SummaryReasons for performing study: To improve the understanding of exercise related sudden death in Thoroughbred racehorses.

SummaryReasons for performing study: Sudden death adversely affects racehorse welfare, jockey safety and the public perception of horseracing. Objective: To describe the risk of racing-associated sudden death in Thoroughbred racehorses in the UK from 2000 to 2007, to identify whether there were risk factors uniquely associated with sudden death and to improve the understanding of the pathogenesis of racing-associated sudden death by identification of risk factors for such cases. Methods: A sudden death was defined as an acute collapse and death, in an apparently healthy Thoroughbred racehorse, during or immediately after racing, in the absence of clinical data indicative of a catastrophic orthopaedic injury. The retrospective study included 201 case race starts and 705,712 control race starts. Univariable and multivariable logistic regression were used to identify risk factors for sudden death at any one start. Results: In the multivariable model, age, distance, race type, season and number of starts in the 60 days prior to the race were associated with sudden death. Conclusions:The risk factors identified in this study are not uniquely associated with sudden death and have been also been identified in studies using all causes of fatality as the outcome. These data suggest that a generic approach to reduce fatal musculoskeletal injury and sudden death may be possible. Potential relevance: The identification of risk factors allows speculation on the underlying mechanisms of sudden death in racing. This may stimulate hypothesis-led investigations into the pathogenesis of exercise-related arrhythmias, exercise-induced pulmonary haemorrhage and blood vessel rupture.

Background: Episodic collapse in horses has equine welfare and human safety implications. There are, however, no published case series describing this syndrome. Objectives: To characterize the cause and outcomes for horses referred for investigation of episodic collapse. Animals: Twenty‐five horses referred for investigation of single or multiple episodes of collapse. Methods: Retrospective study. Clinical records from the Dick Vet Equine Hospital, University of Edinburgh from November 1995 to July 2009 were searched using the following keywords: collapse, collapsing, fall, syncope. Collapse was defined as an incident in which the horse lost postural tone with or without progression to recumbency and with or without loss of consciousness. Long‐term follow‐up information was obtained by telephone conversation with the owner. Results: A final diagnosis was reached in 11 cases, namely cardiac arrhythmia (4), right‐sided heart failure (1), hypoglycemia (2), generalized seizures (2), and sleep disorder (2). A presumptive diagnosis was reached in 8 cases, namely neurocardiogenic syncope (5), exercise‐induced pulmonary hemorrhage (2), and generalized seizures (1). No diagnosis was reached in 6 cases despite comprehensive investigations. Three horses were euthanized at presentation. Treatment was attempted in 9 horses with 6 cases having successful outcome before discharge. Follow‐up information was available for 14 of 19 horses discharged from the hospital. Only 1 of these horses was observed to collapse after discharge. Conclusions and Clinical Importance: Definitive diagnosis was more likely to be reached in cases with multiple episodes of collapse. Horses in which 1 episode of collapse occurred did not necessarily collapse again.

EQUINE grass sickness (dysautonomia) is a neurological disease associated primarily with degeneration of neurons in the autonomic nervous system (including the enteric nervous system), although involvement of the somatic nervous system has also been widely reported. It affects all Equidae, is usually fatal and has an approximate incidence of 1 per cent in some parts of the UK. This article discusses the clinical aspects of the disease and summarises the findings of recent research into the aetiology and epidemiology of the condition.

Upper airway endoscopy at rest has been the diagnostic method of choice for equine upper respiratory tract (URT) conditions. Development of high-speed treadmill endoscopy improved the sensitivity of URT endoscopy by allowing observation of the horse’s nasopharynx and larynx during exercise. However, treadmill exercise may not always accurately represent the horse’s normal exercise as track surface, rider, tack and environmental variables are altered. Recently, the development of dynamic overground endoscopy (DOE) has addressed some of these shortcomings. A retrospective study was undertaken to describe the URT abnormalities detected during DOE in racehorses presenting with poor performance and/or abnormal respiratory noise. Patient records of Thoroughbred racehorses undergoing DOE from November 2011 to August 2012 were reviewed. Data collected included signalment, primary complaint, distance exercised, maximum speed and dynamic airway abnormalities detected. Fifty-two horses underwent DOE for investigation of poor performance and/or abnormal respiratory noise. The main abnormalities detected included axial deviation of the aryepiglottic folds (40%), vocal cord collapse (35%), abnormal arytenoid function (33%) and dorsal displacement of the soft palate (25%). A total of 40 horses were diagnosed with one or more abnormalities of the URT (77%). Fifteen horses (29%) had a single abnormality and 25 horses (48%) had multiple abnormalities. This study showed that DOE is a useful technique for investigating dynamic disorders of the URT in racehorses in South Africa. The total number and type of dynamic pathological conditions were comparable with those identified in similar populations in other geographical locations.

Summary The term ‘collapse’ can be used to describe a variety of incidents in which a horse loses postural tone with or without progression to recumbency and with or without loss of consciousness. Depending on the aetiology of the condition the episode may be self‐limiting and may or may not recur. Alternatively the collapse may be secondary to serious injury or disease and require veterinary intervention. This article mainly discusses investigation of the former scenario of self‐limiting single or multiple episodes of collapse in apparently healthy horses. An overview of the various causes of collapse is followed by a suggested approach to the diagnosis of these challenging cases.

Reasons for performing study Adverse effects on renal health and haemostasis have been documented in human patients administered hydroxyethyl starches (HES). Gelatins could provide useful substitutes for HES should similar adverse effects be identified in horses. Objectives To compare the effects of a 4% modified fluid gelatin (MFG) with a 130/0.4 6% tetrastarch (TES) on haemodilution, colloid osmotic pressure (COP), haemostasis and renal parameters in healthy ponies. Study design Randomised crossover. Methods Three treatments (A = 10 ml/kg bwt TES, B = 10 ml/kg bwt MFG and C = 20 ml/kg bwt MFG) were administered to 6 healthy ponies with a one‐week washout period. Packed cell volume (PCV), total serum protein (TSP), COP, platelet count, fibrinogen, prothrombin time (PT), activated partial thromboplastin time (aPTT) and thromboelastography (TEG) were measured at baseline and at multiple time points up to 24 h post infusion. Serum creatinine, urine specific gravity (USG), urine protein:creatinine (UPC), urine GGT:creatinine (UGC) and urine sediment examination (USE) were performed before and 24 h after each treatment, and one week after the final treatment. Results All treatments caused significant haemodilution and increases in COP with treatment C having a significantly greater effect on PCV than other treatments. The platelet count decreased with all treatments and was significantly lower for treatment C compared with treatment B. No significant differences were observed in any TEG parameter within or between treatments. No significant differences in PT, aPTT or fibrinogen were observed between treatments. Serum creatinine, UGC and UPC did not change significantly pre‐ and post study. USG and USE remained within normal limits. Conclusions 4% MFG could be considered as an alternative to 130/0.4 6% TES for volume expansion and oncotic support. Neither MFG nor TES were associated with clinically significant adverse effects on haemostasis or renal parameters. Ethical animal research: This research was approved by the University of Pretoria's Animal Ethics Committee. The animals used in the study were part of a research herd belonging to The University of Pretoria. Sources of funding: The Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, The Abe Bailey Trust Fund, The South African Veterinary Foundation and The South African Equine Veterinary Association. Competing interests: None declared.

Modified fluid gelatin could be considered as an alternative to HES for volume expansion and oncotic support. Neither MFG nor HES were associated with clinically significant adverse effects on haemostasis or renal parameters.