Subjective Gait Assessment of 57 Sports Horses in Normal Work: A Comparison of the Response to Flexion Tests,Movement in Hand,on the Lunge,and Ridden

Historically, lameness has been evaluated in hand or on the lunge, but some lamenesses may only be apparent ridden. The objectives were to compare the response to flexion tests, movement in hand, on the lunge, and ridden in sports horses in regular work, assumed to be sound by the owners. It was hypothesized that lameness may be apparent in ridden horses that was not detectable in hand or on the lunge. Fifty-seven sports horses in regular work and assumed to be sound were assessed prospectively in hand, on the lunge on both soft and firm surfaces, and ridden. Flexion tests of all four limbs were performed. Lameness was graded (0–8) under each circumstance in which the horse was examined and after each flexion test. Fourteen horses (24.6%) were sound under all circumstances. Six horses were sound in hand, on the lunge, and ridden but showed a grade 1 or 2 lameness after flexion of a single limb. Sixteen horses (26.3%) were lame in hand. Twenty-four horses (42.1%) showed lameness on the lunge on a soft surface, and 23 horses (40.4%) were lame on the lunge on a firm surface. Twenty-seven horses (47.4%) showed lameness ridden; seven (12.3%) were only lame ridden. There was no significant association between age (P = .09) or work discipline (P = .1) and lameness. It was concluded that freedom from lameness in straight lines is not a reliable indicator of soundness. Some lamenesses are only apparent ridden.     

Reducing Peak Pressures Under the Saddle Panel at the Level of the 10th to 13th Thoracic Vertebrae May Be Associated With Improved Gait Features,Even When Saddles Are Fitted to Published Guidelines

Saddle–horse interaction is increasingly linked with back pain, performance, and welfare issues. Saddle fit and work quality influence alterations in back shape with exercise at thoracic vertebra 13 level (T13) with exercise. The objectives of experiments were to: determine a repeatable zone and stride point of peak pressure under saddles fitted to industry guidelines; compare peak pressure in this zone and limb kinematics in collected trot between horses own saddles (S) and a saddle designed to reduce pressure at T10–T13 (F); compare thoracolumbar width change after exercise between S and F and with F after 3 months use. Elite dressage (n = 13) horses/riders with no lameness/performance problem had pressure mat data acquired under S, fitted by four qualified saddle fitters, to determine zones of peak pressure. Pressure mat data at T10–T13, forelimb/hindlimb protraction, and carpal/tarsal flexion acquired using simultaneous high-speed motion capture, and difference in thoracolumbar dimensions (T8, T18 at 3, 15 cm) between before and after exercise was compared between S and F. Peak pressures were consistently detected axially around T10–T13 (sensors A4–A7, H4–H7). Peak pressures were significantly less with F than S for each cell and pooled (55%–68% difference. P = .01 to <.0001). Saddle F was associated with 13% greater forelimb and 22.7% hindlimb protraction, 3.5° greater carpal and 4.3° tarsal flexion (P = .02 to .0001), and greater increase in thoracolumbar dimensions after exercise (P = .01 to <.0001). Saddles fitted to published guidelines may still have a nonideal interface with horses. Reducing peak pressures around T10–T13 was associated with improved limb kinematics in trot and greater thoracolumbar expansion after exercise.     

Influence of rider on lameness in trotting horses

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 paired t tests. 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.     

Crooked tail carriage in horses: Increased prevalence in lame horses and those with thoracolumbar epaxial muscle tension or sacroiliac joint region pain

The relationship between lameness and crooked tail carriage (CTC) in horses is unclear. The objectives of this study were (i) to determine the association between CTC and lameness; (ii) among lame horses, to determine associations between CTC and lameness diagnosis, saddle slip, thoracolumbar range of motion (ROM), epaxial muscle tension and pain, and sacroiliac joint region (SIJR) pain, and (iii) to determine whether abolition of lameness and SIJR pain by diagnostic anaesthesia modified CTC. In this study, 520 lame and 170 nonlame sports horses were examined for CTC and other characteristics by one clinician (S.J.D.). All horses were evaluated when ridden. Lame horses were also assessed in hand and on the lunge. Crooked tail carriage, its direction, lameness, musculoskeletal and tack-related parameters were recorded as binary variables and analysed using 2 × 2 contingency tables. Sacroiliac joint region pain was diagnosed using local anaesthesia. Standard errors are shown in square brackets. 32.5% of lame horses had CTC, compared with 5.3% of nonlame horses (odds ratio = 8.6 [confidence intervals 4.4, 16.7]; P = 2×10⁻¹²). Of 169 lame horses with CTC, 103 (60.9% [3.8%]) held their tail to the left. There was no association between the side of the predominant lame limb and CTC direction. However, CTC was more common (P = 0.005) in horses with hindlimb lameness (35.7% [2.4%], N = 401) compared with forelimb lameness (21.0% [4.1%], N = 100). Crooked tail carriage was associated with SIJR pain (P = 0.0007) and thoracolumbar epaxial muscle tension (P = 0.0007), but not with saddle slip, reduced thoracolumbar ROM or thoracolumbar epaxial muscle pain. Limitations of the study included the facts that nonlame horses were a convenience sample and lameness assessment, other clinical observations and determination of the presence of CTC were subjective, with potential for bias. Video recordings and photographs are available for verification of tail position. It was concluded that CTC is more prevalent in lame horses than nonlame horses. There is a positive association between CTC and hindlimb lameness, SIJR pain and thoracolumbar epaxial muscle tension.     

Hindlimb lameness associated with proximal suspensory desmopathy and injury of the accessory ligament of the suspensory ligament in five horses

The accessory ligament of the hindlimb suspensory ligament arises from the plantar aspect of the calcaneus and fourth tarsal bones and blends with the suspensory ligament in the proximal aspect of the metatarsus. The accessory ligament of the suspensory ligament of both hindlimbs of 12 mature horses, with no history of hindlimb lameness, was assessed ultrasonographically. The ligament comprised linear parallel echoes which were consistently shorter than those of the lateral digital flexor tendon; the dorsal and plantar borders were parallel. Lameness associated with injury of the accessory ligament of the suspensory ligament was identified in 6 of 8 lame hindlimbs of 5 horses, unilaterally in 4 horses and bilaterally in one horse. In all horses there was concurrent proximal suspensory desmopathy. There was localised oedematous swelling on the distal medial aspect of the chestnut extending distally in 2 horses. Lameness was best identified when the horses were ridden. Perineural analgesia of the deep branch of the lateral plantar nerve abolished lameness in 3 horses but perineural analgesia of the tibial nerve was required to abolish lameness in the hindlimb with injury of the accessory ligament of the suspensory ligament in 2 horses. Injury of the accessory ligament of the suspensory ligament was characterised by marked decrease in echogenicity of the ligament and loss of parallel alignment of the linear echoes, which were shorter than normal in longitudinal images.     

The effect of induced hindlimb lameness on thoracolumbar kinematics during treadmill locomotion

REASON FOR PERFORMING STUDY: There are no detailed studies describing a relationship between hindlimb lameness and altered motion of the back. OBJECTIVES: To quantify the effect of induced subtle hindlimb lameness on thoracolumbar kinematics in the horse. METHODS: Kinematics of 6 riding horses were measured during walk and trot on a treadmill before and during application of pressure on the sole of the left hindlimb using a well-established sole pressure model. Reflective markers were located at anatomical landmarks on the limbs, back, head and neck for kinematic recordings. Ground reaction forces (GRF) in individual limbs were calculated from kinematics to detect changes in loading of the limbs. RESULTS: When pressure on the sole of the hindlimb was present, horses were judged as lame (grade 2 on the AAEP scale 1-5) by an experienced clinician. No significant unloading of this limb was found in the group of horses (unloading was observed in 4 animals, but was not detectable in the other 2), but statistically significant effects on back kinematics were detected. The overall flexion-extension (FE) range of motion (ROM) of the vertebral column was increased at walk, especially in the thoracic segments. Axial rotation (AR) ROM of the pelvis was also increased. At trot, the FE ROM was decreased only in the segment L3-L5-S3. During the stance phase of the lame limb, the segment T6-T10-T13 was more flexed and the neck was lowered at both gaits; the thoracolumbar segments were more extended at walk and trot. There were no significant changes in the stride length or protraction-retraction angles in any of the limbs. CONCLUSIONS: Subtle hindlimb lameness provoked slight but detectable changes in thoracolumbar kinematics. The subtle lameness induced in this study resulted in hyperextension and increased ROM of the thoracolumbar back, but also in decreased ROM of the lumbosacral segment and rotational motion changes of the pelvis. POTENTIAL RELEVANCE: Even subtle lameness can result in changes in back kinematics, which emphasises the intricate link between limb function and thoracolumbar motion. It may be surmised that, when chronically present, subtle lameness induces back dysfunction.     

Clinical significance of osseous spurs on the dorsoproximal aspect of the third metatarsal bone

Reasons for performing study: Osseous spurs on the dorsoproximal aspect of the third metatarsal bone (MtIII) are common, but their clinical significance is unknown. Objectives: To verify the sites of insertion of the dorsal metatarsal ligament and the tendons of tibialis cranialis and fibularis tertius in order to determine if periarticular osteophytes and entheseophytes could be differentiated radiologically; and to determine the frequency of occurrence of osseous spurs on the dorsoproximal aspect of MtIII. Hypotheses: The frequency of osseous spurs on the dorsoproximal aspect of MtIII would be higher in lame than in clinically normal horses and higher in horses with distal hock joint pain or proximal suspensory desmitis than in horses with other causes of hindlimb lameness. Methods: A retrospective study of data from the clinical work up and tarsal radiographs of 455 horses was performed. Horses were divided into: Group 1, clinically normal horses; Groups 2–5, according to the diagnosis of hindlimb lameness. Radiographs were examined for the presence of an osseous spur on the dorsoproximal aspect of MtIII; pathology of the distal tarsal joints was graded. The associations between the presence of a spur and lameness, diagnosis group and the grade of distal tarsal joint abnormalities were analysed statistically using Chi‐squared tests. Results: An osseous spur was present in 25% of horses; 13% of horses with bilateral radiographs had bilateral spurs. There was no significant difference in frequency of the presence of a spur between lame and nonlame horses, or between horses with other causes of hindlimb lameness and horses with proximal suspensory desmitis and/or distal tarsal joint pain. The presence of an osseous spur was significantly associated with the grade of radiological abnormality in the distal tarsal joints (tarsometatarsal joint P = 0.018: centrodistal joint P = 0.027). In many horses it was not possible to differentiate accurately between osteophytes and entheseophytes. Conclusions and potential relevance: The presence of an osseous spur on the dorsoproximal aspect of MtIII in the absence of other radiological abnormalities may be an incidental finding. Osseous spurs occur more frequently in hocks with radiological abnormalities in the distal tarsal joints and may be an indicator of distal tarsal joint osteoarthritis. The clinical significance must be established by intra‐articular analgesia.     

Effect of rider experience and evaluator expertise on subjective grading of lameness in sound and unsound sports horses under saddle

The primary objective of this study was to investigate whether rider experience influences the assessment and grading of lameness in horses based on under-saddle gait analysis. Thirteen adult sports horses in active training were included in the study. After a baseline lameness and neurologic examination by the principal investigators, horses were videotaped while being ridden by an experienced and a less experienced rider. A 3-minute video was made for each horse and rider and 26 videos were randomly ordered and compiled on a DVD. Veterinarians with different levels of experience in evaluating lameness and veterinary students viewed the DVD and assigned a lameness score to each horse/rider combination. In a model accounting for the expertise of the evaluator, there was no difference in overall lameness scores between experienced and less experienced riders. This result was consistent for both sound and unsound horses. The overall lameness scores reported by specialists and students, however, differed significantly. The lameness score reported by the study participants while the horse was ridden was significantly associated with the subjective baseline lameness assessment reported by the principal investigators for the same limb when the horse was not under saddle. Additional work is necessary to determine whether riders with even lower skill levels would further alter the balance and motion pattern of the horse and have more influence on subjective grading of lameness.     

A comparative study of proximal hindlimb flexion in horses: 5 versus 60 seconds

Reasons for performing study: The flexion test is routinely used in lameness and prepurchase examinations. There is no accepted standard for duration of flexion or evidence that interpretation of results would differ with different durations of flexion. Hypothesis: There will be no difference in interpretation of proximal hindlimb flexion for 5 or 60 s. Methods: Video recordings of lameness examinations of 34 client‐owned horses were performed that included: baseline lameness, proximal hindlimb flexion for 60 s, and flexion of the same limb for 5 s. Videos were edited to blind reviewers to the hypothesis being tested. The baseline lameness video from each horse was paired with each flexion to make 2 pairs of videos for each case. Twenty video pairs were repeated to assess intraobserver repeatability. Fifteen experienced equine clinicians were asked to review the baseline lameness video followed by the flexion test and grade the response to flexion as either positive or negative. Potential associations between the duration of flexion and the likelihood of a positive flexion test were evaluated using generalised linear mixed models. A kappa value was calculated to assess the degree of intraobserver agreement on the repeated videos. Significance level was set at P<0.05. Results: Proximal hindlimb flexion of 60 s was more likely to be called positive than flexion of 5 s (P<0.0001), with the likelihood of the same interpretation 74% of the time. The first flexion performed was more likely to be called positive than subsequent flexions (P = 0.029). Intra‐assessor agreement averaged 75% with κ= 0.49. Conclusions: Proximal hindlimb flexion of a limb for 5 s does not yield the same result as flexing a limb for 60 s. Potential relevance: Shorter durations of flexion may be useful for clinicians that have good agreement with flexions of 5 and 60 s.     

Idiopathic hopping‐like forelimb lameness syndrome in ridden horses: 46 horses (2002–2014)

There has been no analysis of a hopping‐type forelimb lameness syndrome seen in ridden horses. The objectives of this retrospective study were to describe the clinical features of this syndrome, response to diagnostic analgesia and imaging findings and to document post mortem findings. Clinical records from 2002 to 2014 were reviewed and data concerning signalment, history, lame limb(s), lameness characteristics, response to diagnostic analgesia and diagnostic imaging were recorded. There were 46 horses from 4 to 13 years of age, 6 of which had a history of known or suspected trauma immediately before the onset of reduced performance or lameness. Lameness seen when ridden was characterised by an intermittent shortened cranial phase of the step of the lame forelimb at the trot and marked elevation of the head as the affected limb was protracted, with the horse appearing to ‘hop’ (on the contralateral limb) as if trying to break to canter. When lameness was at its worst horses were unwilling to trot. Three horses showed sporadic severe stumbling. Local analgesia of the affected limb did not improve the lameness and in 16 horses lameness deteriorated. Three of 5 horses showed some improvement (≥2/8 grades) in the hopping‐type lameness after intra‐articular analgesia of the articular process joints of the sixth and seventh cervical vertebrae, ipsilateral to the lame forelimb. Radiographic, ultrasonographic and nuclear scintigraphic examinations were inconclusive. Two of 4 horses responded to treatment with gabapentin. In 3 horses post mortem examination revealed mild lymphocytic inflammation within or around the dorsal root ganglia of the fifth and sixth cervical nerve roots, sixth cervical nerve root or second thoracic nerve root ipsilateral to the lame limb. Idiopathic hopping‐type lameness syndrome in ridden horses may be a pain‐related condition ± a neurological component and currently has a guarded prognosis.     

Retrospective study of the effect of intra-articular treatment of osteoarthritis of the distal tarsal joints in 51 horses

Osteoarthritis of the distal tarsal joints, affecting the centrodistal and tarsometatarsal joints, is a common cause of hindlimb lameness in horses. This paper describes the outcome of the intra-articular treatment of 51 horses with the condition with either methylprednisolone acetate (mpa) or triamcinolone acetonide (tr), either with or without hyaluronic acid (ha). The outcome was assessed in terms of the changes in the horses' grade of lameness. Follow-up information was obtained from the owners by means of a telephone questionnaire. Horses treated once with mpa or tr, either with or without ha, improved after a median of 56 days (P<0.0001), and there was no significant difference between mpa and tr. There was no significant further improvement in the horses treated twice. In the horses in which there was a diffuse increase in the uptake of a radiopharmaceutical by the distal tarsal joints, identified by scintigraphy, the lameness tended to improve (P=0.032), whereas in the horses in which the uptake was focal, it did not. At telephone follow-up 13 of 34 horses were reported to have had a positive outcome, but the outcome in the other 21 was reported to have been negative.     

Surgical arthrodesis of distal tarsal joints in 17 horses clinically affected with osteoarthritis

Objective To evaluate the outcome of 17 horses that underwent surgical arthrodesis of the tarsometatarsal and distal intertarsal joints for treatment of lameness due to osteoarthritis.
Design Retrospective clinical study using client-owned animals.
Procedure Horses with hindlimb lameness were diagnosed with osteoarthritis of the distal tarsal joints following relief of lameness after intra-articular anaesthesia or intra-articular corticosteroid injection. Surgery to stimulate ankylosis was performed on 27 hocks by placing 3 diverging 3.2 mm drill holes approximately 3 cm through the tarsometatarsal and distal intertarsal joints from the medial aspect of the limb. The results of surgery were assessed by postoperative examinations, telephone communication with clients and analysis of race results.
Results In 71% of horses, surgery was considered to be successful as determined by clinical examination or telephone communication with clients: six of these horses had unilateral surgery and six had bilateral surgery. This represented 85% (6/7) of horses undergoing unilateral surgery and 60% (6/10) of horses having bilateral surgery. All (8/8) racing Standardbreds and 67% (4/6) of racing Thoroughbreds were considered a success. The average time between surgery and a return to racing was 9.5 months.
Conclusions The surgical technique used here can provide resolution of lameness from osteoarthritis of distal tarsal joints with a success rate similar to other reported surgical arthrodesis techniques that are more invasive and have a greater morbidity.     

The hindlimb in walking horses: 1. Kinematics and ground reaction forces

The objective was to study associations between kinematics and ground reaction forces in the hindlimb of walking horses. Video (60 Hz) and force (2000 Hz) data were gathered for 8 strides from each of 5 sound horses during the walk. Sagittal plane kinematics were measured concurrently with the vertical and longitudinal ground reaction forces. The hindlimb showed rapid loading and braking in the initial 10% stride. The stifle, tarsal and coffin joints flexed and the fetlock joint extended during this period of rapid loading. The vertical ground reaction force showed 2 peaks separated by a dip; this pattern was similar to the fetlock joint angle-time graph. Peaks in the longitudinal ground reaction force did not appear to correspond with kinematic events. Total braking impulse was equal to total propulsive impulse over the entire stride. Flexion and extension of the hip were responsible for protraction and retraction of the entire limb. Maximal protraction occurred shortly before the end of swing and maximal retraction occurred during breakover. During the middle part of stance the tarsal joint extended slowly, while the stifle began to flex when the limb was retracted beyond the midstance position at 28% stride. Flexion cycles of the stifle and tarsal joints were well coordinated during the swing phase to raise the distal limb as it was protracted. The results demonstrate a relationship between limb kinematics and vertical limb loading in the hindlimbs of sound horses. Future studies will elucidate the alterations in response to lameness.     

Tiludronate infusion in the treatment of bone spavin: A double blind placebo‐controlled trial

Reasons for performing study: Tiludronate regulates bone remodelling through a decrease of the resorptive process and should therefore ameliorate the remodelling processes active in osteoarthritis of the distal tarsal joints (‘bone spavin’) and alleviate pain associated with abnormal bone lysis. Objective: To confirm the efficacy of tiludronate, administered as a single infusion at a dose of 1 mg/kg bwt, in the treatment of bone spavin in the horse. Methods: A double blind placebo controlled trial on 108 clinical cases of bone spavin was undertaken. The lameness score of the lamest limb was assessed following distal tarsal analgesia of the contralateral limb and followed‐up using the same procedure throughout the study. Bone spavin in the lamest limb was confirmed by distal tarsal analgesia and radiography. Horses were treated at Day 0 and reassessed 60 days later after controlled exercise. A second nonblinded treatment was given to unresponsive horses and all horses were re‐examined at Day 120. Exercise levels were recorded at each examination. Results: Eighty‐seven horses completed the trial as per the protocol. The tiludronate horses were significantly less lame than the placebo horses (P = 0.0318). Horses treated at Day 60 with tiludronate showed further improvement in lameness at Day 120 (P = 0.0096 and P = 0.0034 for horses treated with tiludronate and placebo at Day 0, respectively). The only significant difference in radiographic findings between tiludronate and placebo was for presence of periarticular osteophytes (P = 0.006). Conclusions: Tiludronate treatment is proven to be effective in bone spavin in horses in association with a controlled exercise programme. Clinical relevance: Tiludronate in combination with controlled exercise offers an alternate medical treatment for bone spavin.     

Clinical features and diagnosis of sacroiliac joint region pain in 296 horses: 2004–2014

There has been no large‐scale study of the clinical signs of sacroiliac (SI) joint region pain and its association with lameness and/or thoracolumbar pain. Horses with a positive response to infiltration of local anaesthetic solution around the SI joint regions (SI block) and/or abnormal radiopharmaceutical uptake (RU) in the region of the SI joints were included. History, clinical signs, diagnostic imaging findings, response to SI block, and concurrent lameness and/or thoracolumbar pain were recorded. Horses (n = 296) were divided into 2 groups: SI joint region pain only (Group 1, n = 43) and SI joint region pain and concurrent source(s) of pain (Group 2, n = 253). Clinical signs in Group 1 included increased tension in the longissimus dorsi muscles (40%), restricted flexibility of the thoracolumbar region (44%), trunk stiffness during exercise (61%) and poor hindlimb impulsion (56%). When ridden 65% had a poor contact with the bit, in 81% canter quality was worse than trot, and 35% bucked or kicked out with a hindlimb during canter. In both Groups 1 and 2 clinical signs were seen in a significantly greater proportion of horses during ridden work than lungeing (P<0.0001). Following SI block, 98% of horses showed dramatic improvement in clinical signs, including greater overall movement through the trunk, increased hindlimb impulsion and better quality canter. Abnormal RU in the SI joint regions was seen in 85/180 (47%) horses. Of horses with a positive response to SI block that underwent scintigraphy, only 43% had abnormal RU. Per rectum ultrasonographic examination of the SI joint region revealed abnormalities in 41/129 (32%) horses. Clinical signs of SI joint region pain are worse when horses are ridden. Sacroiliac joint region diagnostic analgesia is a useful, safe but nonspecific block. Ultrasonography and scintigraphy can provide additional information in some horses, but negative results do not preclude SI joint region pain.     

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 followup, 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.     

Lameness and poor performance in horses used for team roping: 118 cases (2000-2003)

OBJECTIVE: To determine the types of musculoskeletal problems that result in lameness or poor performance in horses used for team roping and determine whether these problems are different in horses used for heading versus heeling. DESIGN: Retrospective study. ANIMALS: 118 horses. PROCEDURE: Medical records of team roping horses that were evaluated because of lameness or poor performance were reviewed to obtain information regarding signalment, primary use (ie, head horse or heel horse), history, results of physical and lameness examinations, diagnostic tests performed, final diagnosis, and treatment. RESULTS: Among horses evaluated by lameness clinicians, the proportion with lameness or poor performance was significantly greater in horses used for heading (74/118) and lower in horses used for heeling (44/118) than would be expected under the null hypothesis. Most horses examined for poor performance were lame. A significantly greater proportion of horses used for heading had right forelimb lameness (26/74 [35%]), compared with horses used for heeling (7/44 [16%]). Horses used for heading had more bilateral forelimb lameness (18/74 [24%]), compared with horses used for heeling (4/44 [9%]). Horses used for heeling had more bilateral hind limb lameness (3/44 [7%]), compared with horses used for heading (0%). The most common musculoskeletal problems in horses used for heading were signs of pain limited to the distal sesamoid (navicular) area, signs of pain in the navicular area plus osteoarthritis of the distal tarsal joints, and soft tissue injury in the forelimb proximal phalangeal (pastern) region. Heeling horses most commonly had signs of pain in the navicular area, osteoarthritis of the metatarsophalangeal joints, and osteoarthritis of the distal tarsal joints. CONCLUSIONS AND CLINICAL RELEVANCE: Horses used for heading were most commonly affected by lameness in the right forelimb. Horses used for heeling had more bilateral hind limb lameness than horses used for heading.     

SCINTIGRAPHIC EVALUATION OF THE DISTAL TARSAL REGION IN HORSES WITH DISTAL TARSAL PAIN

Distal tarsal pain is a common reason for hind limb lameness, but diagnosis cannot always be made on radiographic examination. Scintigraphy may allow detection of subtle changes undetected by other diagnostic methods. We hypothesized that (1) distal tarsal pain would be associated with a loss of the expected pattern of radiopharmaceutical uptake (RU) detected in normal horses, (2) distal tarsal RU would be greater in limbs with tarsal pain than without pain, (3) RU in painful tarsi with radiographic evidence of osteoarthritis (OA) would be greater than in distal tarsal pain with no radiographic evidence of OA. The study aimed to describe radiopharmaceutical distribution in the distal tarsal region of horses with distal tarsal pain, and to compare this with the contralateral limb and results from horses without tarsal pain. Retrospective evaluation of scintigraphic images of the distal tarsal region was performed for 52 horses with distal tarsal pain: 15 with no radiographic evidence of OA (Group 1) and 37 with radiographic evidence (Group 2). The images were assessed using vertical and horizontal profile analysis across the distal tarsal region and regions of interest comparisons between the distal tarsal region and tibia within each horse (RU ratio). Painful limbs in unilaterally lame horses from Groups 1 and 2 had a significantly greater RU ratio than the respective contralateral limbs, and were significantly greater than the RU ratio in normal horses. On plantar images, mean region of interest counts were greater in the lame than the contralateral limb in Group 2 but not in Group 1. Although there was a positive correlation between lame and contralateral limb RU ratio in group 1, this was lost in group 2 horses. In lame limbs, the normal vertical activity profile was lost in 85% of group 1 and all of group 2, and the normal horizontal activity profile was lost in all of group 1 and 96% of group 2. There was a significant effect of lameness, but not of group on sites of peak activity on all profiles. The results of this study indicate that distal tarsal pain is associated with loss of the expected pattern of RU detected in normal horses. The findings also suggest that distal tarsal RU in lame limbs is greater than in limbs without pain, and that painful limbs with radiographic evidence of OA have a greater RU than painful limbs without radiographic evidence of OA.     

Risk factors associated with hindlimb lameness and degenerative joint disease in the distal tarsus of Icelandic horses

The aim of this study was to evaluate potential risk factors associated with hindlimb lameness and radiographic signs of degenerative joint disease (DJD) in the distal tarsus in Icelandic horses. The material consisted of riding horses (n = 420) age 6-12 years sired by 17 selected sires representing all major breeding lines, and of riding horses (n = 194) in the same age range sired by other sires. The examination protocol included the following: interview with owners/trainers, assessment of conformation, motion evaluation and radiographic examination. At the interview, data related to factors outside the horse (environmental variables) and data associated directly with the horse (intrinsic variables) were obtained. Data analysis was performed in 2 steps: screening using bivariate analysis, followed by testing with a multivariate logistic regression model. In the multivariate analysis, the factors of sire, age when broken to saddle and stud show participation were strongly associated with the prevalence of lameness. Height at the croup and ability to perform different gaits were also associated with the prevalence of lameness, but to a lesser degree. The risk factors of age, tarsal angle and birthplace were significantly associated with radiographic signs of DJD in the distal tarsus. Neither the variation in applied training intensity, the use of a professional or amateur trainer nor the temperament or front limb action of the individual horse was significantly associated with the prevalence of hindlimb lameness and/or radiographic signs of DJD in the distal tarsus in the Icelandic horse.     

Kinematics of the hind limb in trotting horses after induced lameness of the distal intertarsal and tarsometatarsal joints and intra-articular administration of anesthetic

OBJECTIVE: To identify hind limb and pelvic kinematic variables that change in trotting horses after induced lameness of the distal intertarsal and tarsometatarsal joints and after subsequent intra-articular administration of anesthetic. ANIMALS: 8 clinically normal adult horses. PROCEDURE: Kinematic measurements were made before and after transient endotoxin-induced lameness of the distal intertarsal and tarsometatarsal joints and after intra-articular administration of anesthetic. Fourteen displacement and joint angle (metatarsophalangeal [fetlock] and tarsal joints) measurements were made on the right hind limb, sacrum, and the right and left tubera coxae. Kinematic measurements were compared by general linear models, using a repeated measures ANOVA. Post hoc multiple comparisons between treatments were evaluated with a Fisher least squared difference test at alpha = 0.05. RESULTS: After lameness induction, fetlock and tarsal joint extension during stance decreased, fetlock joint flexion and hoof height during swing increased, limb protraction decreased, and vertical excursion of the tubera coxae became more asymmetric. After intra-articular administration of anesthetic, limb protraction returned to the degree seen before lameness, and vertical excursion of the tubera coxae became more symmetric. CONCLUSIONS AND CLINICAL RELEVANCE: Increased length of hind limb protraction and symmetry of tubera coxae vertical excursion are sensitive indicators of improvement in tarsal joint lameness. When evaluating changes in tarsal joint lameness, evaluating the horse from the side (to assess limb protraction) is as important as evaluating from the rear (to assess pelvic symmetry).