bluuebunny/crossref_metadata_2025 huggingface dataset:
The sacroiliac joints: evaluation using nuclear scintigraphy. Part 2: Lame horses
Authors: DYSON S. , MURRAY R. , BRANCH M. , HARDING E.
Published: April 2007

Reasons for performing study: Sacroiliac (SI) joint disease is difficult to diagnose definitively on clinical grounds.

Hypotheses: Lameness not attributable to SI joint pain may result in asymmetrical uptake of radiopharmaceutical in the tubera sacrale and SI joints; and that horses with clinical signs suggestive of sacroiliac joint disease would have differences in the ratios of radiopharmaceutical uptake between the fifth lumbarvertebra (L5) and either the tubera sacrale or SI joints compared with normal horses.

Objectives: To determine whether differences in radiopharmaceutical activity could identify individuals with presumed SI joint region pain.

Methods: The scintigraphic appearance of the pelvic region of 234 horses (Group I) with lameness unrelated to the SI joints was compared with that for 40 normal horses (Group N) in full work and that for 41 horses with suspected SI joint disease (Group II). The effect of age, sex, lame limb and discipline were assessed in Group I.

Motion‐corrected scintigraphic images were assessed grossly, using profile analysis and by comparing ratios of uptake of mean count per pixel between L5 and each of the left (L) tuber sacrale (TS), right (R) TS, LSI and RSI joints. Left‐right symmetry was compared.

Results: Lame horses (Group I) had greater asymmetry of radiopharmaceutical uptake in the tubera sacrale compared with normal horses. Horses with right hindlimb lameness had a larger RSI/LSI ratio compared to normal horses. In Group I L5/LTS, L5/RTS and L5/RSI increased with age, and there was a trend for L5/LSI to increase with age.

In horses with presumed sacroiliac joint disease (Group II), L5/LTS, L5/RTS and L5/RSI were all greater compared with normal horses. Detection of marked left‐right asymmetry by quantitative analysis or profile analysis was helpful in discriminating between those horses with clinical signs compatible with SI joint disease and either normal horses or those lame due to another cause.

Conclusions and potential relevance: Scintigraphic evaluation of the SI region is useful to identify SI joint disease in combination with other clinical signs supportive of the diagnosis. However, diagnosis should not be based on this alone because of some degree of overlap in the range of radiopharmaceutical uptake between horses with SI joint disease and both normal horses and those with other causes of lameness.
Mucin genes in horse airways: MUC5AC, but not MUC2, may play a role in recurrent airway obstruction
Authors: GERBER V. , ROBINSON N. E. , VENTA P. J. , RAWSON J. , JEFCOAT A. M. , HOTCHKISS J. A.
Published: April 2007

Reasons for performing study: Increased mucin gene expression may be an important cause of mucus accumulation observed in recurrent airway obstruction (RAO)‐affected horses. To date, however, no mucin gene sequences are available for the horse.

Objectives: To identify equine homologues of gel‐forming mucins and investigate their expression at different airway generations of healthy and RAO‐affected horses.

Methods: Two equine homologues were identified by cloning and sequencing fragments of equine (eq)MUC5AC and eqMUC2.

Results: Semiquantitative RT‐PCR on RNA from airways (generations 1, 5, 10, 15; small airways and parenchyma), stomach (glandular), and colon revealed that eqMUC5AC is expressed in equine stomach and in all of the airway samples. In contrast, eqMUC2 steady‐state mRNA levels were detected in colon and very faintly in stomach, but not in airway tissue. EqMUC5AC expression was also compared to that of ZO‐1, a tight junction protein, and eqMUC5AC/ZO‐1 ratios were higher in RAO‐affected compared to control horses at all airway generations.

Conclusions: That eqMUC5AC is expressed in horse airways, but any expression of MUC2 is undetectable and unlikely to be of physiological consequence.

Potential relevance: EqMUC5AC up‐regulation may be a primary mechanism responsible for mucus hypersecretion and accumulation in RAO.
Idiopathic mucosal lesions of the arytenoid cartilages of 21 Thoroughbred yearlings: 1997–2001
Authors: KELLY G. , LUMSDEN J. M. , DUNKERLY G. , WILLIAMS T. , HUTCHINS D. R.
Published: April 2007

Reasons for performing study: Mucosal ulcers and, occasionally, small granulomas on the axial surface of one or both arytenoid cartilages have been found in TB yearlings presented for post sale endoscopic examination.

Objectives: To determine the incidence, endoscopic characteristics and outcome of a group of Thoroughbred yearlings affected with mucosal ulcers and granulomas of the arytenoid cartilage.

Hypothesis: The incidence of mucosal ulceration of the arytenoid cartilages of yearling Thoroughbreds is relatively high compared to other upper airway abnormalities; and that the majority of mucosal ulcers heal uneventfully, although a small percentage may progress to a granuloma and, less commonly, to arytenoid chondropathy.

Methods: The findings of post sale, upper airway endoscopic examinations of 3312 Thoroughbred yearlings, during a 5 year period, were reviewed, including those abnormalities listed in the conditions of sale and others not listed but considered likely to cause airway obstruction. Information obtained from the medical record of horses that had mucosal ulceration or granuloma of the arytenoid cartilage included the location and size of the lesion(s), sex of the affected horse and the presence and nature of other concurrent abnormalities of the upper portion of the respiratory tract. Additional information included treatment and results of follow‐up, endoscopic examination by the authors or attending veterinarian.

Results: Mucosal lesions were seen in 0.63% of yearlings evaluated, which represented the most common, documented condition of the upper portion of the respiratory tract. The mucosal ulcers of 15 of 19 horses were considered to have healed without complication during follow‐up examination; one of the 19 horses was lost to follow‐up. Two horses affected with bilateral, arytenoid mucosal ulceration developed a granuloma at each site of ulceration. One horse developed a granuloma at a site of ulceration and, subsequently, arytenoid chondropathy.

Conclusions: Arytenoid mucosal ulceration in sales yearlings was a relatively commonly encountered abnormality and a small percentage progressed to granuloma or chondropathy.

Potential relevance: The mucosa of the arytenoid cartilage, particularly at the rostral margin of the vocal process, should be examined carefully during endoscopic examination of the upper portion of the respiratory tract of Thoroughbred yearlings presented for sale. Because a small percentage of mucosal ulcers may progress to granuloma or, less commonly, chondropathy, identification of mucosal ulcers of the arytenoid cartilage seen during post sale, endoscopic examination warrants notification to the purchaser and sales company. Medical therapy of affected horses should be considered and follow‐up endoscopic examination performed to determine if the lesion has healed.
Verification of skin‐based markers for 3‐dimensional kinematic analysis of the equine tarsal joint
Authors: KHUMSAP S. , LANOVAZ J. L. , CLAYTON H. M.
Published: April 2007

Reasons for performing study: Kinematic studies are usually based on tracking markers attached to the skin. However, complex joints, such as the tarsal joint, function in 3‐dimensions (3D), and have therefore necessitated application of the invasive bone pin technique, limiting kinematic studies to the research laboratory. This study investigates the feasibility of using skin‐based markers for 3D analysis of tarsal joint motion.

Hypothesis: Three‐dimensional motions of the tarsal joint can be measured with an acceptable degree of accuracy using skin markers.

Methods: Retroreflective markers were attached over the tibial and metatarsal segments. Markers were tracked automatically at trot. Three‐dimensional skin correction algorithms were used for correction of skin displacement, and 3D motions derived from the corrected (CSD) and uncorrected (USD) skin displacement were compared with data from a previous study in which those motions were described using bone‐fixed markers (BFM) by correlation, root mean square errors (RMS) and shape agreement (SA) of the curves.

Results: The RMS of BFM and CSD were smaller than those of BFM and USD for all motions. The correlation coefficients of BFM and CSD were higher than those of BFM and USD. SA was good or fair for all motions except internal/external rotation and medial/lateral translation.

Conclusions and potential relevance: With appropriate correction for skin movement relative to skeletal landmarks, skin markers can identify tarsal 3D motions for flexion/extension, abduction/adduction, cranial/caudal translation, and proximal/distal translation, allowing analysis and comparison of information between horses during swing and stance phases.
Dynamic pressure measurements for the detailed study of hoof balance: the effect of trimming
Authors: VAN HEEL M. C. V. , BARNEVELD A. , VAN WEEREN P. R. , BACK W.
Published: April 2007

Reasons for performing study: Studies on hoof balance have, so far, only assessed the effects of strong and relatively unrealistic interventions due to technical limitations of measuring equipment. For the assessment of more subtle interventions, other techniques are necessary.

Objectives: To test a sensitive pressure measurement system during locomotion and to set a standard for further studies by using the system to evaluate the effects of trimming.

Methods: Eighteen horses were measured before and after trimming with an interval of 4 weeks. Trimming was standardised to a straight hoof‐pastern axis. The horses trotted over a pressure/force measuring system, with a temporal resolution of 240 Hz and a spatial resolution of 0.39 cm2.

Results: The preferred way of landing was lateral, asymmetrical in both front and hind feet. The duration of landing was shorter in forelimbs than in hindlimbs with an equal decreasing trimming effect. Horses had a fixed hoof‐unrollment pattern; the centre of pressure (CoP) travelled towards a maximum lateral deviation and returned towards the dorsopalmar/plantar axis of the hoof. Trimming decreased the intra‐individual left/right difference in maximum lateral displacement.

Conclusions: The technique used provided easily accurate data to quantify hoof balance characteristics and to measure short‐term trimming effects.

Potential relevance: Determination of CoP patterns has added value in gait analysis and can improve our understanding of the effects of different interventions on hoof balance.
Effects of girth, saddle and weight on movements of the horse
Authors: DE COCQ P. , VAN WEEREN P. R. , BACK W.
Published: April 2007

Reasons for performing study: Although the saddle is seen as one of the biggest causes of back pain, and weightbearing is seen as an important aetiological factor in ‘kissing spine’ syndrome (KSS), the effects of a saddle and weight on the back movements of the horse have never been studied.

Objective: To determine the effects of pressure on the back, exerted by tack and weight, on movements of the horse.

Hypothesis: Weight has an extending effect on the horse's back and, as a compensatory mechanism to this extension, an alteration in pro‐ and retraction angles was expected. A similar but smaller effect was expected from a saddle only and a lungeing girth.

Methods: Data were captured during treadmill locomotion at walk, trot and canter under 4 conditions: unloaded; with lungeing girth; saddle only; and saddle with 75 kg of weight. Data were expressed as maximal extension, maximal flexion angles, range of motion of L3 and L5 and maximal pro‐ and retraction angles of the limbs.

Results: At walk and trot, there was a significant influence on back kinematics in the ‘saddle with weight’ situation, but not in the other conditions. Overall extension of the back increased, but the range of movement remained the same. Limb kinematics changed in the sense that forelimb retraction increased. At canter, both the ‘saddle with weight’ and ‘saddle only’ conditions had a significant extending effect on the back, but there was no effect on limb kinematics.

Conclusions and potential relevance: Weight and a saddle induce an overall extension of the back. This may contribute to soft tissue injuries and the KSS. The data from this study may help in understanding the reaction of the equine back to the challenges imposed by man when using the animal for riding.
Influence of rider on lameness in trotting horses
Authors: LICKA T. , KAPAUN M. , PEHAM C.
Published: April 2007

Reasons for performing study: Equine lameness is commonly evaluated when the horse is being ridden, but the influence of the rider on the lameness has not been documented.

Objective: To document the effect of 2 riders of different training levels on the vertical movement of the head and croup.

Methods: Twenty mature horses were ridden at trot by an experienced dressage rider and a novice rider, as well as trotted in hand. Kinematic measurements of markers placed on the horse's head and sacral bone were carried out. The asymmetries of the vertical head and sacral bone motion were calculated as lameness parameters and compared with pairedttests.

Results: Trotting in hand, 17 horses showed forelimb lameness (1–4/10) and 13 hindlimb lameness (1–2/10). Intra‐individually, 11 horses showed significant differences in forelimb lameness and 4 horses showed significant differences in hindlimb lameness when ridden. Over all horses, hindlimb lameness increased significantly under the dressage rider compared to unridden horses.

Conclusions: The presence of a rider can alter the degree of lameness; however, its influence cannot be predicted for an individual horse.

Potential relevance: In order to evaluate mild lameness, horses should be evaluated at trot both under saddle and in hand. If lameness is exacerbated, a second rider may be helpful; the level of training of the rider should be taken into consideration.
Three‐dimensional carpal kinematics of trotting horses
Authors: CLAYTON H. M. , SHA D. , STICK J. A. , MULLINEAUX D. R.
Published: April 2007

Reasons for performing study: Descriptions of 3D kinematics assist in understanding joint function and dysfunction, and are an essential step toward 3D inverse dynamic analysis.

Objectives: To measure 3D carpal joint motion during trotting.

Methods: Three‐dimensional trajectories of bone‐fixed markers on the radius and third metacarpus of the right forelimb of 3 healthy horses were recorded at 120 Hz using a 6‐camera analysis system. Joint kinematics were calculated in terms of helical angles between the 2 segments using a spatial attitude method.

Results: All horses showed carpal extension and internal rotation of the metacarpus relative to the radius as the carpus assumed the close‐packed position. In late stance, the carpus began a cycle of flexion that continued through midswing, accompanied by a small cycle of internal rotation. The direction of abduction/adduction varied between horses. The predominant rotational movement was flexion/extension, which showed a range of motion of 15 ± 6° in stance and 76 ± 13° in swing.

Conclusions: Carpal motions were generally similar between horses with the exception of abduction/adduction.

Potential relevance: Knowledge of carpal joint motion should assist in understanding the pathogenesis of carpal injuries. However, it seems probable that real differences exist between individuals; therefore, further investigations of the effect of conformation on carpal motion should be performed in a much larger population of horses.
Three‐dimensional kinematic analysis of horses with induced tarsal synovitis
Authors: KHUMSAP S. , LANOVAZ J. L. , CLAYTON H. M.
Published: April 2007

Reasons for performing study: Techniques for 3D analysis have recently been developed. This study applied 3D kinematic analysis to describe the effects of lameness in the distal intertarsal (DIT) and tarsometatarsal (TMT) joints; complex joints such as this may show measurable amounts of movement outside the sagittal plane that may change in response to pathological conditions.

Hypothesis: Three‐dimensional motions of the tarsal joint change after the induction of synovitis at the DIT and TMT joints.

Methods: Twelve retroreflective markers, attached on the skin over the right limb, were used to develop 3D coordinate systems for tibial and metatarsal segments. Data were collected at trot from 4 horses on 2 occasions, before (sound condition) and after (lame condition) induction of synovitis of the DIT and TMT joints. Ranges of 3D motions of the metatarsal segment relative to the tibial segment were compared between sound and lame conditions usingttests.

Results: There were significant decreases (P<0.05) in tarsal joint flexion and cranial translation of the metatarsus relative to the tibia during stance, and in proximal translation of the metatarsus during swing.

Conclusions and potential relevance: In the lame condition, reduced cranial translation at the DIT and TMT joints may lead to a reduction in the motion of the articular cartilage surfaces relative to each other, which may have adverse effects on cartilage nutrition and function. Further studies of tarsal 3D kinematics in horses with bone spavin could allow quantification of the biomechanical effects of the special shoes used for conservative treatment.
Surface strains around the midshaft of the third metacarpal bone during turning
Authors: DAVIES H. M. S. , MERRITT J. S.
Published: April 2007

Reasons for performing study: Bone strains quantify skeletal effects of specific exercise and hence assist in designing training programmes to avoid bone injury.

Objective: To test whether compressive strains increase on the lateral surface of the inside third metacarpal bone (McIII) and the medial surface of the outside McIII in a turn.

Methods: Rosette strain gauges on dorsal, medial and lateral surfaces of the midshaft of the left McIII in 2 Thoroughbred geldings were recorded simultaneously during turning at the walk on a bitumen surface.

Results: Medial surface: Compression peaks were larger in the outside limb. Tension peaks were larger in the inside limb and in a tighter turn. On the lateral surface compression and tension peaks were larger on the inside limb, which showed the largest recorded strains (compression of ‐1400 microstrains). Dorsal compression strains were larger on the outside limb and on a larger circle. Tensile strains were similar in both directions and larger on a larger circle.

Conclusions: Compressive strains increased on the lateral surface of the inside McIII and medial surface of the outside McIII in a turn.

Potential relevance: Slow‐speed turning exercise may be sufficient to maintain bone mechanical characteristics in the inside limb lateral McIII cortex. Further work is needed to confirm these findings and to determine whether faster gaits and/or tighter turns are sufficient to cause bone modelling levels of strain in the medial and lateral McIII cortex.
Mepivacaine local anaesthetic duration in equine palmar digital nerve blocks
Authors: BIDWELL L. A. , BROWN K. E. , CORDIER A. , MULLINEAUX D. R. , CLAYTON H. M.
Published: April 2007

Reasons for performing study: Perineural analgesics are used for lameness diagnosis but the duration of effect, knowledge of which would provide valuable information when performing subsequent blocks, is unknown.

Objective: To evaluate the duration of a palmar digital nerve block using force plate measurements.

Methods: Ten horses diagnosed with unilateral navicular syndrome were trotted at range of 3 ± 0.15 m/sec over a force plate to record ground reaction forces for 5 trials of each forelimb. Data were recorded before nerve block, and then at 15 mins, 1, 2 and 24 h post nerve block.

Results: Before nerve block, peak vertical force (mean ± s.e.) was significantly higher in the contralateral forelimb (CL = 5345 ± 188 N) than in the lame forelimb (L = 4256 ± 204 N; P<0.05). At 15 mins post nerve block there was no significant difference between the 2 forelimbs (CL = 5140 ± 184 N; L = 5126 ± 129 N), and this remained the case for 1 h. By 2 h, the mean score for the lame leg had decreased (L = 4642 ± 182 N) but was still greater than preblock. By 24 h, vertical forces had returned to preblock values.

Conclusions: The palmar digital nerve block was fully effective between 15 mins and 1 h. The analgesic effect began to subside between 1 and 2 h but sufficient analgesia persisted to affect gait characteristics beyond 2 h.

Potential relevance: When using a palmar digital nerve block, it is important to perform lameness evaluations between 15 mins and 1 h to be sure of effective nerve blockade.
Detection of spinal ataxia in horses using fuzzy clustering of body position uncertainty
Authors: KEEGAN K. G. , ARAFAT S. , SKUBIC M. , WILSON D. A. , KRAMER J. , MESSER N. M. , JOHNSON P. J. , O'BRIEN D. P. , JOHNSON G.
Published: April 2007

Reasons for performing study: Subjective neurological evaluation in horses is prone to bias. An objective method of spinal ataxia detection is not subject to these limitations and could be of use in equine practice and research.

Hypothesis: Kinematic data in the walking horse can differentiate normal and spinal ataxic horses.

Methods: Twelve normal and 12 spinal ataxic horses were evaluated by kinematic analysis walking on a treadmill. Each body position signal was reduced to a scalar measure of uncertainty then fuzzy clustered into normal or ataxic groups. Correct classification percentage (CCP) was then calculated using membership values of each horse in the 2 groups. Subsequently, a guided search for measure combinations with high CCP was performed.

Results: Eight measures of body position resulted in CCP≥70%. Several combinations of 4–5 measures resulted in 100% CCP. All combinations with 100% CCP could be obtained with one body marker on the back measuring vertical and horizontal movement and one body marker each on the right fore‐ and hindlimb measuring vertical movement.

Conclusions and potential relevance: Kinematic gait analysis using simple body marker combinations can be used objectively to detect spinal ataxia in horses.
Ground reaction forces and limb function in tölting Icelandic horses
Authors: BIKNEVICIUS A. R. , MULLINEAUX D. R. , CLAYTON H. M.
Published: April 2007

Reasons for performing study: Gaited horses employ 4‐beat stepping (singlefoot) gaits that extend into speeds typical of trots. Ground reaction force (GRF) patterns of these specialised gaits have not been reported; therefore, appraisal of these gaits using nongaited horse kinetics may lead to clinical misjudgements.

Hypothesis: GRFs of tölting Icelandic horses will be comparable in profile and magnitude with those of trotting horses.

Methods: Forelimb and hindlimb GRFs were obtained for 10 Icelandic horses ridden at a tölt. These data were evaluated across 3 speed ranges: <2, 2.5–5 and >5 m/sec.

Results: Virtually all vertical force tracings were single‐peaked. Forelimbs typically had greater peak vertical forces and impulses compared with hindlimbs. Support duration and forelimb vertical impulse were correlated negatively with speed, whereas peak vertical, braking and propulsive forces and hindlimb braking and propulsive impulses were correlated positively with speed.

Conclusions: GRF profiles of tölting Icelandic horses are more similar to profiles of trots than walks, suggesting that tölts follow bouncing mechanics.

Potential relevance: Greater overlap of limb support in 4‐beat gaits (even at high speeds) is associated with lower peak vertical force magnitudes of tölts compared with those reported for trots at comparable speeds, which may help limit the occurrence of overloading injuries in Icelandic horses.
Influence of support boots on fetlock joint angle of the forelimb of the horse at walk and trot
Authors: KICKER C. J. , PEHAM C. , GIRTLER D. , LICKA T.
Published: April 2007

Reasons for performing study: Support boots are thought to reduce tension on the superficial digital flexor tendon (SDTF) of the horse and are frequently recommended for horses convalescing after tendonitis, but evidence of their effectiveness is conflicting.

Objective: To document the effects of 4 different types of support boots on fetlock joint angle in comparison to the unprotected fetlock.

Methods: In 26 horses, the kinematics of the forelimb fetlock joint angle was measured at walk and trot on a treadmill when wearing 3 different types of support boots and 1 protective boot, as well as without boots. As outcome parameters, maximum extension of the fetlock joint and the moment at which maximum extension occurred in the stride cycle were determined.

Results: At walk, 2 of the support boots reduced the maximum extension significantly by 0.8 and 0.9°, respectively (P<0.05). Additionally, one type of boots also delayed the occurrence of maximal extension within the stride cycle. At trot, all support boots reduced maximum extension significantly by 0.56–1.44° (P<0.01), and the protective boot reduced maximum extension by 0.56° (P<0.05).

Conclusions and potential relevance: The results demonstrate the effectiveness of support boots in reducing maximum extension of the fetlock, which can be assumed to reduce tension in the suspensory apparatus and SDFT. The delay of the moment of maximal extension may be relevant in reducing dynamic forces. However, it should be noted that the long‐term consequences of reduction of maximum fetlock extension are still uncertain. Such a reduction over a prolonged period might negatively affect fibre alignment in the healing tendon.
Kinematic evaluation of the back in the sport horse with back pain
Authors: WENNERSTRAND J. , JOHNSTON C. , ROETHLISBERGER‐HOLM K. , ERICHSEN C. , EKSELL P. , DREVEMO S.
Published: April 2007

Reasons for performing study: Earlier studies have developed a clinical tool to evaluate objectively the function of the equine back. The ability to differentiate horses with back pain from asymptomatic, fully functioning horses using kinematic measures from this tool has not been evaluated.

Objectives: To compare the kinematics of the back at walk and trot in riding horses with back dysfunction to the same parameters in asymptomatic sport horses.

Methods: The kinematics of the back in 12 horses with impaired performance and back pain were studied at walk and trot on a treadmill. Data were captured for 10 secs at 240 Hz. Range of movement (ROM) and intravertebral pattern symmetry of movement for flexion and extension (FE), lateral bending (LB) and axial rotation (AR) were derived from angular motion pattern data and the results compared to an earlier established database on asymptomatic riding horses.

Results: At walk, horses with back dysfunction had a ROM smaller for dorsoventral FE in the caudal thoracic region (T13 = 7.50°, T17 = 7.71°; P<0.05), greater for LB at T13 (8.13°; P<0.001) and smaller for AR of the pelvis (10.97°; P<0.05) compared to asymptomatic horses (FE‐T13 = 8.28°, FE‐T17 = 8.49°, LB‐T13 = 6.34°, AR‐pelvis = 12.77°). At trot, dysfunctional horses had a smaller (P<0.05) ROM for FE at the thoracic lumbar junction (T17 = 2.46°, L1 = 2.60°) compared to asymptomatic horses (FE‐T17 = 3.07°, FE‐L1 = 3.12°).

Conclusions: The objective measurement technique can detect differences between back kinematics in riding horses with signs of back dysfunction and asymptomatic horses. The clinical manifestation of back pain results in diminished flexion/extension movement at or near the thoracic lumbar junction. However, before applying the method more extensively in practice it is necessary to evaluate it further, including measurements of patients whose diagnoses can be confirmed and long‐term follow‐ups of back patients after treatment.

Potential relevance: Since the objective measurement technique can detect small movement differences in back kinematics, it should help to clinically describe and, importantly, objectively detect horses with back pain and dysfunction.
Compensatory load redistribution of horses with induced weightbearing hindlimb lameness trotting on a treadmill
Authors: WEISHAUPT M. A. , WIESTNER T. , HOGG H. P. , JORDAN P. , AUER J. A.
Published: April 2007

Reasons for performing study: The compensatory mechanisms of horses with weightbearing hindlimb lameness are still not fully understood.

Hypothesis: That weightbearing, unilateral hindlimb lameness would not only alter stride characteristics to diminish structural stress in the affected limb but also induce compensatory load adjustments in the other supporting limbs.

Objective: To document the load and time shifting mechanisms of horses with unilateral weightbearing hindlimb lameness.

Methods: Reversible lameness was induced in 8 clinically sound horses by applying a solar pressure model. Three degrees of lameness (subtle, mild and moderate) were induced and compared with the nonlame (sound) control measurement. Vertical ground reaction forces were recorded for all 4 limbs simultaneously on an instrumented treadmill.

Results: Compared to the sound situation, moderate hindlimb hoof lameness induced a decrease in stride duration (‐3.3%) and stride impulse (‐3.1%). Diagonal impulse decreased selectively in the lame diagonal stance (‐7.7%). Within the diagonal limb pair, vertical impulse was shifted to the forelimb during the lame diagonal stance (+6.5%) and to the hindlimb during the sound diagonal stance (+3.2%). Peak vertical force and vertical impulse decreased in the lame limb (‐15%), but only vertical impulse increased in the contralateral hindlimb (+5.7%). Stance duration was prolonged in both hindlimbs (+2.5%). Suspension duration was reduced to a greater extent after push‐off of the lame diagonal limb pair (‐21%) than after the sound diagonal limb pair (‐9.2%).

Conclusions: Four compensatory mechanisms could be identified that served to reduce structural stress, i.e. peak vertical force on the affected limb: 1) reduction of the total vertical impulse per stride; 2) diagonal impulse decreased selectively in the lame diagonal; 3) impulse was shifted within the lame diagonal to the forelimb and in the sound diagonal to the hindlimb; and 4) the rate of loading and peak forces were reduced by prolonging the stance duration.

Potential relevance: Load shifting mechanisms are not only effective in diminishing peak forces in the affected limb, but also suppress compensatory overload in other limbs. Selected force and time parameters allow the unequivocal identification of the lame limb. Future studies have to examine how far these compensatory mechanisms may be generalised for other defined orthopaedic problems in the hindlimb.
The displaced equine soft palate as a source of abnormal respiratory noise during expiration
Authors: FRANKLIN S. H. , PRICE C. , BURN J. F.
Published: April 2007

Reasons for performing study: To develop the technique of respiratory sound analysis for the diagnosis of dorsal displacement of the equine soft palate.

Objectives: To show that 1) the displaced soft palate can spontaneously vibrate in the presence of expiratory airflow; 2) the observed frequency of vibration can be detected in respiratory sound recordings; and 3) the frequency of vibrations measured in cadaveric specimens are similar to those obtained from audio spectra in exercising horses with DDSP.

Methods: Palatal movements and respiratory sounds were recorded from artificially ventilated cadaveric heads. The fundamental mode of palate vibrations calculated from high‐speed videoendoscopic recordings was compared with frequencies detected in the audio spectra and with data collected from exercising horses with DDSP.

Results: Palate vibrations occurred when air was blown through the trachea. The fundamental mode of vibrations was present in the audio spectra and was not significantly different from those recordedin vivo.

Conclusions: Vibrations of the soft palate are the probable source of expiratory sounds recorded in horses with DDSP.

Potential relevance: This study strengthens the case for the application of respiratory sound analysis in the diagnosis of DDSP in exercising horses.
Longitudinal development of equine conformation from weanling to age 3 years in the Thoroughbred
Authors: ANDERSON T. M. , McILWRAITH C. W.
Published: April 2007

Reasons for performing study: There is little information available to define conformational changes with age using an objective but practical method of recording specific body measurements.

Objective: To analyse conformation objectively in a population of racing Thoroughbreds and describe the changes from weanling to age 3 years.

Methods: Annual photographs were taken over 4 years and conformation measurements made from photographs using specific reference points marked on the horses.

Results: Correlation analysis revealed highly significant, moderate to strong relationships between long bone lengths and wither height for all ages. All long bone lengths showed moderate to strong relationships with each other for all ages. The front and rear pastern angles were significantly correlated with the angle of the dorsal surface of the front and rear hooves, respectively, for all. Wither height, croup height and length of neck topline, neck bottomline, scapula, humerus, radius and femur increased significantly from age 0–1 year and age 1–2 years. Hoof lengths (medial and lateral, right and left) grew significantly between the ages of 0 and 1 and 1 and 2 years, but decreased in length between age 2 and 3 years. Horses became more offset in the right limb between weanling and age 3 years, but the offset ratios did not change with age on the left limb. The angle of the scapula (I), shoulder and radiometacarpus significantly increased between all age groups (became more upright). The angle of the dorsal surface of the hooves (both front and hind) decreased significantly from ages 0 to 1 and 1 to 2 years, but showed no significant difference between ages 2 and 3 years.

Conclusions: A strong relationship between long bone lengths and wither height for all ages supports the theory that horses are proportional. Longitudinal bone growth in the distal limb increased only 5–7% from weanling to age 3 years and is presumably completed prior to the yearling year. Several growth measures increased from ages 0 to 1 and 1 to 2 years, but did not increase from age 2–3 years; indicating that growth rate either showed or reached a plateau at this time.

Potential relevance: This study provides objective information regarding conformation and skeletal growth in the Thoroughbred which can be utilised for selection and recognition of significant conformational abnormalities.
Use of intravenous flecainide in horses with naturally‐occurring atrial fibrillation
Authors: van LOON G. , BLISSITT K. J. , KEEN J. A. , YOUNG L. E.
Published: April 2007

Reasons for performing study: It has been reported that i.v. flecainide has a high efficacy for the treatment of experimentally‐induced acute atrial fibrillation (AF) in horses and that its use is associated with minimal toxic side effects.

Objectives: The objectives were to study the efficacy of i.v. flecainide as a treatment for atrial fibrillation in horses with naturally‐occurring AF.

Methods: Ten horses with naturally‐occurring AF were treated with 2 mg/kg bwt flecainide i.v. at a rate of 0.2 mg/kg bwt/min. In 3 horses, the infusion was continued at 0.05–0.10 mg/kg bwt/min until a total dose of 3.0 mg/kg bwt had been administered. Heart rate, QRS duration and average interval between fibrillation waves were measured before, during and following flecainide infusion. If conversion to normal sinus rhythm was not achieved, horses were treated with quinidine sulphateper osat a dose of 22 mg/kg bwt given every 2 h.

Results: None of the horses with chronic AF (n = 9) converted to sinus rhythm with flecainide i.v. The only horse treated successfully had acute AF of 12 days' duration. The QRS duration and fibrillation cycle length increased significantly (P = 0.006 and 0.002, respectively) during and following flecainide infusion. Heart rate did not increase significantly over time however, 3 horses developed heart rates in excess of 100 beats/min. Two horses developed a potentially dangerous ventricular dysrhythmia during the first 15 mins of treatment. Quinidine sulphate givenper osrestored sinus rhythm in 8 out of 9 horses, with minimal adverse effects.

Conclusions: Although flecainide might be efficacious in cases of acute AF, it was not possible to restore sinus rhythm in horses with naturally‐occurring chronic AF at the dosages used in this study. In 2 horses, 2.0 mg/kg bwt flecainide was associated with potentially dangerous dysrhythmias.

Potential clinical relevance: Intravenous administration of 2 mg/kg bwt flecainide is unlikely to convert chronic AF in horses and could induce dangerous dysrhythmias.
Tegaserod (HTF 919) stimulates gut motility in normal horses
Authors: LIPPOLD B. S. , HILDEBRAND J. , STRAUB R.
Published: April 2007

Reasons for performing study: It has been shown that the selective 5‐HT4 receptor agonist tegaserod induces an increase in frequency and amplitude of contractions in isolated muscle preparations of equine ileum and pelvic flexure.

Objectives: To investigate the effects of tegaserod on gut motility and transit of spheres in normal horses.

Methods: Six mature Freiberger horses were kept under standardised conditions. Effects of tegaserod (0.02 mg/kg bwt i.v. b.i.d. for 2 days) or vehicle on intestinal transit of barium‐filled spheres, defaecation and gut sounds were studied in a cross‐over design. Spheres were given via stomach tube prior to the first dosing of tegaserod or vehicle. Faeces were collected every 3 h and spheres eliminated were identified radiologically in the faeces.

Results: Tegaserod significantly accelerated the gastrointestinal (GI) transit time of spheres and increased the frequency of defaecation and scores of gut sounds compared to vehicle. The compound was well tolerated; no effects on behaviour, body temperature, heart rate, respiratory rate and clinical laboratory data were observed.

Conclusions: Tegaserod efficaciously stimulated motility and accelerate GI transit in healthy horses.

Potential relevance: Tegaserod may offer therapeutic potential in horses suffering from impaction or paralytic ileus.
A prospective cohort study to investigate risk factors for horse falls in UK hurdle and steeplechase racing
Authors: PINCHBECK G. L. , CLEGG P. D. , PROUDMAN C. J. , MORGAN K. L. , FRENCH N. P.
Published: April 2007

Reasons for performing study: Equine fatalities during racing continue to be a major welfare concern and falls at fences are responsible for a proportion of all equine fatalities recorded on racecourses.

Objectives: To identify and quantify risk factors for horse falls in National Hunt (NH) racing and to report the frequency of falling and falling‐associated fatalities.

Methods: A prospective cohort study was conducted on 2879 horse starts in hurdle and steeplechase races on 6 UK racecourses. Any horse that suffered a fall at a steeplechase or hurdle fence during the race was defined as a case. Data were obtained by interview and observations in the parade ring and from commercial databases. Multivariable logistic regression models, allowing for clustering at the level of the track, were used to identify the relationship between variables and the risk of falling.

Results: There were 124 falling cases (32 in hurdling and 92 in steeplechasing) identified. The injury risk of fallers was 8.9% and fatality risk 6.5%. Duration of journey to the racecourse, behaviour in the parade ring and weather at the time of the race were associated with falling in both hurdle and steeplechase racing. Age, amount of rainfall and going were also associated with falling in steeplechase racing.

Conclusions: Falls at fences are significant contributors to equine fatalities during NH racing. Potentially modifiable risk factors identified were the condition of track surfaces and journey time to the racecourse.

Potential relevance: It is hoped that information from this study may be used in future interventions to improve horse and jockey safety in racing. The study has also identified areas requiring further research, such as equine behaviour and its effect on racing performance, and the effect of light conditions on jumping ability.
Surgical repair of rib fractures in 14 neonatal foals: case selection, surgical technique and results
Authors: BELLEZZO F. , HUNT R. J. , PROVOST P. , BAIN F. T. , KIRKER‐HEAD C.
Published: April 2007

Reasons for performing study: Fractured ribs are encountered quite frequently in newborn Thoroughbred foals, often with fatal outcome. Surgical repair of fractures therefore requires consideration as a means of reducing mortality.

Objectives: To evaluate the repair of rib fractures using internal fixation techniques in foals at 2 different equine hospitals following similar diagnostics and case selection.

Methods: The records of 14 foals that underwent internal fixation of fracture ribs were reviewed. Subject details, clinical presentation, diagnosis, surgical technique, post operative care and complications were recorded. Follow‐up information was obtained in 7 foals.

Results: The fractured ribs were reduced and stabilised using reconstruction plate(s), self‐tapping cortical screws and cerclage wire in 12 cases, Steinmann pins and cerclage wires in 1 case and both techniques in 1 case. Not every rib was reduced on each case. Surgical reduction was performed on an average of 2 ribs, range 1–3 ribs in each foal. At the time of writing, 4 foals had been sold, one age 2 years was in training and 2 others died from unrelated causes.

Conclusions: Our data support the use of surgical stabilisation utilising reconstruction plates, self‐tapping cortical screws and cerclage wire for selected cases of thoracic trauma in neonatal foals. The use of Steinmann pins may be suboptimal due to cyclic failure, implant migration and the potential for iatrogenic internal thoracic trauma.

Potential relevance: Foals with existing extensive internal thoracic trauma resulting from rib fracture(s), or the potential for such trauma, previously considered to have a guarded to poor prognosis for survival, may be successfully managed with internal fixation of selected fracture sites.
Respiratory and metabolic effects of massive administration of isotonic saline solution in heaves‐affected and control horses
Authors: JEAN D. , VRINS A. , LAVOIE J.‐P.
Published: April 2007

Reasons for performing study: It has been suggested that rapid administration of isotonic saline solution relieves airway obstruction in heaves‐affected horses, but the efficacy and tolerability of this treatment is poorly documented.

Objectives: To determine the respiratory and metabolic effects of a rapid administration of isotonic saline solution in control horses and those with heaves.

Methods: Thirty litres isotonic saline solution were administered i.v. to 5 control (Group C) and 9 heaves‐affected horses (Group H). Pulmonary function testing and arterial blood gas analysis were performed prior to saline infusion, at 90 and 180 mins after starting the infusion, and 1, 3, 6 and 10 days later. PCV, plasma total solids, plasma electrolytes (Na+, Cl‐ and K+) and venous blood gas analysis were performed prior, during and after saline infusion.

Results: Rapid saline administration was shown to have no beneficial effects on lung function during infusion inGroup H.On the contrary, they had significantly increased pulmonary resistance (RL) at 180 mins following the initiation of saline administration compared to baseline. InGroup C, saline administration resulted in a significant increase in RLat 180 mins and a significant decrease in PaO2at 90 mins. These results suggest a transient decrement in lung function caused by rapid saline administration.Group Hhad a metabolic alkalosis with hypochloraemia at baseline compared to control horses. This resolved following i.v. saline administration and returned to baseline within 6 h after treatment had been discontinued.

Conclusion: The administration of saline toGroup Hdid not improve airway function significantly, but resulted in mild and transient side effects.

Potential relevance: Rapid administration of isotonic saline alone is not an effective therapy for heaves in horses.
Total and partial ovariohysterectomy in seven mares
Authors: Rötting A. K. , Freeman D. E. , Doyle A. J. , Lock T. , Sauberli D.
Published: April 2007

Reasons for performing study: Ovariohysterectomy appears to have a low mortality rate in mares, but the procedure needs to be reviewed because of the high risk of life‐threatening complications.

Hypothesis: That ovariohysterectomy can be effective treatment for a variety of uterine diseases in mares and carries a good prognosis.

Methods: Diagnosis, clinical data, surgical technique, post operative care, complications and outcome were recorded from medical records of 7 mares that underwent total (6) and partial (1) ovariohysterectomy at the University of Illinois from 1994 to 2001.

Results: The indications for ovariohysterectomy were chronic pyometra (4 mares), chronic uterine torsion (n = 2) and chronic intramural haematoma (n = 1). Surgical exposure was difficult but was improved by traction on stay sutures and right‐angled clamps. In some cases, application of the TA‐90 autosuture instrument as a right‐angled clamp to the caudal part of the uterus improved access to the uterine stump. The most common post operative complications were decreased faecal output, decreased intestinal sounds (4 mares) and mild abdominal pain (2). Two mares had mild to moderate incisional infections. Other previously reported complications, such as haemorrhage, septic peritonitis, uterine stump infection or necrosis, and diarrhoea, did not occur. All mares survived over follow‐up periods of 6 months to 5 years and were used for riding (6 mares) and embryo transfer (1 mare, after partial ovariohysterectomy).

Conclusions and potential relevance: According to this study, the prognosis for mares after ovariohysterectomy appears to be good, despite the technical difficulties of the procedure. The prevalence of life‐threatening complications can be lower than reported.