Fundamentals of arrhythmogenic mechanisms and treatment strategies for equine atrial fibrillation.

Atrial fibrillation (AF) is the most common pathological arrhythmia in horses. Although it is not usually a life-threatening condition on its own, it can cause poor performance and make the horse unsafe to ride. It is a complex multifactorial disease influenced by both genetic and environmental factors including exercise training, comorbidities or ageing. The interactions between all these factors in horses are still not completely understood and the pathophysiology of AF remains poorly defined. Exciting progress has been recently made in equine cardiac electrophysiology in terms of diagnosis and documentation methods such as cardiac mapping, implantable electrocardiogram (ECG) recording devices or computer-based ECG analysis that will hopefully improve our understanding of this disease. The available pharmaceutical and electrophysiological treatments have good efficacy and lead to a good prognosis for AF, but recurrence is a frequent issue that veterinarians have to face. This review aims to summarise our current understanding of equine cardiac electrophysiology and pathophysiology of equine AF while providing an overview of the mechanism of action for currently available treatments for equine AF.

Flight patterns in zoo-housed fruit bats (Pteropus spp.).

Maintaining the capacity for sustained flight in captivity is a key goal for the management of threatened fruit bats. We developed quantifiable descriptions of flight complexity and used them to assess the suitability of an enclosure for two species of fruit bat of differing size, the large Livingstone's fruit bat, Pteropus livingstonii, and the smaller Rodrigues fruit bat, Pteropus rodricensis, in a two-part study. In Phase 1, Rodrigues fruit bats flew more often than Livingstone's fruit bats and although the majority of flights in both species were linear, Rodrigues fruit bats were more likely to display complex flight paths involving turns, while flights by Livingstone's fruit bats were more likely to end in a crash-landing than Rodrigues fruit bat flights. The enclosure may therefore not have been large enough for Livingstone's fruit bats to display a full range of flight behavior over longer distances. In Phase 2, juvenile Livingstone's fruit bats ( < 3 years old) flew more than twice as often as younger adults (3-10 years old) did. Older adult Livingstone's fruit bats over the age of 10 years were not observed to fly. We could not separate out the effects of age, weight and environment during development as these factors were strongly correlated in our study; future work in this area will be very important in understanding the factors that affect flight in captive bats, and how it can be encouraged by appropriate enclosure design.