Validation of an equine fitness tracker: ECG quality and arrhythmia detection.

BACKGROUND: Cardiac arrhythmias in exercising horses are the focus of much interest, both in terms of what is considered normal and potential associations with poor performance and sudden cardiac death. One barrier to performing large-scale studies is the lack of an easily applicable device, to allow recording of large numbers of high-quality exercising electrocardiograms (ECGs). The EquimetreTM is a new wearable device which records a single lead ECG, amongst other parameters. Validation of such wearable devices is essential before further studies are undertaken. OBJECTIVES: To evaluate the quality of ECG using the EquimetreTM and compare arrhythmia detection during exercise with the reference TelevetTM system. STUDY DESIGN: Prospective blinded clinical study. METHODS: Simultaneous ECGs were recorded with both systems in 49 healthy horses during exercise. High intensity exercise (>40km/h) was performed by 29 racehorses, and lower intensity exercise for the remainder of the racehorses and show jumpers. Tracings were excluded if >10% artefact was present (duration of artefact relative to duration of exercise). For included ECGs, the duration of artefact was recorded and compared. ECGs were evaluated using Kubios premium software. Arrhythmia detection (yes/no) and arrhythmia classification (sinus arrhythmia, narrow complex of similar morphology to the sinus complexes or wide complex with a different morphology) were compared using Cohen's Kappa coefficient. RESULTS: Nine TelevetTM ECGs and 3 EquimetreTM ECGs were excluded due to artefact >10%. TelevetTM ECGs included significantly more artefact during exercise than EquimetreTM ECGs (5% vs. 0.25% p<0.001). Arrhythmia analysis was performed on 38 horses' paired ECGs. The Kappa coefficient was excellent for arrhythmia detection (K=0.97) and arrhythmia classification (K=0.93). MAIN LIMITATIONS: Relatively low numbers of horses with arrhythmias (n=21) were included. The ECG recordings only provided one lead, making arrhythmia classification challenging in some cases. CONCLUSIONS: The Equimetre device provides a reliable ECG for arrhythmia detection during exercise. This system may be useful clinically and for future large-scale investigations into the occurrence and significance of exercising arrhythmias.

Fungi in respiratory samples of horses with inflammatory airway disease.

BACKGROUND: Fungi contribute to the inflammatory response of lungs in horses with recurrent airway obstruction and in some forms of asthma in humans. The role of fungi in inflammatory airway disease (IAD) has not been assessed. OBJECTIVES: Evaluate the prevalence of fungi in the respiratory samples of horses diagnosed with IAD, describe clinical signs associated with the presence of fungi in respiratory samples, and assess the risk factors associated with IAD and with the presence of fungi in the airways. ANIMALS: Seven-hundred thirty-one active horses referred to a specialized ambulatory practice for signs of respiratory disease or poor performance. METHODS: A prospective observational study was performed, collecting clinical data, environmental conditions, and results of a tracheal wash (TW; cytology, fungal culture, and bacterial culture), and bronchoalveolar lavage (cytology). RESULTS: A positive fungal culture was obtained in 55% (402/731) of horses. Horses with fungal elements observed on the TW cytology had 2 times greater chance of having IAD than horses without fungi (odds ratio [OR] = 2.1; 95% CI 1.08-3.33; P = .0003). Risks of being diagnosed with IAD and likelihood of fungi in TW were higher when horses were bedded on straw (OR = 2.0; 95% CI 1.2-3.2 and OR = 1.9; 95% CI 1.3-2.6, respectively) or fed dry hay (OR = 2.7; 95% CI 1.7-4.4 and OR = 2.6; 95% CI 1.6-3.4, respectively). CONCLUSIONS AND CLINICAL IMPORTANCE: Horses inhaling aerosolized fungal particles are at a significantly higher risk of developing IAD. The type of bedding and forage represent significant risk factors for IAD and fungal contamination of equine airways.

Histologic investigation of airway inflammation in postmortem lung samples from racehorses.

OBJECTIVE To describe histologic findings in the small airways during postmortem examination of actively racing horses and to quantify the degree of airway inflammation by use of a semiquantitative scoring system. SAMPLE Lung tissues obtained from 95 horses (Thoroughbreds, Standardbreds, and Quarter Horses) that had been actively racing or training. PROCEDURES 10 standardized lung sections were obtained during postmortem examination of 37 horses that had been actively racing or training, and 2 histologic sections of the caudodorsal lung lobes previously collected from each of 58 horses that died or were euthanized during racing or training were also obtained. Sections were evaluated by use of a validated histologic small airway scoring system. RESULTS Scores for inflammatory cells, smooth muscle, and hemosiderin typically were high. Signalment and cause of death were not significant predictors of lung scores. Lung sample location was a significant predictor, with the highest scores in the caudal and dorsal sections. Inflammatory cell infiltration in peribronchiolar tissues, smooth muscle hyperplasia, and hemosiderin (prevalence of 86%, 98%, and 80%, respectively) were common findings in lungs of these horses, with the caudodorsal regions more severely affected. Correlation was moderate between smooth muscle hyperplasia and inflammatory cell infltration, with minimal correlation between hemosiderin and inflammatory cell infiltration. CONCLUSIONS AND CLINICAL RELEVANCE Inflammatory airway disease has been identified by use of bronchoalveolar lavage in young athletic horses throughout the world. In the study reported here, pathological changes were detected in the wall of small airways of horses that were actively training or racing.