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

This research studied the effectiveness of common treatments for atrial fibrillation in horses, a common heart condition among the species. They concluded that the combined use of digoxin and quinidine sulfate improved successful treatment of the condition, regardless of horse breed or period of previous affliction.

Research Objective and Methodology

• The primary objective of this research was to identify the factors that contributed to the success of atrial fibrillation treatment in horses with the traditional oral medications—quinidine alone, or quinidine in combination with digoxin.
• The study was a retrospective one based on the patient records of two veterinary clinics: the Equine University Clinic of Utrecht University and Rossdales Equine Hospital in Newmarket. Data from forty-nine horses was analyzed, comprising different breeds (29 Warmbloods, 20 Thorougbreds, 1 Anglo-Arabian).
• Information like horses’ history, physical examination records, echocardiography, left atrial size, and presence of mitral regurgitation were extracted from their medical records and analyzed.
• A statistical technique, the backwards logistic regression based on the Akaike’s information criterion (AIC), was used to evaluate the relationship between these variables and the successful treatment of the heart condition.

Results and Interpretation

• The results showed that the treatment of 80% of the horses converted them back to a normal sinus rhythm. That is, in four out of every five horses, the heart condition was successfully treated.
• However, it was found that the successful treatment related to atrial fibrillation in horses was significantly correlated with those treated with a combination of digoxin and quinidine sulfate, according to the statistical AIC analysis. The study reported an odds ratio of 12.4 for this combination treatment, indicating that horses treated with both medications were 12.4 times more likely to recover.
• This improvement in treatment outcome was consistent across all the horse breeds studied, and it remained irrespective of the duration the horses had experienced atrial fibrillation. The latter is especially important as the duration of the condition is often unknown in the majority of horses.

Conclusion and Ethical Considerations

• Although potential bias is acknowledged due to the nature of retrospective studies, the researchers concluded that the use of digoxin in combination with quinidine was the more effective treatment for equine atrial fibrillation.
• It’s important to note that the research is based on past clinical records where no explicit owner informed consent for inclusion in the study was stated.
• The conference under which this research was presented didn’t demand oversight by a research ethics committee, given the retrospective nature of the study.
• There were no competing interests reported behind the research.