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Summary Reasons for performing study: Inflammatory airway disease (IAD) is a nonseptic condition of the lower respiratory tract. Its negative impact on respiratory function has previously been described using either forced expiration or forced oscillations techniques. However, sedation or drug-induced bronchoconstriction were usually required. The impulse oscillometry system (IOS) is a noninvasive and sensitive respiratory function test validated in horses, which could be useful to evaluate IAD-affected horses without further procedures. Objectives: To determine the sensitivity of IOS in detecting alterations of the respiratory function in subclinically IAD-affected horses without inducing bronchoprovocation and to characterise their respiratory impedance according to frequency for each respiratory phase. Methods: Pulmonary function was evaluated at rest by IOS in 34 Standardbred trotters. According to the cytology of bronchoalveolar lavage fluid (BALF), 19 horses were defined as IAD-affected and 15 horses were used as control (CTL). Total respiratory resistance (Rrs) and reactance (Xrs) from 1–20 Hz as well as their inspiratory and expiratory components were compared between groups. Results: A significant increase of Rrs at the lower frequencies (R1–10 Hz) as well as a significant decrease of Xrs beyond 5 Hz (X5–20 Hz) was observed in IAD compared to CTL horses. IOS-data was also significantly different between inspiration and expiration in IAD-affected horses. In the whole population, both BALF eosinophil and mast cell counts were significantly correlated with IOS measurements. Conclusions: Functional respiratory impairment may be measured, even in the absence of clinical signs of disease. In IAD-affected horses, the different parameters of respiratory function (Rrs or Xrs) may vary depending on the inflammatory cell profiles represented in BALF. Potential relevance: Impulse oscillometry could be used in a routine clinical setting as a noninvasive method for early detection of subclinical respiratory disease and of the results of treatment in horses.

Summary Reasons for performing study: Bisphosphonates, such as tiludronate, are used to normalise bone metabolism via inhibition of bone resorption. Areas of increased bone resorption and formation are typical lesions in a diseased navicular bone. Objectives: To determine if bone remodelling changes occurring in navicular disease may be corrected with therapies regulating bone metabolism. Methods: We designed a double-blind, placebo-controlled clinical trial to compare 2 doses of tiludronate, 0.5 mg/kg and 1 mg/kg bwt administered via daily i.v. injections over 10 days for the treatment of navicular disease. Seventy-three horses, split into 2 subpopulations of recent and chronic cases, were enrolled to be followed-up over 6 months. Of these, 33 recent and 17 chronic cases meeting the selection criteria were maintained in the final efficacy analyses. Clinical examinations were videorecorded and reviewed blindly by an independent expert. Results: Horses treated with the higher dose showed optimal improvement of lameness and return to normal level of activity 2–6 months post treatment. The more recent the onset of clinical signs at the time of treatment, the greaterthe efficacy. The treatment did not modify the response to extension and flexion tests. The lower dose failed to significantly improve the condition. Conclusions: Tiludronate efficacy is demonstrated in the treatment of navicular disease at the dose of 1 mg/kg bwt. Potential relevance: Our results support the clinical relevance of bone remodelling changes in the outcome of navicular disease.

Summary The purpose of this study was to investigate the kinetics of blood lactate concentration in 5 saddle horses during an incremental test on an inclined treadmill (3%). In order to mimic field conditions, the exercise test consisted of five 3 min bouts at increasing speeds (7.5, 8.3, 9.2 and 10 m/s); each bout being followed by 1 min rest. Blood samples were taken prior to each step, every minute during each step and every 30 s during each rest period. At low intensities of exercise, stability of blood lactate concentration was sometimes observed during the first minutes of the bout, followed by an increase in the second part. At higher intensities, blood lactate concentration rose more quickly and no stability was observed. Lactate concentration in the blood sample taken at t3′30 during the rest period, often reached a higher value than in the preceeding bout. The VLa4 calculated from blood lactate concentrations obtained at t3′ and t3′30 were not significantly different (P>0.05); mean ± s.d. 9.8 ± 0.7 and 9.8 ± 0.6 m/s, respectively. By using the blood lactate concentrations obtained at t4', the VLa4 appeared higher (mean ± s.d. 10.1 ±0.7 m/s).

Summary Reasons for performing study: As critical locomotion events (e.g. high-speed and impacts during racing, jump landing) may contribute to tendinopathies, in vivo recording of gaits kinematic and dynamic parameters is essential for 3D reconstruction and analysis. Objective: To propose a 3D model of the forelimb and a ground reaction force recording shoe (GRF-S) for noninvasively quantifying tendon and ligament loads and strains. Methods: Bony segments trajectories of forelimbs placed under a power press were recorded using triads of ultrasonic kinematic markers linked to the bones. Compression cycles (from 500–6000 N) were applied for different hoof orientations. Locations of tendon and ligament insertions were recorded with regard to the triads. The GRF-S recorded GRF over the hoof wall and used four 3-axis force sensors sandwiched between a support shoe and the shoe to be tested. Results: Validation of the model by comparing calculated and measured superficial digital flexor tendon strains, and evaluation of the role of proximal interphalangeal joint in straight sesamoidean ligament and oblique sesamoidean ligament strains, were successfully achieved. Objective comparisons of the 3 components of GRF over the hoof for soft and hard grounds could be recorded, where the s.d. of GRF norm was more important on hard ground at walk and trot. Conclusions: Soft grounds (sand and rubber) dissipate energy by lowering GRF amplitude and diminish bounces and vibrations at impact. At comparable speed, stance phase was longer on soft sand ground. Potential relevance: The conjugate use of the GRF-S and the numerical model would help to quantify and analyse ground/shoe combination on comfort, propulsion efficiency or lameness recovery.

Summary Reasons for performing study: Comprehensive understanding of the 3-dimensional (3D) kinematics of the distal forelimb and precise knowledge of alterations induced by dorsopalmar foot imbalance remains incomplete because in vivo studies performed with skin markers do not measure the actual movements of the 3 digital joints. Objective: To quantify the effects of 6° heel or toe wedges on the 3D movements of the 4 distal segments of the forelimb in horses trotting on a treadmill. Methods: Three healthy horses were equipped with ultrasonic markers fixed surgically to the 4 distal segments of the left forelimb. The 3D movements of these segments were recorded while horses were trotting on a treadmill. Rotations of the digital joints were calculated by use of a joint coordinate system. Data obtained with 6° heel or toe wedges were compared to those obtained with flat standard shoes. Results: Use of heel wedges significantly increased maximal flexion and decreased maximal extension of the proximal (PIPJ) and distal (DIPJ) interphalangeal joints. Inverse effects (except for PIPJ maximal extension) were observed with the toe wedges. In both cases, neither flexion-extension of the metacarpophalangeal joint nor extrasagittal motions of the digital joints were statistically different between conditions. Conclusions: At a slow trot on a treadmill, heel and toe wedges affect the sagittal plane kinematics of the interphalangeal joints. Potential relevance: Better understanding of the actual effects of toe and heel wedges on the 3D kinematics of the 3 digital joints may help to improve clinical use of sagittal alteration of hoof balance in the treatment of distal forelimb injuries.

Summary Reasons for performing study: Sacroiliac joint (SIJ) disease is associated with poor hindlimb action, lameness and poor performance in horses. However, little is known about the biomechanics of this low-motion joint. Objectives: To determine in vitro the capacities of movement of the SIJ in the sagittal plane, and to test the effect of a sacrosciatic and sacrotuberal desmotomy on its stabilisation. Methods: Six anatomical specimens underwent cycles of flexion-extension of the lumbosacral joint (LSJ) before and after desmotomy. Kinematic triads were linked rigidly to the sacrum, spinous process of vertebra L5 and iliac wing. Angles were measured using a joint coordinate system based on anatomical frames. Results: The LSJ underwent regular movements of flexion and extension (overall mean ± s.d. range 23.4 ± 0.6°). The only recorded movement of the SIJ was a nutation during LSJ flexion (overall mean ± s.d. 0.8 ± 0.5°). Desmotomy induced an increase of that nutation (overall mean ± s.d. 1.7 ± 0.2°). Conclusions and potential relevance: Movements of the SIJ were small and coupled only with the flexion of the LSJ. The ligaments surrounding the SIJ have a strong effect on the stabilisation of this joint. Due to the limited amount of movement, its biomechanical study in vivo seems to be difficult. Further in vitro studies would be useful to determine the role of each ligament, to better understand the clinical consequences of the tears frequently observed during necropsy.

REASONS FOR PERFORMING STUDY Understanding of the biomechanical effects of egg-bar shoes remains incomplete because kinematic studies are usually performed on hard tracks and with skin markers that do not measure the actual 3-dimensional (3D) movements of the 3 digital joints. OBJECTIVE To quantify the effects of egg-bar shoes on the 3D kinematics of the distal forelimb in horses walking on a sand track. METHODS Four healthy horses were equipped with ultrasonic markers fixed surgically to the 4 distal segments of the left forelimb. The 3D movements of these segments were recorded while the horses were walking on a sand track. Rotations of the digital joints were calculated by use of a joint coordinate system. Data obtained with egg-bar shoes were compared to those obtained with standard shoes. Mean differences were expressed in a 0.95 confidence interval. RESULTS With egg-bar shoes, the initial sinking of the heels into the ground during landing was reduced and the heels were raised by up to 5.1 degrees (3.5-6.7 degrees) compared to standard shoes at mid-stance. Concurrently, maximal flexion of the distal (DIPJ) and proximal (PIPJ) interphalangeal joints was increased by up to 3.2 degrees (2.2-4.2 degrees) and 1.8 degrees (1.1-2.5 degrees), respectively, at the beginning of the stance phase. At heel-off, extension of the DIPJ was reduced by 3.8 degrees (2.6-5.0 degrees). In extrasagittal planes of movement, egg-bar shoes prevented sinking of the medial quarter into the ground which led to a slight decrease of DIPJ medial rotation and lateromotion. CONCLUSIONS Egg-bar shoes prevent the heels and, to a lesser extent, the medial side of the hoof from sinking into the ground on a sand track. They contribute to a decrease of DIPJ maximal extension at heel-off and to hoof stabilisation in the transversal plane. POTENTIAL RELEVANCE Such quantitative results support the clinical indications of egg-bar shoes.

Summary Reasons for performing study: The relationship between the presence of radiological abnormalities and subsequent racing performance is controversial. However, as training is expensive and time consuming, it would save time and money to identify subjects with osteo-articular lesions not compatible with a normal racing career on the basis of routine radiographic screenings at yearling age. Objectives: To evaluate the impact of osteo-articular lesions on racing ability in French Trotters and identify radiographic changes associated with failure in ‘qualification’, in order to provide objective criteria for selection of horses based on their osteo-articular status. Hypothesis: The influence of radiographic findings (RF) on racing ability depends on their nature, location, clinical relevance and number. Methods: The limbs of 202 French Trotters were radiographed just before they started training. All the RF were graded according to a standardised protocol depending on their severity. The success in ‘qualification’ (first race in career of French Trotters) was the criteria used to assess racing ability. Breeders and trainers were questioned about the causes for horses not racing. Results: Overall 113 (55.9%) horses qualified. Osteoarticular lesions were directly responsible for nonqualification in 31% of the horses. Subjects with more than one abnormal RF, with abnormal RF on the fore-, hind-fetlock or proximal tarsus were less likely to qualify. Dorsal modelling in the front fetlock and osteochondrosis of the lateral trochlear ridge of the femur also significantly reduced the qualification rate. Conclusions: Most RF are compatible with beginning a racing career, but severe RF or multiple abnormal RF significantly compromise future racing career. Potential relevance: This study supports the use of routine radiographic programmes for detection of osteoarticular lesions in yearlings. A synthetic radiographic score, based on both the severity and the number of lesions, could be useful for breeders and trainers as complementary information to select their horses.

Introduction Increasing cardiac dimension with endurance training is well known in adult athletes. However, adaptation of the heart to training in growing Arabian type horses is less well documented. Methods During the national finals for young endurance horses, standardized echocardiographic examinations were performed before the races by two experienced examiners. In 2011 left ventricle (LV) was assessed in 74 horses aged 4-years (18), 5-years (33) and 6-years (23). In 2012 left atrial (LA) dimensions and the great heart vessels were measured in 122 horses aged 4-years (32), 5-years (40) and 6-years (50). Data were normally distributed; age groups and gender were compared by one-way ANOVA (Holm-Sidak test for multiple comparisons, significance P

Introduction The aim of this study was to determine whether serum anti-oxidant defenses are impaired by endurance exercise and to investigate possible correlation with performance in the race. Methods Blood samples were obtained from 23 Arabian or half-Arabian horses (6 years old) the day before (T0) and 30 minutes after (T1) a 90-km race. Performance records available included speed, heart rate 10 and 30 minutes after arrival and the rating by veterinarians based on recovery and gait (5 categories from ‘eliminated’ to ‘excellent’). Absorbance at 413 nm (A413), at 650 nm (A650) and absorbance of Rose Bengal (RB) were measured in sera at T0 and T1 (a higher absorbance means a lower antioxidant capacity). Relationships between blood variables and between T0 values and race results were evaluated using correlation analysis and means comparisons. Results All horses finished the race with an average speed of 16.3 km/h. Three horses were eliminated for lameness, one was excellent and the others were distributed between the other three categories. After the race, a significant increase of RB, A413, A413-A650, PT and CK (P

Introduction Equine training often includes running on tracks with different uphill (UP) or downhill (DOWN) slopes and examination of lame horses on a slope can be used to investigate the origin of lameness. However little is known about the kinetics of horses in such circumstances. The aim of this study was to quantify and compare ground reaction force, acceleration and sliding of the hoof in the forelimb of horses trotting an uphill and downhill slope. Methods The right front hoof of 5 horses was equipped with a dynamometric horseshoe and an accelerometer allowing the measurement of 3D ground reaction force and hoof acceleration and displacement. The horses were trotted in hand (3.5 m/s) on a 7% inclined asphalt area successively uphill and downhill. Data were analysed using an ANOVA, accounting for correlated repeated measurements within each horse (P