 143 (45.7%) feet, 27 (18.8%) of which had osseous and CL injury alone, while the remaining 116 had CL related osseous injury and multiple injuries within the hoof capsule. Entheseous new bone and endosteal irregularity of the middle and distal phalanges were the most frequent types of osseous abnormality. There was a higher incidence of osseous abnormalities medially than laterally and at the ligament insertion than at the origin. There was a significant association between presence of IRU and osseous injury. CONCLUSIONS: A variety of osseous lesions of differing severity are associated with CL injury. Normal radiopharmaceutical uptake does not preclude significant osseous pathology associated with CL injury. CLINICAL RELEVANCE: Further studies are necessary in order to determine if osseous abnormalities associated with CL injury influence prognosis for return to performance.

Osseous abnormalities associated with collateral desmopathy of the distal interphalangeal joint. Part 2: treatment and outcome.

REASONS FOR PERFORMING STUDY: There are currently few long-term follow-up data relating to recovery from injury of a collateral ligament (CL) of the distal interphalangeal (DIP) joint and limited information about the effect of associated osseous injury on prognosis. OBJECTIVES: To describe long-term follow-up results for horses with CL injury, with and without associated osseous injury; and to determine the effect of extracorporeal shock wave therapy (ECSWT) or radial pressure wave therapy (RPWT) on outcome. HYPOTHESES: Prognosis for return to performance for horses with CL-related osseous injury would be worse than for horses with CL injury alone. METHODS: Magnetic resonance images from 313 feet of 289 horses with foot pain and a definitive diagnosis of collateral desmopathy of the DIP joint were analysed retrospectively for presence of osseous abnormality associated with the ligament origin or insertion and the middle and distal phalanges. Horses were assigned to groups according to the combination of their injuries. Type of treatment was recorded and follow-up information obtained. Thirty-two horses with additional sources of lameness were excluded from analysis of outcome. RESULTS: Follow-up data were available for 182 horses, 55 of which had follow-up information for up to 2 years after presentation. Twenty-seven percent of horses with CL injury alone and 34% of horses with CL related osseous injury returned to their previous performance level. Prognosis for a combination of injuries to multiple soft tissue and osseous structures within the hoof capsule was substantially worse. There was no effect of ECSWT or RPWT on outcome. CONCLUSIONS: The presence of mild to moderate CL related osseous injury does not appear to influence prognosis compared with CL injury alone. CLINICAL RELEVANCE: Further studies of a larger number of horses are necessary in order to ascertain if specific types of osseous pathology influence return to performance levels.

Blindness, optic atrophy and sinusitis in the horse.

OBJECTIVE: The case histories described each presented with a visual deficit, varying from permanent total blindness with ophthalmoscopic evidence of optic atrophy to variable and transient visual disturbances, including occasional blindness, but with absence of ophthalmoscopic or any other ocular abnormality. ANIMALS STUDIED: Three horses of widely different age and type, but all with an original history of upper respiratory tract infection. PROCEDURE: All three cases were examined by a specialist veterinary ophthalmologist. In addition, magnetic resonance imaging (MRI) and, where possible, postmortem and histopathological examinations were performed. RESULTS: The common factor to all three cases proved to be infection of the spheno-palatine sinuses with subsequent distension and compression of adjacent optic nerve(s) and optic chiasm. CONCLUSIONS: Specialist veterinary ophthalmological examination proved of extremely limited value. The importance of MRI (and CT) scans for accurate diagnosis, and therefore possible successful treatment, is emphasized. Our cases were compared with similar cases in man, where visual disturbances due to spheno-palatine sinus involvement are recognized, but rare, in similar situation.

Retrospective study of palmar/plantar annular ligament injury in 71 horses: 2001-2006.

REASON FOR PERFORMING STUDY: Constriction of the digital flexor tendon sheath (DFTS) and its contents by the palmar/plantar annular ligament (PAL) is well recognised. However, primary injury of the PAL has not been well documented. OBJECTIVES: To describe the clinical features of PAL injury, determine its prevalence with or without subcutaneous fibrosis and/or concurrent injury within the DFTS, and assess response to treatment. METHODS: Horses were selected for inclusion based upon clinical features consistent with PAL injury and the presence of a thickened PAL (> or =2 mm) verified ultrasonographically. A retrospective analysis of case records from 3 clinics was performed. Details of breed, age and use, and results of clinical and ultrasonographic assessments and response to treatment were recorded. Horses were treated conservatively or surgically by desmotomy of the PAL, with or without tenoscopic evaluation of the DFTS. A telephone questionnaire was performed to assess response to treatment. RESULTS: Seventy-one horses were included in the study and middle aged or older general purpose riding horses predominated. PAL desmopathy occurred more frequently in hind- than in forelimbs. The method of treatment, thickness of the PAL or presence of subcutaneous fibrosis did not significantly affect prognosis; however, <50% of horses were able to return to athletic function. There was a trend for horses with PAL desmopathy alone to have the best outcome. Bilateral thickening of the PAL or concurrent fore- and hindlimb injuries had a negative effect on prognosis, as did the simultaneous presence of subcutaneous fibrosis and lesions within the DFTS. CONCLUSIONS AND CLINICAL RELEVANCE: PAL injury is characterised by a convex contour of the palmar/plantar aspect of the fetlock, associated with thickening of the ligament with or without subcutaneous fibrosis. Bilateral PAL thickening is common in older horses, ponies and cobs; however, bilateral PAL enlargement is often present with only unilateral lameness. Treatment methods used in this study did not appear to influence outcome significantly.

Radiographic, scintigraphic and magnetic resonance imaging findings in the palmar processes of the distal phalanx.

REASON FOR PERFORMING STUDY: Increased radiopharmaceutical uptake (IRU) in the palmar processes of the distal phalanx is recognised but its clinical significance has not been established. OBJECTIVES: To investigate the relationship between radiographic, scintigraphic and MRI findings in the palmar processes of the distal phalanx. HYPOTHESES: Increased radiopharmaceutical uptake in the palmar processes of the distal phalanx is associated with MRI abnormalities; IRU and MRI abnormalities are over-represented in lame limbs. METHODS: Clinical data, radiographic, scintigraphic and MRI findings of 258 horses with unilateral or bilateral foot pain were recorded. Scintigraphic images were assessed subjectively and using region of interest and profile analysis, and intensity of IRU graded. Alteration in signal intensity in T1 and T2 weighted and short tau inversion recovery (STIR) MR images was documented, and MRI abnormalities graded. Relationships between scintigraphic, MRI, radiographic and clinical findings were assessed. RESULTS: Focal IRU was over-represented in palmar processes with most MRI abnormalities. There was a significant correlation between IRU and MRI grades and IRU was over-represented in palmar processes with MRI Grades 2 and 3. Both IRU and MRI abnormalities occurred most frequently in the medial palmar process. MRI abnormalities were generally over-represented in lame limbs. The most common MRI abnormality was mild diffuse decreased signal intensity in T1 and T2 weighted images, which was associated with mild generalised IRU. CONCLUSIONS: There was considerable variation in the radiographic, scintigraphic and MRI appearance of palmar processes of the distal phalanx. Focal IRU in a palmar process was seen in association with MRI abnormalities and lameness or as an incidental finding. Magnetic resonance imaging abnormalities occurred more frequently in lame limbs, either contributing to lameness or as a consequence of lameness. POTENTIAL RELEVANCE: Further investigation is needed to establish the clinical significance of MRI abnormalities in the palmar processes of the distal phalanx and their relationship with lesions in adjacent structures.