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The maintenance of joint homeostasis is integral to joint health. Knowledge of the influence of exercise on joint homeostasis is not only relevant for determining sustainable levels of equine athletic training, but also for the study of early development of osteoarthritis or cartilage repair in animal models. This review provides an overview of findings derived from in vivo studies and postmortem analyses investigating exercise effects on various joint tissue components in the horse, supplemented where appropriate with data from small animal models. The concept of joint homeostasis and possible methods to quantify this are also discussed, with special attention to the potential benefits and pitfalls of biomarker analysis in synovial fluid. The main conclusion is that biomechanical loading in the form of deliberate exercise has a major influence on the delicate homeostatic balance within the tissues constituting the diarthrodial joint and on their interactions, which is crucial for proper and durable joint function. The amount and intensity of exercise can have a lasting effect on tissue characteristics in juvenile animals, but affects joint homeostasis in mature animals and can affect the delicate balance between physiologic adaptation and development of pathology. Biomarkers in synovial fluid can be helpful in assessing joint homeostasis, but their use and interpretation require caution and are often far from straightforward. [ABSTRACT FROM AUTHOR]

Juvenile osteochondral conditions (JOCC) have a major impact on the equine industry and include many musculoskeletal disorders of the young horse, of which osteochondrosis (OC) is the most prominent. The Breeding, Osteochondral Status and Athletic Career (BOSAC) project is the first large, comprehensive, longitudinal field study on the subject conducted in three breeds of performance horses (Thoroughbreds, Standardbred Trotters and Warmbloods) that were monitored in their natural environment where they were reared under common field conditions. The BOSAC study used a radiographic protocol designed for field use coupled to an internally validated severity scoring system, providing weighted radiographic findings as the primary outcome measure. The natural courses of various JOCC appear to differ, according to the joint and condition involved. Genetically, there were also large differences with moderate heritabilities in the tarsocrural and metacarpophalangeal/metatarsophalangeal joints and virtually no heritability for femoropatellar OC. There was a strong influence of exercise history (as an environmental condition) on the manifestation and natural course of JOCC. In the younger age class (<6months) lack of exercise or irregular exercise had a negative effect, as had exposure to excessive exercise. In the yearling category, (exercise-associated) intrinsic trauma seemed to be the most important negative factor. In terms of later function, the association of a poor radiographic score with poorer performance in racing Trotters could be demonstrated. [ABSTRACT FROM AUTHOR]

The author reviews the existing literature on the hyperflexed position of horses used in dressage competitions to shed light on the debate of whether or not it should be condemned. He found no conclusive evidence to support the belief that hyperflexion in itself produces negative anatomical, physiological or welfare effects. He explains that the exception is when it is accomplished coercively on the horse, calling the position obtained in this manner as Rollkur.

The effectiveness of new therapies to treat tendon injuries is difficult to determine and is often based on semi-quantitative methods, such as grey level analysis of ultrasonographic images or subjective pain scores. The alternatives are costly and long-lasting end-stage studies using experimental animals. In this study, a method of ultrasonographic tissue characterisation (UTC), using mathematical analysis of contiguous transverse ultrasonographic images, was used for intra-vital monitoring of the healing trajectory of standardised tendon lesions treated with platelet rich plasma (PRP) or placebo. Using UTC it was possible to detect significant differences between the groups in the various phases of repair. At end stage, over 80% of pixels showed correct alignment in the PRP group, compared with just over 60% in the placebo group (P < 0.05). UTC also showed significant differences in the course of the healing process between PRP treated and placebo treated animals throughout the experiment. It was concluded that computerised analysis of ultrasonographic images is an excellent tool for objective longitudinal monitoring of the effects of treatments for superficial digital flexor tendon lesions in horses. [ABSTRACT FROM AUTHOR]

The author reflects on the developments made in equestrian sports over the years. Topics discussed include technological advances in the field of equine veterinary medicine for the care of the horse and the rider, the seeming lack of innovation in the manufacturing of equipment by traditionalist manufacturers and suppliers, and the effect of animal rights awareness to the use of horses in sports such as equestrian.

The article discusses a research study being done on the use of ultrasound tissue characterization (UTC) in detecting transient use-related alterations in the superficial digital flexor tendons of healthy race horses. It references a study by Doctor Sean Docking of the School of Physiotherapy at Monash University and his colleagues published in the 2012 issue of this journal. The implication of the study for the risk assessment of athlete performance and horse training is mentioned.

The author comments on a study that examined the link between surface properties of dressage arenas and lameness in dressage horses. It is asserted that though the researchers' use of the epidemiological approach is excellent, a more predictive model is needed to account for the effects of surface characteristics on the loading of the internal structures of the equine distal limb when designing the optimal flooring for training and competition. Adopting a model incorporating several aspects of the relationship between horse and surface is suggested.

The author comments on a study on the friction coefficient of young versus old articular cartilage by Noble et al. published in this issue "The Veterinary Journal." According to the author, the paper tackles basic joint biology in horses, particularly changes in cartilage properties depending on age. It found that growing panels of biomarkers offer information on inflammatory and metabolic status.

The purpose of this study was to quantify performance characteristics of good jumping horses, and to determine whether these were already detectable at foal age. Kinematic data were collected of horses performing free jumps over a 0.60 m high fence at six months of age and of these same horses jumping with a rider over a 1.15 m high fence at five years of age. At five years of age the horses were divided into three groups on the basis of a puissance competition: a group of seven best jumpers that made no errors and in the end cleared a 1.50 m high fence, a group of nine worst jumpers that were unable to clear a 1.40 m high fence, and an intermediate group of 13 horses. Longitudinal kinematic data was available for all seven best jumpers and for six of the nine worst jumpers. Average values of variables for the best jumpers were compared with those of the worst jumpers for the jumps over 1.15 m. In the group of best jumpers, the forelimbs were shorter at forelimb clearance due to increased elbow flexion, and the hind limbs were further retroflexed at hind limb clearance. The same superior technique in clearing fences with the limbs was also found in this group at six months of age. Nevertheless, for individual horses it turned out to be too far-fetched to predict adult jumping capacity on the basis of kinematic variables collected during submaximal jumps at foal age. [ABSTRACT FROM AUTHOR]

Recognition and management of equine pain have been studied extensively in recent decades and this has led to significant advances. However, there is still room for improvement in the ability to identify and treat pain in horses that have undergone emergency gastrointestinal surgery. This study assessed the validity and clinical application of the composite pain scale (CPS) in horses after emergency gastro-intestinal surgery. Composite pain scores were determined every 4 h over 3 days following emergency gastrointestinal surgery in 48 horses. Inter-observer reliability was determined and another composite visceral pain score (numerical rating scale, NRS) was determined simultaneously with CPS scores. CPS scores had higher inter-observer reliability (r = 0.87, K = 0.84, P < 0.001 ), compared to NRS scores (r= 0.68, K= 0.72, P < 0.001). Horses that survived without complications had significantly lower CPS and NRS scores compared to horses that were euthanased or had to undergo re-laparotomy (P < 0.001 ). Breed and the location in the intestinal tract (small or large intestine) did not influence pain scores. In conclusion, the use of the CPS improved objectivity of pain scoring in horses following emergency gastrointestinal surgery. High inter-observer reliability allows for comparisons between different observers. This will be of great benefit in larger veterinary hospitals where several attending clinicians are often involved in the care of each case. [ABSTRACT FROM AUTHOR]

Epidural morphine is widely used in veterinary medicine, but there is no information about the antihyperalgesic and anti-inflammatory effects in acute inflammatory joint disease in horses. The analgesic, anti-hyperalgesic and anti-inflammatory effects of epidural morphine (100 mg/animal or 0.17 ± 0.02 mg/ kg) were therefore investigated in horses with acute synovitis. In a cross-over study, synovitis was induced in the talocrural joint by intra-articular lipopolysaccharide (LPS). The effect of epidural morphine was evaluated using physiological, kinematic and behavioural variables. Ranges of motion (ROM) of the metatarsophalangeal and talocrural joints were measured, clinical lameness scores and mechanical nociceptive thresholds (MNTs) were assessed and synovial fluid inflammatory markers were measured. The injection of LPS induced transient synovitis, resulting in clinical lameness, decreased ranges of motion in the talocrural and metatarsophalangeal joints, decreased limb loading at rest and increased composite pain scores. Epidural morphine resulted in a significant improvement in clinical lameness, increased ROM and improved loading of the LPS-injected limb at rest, with no effects on synovial fluid inflammatory markers. Morphine prevented a decrease in MNT and, hence, inhibited the development of hyperalgesia close to the dorsal aspect of inflamed talocrural joints. This study showed that epidural morphine provides analgesic and anti-hyperalgesic effects in horses with acute synovitis, without exerting peripheral anti-inflammatory effects. [ABSTRACT FROM AUTHOR]