Asymmetry Thresholds Reflecting the Visual Assessment of Forelimb Lameness on Circles on a Hard Surface.

The assessment of lameness in horses can be aided by objective gait analysis tools. Despite their key role of evaluating a horse at trot on a circle, asymmetry thresholds have not been determined for differentiating between sound and lame gait during this exercise. These thresholds are essential to distinguish physiological asymmetry linked to the circle from pathological asymmetry linked to lameness. This study aims to determine the Asymmetry Indices (AIs) with the highest power to discriminate between a group of sound horses and a group of horses with consistent unilateral lameness across both circle directions, as categorized by visual lameness assessment conducted by specialist veterinarians. Then, thresholds were defined for the best performing AIs, based on the optimal sensitivity and specificity. AIs were calculated as the relative comparison between left and right minima, maxima, time between maxima and upward amplitudes of the vertical displacement of the head and the withers. Except the AI of maxima difference, the head AI showed the highest sensitivity (≥69%) and the highest specificity (≥81%) for inside forelimb lameness detection and the withers AI showed the highest sensitivity (≥72%) and the highest specificity (≥77%) for outside forelimb lameness detection on circles.

Acupuncture has potential in managing axial stiffness in steeplechase racehorses: a blinded prospective randomized preliminary study.

OBJECTIVE: Evaluate the short-term effects of acupuncture on the dynamic manifestations of axial stiffness in steeplechase racehorses. ANIMALS: 12 steeplechase racehorses presenting signs of axial stiffness during training. METHODS: Horses were randomly assigned to either an acupuncture treatment by an experienced certified acupuncturist (n = 6) or no treatment as negative controls (6). The horses' locomotion was evaluated during training before treatment (D0) and 7 (D7) and 14 (D14) days after by their rider and trainer through a questionnaire. Additionally, the improvement of their dorsal flexibility 2 days after treatment was evaluated subjectively at the trot, free jumping at the canter was evaluated by expert clinicians, and free jumping at the trot was evaluated objectively via inertial measurement units. RESULTS: Significantly more horses were improved on D7 and D14 in the acupuncture group (6/6) compared with the control group (1/5; P =.01) according to the scores set by the trainer and riders. Subjective evaluation of the dorsal flexibility also revealed a significant improvement (P = .04) for horses receiving the acupuncture treatment (median improvement score, 0.50 [reference range, 0.5 to 0.9]) compared with control horses (-0.25 [reference range, -0.5 to 0]). CLINICAL RELEVANCE: Acupuncture may be an interesting nondoping strategy to improve clinical signs of axial stiffness and performance on steeplechase racehorses.

Conservative management of equine tarsal collateral ligament injuries may allow return to normal performance.

OBJECTIVE: To describe type and distribution of tarsal collateral ligament (CL) injuries and to assess the long-term outcome in horses treated conservatively. ANIMALS: 78 horses (median age, 7 years [IQR, 4 to 9.75 years]) of different breeds and disciplines. PROCEDURES: Retrospective analysis (2000 through 2020) of horses with tarsal CL lesions diagnosed on ultrasound. The resting time, ability to return to work, and performance level after the injury were compared between horses having a single ligament (group S) or multiple ligaments (group M) affected and according to the case severity. RESULTS: Most of the horses (57/78) presented a single CL injury, while 21 had multiple CLs affected simultaneously, for a total of 108 CLs injured and 111 lesions. In both groups, the short lateral CL (SLCL) was the most commonly affected (44/108), followed by the long medial CL (LMCL; 27/108). Enthesopathies (72.1%) were more frequent than desmopathies alone (27.9%) and involved mostly the proximal insertion of the SLCL and the distal attachment of the LMCL. Conservative treatment (n = 62) consisted mainly of stall rest. The median resting time (120 days [IQR, 60 to 180 days]) did not significantly differ between the 2 groups (group S vs M) or according to the severity. Most horses (50/62) were able to return to work within 6 months. Horses that did not return (12/62) were more likely to have severe lesions (P = .01). Thirty-eight horses were able to perform at a level equal to or higher than before the injury. CLINICAL RELEVANCE: This study highlights the importance of thorough ultrasound assessment of tarsal CL injuries and demonstrates that conservative management is a viable option to allow these horses to return to previous performance level.

Investigation of Thresholds for Asymmetry Indices to Represent the Visual Assessment of Single Limb Lameness by Expert Veterinarians on Horses Trotting in a Straight Line.

Defining whether a gait asymmetry should be considered as lameness is challenging. Gait analysis systems now provide relatively accurate objective data, but their interpretation remains complex. Thresholds for discriminating between horses that are visually assessed as being lame or sound, as well as thresholds for locating the lame limb with precise sensitivity and specificity are essential for accurate interpretation of asymmetry measures. The goal of this study was to establish the thresholds of asymmetry indices having the best sensitivity and specificity to represent the visual single-limb lameness assessment made by expert veterinarians as part of their routine practice. Horses included in this study were evaluated for locomotor disorders at a clinic and equipped with the EQUISYM® system using inertial measurement unit (IMU) sensors. Visual evaluation by expert clinicians allocated horses into five groups: 49 sound, 62 left forelimb lame, 67 right forelimb lame, 23 left hindlimb lame, and 23 right hindlimb lame horses. 1/10 grade lame horses were excluded. Sensors placed on the head (_H), the withers (_W), and the pelvis (_P) provided vertical displacement. Relative difference of minimal (AI-min) and maximal (AI-max) altitudes, and of upward (AI-up) and downward (AI-down) amplitudes between right and left stance phases were calculated. Receiver operating characteristic (ROC) curves discriminating the sound horses from each lame limb group revealed the threshold of asymmetry indice associated with the best sensitivity and specificity. AI-up_W had the best ability to discriminate forelimb lame horses from sound horses with thresholds (left: -7%; right: +10%) whose sensitivity was greater than 84% and specificity greater than 88%. AI-up_P and AI-max_P discriminated hindlimb lame horses from sound horses with thresholds (left: -7%; right: +18% and left: -10%; right: +6%) whose sensitivity was greater than 78%, and specificity greater than 82%. Identified thresholds will enable the interpretation of quantitative data from lameness quantification systems. This study is mainly limited by the number of included horses and deserves further investigation with additional data, and similar studies on circles are warranted.

Outcome of Pelvic Fractures Identified in 75 Horses in a Referral Centre: A Retrospective Study.

OBJECTIVE: The aim of this study was to evaluate the reliability of fracture location and horse sporting discipline as prognostic indicators after a pelvic fracture in a referral centre caseload. MATERIALS AND METHODS: Data were collected for the short- and long-term follow-up of all cases with a diagnosis of pelvic fracture in a 7-year period. Information was obtained for 75 horses through a postal and internet survey. The proportion of horses returning to competition following fractures was compared between groups according to the competition discipline and the characteristics of the fracture. RESULTS: Forty-six of 75 horses returned to or began their intended activity. This proportion was significantly lower in the group of horses that sustained a comminuted fracture irrespective of the fracture location (11/25, p = 0.05). The proportion of Standardbred trotter racehorses returning to a sporting career after pelvic fracture (9/20) was not significantly different from horses competing in other disciplines (37/55). Cases of multiple pelvic fractures in the study population, and particularly those involving the acetabulum, had the worst sports prognosis (2/8 and 0/4). Nevertheless, two foals and one yearling (3/5) with isolated fracture of the acetabulum went on to race. CLINICAL SIGNIFICANCE: A clear characterization of the fracture is essential for prognosis, as comminuted fractures seem to entail a poorer athletic prognosis. Despite a lack of significance, prognosis seems poorer for Standardbred trotter racehorses and for cases with acetabulum involvement in multiple fractures. These results should be confirmed in larger samples.

Distribution of Pelvic Fractures in Racing and Non-racing Sport Horses: A Retrospective Study of 86 Cases Examined in a Referral Centre.

OBJECTIVE: The aim of this study was to analyse the pelvic fracture distribution and location in a referral centre caseload. MATERIALS AND METHODS: Medical records of 6,717 horses examined in a referral centre over a 7-year period were reviewed to identify all horses diagnosed with a pelvic fracture. Eighty-six horses were identified and divided into three disciplines, namely Thoroughbred racehorses (TBR), Standardbred trotter racehorses (STR) and non-racing sport horses (NRSH). RESULTS: A pelvic fracture was diagnosed in 1.3% of the cases examined during the study period. Prevalence was significantly higher in TBR (4.2%) and, regardless of the discipline, in horses under the age of 6 years (2.2%) (p < 0.01). STR were significantly younger than TBR and NRSH at the time of fracture (median ages = 1, 3 and 4 years old, respectively; p < 0.01). The fractures occurred most frequently in the ilium (44/86). No ilial wing fractures were diagnosed in STR and isolated acetabular fractures were only diagnosed in foals and yearlings. Fatigue fractures were diagnosed in TBR alone, affecting 9/22 TBR (foals and yearlings excluded) and most often located in the ilial wing (7 fatigue fractures out of the 12 ilial wing fractures) (p < 0.01). The median age of horses suffering from a pelvic fatigue fracture was 4 years. CLINICAL SIGNIFICANCE: This study confirms that young horses (under the age of 6 years) as well as TBR are likely to be at higher risk of a pelvic fracture. Fatigue fractures of the ilial wing seem to be a rare condition in STR while they are more frequent in young TBR in training.

Evaluation of standing low-field magnetic resonance imaging for diagnosis of advanced distal interphalangeal primary degenerative joint disease in horses: 12 cases (2010-2014).

OBJECTIVE To report history, findings from clinical examinations and diagnostic imaging, treatment, and outcomes associated with distal interphalangeal primary degenerative joint disease (DIP-PDJD) and to evaluate diagnostic usefulness and limitations of standing low-field MRI, relative to radiography and ultrasonography, for the diagnosis of DIP-PDJD in horses. DESIGN Retrospective case series with nested evaluation study. ANIMALS 12 client-owned horses. PROCEDURES Medical records were reviewed, and data were collected regarding signalment, history, results of physical and diagnostic imaging examinations, treatments, and outcomes of horses that underwent radiography, ultrasonography, and standing MRI for DIP-PDJD. Findings from radiography, ultrasonography, and MRI were recorded, and abnormal findings were graded. The diagnostic usefulness of MRI, relative to radiography and ultrasonography, in the diagnosis of DIP-PDJD in horses was evaluated. RESULTS A diagnosis of DIP-PDJD was established in 12 of 176 (6.8%) horses that underwent MRI examination of a foot for locomotor disorders. Radiography and ultrasonography enabled confirmation of DIP-PDJD in 3 of the 12 horses, and standing MRI enabled confirmation of DIP-PDJD in the remaining 9. Mean grade for thinning joint space and cartilage were significantly greater when determined with MRI, compared with radiography. Mean grade for osteophytes and periarticular bone remodeling were significantly greater when determined with radiography and ultrasonography, compared with MRI. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that DIP-PDJD can be challenging to detect with routine imaging, especially when synovial effusion and periarticular new bone formation are absent. Standing low-field MRI represents a potentially useful diagnostic tool to diagnose advanced DIP-PDJD in horses.

Synostosis of the first and second ribs in six horses.

CASE DESCRIPTION Over a 2-year period, 6 horses (4 Selle Français, 1 Hanoverian, and 1 Thoroughbred) were referred for evaluation of forelimb lameness. All horses had radiographic evidence of synostosis of the first and second ribs (SFSR). CLINICAL FINDINGS For 1 horse, the SFSR was considered the probable cause of the lameness (grade 3/5), with a shortening of the cranial phase of the stride in the affected limb. For 3 horses, it was considered a possible cause of the lameness (grade 1/5) for the same reason. For 2 horses, SFSR was considered an incidental finding unassociated with any clinical signs. The 4 horses with lameness suspected as attributable to SFSR had a moderate to severe amount of irregularly marginated new bone formation at the site of the SFSR, with a cranial displacement of the first rib, compared with findings for the 2 horses in which the SFSR was considered incidental. A likely congenital abnormality of the first rib was first suspected on nuclear scintigraphy in the 1 horse for which it was performed or on radiography of the caudal cervical portion of the vertebral column (3 horses) or shoulder joint (2 horses). TREATMENT AND OUTCOME The horse in which SFSR was considered the probable cause of the lameness was retired to the field and remained chronically lame. Two of the 3 horses in which SFSR was considered a possible cause of lameness received an IV infusion of tiludronate disodium and mesotherapy over the caudal cervical and cranial thoracic regions; both returned to competition but with poor results. One of the 2 horses with subclinical SFSR never developed lameness on the affected side. No follow-up information was available for the other 2 horses. CLINICAL RELEVANCE SFSR can be an incidental finding in horses, with or without clinical manifestations. This abnormality should be considered as a differential diagnosis for horses with forelimb lameness and associated shortening of the cranial phase of the stride that fails to improve with diagnostic analgesic techniques.

Randomized controlled trial demonstrates the benefit of RGTA® based matrix therapy to treat tendinopathies in racing horses.

A randomized controlled trial was performed on racing horses, to evaluate the efficacy of a new class of therapeutic agents in regenerative medicine-ReGeneraTing Agents® (RGTA®), to treat tendinopathies. Preliminary uncontrolled studies on tendon healing in racing horses with RGTA® (OTR4131)-Equitend® showed encouraging results, justifying performing a randomized, controlled, multicenter study with a two-year racing performance follow up. The objective of this study was to evaluate the effect of Equitend® versus placebo on acute superficial digital flexor tendonitis in racing French Standardbred Trotters (ST). Twenty-two ST were randomly and blindly assigned to receive with a ratio of 2 to 1, a single Equitend® (n = 14) or placebo (n = 8) intralesional injection under ultrasonographic guidance. Horses were evaluated over 4 months, by clinical and ultrasonographic evaluations (day 0, months 1, 2, 4), and their racing performances followed up over the 2 years after treatment. During the first month of treatment, a significant decrease in the cross-sectional area (CSA) was found in the Equitend® group (p = 0.04). After 4 months, the number of Equitend® treated horses with an improved CSA was significantly higher than the placebo-treated horses (p = 0.03571). The Equitend® group returned to their pre-injury performance level, racing in, and winning, significantly more races than the placebo group (p = 0.01399 and 0.0421, respectively). Furthermore, recurrence was significantly higher in the placebo group than in the Equitend® group (71.4% vs 16.6%, p = 0.02442). In conclusion, we measured a significant, short-term, reduction effect on CSA and demonstrated a long-term beneficial effect of intralesional injection of Equitend® for the treatment of superficial digital flexor tendonitis on racing ST, racing 2. 3 times more often than placebo, with 3.3 times fewer recurrences maintaining pre-injury performance level. This study may open the way for the development of a human treatment of tendonitis.

Peripheral neuropathy of a forelimb in horses: 27 cases (2000-2013).

OBJECTIVE To describe the clinical features, diagnostic procedures, management, and outcome of horses with peripheral neuropathy of a forelimb. DESIGN Retrospective case series. ANIMALS 27 horses. PROCEDURES Records from 2000 to 2013 were reviewed to identify horses with peripheral neuropathy of a forelimb. Horses were grouped as having predominant lesions of a suprascapular nerve, axillary nerve, or radial nerve (alone or in association with other brachial plexus nerves) on the basis of physical examination and diagnostic imaging findings. Treatments were primarily conservative. Signalment, history, lameness characteristics, diagnostic imaging features, case management, and outcomes were evaluated. RESULTS Predominant lesions of a suprascapular nerve, axillary nerve, and radial nerve were identified in 11, 2, and 14 horses, respectively. Eight horses with predominant suprascapular nerve injury and 9 with injury to a radial nerve alone or in association with other nerves returned to their previous activity level or intended use after mean recovery periods of 9.3 and 13.3 months, respectively; 2 horses with a predominant axillary nerve injury had this outcome after a mean 3.5-month recovery period. Ultrasonography was useful for evaluation of muscle atrophy and other injuries during the initial examination (in 27 horses) and the rehabilitation period (in 7 horses). CONCLUSIONS AND CLINICAL RELEVANCE Most horses with peripheral neuropathy of a forelimb returned to athletic soundness following an adequate period of rest. Horses with lesions of a radial nerve alone or in association with other nerves typically required longer recovery times than did those with predominant injuries of a suprascapular nerve.

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

OBJECTIVE: To determine history; clinical, radiographic, ultrasonographic, and scintigraphic features; management; and outcome associated with third trochanter fractures in horses. DESIGN: Retrospective case series. ANIMALS: 8 horses. PROCEDURES: 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. RESULTS: 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. CONCLUSIONS AND CLINICAL RELEVANCE: 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.

Exostoses on the palmar or plantar aspect of the diaphysis of the third metacarpal or metatarsal bone in horses: 16 cases (2001-2010).

OBJECTIVE: To characterize the clinical features, diagnostic procedures, treatment, and outcome for horses with an exostosis on the palmar or plantar cortex of the third metacarpal bone (MC3) or third metatarsal bone (MT3). DESIGN: Retrospective case series. ANIMALS: 16 horses. PROCEDURES: Records from 2001 through 2010 were evaluated to identify horses with radiographic and ultrasonographic evidence of an exostosis on an MC3 or MT3. Signalment, history, lameness examination results, diagnostic imaging results, surgical and histopathologic findings, treatment, and outcome were evaluated. RESULTS: 9 horses (group A) had unilateral lameness of the exostosis-affected limb that was alleviated with local or perineural analgesia. Seven horses (group B) had inconsistent lameness of the affected limb. The exostosis was located between the middle and distal third of the MC3 or MT3 in all horses. Desmopathy or peritendinous fibrosis (or both) of the suspensory ligament at the exostosis site was identified in 6 horses. All horses in group A returned to full function after conservative or surgical management. Lameness did not recur in any of the horses in group B despite no treatment or only conservative management. CONCLUSIONS AND CLINICAL RELEVANCE: Exostosis of the palmar cortex of an MC3 or plantar cortex of an MT3 should be considered as a cause of lameness in horses. The diagnosis can be made by the use of radiography and ultrasonography combined with specific diagnostic analgesia. Prognosis for return to athletic activity can be good but should be modified contingent on concurrent desmopathy of the suspensory ligament.

Myocardial fibrosis in a horse with polymorphic ventricular tachycardia observed during general anesthesia.

Ventricular dysrhythmias are more commonly associated with myocardial disease than are supraventricular dysrhythmias. Management of arrhythmias under general anesthesia is difficult because of the dysrhythmogenic effects of the anesthetic drugs. This report describes a severe ventricular dysrhythmia observed in a pony under general anesthesia, with a severe and old myocardial fibrosis found on postmortem examination.

Efficacy of tiludronate in the treatment of horses with signs of pain associated with osteoarthritic lesions of the thoracolumbar vertebral column.

OBJECTIVE: To evaluate the efficacy of tiludronate for the treatment of horses with signs of pain associated with lesions of the thoracolumbar vertebral column. ANIMALS: 29 horses with clinical manifestations of pain associated with lesions of the thoracolumbar vertebral column and abnormal radiographic findings indicative of osteoarthritis of the articular processes-synovial intervertebral joints. PROCEDURES: Horses were initially examined in accordance with a standardized protocol, which included radiographic, ultrasonographic, and scintigraphic examinations. Fifteen horses were randomly assigned to receive tiludronate (1 mg/kg, IV, as a slow-rate infusion), and 14 horses received a control substance (day 0). Horses were monitored for the subsequent 120 days. Clinical evaluations were performed on days 60 and 120. Horses that had no evidence of clinical improvement on day 60 were administered tiludronate. Statistical analyses were performed to compare efficacy at day 60, improvement of dorsal flexibility at day 120, and dorsal flexibility before and 60 days after administration of tiludronate. RESULTS: Horses treated with tiludronate had significant improvement in dorsal flexibility between days 0 and 60, compared with control horses. Clinical improvement in dorsal flexibility was still evident at day 120. The percentage of positive responses was higher in the tiludronate group at 60 days. CONCLUSIONS AND CLINICAL RELEVANCE: Tiludronate had efficacy in the treatment of horses with signs of pain induced by osteoarticular lesions of the thoracolumbar vertebral column, causing a significant improvement in dorsal flexibility. Tiludronate may offer a treatment option for the management of horses with intervertebral lesions and the associated pain.