Effect of standing tarsal angle on joint kinematics and kinetics

Relationships between morphometric measurements and musculoskeletal disorders in jumping Thoroughbred horses

There is limited knowledge about causes of musculoskeletal injury in jumping Thoroughbred horses. The objective of this study was to describe the relationships between musculoskeletal disorders and linear and angular limb measurements acquired from photographs of horses with markers at specific reference points. The diagnosed musculoskeletal disorders in either fore or hind limbs were flexor tendonitis, suspensory ligaments desmitis, and osteoarthritis of the distal intertarsal and tarso-metatarsal and carpometacarpal joints. Lengths and angles in 17 clinically normal jumping Thoroughbred horses and 34 horses with musculoskeletal problems were measured. Horses with musculoskeletal disorders had significantly shorter neck, shoulder, and pelvis lengths (P<0.05), significantly longer arm and forearm front lengths (P<0.05), and significantly lower front shoulder, elbow, and hind fetlock joint angles (P<0.05). In conclusion, this study describes significant relationships between linear and angular morphometric measurements and musculoskeletal disorders in jumping Thoroughbred horses. These data could possibly provide indicators for better selection of jumpers with less risk of developing orthopedic disorders.

The Evolution of a Single Toe in Horses: Causes, Consequences, and the Way Forward

Horses are a classic example of macroevolution in three major traits-large body size, tall-crowned teeth (hypsodonty), and a single toe (monodactyly)-but how and why monodactyly evolved is still poorly understood. Existing hypotheses usually connect digit reduction in horses to the spread and eventual dominance of open-habitat grasslands, which took over from forests during the Cenozoic; digit reduction has been argued to be an adaptation for speed, locomotor economy, stability, and/or increased body size. In this review, we assess the evidence for these (not necessarily mutually exclusive) hypotheses from a variety of related fields, including paleoecology, phylogenetic comparative methods, and biomechanics. Convergent evolution of digit reduction, including in litopterns and artiodactyls, is also considered. We find it unlikely that a single evolutionary driver was responsible for the evolution of monodactyly, because changes in body size, foot posture, habitat, and substrate are frequently found to influence one another (and to connect to broader potential drivers, such as changing climate). We conclude with suggestions for future research to help untangle the complex dynamics of this remarkable morphological change in extinct horses. A path forward should combine regional paleoecology studies, quantitative biomechanical work, and make use of convergence and modern analogs to estimate the relative contributions of potential evolutionary drivers for digit reduction.

Limb and thoracolumbosacral kinematics over an upright and parallel spread fence

Jumping mechanics have been investigated at take-off, flight and landing, mainly in reference to the limbs with limited evaluation of the thoracolumbosacral region. The objectives of this study were to investigate head, neck, thoracolumbosacral and limb angles in a group of experienced showjumping horses (competing at 1.20-1.60 m) over an upright and parallel spread fence. Ten horses in active showjumping training were recruited (mean 8 years old). High-speed videography (240 Hz) was used to determine thoracolumbosacral kinematic variables of the approach and take-off. No significant differences between the upright and parallel spread fences were observed for any of the variables measured. Individual horse review showed that neck-trunk, thoracolumbar, lumbosacral, coxofemoral angles, take-off distance and speed patterns at take-off were consistent among horses and also repeatable between fence types. Head-neck, stifle and tarsal angles had great variability among horses. The main limitation of this study was that only 2D motion analysis was carried out. In conclusion, analysis of individual horse patterns showed that head, neck, back and limb angles were repeatable over submaximal upright and spread fences in ten horses. Some angles were consistent among horses, but others had individual horse variation.

Lameness Evaluation of the Athletic Horse

Lameness examination is commonly performed in the athletic horse. A skilled lameness diagnostician must have keen clinical and observational skills. Evaluation starts with a detailed history and thorough physical examination. Next, gait evaluation in the moving horse is performed. Lame horses have asymmetrical body movement due to unconscious shift of body weight. Recognition of the resultant head nod and pelvic hike is the basis for lameness diagnosis. Lameness identification is enhanced by circling, limb flexions, and riding. Most lame horses do not exhibit pathognomonic gait characteristics, and therefore, diagnostic analgesia is the best way to authenticate underlying sites of pain.

Validity and repeatability of goniometry in normal horses

PURPOSE

To assess validity and inter- and intra-tester reliability of equine goniometry and to establish values for carpal, metacarpophalangeal, tarsal, and metatarsophalangeal flexion and extension in horses.

SUBJECTS

Seventeen healthy equine subjects of varied breeds were used.

METHODS

Three investigators blindly and independently measured in triplicate the extension and flexion of carpal, metacarpophalangeal, tarsal, and metatarsophalangeal joints of 17 horses after sedation. Radiographs of these joints in flexion and extension were acquired while under sedation. Goniometric and radiographic measurements were compared statistically and were correlated. A Bland-Altman plot was constructed. Inter- and intra-tester repeatability of goniometry were evaluated by calculating intraclass correlation coefficients (ICC). Mean flexion and extension of carpal, metacarpophalangeal, tarsal, and metatarsophalangeal joints were calculated.

RESULTS

Goniometric and radiographic measurements did not differ statistically and were significantly correlated (correlation coefficients ranged from 0.59 - 0.89). The mean difference between goniometric and radiographic measurements was 0.4°. Triplicate measurements collected by the three raters did not differ significantly within raters (ICC ranging from 0.950 - 0.995) and between raters (ICC ranging from 0.942 - 0.989).

CONCLUSION

Goniometry is a valid and repeatable tool for evaluation of the range of motion of carpal, metacarpophalangeal, tarsal, and metatarsophalangeal joints in standing, sedated healthy horses.

The centrodistal joint interosseous ligament region in the tarsus of the horse: Normal appearance, abnormalities and possible association with other tarsal lesions, including osteoarthritis

REASONS FOR PERFORMING STUDY

There have been no detailed descriptions of the radiological appearance of the centrodistal joint interosseous ligament region in horses with and without distal tarsal joint pain.

OBJECTIVES

To describe the normal radiological appearance of the centrodistal joint interosseous ligament region; to determine the prevalence of mineralisation or ossification of the interosseous ligament; and to describe radiological abnormalities surrounding the interosseous space and concurrent radiological abnormalities in the tarsus. The association between interosseous ligament region abnormalities and radiological evidence of osteoarthritis of the centrodistal joint was assessed.

STUDY DESIGN

Retrospective study.

METHODS

Case records and radiographs of all horses/ponies (n = 700) that underwent radiographic examination of one/both tarsi over 7 years were reviewed. Case history, height, bodyweight and cause(s) of lameness were recorded. Factors associated with abnormalities of the centrodistal interosseous ligament region were assessed using logistic regression analysis.

RESULTS

The normal interosseous space was an oval or circular-shaped radiolucent area bordered proximally and distally by a rim of bone of uniform opacity and thickness, which varied in thickness among animals. Abnormalities of the interosseous ligament region of the lame(r) limb were evident in 121/700 (17.3%; 95% confidence interval 14.5-20.1%) animals. Increasing bodyweight was associated with decreased odds of interosseous ligament region abnormalities. Forty-seven animals (6.7%; 95% confidence interval 4.9-8.6%) had radiological evidence of osteoarthritis of the centrodistal joint. A greater proportion of animals with interosseous ligament region abnormalities (36.4%) had radiological evidence of osteoarthritis of the centrodistal joint, compared to those with normal interosseous ligament regions (0.5%; P<0.001). Interosseous ligament region abnormalities and osteoarthritis of the centrodistal joint were not necessarily associated with distal tarsal joint pain.

CONCLUSIONS

There is an association between abnormalities of the centrodistal joint interosseous ligament region and osteoarthritis. Radiological evidence of abnormalities of the centrodistal intertarsal ligament region alone or in association with osteoarthritis may be present asymptomatically.

Variation in frontal plane joint angles in horses

REASONS FOR PERFORMING STUDY

Conformation in horses is often considered an indicator of athletic ability, performance and resistance to orthopaedic disease. Evaluation is performed in the standing horse and repeatability influenced by stance. Ground reaction forces increase in the moving horse as speed increases.

OBJECTIVES

To determine the effect of locomotion on equine carpus, tarsus, metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints in the frontal plane.

HYPOTHESIS

Valgus/varus angulation will change when moving.

MATERIALS AND METHODS

Kinematic data were collected standing, walking and trotting for 2 groups of horses. The change in angle for carpus, tarsus, MCP and MTP joints was calculated standing and midstance for each stride. Comparison of joint angles between left and right limbs, standing, walking and trotting were made. Inter- and intrahorse variations were investigated.

RESULTS

Significant differences were observed between groups of horses and left and right forelimbs. Between walk and trot, the MCP joint changed from valgus to varus, and the tarsus and MTP joints increased in valgus deformity. Between standing and walk the carpus increased in valgus deformity. Interhorse variation was significantly different, intrahorse variation was not. Variation in measurements between gaits was minimal.

CONCLUSIONS

This study validates the measurement of joint angles from the front in the walking and trotting horse using kinematic data, interhorse variation in joint angle measurements exceeding intrahorse variation. The increases in joint angles between standing and walking, and walking and trotting warrant further investigation.

A survey of health care and disease in geriatric horses aged 30 years or older

This study reports on aspects of preventive health care and on the prevalence of disease in geriatric (≥30 years old) horses and ponies in North-West England and North Wales. Of 128 questionnaires mailed to horse owners, 87 useable responses were received and 69 horses were subject to veterinary examination. Of the animals examined, 16% were underweight with body condition scores (BCS)<2/5, and 10% were overweight (BCS>3/5). This contrasted with the owner responses that reported 23% of the animals surveyed to be underweight and only 3% to be overweight. When assessed at trot, 77% of the horses were lame on at least one limb, with 97% having a reduced range of motion in at least one joint. Only 16% of these animals were reported by owners to have been lame within the previous 12 months. Owner-reported changes to hair coat were significantly associated with hirsutism or abnormal moulting detected at clinical examination (39%). At least one ophthalmic lesion was identified in all of the horses and ponies examined and 17% of owners reported that their animal had experienced visual problems within the previous year. Although dental abnormalities were detected in all animals where an oral examination was performed, only 42% of owners reported that their horse suffered from a known dental disorder. In general, despite a high prevalence of disease detected in these geriatric animals and with the majority having multiple abnormalities at clinical examination, there was under-reporting/under-recognition of these health problems by owners.