A microbiome analysis of equine peripheral dental caries using next generation sequencing.

BACKGROUND: Although, peripheral caries (PC) affects almost half of UK horses, no comprehensive microbiological study has been performed on this disorder. As a high proportion of oral bacteria cannot be conventionally cultured, molecular microbiological techniques such as Next Generation Sequencing are required to examine the complex oral bacteria community. OBJECTIVES: To identify the microbiota involved in equine PC, including comparing microbiota at the more commonly and severely affected three caudal cheek teeth with the less commonly affected three rostral cheek teeth. STUDY DESIGN AND METHODS: Equine dental plaque samples were collected from the palatal aspects of cheek teeth of 63 horses. DNA was isolated and amplified using PCR, targeting the V4 region of the 16S rRNA gene and Next Generation Sequencing of these gene amplicons was performed. The acquired data were processed and analysed using Mothur and R. RESULTS: Streptococcus species was the genus most commonly associated with equine PC, whereas Gemella species was the genus most associated with the control group. In a further analysis where the rostral and caudal cheek teeth were compared with each other and with the control group. Veillonella species was the most commonly associated genus with PC of the rostral cheek teeth, Streptococcus species was the most associated genus with the caudal cheek teeth, and Corynebacterium with the control group. MAIN LIMITATIONS: Some bacteria can have multiple heterogeneous copies of the 16S rRNA gene, which can affect the estimation of their relative abundance. CONCLUSIONS: Similar to caries studies in other species, acidogenic and aciduric microorganisms including Streptococcus species were found to be associated with equine peripheral caries.

Evaluation of ex vivo restoration of carious equine maxillary cheek teeth infundibulae following debridement with dental drills and Hedstrom files.

An ex-vivo study was performed on vertically mounted equine maxillary cheek teeth that had caries of 30 infundibulae, using high and low speed contra-angle dental drills and Hedstrom files to debride infundibular food debris and carious dental tissues. This technique effectively debrided 27/30 infundibulae with a mean depth of 19mm (range 9.4-34.3mm) as assessed by computed tomographic (CT) imaging. The debrided infundibulae were treated with sodium hypochlorite, EDTA and a bonding agent, and then then filled in layers with endodontic restoration materials. Further CT imaging and direct examination of sectioned restored teeth showed 6/30 infundibulae, including three that were incompletely debrided, to have defects between the restoration and the infundibular wall/apex. Twenty-one of the remaining 24 infundibulae contained air bubbles, largely within restorations. It is concluded that the use of drills and Hedstrom files is effective in debriding carious infundibulae but improved techniques and materials are required to more effectively fill infundibulae with restorative material.

Heritability and prevalence of selected osteochondrosis lesions in yearling Thoroughbred horses.

BACKGROUND: Osteochondrosis is considered multifactorial in origin, with factors such as nutrition, conformation, body size, trauma and genetics thought to contribute to its pathogenesis. Few studies have investigated the effects of genetic variability of osteochondrosis in Thoroughbreds. OBJECTIVES: To describe the prevalence and genetic variability of a subset of osteochondrosis lesions in a group of Thoroughbred yearlings. STUDY DESIGN: Retrospective cohort study. METHODS: Radiographs of 1962 Thoroughbred yearlings were retrieved from clinical records obtained between 2005 and 2013. Pedigree information was obtained from the Australian Stud Book. Osteochondrosis lesions were documented in selected joints and estimates of heritability were obtained by fitting linear mixed models in ASREML software. RESULTS: The overall prevalence of osteochondrosis was 23%. Osteochondrosis was identified in 10% of stifle joints, 6% of hock joints and 8% of fetlock joints. The heritability estimates ranged from 0 to 0.21. The largest estimates were 0.10, 0.14, 0.16 and 0.21 for lesions of the distal intermediate ridge of the tibia, dorso-proximal proximal phalanx (P1), any stifle osteochondrosis, and lesions of the lateral trochlear ridge of the distal femur, respectively. Although calculated heritability estimates had high standard errors, meta-analyses combining the present results with published estimates were significant at 0.10, 0.17, 0.15 and 0.20 for stifle, tarsal, fetlock and these joints combined, respectively. In addition, there was a permanent environment attributable to the dam effect. MAIN LIMITATIONS: Inclusion criteria were based on radiographic findings in specific joints at a specific age range in Thoroughbreds. CONCLUSIONS: The present results indicate that only a proportion of osteochondrosis in Thoroughbreds is heritable. The permanent environment effects of the dam were observed to have effects on some categories of osteochondrosis.

Neurodegeneration in equine grass sickness is not attributable to niacin deficiency.

BACKGROUND: The aetiology of equine grass sickness (EGS) is currently unknown. We hypothesised that an acute deficiency of niacin (vitamin B3), which plays a key role in neural homeostasis, may contribute to neurodegeneration in EGS. Niacin deficiency can potentially result from ingestion of niacin antagonists produced by pasture mycotoxigenic fungi. OBJECTIVES: To compare the niacin status of EGS and control grazing horses. A secondary objective was to compare blood concentrations of vitamins B1, B2 and B6 in EGS and control grazing horses to determine if the status of these vitamins was altered in EGS. STUDY DESIGN: Case-control study. METHODS: Indices of niacin status, namely the erythrocyte nicotinamide adenine dinucleotide:nicotinamide adenine dinucleotide phosphate ratio (NAD:NADP ratio) and erythrocyte concentrations of NAD and NADP, were compared in blood collected from EGS and healthy control grazing horses. Blood concentrations of vitamins B1, B2 and B6 were also compared. RESULTS: There was no significant intergroup difference in the NAD:NADP ratio, the main index of functional niacin status (control group: median 2.1, interquartile range [IQR] 1.8-2.6; EGS group: median 2.1, IQR 1.9-2.6). EGS horses had significantly higher (median value increased by 25%) concentrations of NADP. There were no intergroup differences in blood concentrations of vitamins B1, B2 and B6. MAIN LIMITATIONS: The interpretation of data was limited by the lack of previously defined equine reference ranges for many of the analytes. Sample size was low. CONCLUSIONS: Niacin deficiency does not contribute to EGS neurodegeneration.

An epidemiological survey on the prevalence of equine peripheral dental caries in the United Kingdom and possible risk factors for its development.

BACKGROUND: Equine peripheral caries (PC) is an increasingly recognised disorder that causes premature wear of teeth and dental fractures and thus has major welfare implications. Little information is available on its prevalence or severity in UK horses and there are no proven associations with any risk factors. OBJECTIVES: To document the prevalence of PC over a wide area of the UK, assess its intraoral distribution and severity in affected horses and examine for potential risk factors for its development. STUDY DESIGN: Cross sectional study. METHODS: Experienced personnel were recruited for a UK wide dental survey on their patients during dental examinations. Established guidelines were used for grading PC. Frequency of PC occurrence was compared between teeth and dental arcades using McNemar's tests. Potential risk factors for PC were screened using univariable logistic regression prior to building a multivariable model. RESULTS: A total of 706 horses were examined by 25 participants, showing a 51.7% prevalence of PC (365/706). Some regional differences in prevalence were found. The PC primarily affected the cheek teeth with the 12 caudal being significantly more commonly affected than the 12 rostral cheek teeth. Most of the hypothesised risk factors including age, breed, sex, time at pasture and feeding of silage (haylage) were unproven. A limited association with moderate levels of concentrate feeding was observed. The presence of concurrent dental abnormalities were significantly associated with the likelihood of having PC. MAIN LIMITATIONS: Not all regions in UK were included and there may be inconsistencies between examiners. CONCLUSIONS: Peripheral caries is common in British horses, primarily affecting the caudal cheek teeth. There was limited evidence of an association between feeding and PC. The association between PC and concurrent dental disorders indicates that these should be addressed in affected horses.

Orthodontic correction of overjet/overbite ('parrot mouth') in 73 foals (1999-2013).

REASONS FOR PERFORMING STUDY: There are limited reports on the efficacy of functional orthodontic correction of overjet or overbite in foals. OBJECTIVES: To report the outcome of using orthodontic tension bands in combination with an inclined plane biteplate in the treatment of overjet, with or without concurrent overbite, rates of correction of these 2 malocclusions and associated complications. And to examine factors associated with outcomes. STUDY DESIGN: Retrospective case series. METHODS: Clinical records for 73 foals treated at a single clinic, by the same surgeon were analysed. Overall change and rates of change in overjet and overbite were calculated. Associations between potential explanatory variables including age, severity of initial malocclusion and surgeon experience were examined using linear regression. RESULTS: Records for 73 foals (43 colts, 30 fillies) were evaluated. The median number of implant placements per animal was 2 (range 1-4). Of 61 cases with complete records, reduction in overjet and overbite dimensions were achieved in 95% and 90% of foals, respectively, with mean reductions in malocclusions of 9.9 and 8.4 mm, respectively. Complete reduction in overjet was achieved in 25% (15/61) and reduction of malocclusion dimensions to ≤5 mm (i.e. functionally corrected) was achieved in 51% (31/61). Increasing animal age was significantly associated with decreased total reduction in overjet and decreased rate of reduction in overbite. Increased original severity of overbite was significantly associated with increased rate of its correction. Short-term complications included intraoperative haemorrhage, transient facial nerve neuropraxia and irritation of the mare's udder by the brace. Longer-term complications included cheek teeth diastema formation and incisor discoloration and maleruption. CONCLUSIONS: Using this technique, correction or improvement of these malocclusions is rapid, with minimal complications. Often more than one implant is required. Animal age at the start of treatment is associated with rate and amount of correction achievable, so initiating treatment at an early age is recommended.

Anatomical and histological study of the dorsal and ventral nasal conchal bullae in normal horses.

The morphology of the dorsal conchal bulla (DCB) and ventral conchal bulla (VCB) are poorly described. The recent recognition that these bullae can become infected, causing chronic unilateral nasal discharge, has stimulated interest in these structures. Fourteen cadaveric horse heads were transected sagittally midline and dissected to expose the nasal conchal bullae. The dimensions of each bulla, the number and orientation of drainage apertures, and cellulae septae were recorded. Randomly selected samples were examined histologically. The mean DCB and VCB lengths were 78  and 57 mm, respectively; equivalent to 13.9 per cent and 10.2 per cent of skull length, respectively. The mean DCB and VCB heights were 29  and 28 mm, respectively; equivalent to 5.2 per cent and 5 per cent of skull length, respectively. The DCB was larger than the VCB, containing more septae, cellulae and drainage apertures. No communications were identified between the bullae and the immediately adjacent paranasal sinuses. Histology revealed that the bullae consist of ciliated, pseudostratified, columnar epithelium over glandular submucosa often overlying turbinate bone and, variably, hyaline cartilage. This more detailed description of equine DCB and VCB anatomy will hopefully facilitate successful treatment of their disorders.

Clinical Research Abstracts of the British Equine Veterinary Association Congress 2015.

REASONS FOR PERFORMING STUDY: The morphology of the dorsal (DCB) and ventral (VCB) nasal conchal bullae, including their cellulae, drainage and histology, are poorly described. The recent recognition that these bullae can become infected, causing chronic unilateral nasal discharge has stimulated interest in these structures. A more complete understanding of their anatomy would be useful in the diagnosis and treatment of their disorders. OBJECTIVES: To document the structure, drainage and histology of the equine DCB and VCB. STUDY DESIGN: Descriptive. METHODS: Fourteen fresh cadaveric horse heads, were transected sagittally midline and dissected to expose the nasal conchal bullae. The dimensions of each bulla, the number of drainage apertures, the number of cellulae and orientation of the septae were recorded. Representative samples were collected for histopathology. RESULTS: The mean lengths of the DCB and VCB were 77.7 mm (range 48-105 mm) and 57.1 mm (range 34-86 mm) respectively; equivalent to 13.8% and 10.2% of skull length, respectively. The mean widths of the DCB and VCB were 28.5 mm (range 21-35 mm) and 28.2 mm (range 13-41 mm) respectively; equivalent to 5.1% and 5% of skull length respectively. The median number of drainage apertures from the DCB and VCB were 2 and 1 respectively. The median number of cellulae within the DCB and VCB were 3 and 2, respectively. No communications were identified between the DCB and VCB and the adjacent paranasal sinuses. Histology revealed that the bullae consisted of ciliated, pseudostratified, columnar epithelium supported by a glandular submucosa often overlying turbinate bone and, variably, hyaline cartilage. CONCLUSIONS: The morphology of the equine nasal conchal bullae is quite variable. The DCB is generally a more complex structure than the VCB, containing more septae, cellulae and drainage apertures. This more detailed description of DCB and VCB anatomy will hopefully facilitate successful treatment of their disorders. Ethical animal research: Research ethics committee oversight not currently required by this conference: the study was performed on material obtained from an abattoir. SOURCE OF FUNDING: None. Competing interests: None declared.

Empyema of the nasal conchal bulla as a cause of chronic unilateral nasal discharge in the horse: 10 cases (2013-2014).

REASONS FOR PERFORMING STUDY: Empyema of the nasal conchal bullae has recently been identified in horses suffering from chronic unilateral nasal discharge. The diagnosis and management of such cases has not been reported previously. OBJECTIVES: To describe the diagnosis and treatment of cases suffering from empyema of the nasal conchal bullae and report the frequency of diagnosis from a population of horses referred for head computed tomography (CT). STUDY DESIGN: Retrospective case review. METHODS: Records from cases diagnosed with nasal conchal bulla disease using CT were reviewed. RESULTS: Abnormalities of the nasal conchal bullae were identified by CT in 10 cases (8 ventral conchal bulla, 2 dorsal conchal bulla), from 102 equine head CT examinations. Eight cases were subsequently treated at the study clinic, 7 of which had concurrent paranasal sinus disease. In 3 cases, fenestration of the ventral conchal bulla per nasum facilitated drainage and clearance of empyema. CONCLUSIONS: Disease of the conchal bullae should be considered as a potential cause of chronic unilateral nasal discharge in horses. Clearance of empyema within these bullae is unlikely to occur through lavage of the paranasal sinuses alone. Where necessary, fenestration of the bulla allows physical removal of infected material.

Critical evaluation of ex vivo restoration of carious equine maxillary cheek teeth infundibulae following high-pressure gas and micro-particle abrasion.

Infundibular caries of the equine maxillary cheek teeth is an important disorder that can lead to dental fracture or apical infection. Treatment by removing food debris and carious dental tissue from affected infundibulae using high-pressure abrasion with aluminium hydroxide micro-particles, followed by filling the cleaned defect with endodontic restorative materials is a recommended treatment. However, although anecdotally considered a successful treatment option, there is currently no objective evidence to support this claim. Forty maxillary cheek teeth (CT) that contained 55 infundibulae with caries (mainly grade 2) were extracted post-mortem from 21 adult horses. Five of the CT were sectioned prior to treatment to facilitate visual examination of the carious infundibulae. The remaining carious infundibulae were cleaned using high-pressure abrasion with aluminium hydroxide particles and five CT were sectioned to assess the efficacy of this cleaning process. The remaining 30 CT containing 39 carious infundibulae were then filled with a composite restorative material. The efficacy of this restoration was assessed by computed tomography imaging followed by direct visual examination after sectioning the teeth. Only 46% (18/39) of restored infundibulae, all with shallow (mean 9.6 mm deep) defects, were fully cleaned of food debris and carious material, and filled with restorative material to their full depth. Of these 18, 11 had peripheral defects around the restoration, leaving just 18% (7/39) of restorations without any gross defects. The remaining 54% (21/39) of infundibulae (mean depth of infundibular caries defect, 18.3 mm) still contained food debris and/or carious material in more apical locations, with infundibulae with the deepest caries defects being the least effectively cleaned. The findings of this study indicate that high-pressure micro-particle abrasion is only effective in cleaning food debris from shallow, carious CT infundibulae and consequently, the majority of subsequent infundibular restorations are imperfect.

Accuracy of distal limb fracture diagnosis at British racecourses 1999-2005.

Accurate diagnosis of racing injuries can be difficult. The objectives of this study were to describe the postmortem (PM) defined distribution of fatal distal limb fractures (DLF) affecting Thoroughbreds racing in Great Britain between February 1999 and August 2005 and then assess the accuracy of veterinary racecourse diagnoses and examine whether these improved following introduction of a computerised recording system. PM examinations were performed on limbs distal to radius or tibia from all cases of fatal DLF occurring on British racecourses during the study period. Results of these examinations were described and compared with the diagnoses made at the racecourses. Over the study period, fatal DLF prevalence in all race types was 0.63 per 1000 starts (344/545,335), with the lowest frequency (0.34 per 1000 starts) in flat racing on turf and the highest frequency (1.56 per 1000 starts) in national hunt flat races. The prevalence of fatal DLF in steeplechase racing had reduced from that reported previously: from 2.3 to 1 per 1000 starts. Racecourse veterinary identification of fracture presence was good (>93 per cent); however, identification of all fractured bones was poor (<55 per cent). Introduction of a computerised recording system did not significantly improve diagnostic accuracy. The prevalence of fatal DLF has not significantly altered since the 1970s. Techniques such as on course digital radiography to help improve racecourse fracture diagnoses could be introduced.

Deep digital flexor tendon injury within the hoof capsule; does lesion type or location predict prognosis?

The type and location of deep digital flexor tendon (DDFT) lesions may be important in predicting outcome. The objectives of this study were to determine the frequency of different types of DDFT lesions within the hoof capsule and to determine whether lesion type predicts return to athletic activity. Lesions of the DDFT were divided into: core lesions, dorsal border lesions and parasagittal splits. Lesion location was documented, and follow-up information was obtained by telephone survey at least 18 months after diagnosis. Of 168 horses with primary DDFT injury, 54 horses had dorsal border lesions, 59 had parasagittal splits and 55 had core lesions. Twenty-five per cent of all horses returned to previous levels of athletic activity within 18 months of MRI evaluation. Horses with complete splits or core lesions of the DDFT were significantly less likely to return to some level of athletic activity than horses with dorsal border lesions P<0.001. Dorsal border lesions of the DDFT appear to have a better prognosis than core lesions or parasagittal splits. This study provides additional information that may help clinicians predict the prognosis for different types of DDFT injury.

Dynamic ventrorostral displacement of the dorsal laryngeal mucosa in horses.

The objectives of this report were to describe the occurrence and features of dynamic ventrorostral displacement of the dorsal laryngeal mucosa (VRDDLM) in a group of Thoroughbred horses presented for investigation of poor performance and/or abnormal respiratory noise. Records from 600, dynamic, endoscopic examinations of the upper respiratory tract of horses were reviewed. Horses with VRDDLM were identified as those in which the dorsal laryngeal mucosa progressively obscured the interarytenoid notch and dorsoaxial portion of the corniculate processes of the arytenoid cartilages during high-speed exercise. The condition was recognised in 12 horses. Concurrent abnormalities of the respiratory tract of eight horses were also identified and included, axial deviation of the aryepiglottic folds, vocal cord prolapse, unilateral and bilateral ventromedial luxation of the apex of the corniculate process of the arytenoid cartilage, and intermittent dorsal displacement of the soft palate. VRDDLM is a rare abnormality of the upper portion of the respiratory tract of horses that may be associated with abnormal respiratory noise and potentially poor performance. The significance of the condition is not known, but the presence of this condition in combination with other, obstructive diseases of the equine airway warrants further investigation.

Comparison of dynamic and resting endoscopy of the upper portion of the respiratory tract in 57 Thoroughbred yearlings.

REASONS FOR PERFORMING THE STUDY: Endoscopic examination of Thoroughbred (TB) yearlings is performed routinely to determine the suitability of horses for racing and to ensure that the conditions of sale are satisfied. However, previous research has demonstrated that resting endoscopic examination can be inaccurate in the diagnosis of functional pathology of the upper portion of the respiratory tract (URT). OBJECTIVES: To investigate the feasibility of performing dynamic overground endoscopy in a group of TB yearlings and to compare the results of resting and dynamic endoscopic examination of the URT. STUDY DESIGN: Prospective cohort study. METHODS: Resting (pre- and post exercise) and exercising endoscopy was performed on 57 TB yearlings at a single training yard. Observed abnormalities were recorded and graded. The results of resting and dynamic examination were compared. RESULTS: Dynamic overground endoscopy was well tolerated and was performed with few complications. Laryngeal asymmetry (29 cases) was the most common abnormality identified at rest, while intermittent dorsal displacement of the soft palate (IDDSP; 19 cases) was the most common at exercise. Significant variation in laryngeal function and variation in the occurrence of IDDSP was noted between examinations. Other potentially significant pathology that was not noted at rest but was present during exercise included collapse of the apex of the corniculate process, pharyngeal collapse and cricotracheal ligament collapse. The occurrence of IDDSP at exercise was significantly associated with epiglottic structure grade>2 and a recent history of respiratory tract infection. CONCLUSIONS: Dynamic overground endoscopy is safe and potentially useful when assessing URT function in TB yearlings. Significant variations in the results of endoscopy at rest and during exercise were identified, which indicate that resting endoscopy may not be sufficient to predict the occurrence of pathology during exercise. POTENTIAL RELEVANCE: Dynamic overground endoscopic examination could be considered a suitable means of assessing URT function in TB yearlings and may provide additional pertinent information to that obtained during standard resting examination.

Risk factors for superficial digital flexor tendinopathy in Thoroughbred racehorses in steeplechase starts in the United Kingdom (2001-2009).

The objective of this study was to identify risk factors for superficial digital flexor (SDF) tendinopathy in Thoroughbred horses in steeplechase races in the United Kingdom. Potential risk factors for SDF tendinopathy were studied between 1st January 2001 and 31st December 2009 using a cohort study design with 648 injuries sustained in 102,894 starts. Potential risk factors were screened using univariable logistic regression prior to multivariable model building. In the final multivariable model, 12 statistically significant risk factors were identified. Variables that increased the odds of SDF tendinopathy included firmer going, increased horse age, and racing in the summer compared to other seasons. Variables that decreased the odds included having a higher official rating and the number of starts in the preceding days. Fewer and different risk factors were identified than in an equivalent model of SDF tendinopathy in hurdle racing, highlighting potential differences between these disciplines. Further collection of training and racecourse information would be beneficial and may help to explain further some of the associations identified in this study. The results will facilitate the development of strategies to improve overall safety of horses in UK steeplechase racing.

Risk factors for superficial digital flexor tendinopathy in Thoroughbred racehorses in hurdle starts in the UK (2001-2009).

REASONS FOR PERFORMING STUDY: Superficial digital flexor (SDF) tendinopathy is a common injury in Thoroughbred horses racing over hurdles. Identification of risk factors may allow the introduction of measures to minimise the incidence of this injury. OBJECTIVE: To identify risk factors for SDF tendinopathy in Thoroughbred horses in hurdle races in the UK. METHODS: Potential risk factors for SDF tendinopathy were studied between 1 January 2001 and 31 December 2009 using a retrospective cohort study design with 1031 case starts and 168,637 control starts. Potential risk factors were screened using univariable logistic regression prior to multivariable model building. RESULTS: IN the final multivariable model, 20 statistically significant risk factors were identified. Variables found to be associated with increased odds of SDF tendinopathy included: firmer going; increased horse age at first race; having had a previous SDFT injury; and racing in the summer compared to other seasons. Variables found to be associated with decreased odds included: being trained by a more successful trainer; and having raced more frequently in the preceding 9-12 months. CONCLUSIONS: This study identified multiple risk factors associated with SDF tendinopathy, some of which are difficult to explain with the current data source. Factors resulting in increased cumulative horse and tendon fatigue (increased years in racing; carrying increased weight; and racing over longer distances), firm ground, and the presence of previous tendon injury should be considered when attempting to reduce the likelihood of sustaining SDF tendinopathy. POTENTIAL RELEVANCE: The results will facilitate the development of strategies to improve the overall safety of horses in hurdle racing in the UK.

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

REASONS FOR PERFORMING STUDY: 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. OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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. POTENTIAL RELEVANCE: 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.

The use of race winnings, ratings and a performance index to assess the effect of thermocautery of the soft palate for treatment of horses with suspected intermittent dorsal displacement. A case-control study in 110 racing Thoroughbreds.

REASONS FOR PERFORMING THE STUDY: There have been no reports of the efficacy of thermocautery of the soft palate (TSP) assessed objectively as a treatment of intermittent dorsal displacement of the soft palate (DDSP). OBJECTIVE: To compare: racing performance of horses that underwent thermocautery of the soft palate with matched controls; and 'Racing Post ratings' (RPR) with prize money won (RE) and a performance index (PI) for each of the horses in the study. HYPOTHESIS: Thermocautery of the soft palate has no beneficial effect on racing performance and the 3 measures of performance are significantly related. METHODS: The inclusion criteria were fulfilled by 110 horses and each was matched with 2 controls. Changes in performance were compared statistically. RPR, RE and PI were analysed using a regression model. RESULTS: The percentage of horses that improved in performance following the procedure was 28-51% for the 3 measures of performance, compared to 21-53% for the matched controls. There was no significant effect of the procedure on the changes in RPR or RE. There was a significant effect of the procedure on the change in PI (P=0.015) with more treated horses achieving an improved PI and fewer acquiring a worse PI than matched control horses. The measures of performance showed significant correlation. CONCLUSIONS: Thermocautery of the soft palate alone may not be the most efficacious treatment of DDSP. POTENTIAL RELEVANCE: Production of a reliable measure of racehorse performance may be possible.