Lameness Examination Research Articles

Towards Reliable Objective Lameness Quantification on the Circle

IntroductionLungeing is part of the standard lameness examination, however it systematically affects movement symmetry even in sound horses. We evaluated a method for objective lameness detection on the circle accounting for this asymmetry bias.MethodsTwenty‐six horses undergoing lameness examination were equipped with inertial sensors (Xsens) on head, sacrum and tubera coxae. Asymmetry in vertical displacement was quantified for trot on straight line and circle using multiple measures. Horses were classified lame when falling outside the directional reference range of sound horses (directional = ‘normal’ margins and lame limb depending on rein and sign of measure). Objective classification on the circle was compared to subjective evaluation, final diagnoses and objective classification on the straight calculating the proportion of matches. Regression analysis evaluated the association of change in asymmetry between straight line and circle and baseline asymmetry on the straight.ResultsThe match between objective classification on the circle and the exact fore‐/hindlimb(s) scored lame subjectively was 81% / 79%. The match with the diagnosed limb(s) was 71% / 85%. There was a high frequency of false positives compared to subjective evaluation. Objective evaluation on the circle added new information compared to assessment on the straight line in 70% (forelimb) / 58% (hindlimb) of instances (contralateral limb lame, bilateral lameness, lame on circle but sound on straight). Change in asymmetry was not associated with baseline lameness (P≥0.062).ConclusionsObjective lameness evaluation on the circle makes a valuable contribution to patient assessment: e.g. subtle lameness falling within the margins of ‘normal’ on the straight or bilateral lameness could be identified. In future, the predictive value of the proposed technique should be determined.Ethical Animal ResearchThe study was approved by the local ethics committee. Explicit owner informed consent for participation in this study is not stated. Sources of funding: Sandra Starke's PhD studentship was funded through the Mellon Trust via the Royal Veterinary College. Competing interests: none.

Subjective Evaluation of Lameness in Horses During Lungeing

IntroductionLungeing is an important part of lameness examination since the circular path is thought to accentuate low‐grade lameness. Circle dependent, compensatory movement, and pain related asymmetries make lameness evaluation complex. Subjective evaluation, by watching the horse in motion, is standard practice but studies have shown that inter‐observer variation is high when assessing lameness (straight line movement). The aim was to estimate inter‐ and intra‐rater agreement between equine practitioners evaluating lameness from videos of sound and lame horses during lungeing.MethodsEquine practitioners (n = 86), including 43 deemed as experienced, participated in a web‐based survey. Horses (n = 23, including two horses with solar‐pressure induced lameness) [defined as forelimb‐, hind limb‐lame or sound from objective kinematic straight line measurements] trotted on a circle in both directions on soft/hard ground surfaces (one condition/video). Of 104 recordings, 60 were selected of which 10 were repeated (numbers chosen to make compliance possible). The practitioners were asked to report which limb was most lame on each video. Kappa statistics were used to analyze the inter‐rater and intra‐rater agreement. The κ agreement was set to poor <0.3, acceptable 0.31–0.5, good 0.51–0.8, excellent >0.8.ResultsInter‐rater agreement kappa (n = 86) was 0.31 (0.38/0.25 for experienced/less experienced). Evaluating forelimb compared to hind limb lameness agreement increased 11%. Intra‐rater agreement kappa (percentiles) was (P10‐50‐90, 0.21, 0.57, 0.84).ConclusionsSince identification of the lame limb/limbs is a prerequisite for successful diagnosis, treatment and recovery, the high inter‐observer variation when evaluating lameness during lungeing may decrease the accuracy of lameness examinations.Ethical Animal ResearchThe experimental procedures were approved by a local Ethical Committee on Animal Experiments (Uppsala, Sweden), and there was a written consent from the horse owners. Sources of funding: Swedish‐Norwegian Foundation for Equine Research. Competing interests: none.

Is There a Relationship between Tail Carriage and Lameness in Horses?

IntroductionTail deviation in horses is anecdotally viewed as an indicator of lameness. Compensatory mechanisms in lame horses are well documented, however there is no information published on the relationship between lameness and tail carriage in horses. The objectives of this study were to quantify differences in tail carriage in relation to the type of lameness (front/hind, left/right) and to establish a relationship with confounding variables.MethodsVideos of 150 horses presented for lameness examination were evaluated. Tail carriage angles were measured in 50 horses and subjectively assessed using a categorical 4‐point scale in 100 horses. Lame leg(s), lameness score(s), age, sex, breed, duration and cause of lameness were recorded. Differences in tail carriage between lameness types were assessed using paired T‐tests (continuous data) or chi‐square tests (categorical data). Logistic regression evaluated the effect of degree and duration of lameness, and age on degree of tail deviation.Results87.2% of the horses showed some degree of tail deviation. The mean ± SD tail angle was 92 ± 14.5° (90° = midsagittal) for forelimb and 87 ± 11.2° for hindlimb lameness. The mean ± SD tail angle was 91.1 ± 17.3° for right‐sided and 89.5 ± 16.9° for left forelimb lameness; 89.8° ± 8.8 for right and 86.5°± 9.8 for left hindlimb lameness with no statistically significant difference between front/hind (P = 0.52) or left/right lameness (P = 0.237). No statistically significant correlation was found between degree and duration of lameness, age of horse and presence or degree of tail deviation.ConclusionsNo significant relationship between tail carriage and lameness was identified in this study and tail carriage should therefore not be considered an indicator for lameness.Ethical Animal ResearchThis study was approved by the authors′ institution's ethics and welfare committee. Explicit owner informed consent for participation in this study is not stated. Sources of funding: Royal Veterinary College. Competing interests: none.

Effect of Lungeing and Circle Size on Movement Symmetry in Sound Riding Horses

IntroductionEvaluation of the movement during trot in circles is commonly used in clinical equine lameness examinations to exacerbate mild or bilateral lameness. Sound horses trotting in a straight line have a high degree of movement symmetry, which decreases with lameness. The aim of this study was to investigate the effect of lungeing and circle size on movement symmetry in sound horses.MethodsTwenty five riding horses categorized sound by inspection on straight line and lungeing were trotted in a straight line and in circles of 8, 10, 12, 14 and 16 metres diameter on both reins. Overall symmetry (S), symmetry of diagonal limb pair loading (A), and symmetry of diagonal limb pair timing (W) were calculated from trunk accelerations measured over the 13th thoracic vertebrae (T13) with a 3‐axis accelerometer. Data were analysed via ANOVA with horse as random effect.ResultsS, A, and W showed high degree of symmetry of straight line trot with mean ± SE = −6.0 ± 0.1, 0.01 ± 0.02 and −0.001 ± 0.003, respectively, that decreased with circular trot (P<0.02 in pairwise tests). S and A showed decreasing symmetry with decreasing circle size. For 16 and 8 metres, respectively; S = −5.2 ± 0.1 and −4.7 ± 0.1; A = 0.10 ± 0.01 and 0.16 ± 0.01; W = −0.009 ± 0.002 and −0.012 ± 0.002.ConclusionsIn sound horses, movement symmetry measured over T13 decreased with circular trot and decreasing circle size as shown in earlier studies of movement of the poll and sacrum. The asymmetry mimicked inside diagonal lameness. Effect of circular movement and circle size should be considered in interpretation of lameness signs and asymmetry measured during circular trot.Ethical Animal ResearchThe study was approved by the department ethical committee. The horses belonged to the Danish army, who gave their informed consent. As no invasive procedures were applied approval from the Danish Animal Experimental board was not needed. Sources of funding: Foreningen KUSTOS af 1861. Competing interests: none.

Preliminary investigation of the treatment of equine medial femoral condylar subchondral cystic lesions with a transcondylar screw.

To determine if medial femoral condylar (MFC) subchondral cystic lesions (SCL) causing lameness will demonstrate radiographic evidence of healing and lameness reduction after placement of a transcondylar screw in lag fashion. Retrospective case series. Horses (n = 20) with lameness attributed to a MFC SCL. A 4.5 mm screw was inserted in lag fashion across MFC SCL in horses with hindlimb lameness. Post-operative radiography and lameness examinations were performed at 30-60 day intervals after surgery for 120 days, and SCL radiographic area and lameness were graded. Treatment was considered successful if lameness was eliminated and the radiographic area of the SCL on a caudocranial projection decreased ≥ 50% by 120 days. Twenty-six limbs were treated. Nine horses (11 limbs) had autologous adjunctive biologics placed into the SCL. Lameness was reduced by 1-2 grades by 60 days after surgery in 18 horses and was eliminated in 15 horses by 120 days, at which time the SCL area had decreased ≥ 50% and work had resumed without lameness (mean follow-up, 12 months). Biologic therapies had no impact on treatment success. Treatment was less successful in horses >3 years of age. A MFC transcondylar screw decreases the area of a MFC SCL on craniocaudal radiographs and eliminates lameness in ∼ 75% of horses by 120 days. The simplicity and lack of specialized equipment required make this technique a useful option for the treatment of equine SCL causing lameness.

Bilateral hypoplasia of the minor tubercle of the humerus with medial luxation of the biceps tendon in two Quarter Horses

Summary Two Quarter Horses were examined at the Washington State University Veterinary Teaching Hospital with forelimb lameness. Case 1 was a 4-year-old female with a 4 month history of intermittent forelimb lameness that had partially responded to oral anti-inflammatories. The horse was in full training and actively competing in cutting. Case 2 was a one-year-old filly bred for cutting that presented with a right forelimb lameness of 3 weeks’ duration, which was not responsive to oral anti-inflammatories. The horse was not in training. On lameness examination, Case 1 was grade 1/5 (American Association of Equine Practitioners scale) lame in the left forelimb in a straight line on a hard surface, extension and flexion of the shoulder was resented and exacerbated the lameness. Case 2 was grade 3/5 lame in the right forelimb in a straight line on a hard surface, flexion and extension of the shoulder was resented and exacerbated the lameness. Both horses had a characteristic dished appearance to the dorsal aspect of the shoulder, with prominence of the proximal aspect of the humerus. Ultrasound and proximodistal oblique (skyline) radiographic views of the scapulohumeral joints demonstrated bilateral hypoplasia of the minor tubercle of the humerus with bilateral medial luxation of the proximal biceps tendon in both cases. To the authors' knowledge this is the first report of 2 cases of bilaterally affected horses, as well as the first report of the condition in the Quarter Horse breed.

Radiographic measurements of front feet of the sound Akhal-Teke horses

BACKGROUND: The Akhal-Teke is an ancient horse originat- ing from Asia where it was used by nomadic tribes and used as a warhorse. Lameness examinations require proper interpretation of clinical and radiographic findings. Therefore, understanding of normal radiographic findings of the foot is necessary. Although the radiographic appearance of the normal foot must be understood to recognize abnormalities ,there are no studies examining the normal hoof and digital soft tissues in Akhal-Teke horses. OBJECTIVES:The purpose of the study reported here was to determine a normal radiographic appearance and morpho- metry of the distal phalanx and its related soft tissue in mature Akhal-Teke racehorses without any clinical signs of lameness and foot problems. METHODS: Radiography of the distal phalanx and associated soft-tissue structures of the front feet of 10 healthy pure Akhal-Teke horses were performed to determine normal radiographic appearance and morphometry. Lateromedial radiographic views of each front distal phalanx were used to measure important distances, angles and ratios of the hoof wall. All the measurements from lateromedial radiographs were multiplied by the magnification correction factor to gain the actual distances. RESULTS: Mean ± SD thickness of the soft tissues dorsal to the middle aspect of distal phalanx was 18.3 ± 1.22 mm. There was not any significant difference between left and right digits for any radiographic determination. CONCLUSIONS: This study introduced S-Founder and CF-Founder as important criteria in evaluating laminitis and sinking of P3.

Correlation of Acupuncture Point Sensitivity and Lesion Location in 259 Horses

Palpation of Channels and acupoints is part of the equine traditional Chinese veterinary medicine examination. Sensitivity of acupoints and acupoint combinations have been used to localize disease to certain regions and structures in horses. The objective of this clinical observational study was to scan and record sensitive acupoints of horses presented for lameness, poor performance or pre-purchase examinations and then evaluate the anatomic sites previously suggested for problems, using ultrasound, radiography or nerve blocks. Between January and April 2007, 259 horses, presented for examination, had sensitive acupoints and were evaluated for lesions. Of these, 139/259 (53.7%) horses were presented for lameness and pain, 91/259 (35.1%) horses were presented for general complaints about poor performance and 29/259 (11.2%) horses were presented for pre-purchase examinations. Sensitive acupoints were associated with disorders of tendons (12.9%), ligaments (19.4%), muscles (5.8%), bone (1.4%), joints (23%), hooves (7.2%) and sciatic nerves (10.8%), as well as back pain (13.7%), metacarpal and metatarsal fractures (1.4%) and general poor performance issues (5.81%). Diagnosis was confirmed with ultrasonography (44%), radiography (40%) and/or nerve blocks (16%). In this group of 259 horses, there was 100% correlation with acupoint sensitivity and lesion location reported elsewhere. Integration of palpation of acupoints into the routine conventional examination can be useful to localized lesions in horses with musculoskeletal and performance problems and detect potential problems during pre-purchase examinations.

Management of Bilateral Patellar Luxation in an Alpaca

To report surgical management bilateral lateral patellar luxation in a mature alpaca using a combination of trochlear wedge recession (TWR), tibial tuberosity transposition (TTT), and joint capsule imbrication. Clinical case report. 9-year-old castrated male Alpaca. Bilateral, grade III/IV, lateral patellar luxation was identified by palpation, lameness examination and confirmed with radiography and ultrasonography. Surgical procedures were staged, with the left stifle treated first. Bilateral TWR, TTT, and joint capsule imbrication were performed. Outcome was assessed by radiography and follow up lameness examinations. An immediate improvement in weight bearing occurred after surgery of the left hind limb. Five months after initial surgery, right hind limb patella luxation was corrected. After surgery on the 2nd limb, the alpaca had progressive improvement in weight bearing during hospitalization. At 12 months, there were no signs of lameness and the alpaca had resumed normal activities. For bilateral lateral patellar luxation, a combination of TWR, TTT, and joint capsule imbrication resulted in excellent long-term outcome.

Carbomer Viscosupplementation in the Equine Middle Carpal Joint

Joint visco supplementation is widely used in the sport horse industry, commonly utilizing hyaluronan. Similar to hyaluronan, the carbomer molecule has bioadhesive and viscoelastic properties, and has been 15 studied for use in human medicine. Carbomers are generally inert biologically, non-irritating, and have been used in humans as injectable depots for time-release medications. Our objective was to describe the outcome of intra-articular viscosupplementation with carbomer in four horses. Four healthy adult mares participated in this study. Baseline lameness examinations, aseptic arthrocenteses and synovial fluid analyses were performed. Three mL of 3% carbomer was then 20 injected into each left middle carpal joint. Lameness evaluations were repeated daily for each horse for ten days post-injection or until the time of euthanasia. At euthanasia, synovial fluid analyses were repeated on the left middle carpal joint. Samples of synovium from the left middle carpal joints were submitted for histopathology. Articular cartilage of the third carpal bone including subchondral bone was submitted for histology and confocal microscopy. 25 Carbomer viscosupplementation of the middle carpal joint caused severe lameness in 3 /4 mares. The fourth mare developed moderate lameness after injection. Confocal microscopy was negative for cartilaginous defects. Histology of all treated samples revealed varying degrees of small cell inflammatory infiltrate into the subsynovia. With no abnormal findings in samples of cartilage or subchondral bone, lameness is attributable to 30 severe synovitis, which is consistent with histologic findings of synovium in all cases. The current formulation of carbomer is therefore not suitable for intra-articular viscosupplementation in horses.

Kinetic and kinematic evaluation of compensatory movements of the head, pelvis and thoracolumbar spine associated with asymmetric weight bearing of the pelvic limbs in trotting dogs.

To determine ground reaction forces, head and pelvis vertical motion (HVM and PVM, respectively), and thoraco-lumbar lateral angular motion (LAM) of the spine using kinematic gait analysis in dogs with mild asymmetric weight-bearing of the pelvic limbs while trotting. Twenty-seven hound-type dogs were fitted with reflective markers placed on the sagittal crest of the skull, the ischiatic tuberosity, and thoracolumbar spine of dogs to track motion while trotting. Kinetic and kinematic data were used to characterize asymmetry between the left and right pelvic limbs, and to describe HVM, PVM and thoraco-lumbar LAM. Maximum and minimum position and total motion values were determined for each measured variable. Dogs with asymmetric weight bearing of the pelvic limbs had greater PVM on the side with a greater peak vertical force (PVF), and greater thoraco-lumbar LAM toward the side with a lower PVF while trotting. No differences in mean HVM were detected, and there were no significant correlations between the magnitude of HVM, PVM and thoraco-lumbar LAM and the degree of asymmetric weight bearing. Dogs with subtle asymmetric weight bearing of a pelvic limb had patterns of body motion that may be useful in identifying subtle lameness in dogs; greater PVM on the side with greater weight bearing and greater thoraco-lumbar LAM toward the side with less weight bearing while trotting. Description of these compensatory movements is valuable when evaluating dogs with subtle weight bearing asymmetry in the pelvic limbs and may improve the sensitivity of lameness detection during subjective clinical lameness examination.

Magnetic resonance protocols in equine lameness examination, used sequences, and interpretation

Magnetic resonance is a great diagnostic tool in equine lameness examination. Its value is most significantly visible in evaluating distal extremities. Problems with podotrochlear apparatus, laminitis or distal interphalangeal joint osteoarthritis are the most common disorders diagnosed in equine patients. Without using magnetic resonance it was impossible to clearly assess which structures are involved in each of these diseases. One of the most important things in MRI is the choice of sequence. Most commonly used are T1 GE, T2 FSE, STIR and T2* GE, in sagittal, transverse and dorsal planes. To make a reliable diagnosis it is important to compare findings in all these sequences.

Effect of turn direction on body lean angle in the horse in trot and canter

Turning is commonly used as a diagnostic aid in equine lameness examinations. Forces experienced on the circle differ from those in a straight line, necessitating an inward lean of the body and asymmetric head/pelvic excursion, which are important parameters for lameness investigations. To better understand gait adaptations to lungeing in normal horses, the effect of turn direction on body lean in trot and in canter warrants further investigation. In this study, it was hypothesised that, on average and independent of gait, the observed body lean angle would be consistent with the ratio between gravitational and centripetal acceleration, but with variations for individual horses showing differences between reins. Twenty horses were fitted with a global positioning system (GPS)-aided inertial measurement unit quantifying body lean angle, speed and circle radius in trot and canter in both directions. The difference between predicted (from speed and circle radius) and observed body lean (Δobs,pred) was compared between horses, directions and gaits using a generalised linear model. The mean speed and circle radius were 3.3m/s and 4.9m in trot and 4.5m/s and 5.7m in canter. Mean Δobs,pred was −1.1° (range −7.6° to 5.4°) in trot and −0.8° (range −7.6° to 8.3°) in canter and was significantly different between horses (P<0.0001) and directions (P<0.0001), but not between gaits (P=0.14). Interactions between horse and direction (P<0.0001) and horse and gait (P=0.011) were also significant. Horses leaned marginally less into the circle than predicted. However, this study provides additional evidence for horse specific adaptations, showing significant differences between horses and turn directions but not between gaits.

Clinical and diagnostic imaging characteristics of lateral digital flexor tendinitis within the tarsal sheath in four horses.

Lateral digital flexor tendonitis is a rarely reported cause of hind limb lameness in performance horses. The purpose of this retrospective study was to describe clinical and diagnostic imaging findings for a group of horses with lateral digital flexor tendinitis within the tarsal sheath. Equine cases with a diagnosis of lateral digital flexor tendonitis and magnetic resonance imaging (MRI) studies of the affected region were retrieved from North Carolina University’s medical record database. Recorded data for included horses were signalment; findings from history, physical examination, lameness examination, and all diagnostic imaging studies; treatment administered; and outcome. Four horses met inclusion criteria. Lameness was mild/moderate in severity and insidious in onset in all patients. Responses to flexion tests were variable. All horses showed positive improvement(70–90%) in lameness after tarsal sheath analgesia. Radiographic, scintigraphic, and ultrasonographic findings were inconclusive. For all horses, MRI characteristics included increased T2, PD, and STIR signal intensity within the lateral digital flexor tendon in the area of the tarsal sheath. Tarsal sheath effusion was slight in three horses, and mild/moderate in one horse. With medical treatment, two horses were sound at 6-month follow up, one horse was sound at 1-year followup, and one horse had a slight persistent lameness (grade 1/5) at 9-month followup. Findings supported the use of MRI for diagnosing lateral digital flexor tendonitis within the tarsal sheath in horses. Affected horses may have a good prognosis for return to athletic performance following appropriate medical treatment.

Head and pelvic movement symmetry in horses during circular motion and in rising trot

Lameness examinations in horses often include lungeing and ridden exercise. To incorporate these exercises into the evidence-based decision making process aided by quantitative sensor based gait analysis, guideline values for movement asymmetry are needed. In this study, movement symmetry (MS) was quantified in horses during unridden and ridden trot on the straight and on the circle. Systematic changes in MS were expected as a result of the ‘asymmetrical loading’ caused by circular movement, the rising trot and the combination of the two. Out of 23 horses (age 4–20years, height 13.3–17.2 hands), 13 presented within normal limits for head movement and 22 for pelvic movement. Inertial measurement units assessed MS of vertical head and sacral movement during trot in-hand, on the lunge and in rising trot (straight, left/right circle). Changes in MS between straight line trot and ridden exercise on the circle were more pronounced for the head than for the sacrum. The highest amount of asymmetry was observed during rising trot on the circle (symmetry index of the head: 1.23 for the left rein, 0.83 for the right rein; symmetry index of the sacrum 0.84 for the left rein, 1.15 for the right rein). Change in MS was significant between exercise conditions except for the difference between head displacement maxima. Horses had greatest asymmetry during rising trot on the circle, with MS values of comparable magnitude to mild lameness.

Effect of lungeing on head and pelvic movement asymmetry in horses with induced lameness

Lungeing is an important part of lameness examinations, since the circular path enforced during lungeing is thought to accentuate low grade lameness. However, during lungeing the movement of sound horses becomes naturally asymmetric, which may mimic lameness. Also, compensatory movements in the opposite half of the body may mimic lameness. The aim of this study was to objectively study the presence of circle-dependent and compensatory movement asymmetries in horses with induced lameness. Ten horses were trotted in a straight line and lunged in both directions on a hard surface. Lameness was induced (reversible hoof pressure) in each limb, one at a time, in random order. Vertical head and pelvic movements were measured with body-mounted, uni-axial accelerometers. Differences between maximum and minimum height observed during/after left and right stance phases for the head (HDmax, HDmin) and pelvis (PDmax, PDmin) were measured. Mixed models were constructed to study the effect of lungeing direction and induction, and to quantify secondary compensatory asymmetry mechanisms in the forelimbs and hind limbs. Head and pelvic movement symmetries were affected by lungeing. Minimum pelvic height difference (PDmin) changed markedly, increasing significantly during lungeing, giving the impression of inner hind limb lameness. Primary hind limb lameness induced compensatory head movement, which mimicked an ipsilateral forelimb lameness of almost equal magnitude to the primary hind limb lameness. This could contribute to difficulty in correctly detecting hind limb lameness. Induced forelimb lameness caused both a compensatory contralateral (change in PDmax) and an ipsilateral (change in PDmin) hind limb asymmetry, potentially mimicking hind limb lameness, but of smaller magnitude. Both circle-dependent and compensatory movement mechanisms must be taken into account when evaluating lameness.

Movement Symmetry Patterns During Lungeing in Trot on Hard and Soft Surface Differ Between Sound and Mildly Forelimb Lame Horses

AimsLungeing on hard and soft surfaces is crucial to clinical lameness and prepurchase examinations. Here we 1) quantify movement symmetry (MS) in sound horses trotting on hard and soft surfaces, and 2) compare MS patterns for different rein and surface combinations between sound and mildly forelimb lame horses.MethodsTwenty‐three riding horses were equipped with an inertial sensor based gait analysis system and assessed in‐hand on the straight and during lungeing (10 m diameter circle), both on hard and soft surfaces. Assessment of rein (left/right) was performed in a randomised order. Seven published MS parameters (3 poll, 4 pelvis) were quantified from an average of 38 strides per condition. Horses were subdivided into 3 groups: control (9 horses), left (5) and right (9) forelimb lame. Statistical analysis was performed using paired samples t test, ANOVA and post hoc comparisons.ResultsFor control horses, only one MS measure was significantly different between the surfaces; Symmetry Index (P = 0.0122, increased asymmetry on hard ground). When comparing left and right forelimb lame horses, increased head movement asymmetry was found with the affected limb on the inside of the circle on both surfaces (P values between P = 0.0006 and P = 0.0481); circle and lameness induced asymmetry adding up. No differences in pelvic MS were identified between sound and mildly forelimb lame horses.ConclusionsSound horses show similar amounts of movement asymmetry during lungeing on hard and soft surfaces. Mildly forelimb lame horses show characteristic patterns of increased asymmetry in particular with the affected limb on the inside of the circle.Practical significanceThe observed differences between sound and mildly forelimb lame horses will contribute to higher specificity in identification of mildly lame horses based on objective gait analysis. It is recommended to include lungeing into objective gait assessments.AcknowledgementsWe are grateful to the owners of the horses that participated.Ethical animal researchThis project was granted ethical approval by the RVC Ethics and Welfare Committee as part of Hazel Mitchell's and Charlotte Jennings' final year research project and conducted with owners' informed consent. Sources of funding: RVC. Competing interests: None.

In vivo Evaluation of Acoustoelastography in the Normal Equine Superficial Digital Flexor Tendon

IntroductionSuperficial digital flexor tendon (SDFT) injury is common in athletic horses. Recovery requires balancing rest and controlled exercise, resulting in high risk of re‐injury. It is difficult to determine the level of work the damaged tissue can sustain based on serial ultrasound examination alone. However, as small changes in sonographic appearance are associated with large changes in biomechanical strength, it is difficult to determine the degree of activity the tissue can sustain.AimsAcoustoelastography (AEG) is a new ultrasound‐based model to evaluate tendon function. Acoustoelastography deduces stiffness gradient, the rate of change of normalised stiffness as a function of strain, by analysing the changes in echo intensity observed in cine loops captured from gradually deforming tendon. The goal of this project was to establish a reproducible method for applying AEG in the normal equine SDFT.MethodsFifteen horses with no history of lameness and normal lameness examinations were recruited with informed owner consent and in accordance with the University Research Animal Resources Center. Stiffness gradient index (SGI) and dispersion values (DV) for the palmar SDFT were evaluated at 3 sites (5, 10 and 15 cm distal to the accessory carpal bone [DACB]) by 2 observers. Lifting of the contralateral forelimb during image acquisition resulted in the required SDFT deformation. Interobserver repeatability, intraobserver repeatability, and right‐to‐left limb symmetry were evaluated.ResultsThe SGIs and DVs for the SDFT at different locations, as well as effects of age or gender, showed no statistical difference (P&gt;0.05). Interclass correlations evaluating repeatability within the same observer, between observers, and symmetry between right and left limbs demonstrated excellent agreement.Conclusions and practical significanceThis study shows that AEG is a feasible and repeatable technique for measuring stiffness gradients in normal equine SDFTs. This study will provide the basis for developing a simple, noninvasive evaluation of tendon function that could vastly improve the ability to detect, monitor and treat tendon injuries.Ethical animal researchAll animal protocols were approved by the University of Wisconsin Research Animal Resources Center. Client‐owned horses were used for the study and informed consent was obtained. Sources of funding: Research supported by Companion Animal Grant through University of Wisconsin. Competing interests: Co‐author/collaborator Ray Vanderby has patent on acoustoelastography post processing ultrasound‐based tissue evaluation technique.

Assessing the Association Between Hoof Thermography and Hoof Doppler Ultrasonography for the Diagnosis of Lameness in Horses

The objectives of this study were to assess the correlation between hoof surface temperature and ultrasonographic measurements of digital blood vessels in horses and to evaluate the measurements' potential as predictors for clinical lameness. Twelve 3-year-old American Quarter Horses, 6 geldings and 6 mares, with average initial body weight of 459 ± 31 kg were used. On days 0, 30, 60, and 90 of the study, horses were weighed and subjected to clinical lameness examinations. Doppler ultrasonography was used to measure diameter of the medial palmar artery in the distal left forelimb and velocity of blood flow through that artery, starting at 60 minutes after morning feeding and repeated at 30-minute intervals. Temperature measurements on the hoof were collected at 15-minute intervals beginning 75 minutes after feeding, using a digital thermographic camera. A series of bivariate linear mixed models were fitted to estimate the correlation between Doppler and temperature measurements. The within-horse and between-horse correlations between hoof surface temperature and velocity of blood flow in the distal limb through the medial palmar artery was estimated at 0.40 (P > .50) and 0.99 (P < .001), respectively. These results indicate that at the horse level, the correlation between hoof temperature and velocity of blood flow in the distal limb was very high but that the within-horse correlation was not significantly different from 0. Velocity of blood flow at 60 minutes after feeding improved model fit to the lameness data, so it was included as a model predictor for lameness.

Fractures of the third trochanter in horses: 8 cases (2000–2012)

To determine history; clinical, radiographic, ultrasonographic, and scintigraphic features; management; and outcome associated with third trochanter fractures in horses. Retrospective case series. 8 horses. Records from 2000 to 2012 were reviewed, and signalment, case history, severity and duration of lameness, results of physical and lameness examinations, imaging findings, management, and outcome were evaluated. All horses had a history of acute onset of severe lameness. Four of the 8 horses had localizing physical signs of fracture. No specific gait characteristics were identified. Ultrasonographically, there was a single bony fragment displaced cranially in 7 of 8 horses and multiple bony fragments in 1. Concurrent gluteus superficialis muscle enthesopathy was identified in 7 horses. A standing craniolateral-caudomedial 25° oblique radiographic view was obtained in 3 horses to document the lesion and revealed in all 3 horses a simple complete longitudinal fracture between the midlevel and the base of the third trochanter. Nuclear scintigraphy was used to identify the affected area of the limb for further examination in 2 horses. Follow-up revealed that fractures healed with a fibrous union, with persistence of cranial displacement of the fragment. Lameness resolved after nonsurgical management for all horses. Fracture of the third trochanter should be considered as a cause of hind limb lameness in horses when the proximal portion of the limb is affected. Diagnosis can easily be made with ultrasonography, but nuclear scintigraphy may help in identifying the lesion. Prognosis for return to athletic activity is good after an appropriate period of rest and restricted exercise.