Poor Performance In Horses Research Articles

Outcomes Following Transcorneal Diode Laser Ablation of Uveal Cysts: 48 Horses (2006-2020)

Uveal cysts can lead to undesirable behaviors and poor performance in horses. Transcorneal laser ablation has been proposed as a safe and effective treatment for uveal cysts suspected of causing behavioral changes but outcomes have been reported in only a small number of horses. In this retrospective study, records were identified for horses who had undergone transcorneal cyst ablation using a diode laser. Information was collected regarding signalment, behavioral or performance issues reported prior to the procedure, and complications. Owners were contacted to provide follow-up information regarding resolution of behavioral issues. Seventy eyes from 48 horses were treated. Undesirable behaviors or performance issues were reported prior to the procedure in 35 horses, and follow-up information was provided for 22 of those horses. Of these 22 horses, 59% of owners reported significant improvements in behavior or performance, 27% reported some improvement, and 14% reported no improvement. No significant complications were reported in association with the procedure. Although follow-up data were available for only a subset of horses, transcorneal diode laser ablation was an effective means of resolving owner-reported behavioral or performance complaints believed to be caused by uveal cysts for many of the horses in this group. Further work is needed to assess effects of uveal cysts on equine behavior and to characterize effects of transcorneal diode laser ablation prospectively.

Implications of the neuroanatomy of the equine thoracolumbar vertebral column with regional anaesthesia and complications following desmotomy of the interspinous ligament.

Impinging/overriding dorsal spinous processes (DSPs) of the thoracolumbar vertebrae are a common cause of poor performance in horses. In the last five decades, numerous surgical treatments have been reported on, from transverse transection of the affected DSPs, and endoscopic resection of the affected DSPs, to transection of the interspinous ligament. Until recently, cosmetic outcomes have been reported as good to excellent in studies. However, a previously unreported complication of neurogenic atrophy of the contralateral epaxial muscle following desmotomy of the interspinous ligament has been recently reported. The authors hypothesised that this was because of a more lateral approach than previously described, resulting in the scissors being too far across midline and transecting a nerve in the region. Considering this finding, we have reviewed the literature on the neuroanatomy of the thoracolumbar region in the horse. Literature on the neuroanatomy of the horse is lacking when compared with that of humans and companion animals, with most of the work extrapolated from companion animals. Based on the current literature, we hypothesise that transection of an intermediate branch of the dorsal spinal nerve supplying the m. longissimus is potentially the cause of the post-operative neurogenic atrophy. The lack of detailed knowledge of the neural anatomy of the equine back has resulted in the role of local anaesthesia in localising pain in the equine back being poorly understood. The wide variation in techniques used for localising back pain may explain why some horses suffering from poor performance or an abnormal gait because of back pain improve to local anaesthesia of the back while others do not. This review article highlights a lack of anatomical knowledge regarding the equine thoracolumbar region in the literature despite diagnostic local anaesthesia, medication, and surgery in this area being relatively common.

An investigation into the occurrence of, and risk factors for, concurrent suspensory ligament injuries in horses with hindlimb proximal suspensory desmopathy

SummaryHindlimb proximal suspensory desmopathy (PSD) is a common cause of lameness or poor performance in horses and may occur alone or together with other suspensory ligament (SL) injuries in forelimbs or hindlimbs. The aims of this retrospective case‐control study (January 2009 to December 2018) were to describe the occurrence of, and identify risk factors for, concurrent SL injuries in horses with hindlimb PSD. Data concerning age, breed, sex, work discipline, height, bodyweight and work history were collected. Concurrent SL injuries were defined as forelimb proximal suspensory desmitis or SL branch injuries (≥grade 2 [0–3]) in any limb. Hindlimb PSD was graded mild, moderate or severe based on ultrasonography. Data were described, and multivariable logistic regression modelling was used to identify factors associated with concurrent SL injuries. Data were available for 923 horses with hindlimb PSD, 28.6% (n = 264) of which had concurrent SL injuries. Age category (≤5 years of age vs. ≥6 years of age; P = 0.008), bodyweight:height ratio (P = 0.001), breed (P = 0.05), symmetry vs. asymmetry of hindlimb PSD ultrasonography grade (P = 0.005) and asymmetry vs. symmetry of lameness grade (P = 0.02) were associated with concurrent SL injury in horses with hindlimb PSD. Compared with horses aged ≥ 6 years, younger horses (odds ratio [OR] 1.76; 95% confidence interval [CI] 1.2–2.7) were more likely to have concurrent SL injury. The risk for concurrent SL injuries increased for every unit increase in bodyweight:height ratio (OR 2.27; CI 1.4–3.7). Compared with Thoroughbred crosses, Warmblood crosses (OR 3.3, CI 1.4–7.8), Thoroughbreds (OR 2.9, CI 1.1–7.1) and Irish Draught Horses (OR 3.5, CI 1.3–9.9) were more likely to have concurrent SL injuries. Hindlimb PSD ultrasonography grade severity was not associated with concurrent SL injury. In conclusion, age, bodyweight:height ratio and breed influenced the risk for concurrent lesions of the SL ligament. Further prospective studies in young horses are warranted.

The occurrence of dynamic structural disorders in the pharynx and larynx, at rest and during exercise, in horses diagnosed with mild and moderate Equine Asthma (Inflammatory Airway Disease).

horses with diagnosed EA frequently have disorders of the pharynx during treadmill exercise tests, while without EA, often have disorders of the larynx. Endoscopy of upper airways during exercise testing is a valuable tool in the diagnosis of poor performance in horses with lower airway inflammatory disease.

The heart remains the core: cardiac causes of poor performance in horses compared to human athletes

Cardiac remodelling occurs in response to exercise and is generally beneficial for athletic performance due to the increase in cardiac output. However, this remodelling also may lead to an increased prevalence of cardiac murmurs and arrhythmias. In most cases, these are not considered to be significant. However, in some cases, there may be potentially deleterious consequences. Whilst sudden cardiac death (SCD) is a rare occurrence, the consequences are catastrophic for both the horse and potentially the rider or driver. Furthermore, the sudden death of a horse in the public arena has negative connotations in regards to public perception of welfare during equestrian sports. Prediction of which individuals might be susceptible to potential deleterious effects of exercise is a focus of interest in both human and equine athletes but remains a challenge because many athletes experience cardiac murmurs and exercise-induced arrhythmias that are clinically irrelevant. This review summarises the effects of exercise on cardiac remodelling in the horse and the potential effects on athletic performance and SCD. The use of biomarkers and their future potential in the management of athletic horses is also reviewed.

Can the presence of musculoskeletal pain be determined from the facial expressions of ridden horses (FEReq)?

Abstract Poor performance in horses is often attributed to rider or training problems or behavioral abnormalities. Riders often fail to recognize lameness. We need to determine if there are differences in facial expression in lame and nonlame horses when ridden, which may facilitate the identification of horses experiencing pain. A previously developed facial expression specific for ridden horses ethogram was applied blindly by a trained analyst to photographs (n = 519) of the head and neck of lame (n = 76) and nonlame (n = 25) horses acquired during ridden schooling-type work at both trot and canter. These included images of 7 lame horses acquired before (n = 30 photographs) and after diagnostic analgesia had abolished lameness (n = 22 photographs). A pain score (0-3; 0 = normal, 1-3 = abnormal) was applied to each feature in the ethogram, based on published descriptions of pain in horses. Pain scores were higher for lame horses than nonlame horses ( P P P P

Epiduroscopy of the lumbosacral vertebral canal in the horse: Technique and endoscopic anatomy.

Back pain is a common cause of gait alterations and poor performance in horses, but the available imaging modalities are frequently insufficient to isolate the underlying pathology. In human patients, epidural endoscopy (epiduroscopy) is successfully used to diagnose and treat challenging cases of lower back pain. Endoscopy of the cervical epidural space has previously been reported in anaesthetised horses. To develop a technique for lumbosacral epiduroscopy in standing horses and to describe the endoscopic anatomy of the lumbosacral epidural space. Pilot study to assess the feasibility of lumbosacral epiduroscopy in 5 horse cadavers. The cadavers of 5 horses, weighing 457-694kg (mean, 570kg), were suspended in an upright position. Vascular dilators of increasing size were inserted between the first 2 moveable vertebrae caudal to the sacrum to create a minimally invasive approach into the epidural space. A flexible videoendoscope was introduced and advanced as far cranially as the length of the endoscope permitted. The lumbosacral epidural space underwent gross necropsy examination following the procedure. The endoscope was successfully inserted into the epidural space in all horses. Saline injection through the working channel of the endoscope allowed the following anatomical structures to be seen: dura mater, left and right lumbosacral spinal nerves, cauda equina, epidural fat, connective tissue and blood vessels. Using the 60cm working length of the endoscope, the epidural space could be examined as far cranial as L3-T18, depending on the size of the horse. No gross damage to epidural neurovascular structures was observed on necropsy examination. Lumbosacral epiduroscopy is technically feasible in standing horses and may become a valuable diagnostic tool in horses with caudal back or limb pain of unknown origin. Studies in live horses will be necessary to evaluate the safety of the procedure.

A longitudinal study of poor performance and subclinical respiratory viral activity in Standardbred trotters

IntroductionWhile clinical respiratory disease is considered a main cause of poor performance in horses, the role of subclinical respiratory virus infections is less clear and needs further investigation.Aims and objectivesIn...

Sacroiliac Joint Morphology: Influence of Age, Bodyweight and Previous Back Pain

IntroductionDegenerative changes in sacroiliac joints (SIJ) are reported to cause poor performance in horses. The aim of this study was to document the frequency and nature of changes in SIJ surfaces of Thoroughbred (TB) racehorses and to correlate gross morphology and marginal new bone formation to age, body weight and history of back pain.MethodsSIJ surfaces from 37 deceased TBs retired from the Hong Kong Jockey Club were photographed and measurements taken to facilitate subjective and objective analysis of gross changes. SIJ surfaces were described, and the surface area of the joint surfaces determined from the photographs, using Image J. Area and shape of the joint surfaces were recorded and SIJs were graded and allocated a type according to pre‐determined criteria. Changes were compared for horses with and without clinical records of back pain.ResultsMean age was 6.6 ± 2.3 years; weight 494 ± 35 kg; with no differences between horses with (n = 14) and without (n = 23) a history of back pain. There was no relationship between bodyweight (r = 0.08) or age (r = 0.13) and SIJ surface area. SIJs of the back pain group were affected by obvious gross pathology that showed certain characteristics. There was a relationship between surface area of joint and degree of marginal bone formation (P<0.001). SIJs from the group of TBs with no back pain had fewer and less obvious gross findings.ConclusionsClinical evidence of back pain, which may reasonably be expected to have affected the horse's racing performance, was associated with characteristic gross pathology of the SIJ.Ethical Animal ResearchEthical approval for animal use was obtained by the institutional animal ethics committee (University of Queensland) and Hong Kong ethics committee. The study was performed on material collected during post‐mortem examination. Explicit owner informed consent for participation in this study is not stated. Sources of funding: Rural Industries Research and Development Council, Australia. Competing interests: none.

Regenerative Medicine Approach to Reconstruction of the Equine Upper Airway

Airway obstruction is a common cause of poor performance in horses. Structural abnormalities (insufficient length, rigidity) can be a cause for the obstruction. Currently, there are a few effective clinical options for reconstruction of the equine larynx. A regenerative medicine approach to reconstruction may provide the capability to stabilize laryngeal structures and to encourage restoration of site-appropriate, functional, and host-derived tissue. The purpose of this study was the histopathological evaluation of (1) decellularization of equine (horse) laryngeal cartilages (epiglottis and arytenoids); (2) the host response to decellularized laryngeal cartilages implanted subcutaneously in a donkey model as a test of biocompatibility; and (3) the use of decellularized laryngeal cartilages in a clinically relevant pilot study in the horse larynx. Equine laryngeal cartilages were found to be sufficiently decellularized and were subsequently implanted subcutaneously in donkeys to test biocompatibility. After 4 weeks, the implanted cartilage was harvested. In the subcutaneous model, the samples did not elicit a rejection or foreign body type reaction and were judged suitable for implantation in a clinically relevant equine model. Implants were placed in the upper airway (arytenoids and epiglottis) of one horse. At 4 weeks, the implants were observed to remodel rapidly and were replaced by dense connective tissue with signs of new hyaline cartilage formation in the arytenoids and by connective tissue containing glandular structures and an epithelial covering in the epiglottis. The results of the present study demonstrate the feasibility of a scaffold-based regenerative medicine approach to reconstruction of the equine upper airway; however, further studies investigating long-term integration, formation of new cartilage, and mechanical properties are needed.

FEASIBILITY FOR MAPPING CARTILAGE T1 RELAXATION TIMES IN THE DISTAL METACARPUS3/METATARSUS3 OF THOROUGHBRED RACEHORSES USING DELAYED GADOLINIUM‐ENHANCED MAGNETIC RESONANCE IMAGING OF CARTILAGE (dGEMRIC): NORMAL CADAVER STUDY

Osteoarthritis of the metacarpo/metatarsophalangeal joints is one of the major causes of poor performance in horses. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) may be a useful technique for noninvasively quantifying articular cartilage damage in horses. The purpose of this study was to describe dGEMRIC characteristics of the distal metacarpus3/metatarsus3 (Mc3/Mt3) articular cartilage in 20 cadaver specimens collected from normal Thoroughbred horses. For each specimen, T1 relaxation time was measured from scans acquired precontrast and at 30, 60, 120, and 180 min post intraarticular injection of Gd-DTPA(2-) (dGEMRIC series). For each scan, T1 relaxation times were calculated using five regions of interest (sites 1-5) in the cartilage. For all sites, a significant decrease in T1 relaxation times occurred between precontrast scans and 30, 60, 120, and 180 min scans of the dGEMRIC series (P < 0.0001). A significant increase in T1 relaxation times occurred between 60 and 180 min and between 120 and 180 min post Gd injection for all sites. For sites 1-4, a significant increase in T1 relaxation time occurred between 30 and 180 min postinjection (P < 0.05). Sites 1-5 differed significantly among one another for all times (P < 0.0001). Findings from this cadaver study indicated that dGEMRIC using intraarticular Gd-DTPA(2-) is a feasible technique for measuring and mapping changes in T1 relaxation times in equine metacarpo/metatarsophalangeal joint cartilage. Optimal times for postcontrast scans were 60-120 min. Future studies are needed to determine whether these findings are reproducible in live horses.

The horse–saddle–rider interaction

Common causes of poor performance in horses include factors related to the horse, the rider and/or the saddle, and their interrelationships remain challenging to determine. Horse-related factors (such as thoracolumbar region pain and/or lameness), rider-related factors (such as crookedness, inability to ride in rhythm with the horse, inability to work the horse in a correct frame to improve core strength and muscular support of the thoracolumbar spine of the horse), and saddle-related factors (such as poor fit causing focal areas of increased pressure) may all contribute to poor performance to varying degrees. Knowledge of the horse-saddle-rider interaction is limited. Traditionally, saddle fit has been evaluated in standing horses, but it is now possible to measure the force and pressure at the interface between the saddle and the horse dynamically. The purpose of this review is critically to discuss available evidence of the interaction between the horse, the rider and the saddle, highlighting not only what is known, but also what is not known.

Neuroendocrine and non‐neuroendocrine markers of inflammation associated with performance in endurance horses

The inflammatory and neuroendocrine response to endurance exercise and relationship of these parameters to performance is not well documented in horses. HYPOTHESES OR OBJECTIVES: Evidence of systemic inflammation is associated with poor performance in horses competing in endurance events. Blood was collected prior to and at the finish or elimination point from horses competing in both the 80 and 160 km American Endurance Ride National Championship competitions in 2006. Immunoreactive alpha-melanocyte stimulating hormone (α-MSH) and tumour necrosis factor-alpha (TNF-α) were quantified utilising radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) techniques, respectively. The concentration of total thiobarbituric acid reactive substances (TBARS) was measured fluorometrically. Thirty horses were included in the study. Endurance exercise was associated with a significant increase in TBARS in the 80 km group but not the 160 km group. TNF-α and α-MSH did not significantly change as a result of exercise in either distance group. Precompetition TBARS was significantly higher in horses that failed to finish the 80 km race, as well as when distances were combined. In addition, precompetition α-MSH was significantly lower in nonfinishers in the 160 km group. Furthermore, competition speed was positively correlated with precompetition α-MSH in the 80 km and negatively correlated with precompetition TNF-α when distances were combined. Our results suggest that basal oxidative stress markers, circulating cytokines and anti-inflammatory neuroendocrine hormones appear to correlate with endurance performance in horses. Basal oxidative stress markers, circulating cytokines and anti-inflammatory neuroendocrine hormones may be predictive of athletic performance in endurance horses. Future studies evaluating the effect of training on these markers in endurance horses are warranted.

Dynamic respiratory endoscopy without a treadmill: Initial experiences

SummaryThere are potential advantages to imaging the upper portion of the respiratory tract (URT) of horses during ridden exercise within their normal environment. With the advent of a wireless endoscope, this is now possible. The following article describes initial experiences using the dynamic respiratory endoscope (DRS) on horses presented for the investigation of poor performance or abnormal respiratory noise and suggests that this technique can be used to diagnose common causes of URT associated with poor performance in horses during normal training. This has substantial implications for future clinical diagnosis, treatment of URT pathology and equine welfare.

Foot pain - a common cause of poor performance in horses

Foot pain - a common cause of poor performance in horses

Dynamic respiratory endoscopy in 67 Thoroughbred racehorses training under normal ridden exercise conditions

There are potential advantages to imaging the upper portion of the respiratory tract (URT) of horses during ridden exercise. With the advent of a wireless endoscope, this is now possible. However, there has been no detailed validation of the technique and findings have not been compared to ridden speed. To assess the combined use of a Dynamic Respiratory Scope (DRS) and global positioning system (GPS) receiver for examining the URT of a group of Thoroughbred racehorses randomly selected from a single flat racehorse training establishment. Horses were selected randomly from a population of Thoroughbred horses in training at the same training yard. Endoscopic images of the URT were recorded during a ridden exercise test on an 'all-weather-gallop' and were reviewed post testing. Speed was measured using a wrist mounted GPS receiver. A total of 67 (34%) of the 195 horses in training were examined. Endoscopic findings included: normal URT function (44 cases); dorsal displacement of the soft palate (DDSP) (13 cases); laryngeal asymmetry (4 cases); and axial deviation of the aryepiglottic folds (3 cases). Maximum speed obtained by individual horses ranged from 41.8-56.3 km/h. Ridden speed was variably affected by DDSP. The DRS provides a safe effective system for imaging the equine URT during ridden exercise at speed. The abnormalities of the URT identified were similar to those observed during treadmill endoscopy studies reported in the literature. The effect of URT abnormalities on ridden speed requires further investigation. This technique can be used to diagnose common causes of URT associated with poor performance in horses during normal training. This has substantial implications for future clinical diagnosis and treatment of URT pathology.

Osteoarthritis of the thoracolumbar synovial intervertebral articulations: Clinical and radiographic features in 77 horses with poor performance and back pain

Back pain is well recognised as a cause of poor performance in horses, but the role of lesions of the thoracolumbar synovial intervertebral articulations (facet joints) has not been well documented. To describe the clinical features, radiographic appearance and location of facet joint lesions and determine if there was any breed, gender, age, bodyweight or work discipline predilection. Data from 77 horses examined at the Animal Health Trust January 1997-September 2007 with evidence of thoracolumbar pain and radiographic changes of the facet joints were reviewed. The presence of either other osseous abnormalities of the thoracolumbar region or other problems potentially contributing to poor performance were recorded. Facet joint lesions were graded radiographically and their location determined. Influence of breed, gender and discipline on the presence of lesions, effect of location on the type of lesion and the influence of impinging dorsal spinous processes on the clinical features were assessed using Chi-squared tests. There was no effect of breed, gender, age or bodyweight on occurrence of facet joint lesions. Showjumpers were significantly less affected than horses from other disciplines. There were commonly 2-5 affected facet joints, usually in the caudal thoracic and cranial lumbar spine (T15-LI). Sclerosis, periarticular new bone and narrowing of the joint space were the most frequent radiographic lesion types. Clinical features were significantly different between horses with and without impinging dorsal spinous processes. Severity of clinical signs was related to the presence of other osseous abnormalities, not the number of facet joints involved or the lesion grade. Osteoarthritis of the facet joints of the thoracolumbar spine can occur alone, in horses with back pain, or in association with other osseous abnormalities. Osteoarthritis of the thoracolumbar facet joints probably contributes to back pain, but further investigation of the prevalence of osteoarthritis in horses without clinical signs of back pain is merited.

Clinical trials using a telemetric endoscope for use during over‐ground exercise: A preliminary study

Dynamic collapse of the upper respiratory tract (URT) is a common cause of poor performance in horses. These conditions occur predominantly during strenuous exercise when the URT is unable to maintain dilation in the face of high inspiratory pressures. In most cases, these disorders cannot be accurately diagnosed during a resting endoscopic examination. To date, a definitive diagnosis of dynamic URT obstructions has been possible only by performing an endoscopic examination during high-speed treadmill exercise. However, recent technological advances now enable URT endoscopy to be performed while the horse is exercising in its normal environment.

Analysis of Canadian and Irish forage, oats and commercially available equine concentrate feed for pathogenic fungi and mycotoxins

Respiratory infections, recurrent airway obstruction (RAO) and exercise induced pulmonary haemorrhage (EIPH) are major causes of poor performance in horses. Fungi and mycotoxins are now recognised as a major cause of these conditions. The most notable fungi are Aspergillus and Fusarium. Fungal spores can originate from forage, bedding and feed and, in turn, these fungal spores can produce a series of mycotoxins as secondary metabolites.This study set out to ascertain the degree of fungal and mycotoxin contamination in feed and fodder used in Irish racing yards over a one-year period. Weather conditions in forage producing areas were sampled by Met Eireann and the Canadian Meteorological Service.Fifty per cent of Irish hay, 37% of haylage and 13% of Canadian hay contained pathogenic fungi. Of the mycotoxins, T2 and zearalenone were most prominent. Twenty-one per cent of Irish hay and 16% of pelleted feed contained zearalenone. Forty per cent of oats and 54% of pelleted feed contained T2 toxins.

Laboratory investigation of poor performance in horses: Part 2 Investigation of respiratory disease

Laboratory investigation of poor performance in horses: Part 2 Investigation of respiratory disease