RADIOGRAPHIC CARDIAC SILHOUETTE MEASUREMENT IN CAPTIVE LIVINGSTONE'S FRUIT BATS (PTEROPUS LIVINGSTONII)

Abstract

Cardiomyopathies have been increasingly noted in the captive population of Livingstone's fruit bat ( Pteropus livingstonii ). The aim of this study was to produce a set of repeatable quantitative reference measurements that could be used to assess the cardiac size during radiographic examination of this species. Ventro-dorsal and lateral radiographs (n = 129) from a total of 42 individual Livingstone's fruit bats were examined. The control group radiographs (n = 102) consisted of 34 healthy individuals. Radiographic measurements were taken of structures within the thorax and then converted into ratios. These ratios from radiographs (n = 27) were also calculated for eight individuals with diagnosed cardiomyopathy. Vertebral Heart Scores (VHS) were calculated from right lateral radiographs and compared between the two groups. From all the data, only the width of the cardiac silhouette to the width of the thorax (the W : T ratio) in the ventro-dorsal view and the VHS were found to be significantly different between both groups (P < 0.05). The group with cardiomyopathies had a mean W : T ratio of 0.59 (±0.005) and a VHS of 9.77 (±0.89), while a mean W : T ratio of 0.54 (±0.004) and a VHS of 8.71 (±0.93) was established for healthy specimens.

An exploratory investigation of echocardiographic parameters and the effects of posture on cardiac structure and function in the Livingstone's fruit bat (Pteropus livingstonii)

“…Of the 19 assessments completed, four animals presented with markedly different echocardiographic findings, and were therefore considered “abnormal” or “unhealthy.” Three presented with a phenotype in line with the previously observed (clinically and on postmortem) findings of dilated cardiomyopathy . One young male showed marked right heart dilatation, right free wall hypertrophy and severe tricuspid regurgitation.…”

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

“…In a literature search, we could find almost no studies of the effect of enclosure design on flight in captive fruit bats, or on methods for evaluating flight skills, despite the fact that preserving the ability to fly in captivity is essential for health (Charnley et al, ; Dickson et al, ; Killick et al, ), psychological wellbeing (Purcell, Thomas, Leblanc, & Walsh, ), social communication (Chaverri, Ancillotto, & Russo, ), education and display (Luebke, Watters, Packer, Miller, & Powell, ), and ultimately, the success of conservation programs (Markus, ; Ruffell et al, ). We therefore developed definitions of flight patterns that distinguished different levels of complexity, and used these to investigate the factors affecting flight in two Pteropus species.…”

“…We looked at the frequency of flying and the nature of the bats’ flight patterns in relation to species, age and sex in a two‐phase study, and tested the following predictions: The smaller P. rodricensis would exhibit more complex flight paths than the larger P. livingstonii (Phase 1), as their smaller body mass and shorter wingspan should enable them to make tighter turns. As older bats are both heavier and more likely to have health problems, we expected younger Livingstone's fruit bats to fly more than older bats (Phase 2). Dominant male bats defend small feeding territories within the colony, and are therefore often more sedentary (Thorncroft, Wormell, & Price, ). This age‐sex class also tends to be heavier, and exhibits a higher frequency of cardiomyopathy (Dickson et al, ; Killick et al, ). We therefore expected that older, dominant male Livingstone's bats would fly less than older female bats, but that a sex difference would not be apparent in younger bats (Phase 2).…”

“…Bringing them into captivity, with its constraints on movement and activity, is therefore likely to have consequences for weight, fitness and ultimately health and reproduction unless adequate space is provided for extended flight. Captive Livingstone's fruit bats, though not Rodrigues fruit bats, are prone to obesity and, probably as a result, cardiac disease (Charnley, Goatman, Thomasson, Routh, & Barbon, ; Dickson, Davies, Routh, Killick, & Barbon, ; Killick et al, ). Greater activity should lead to improved health, but achieving this for bats presents challenges.…”

“…Dominant male bats defend small feeding territories within the colony, and are therefore often more sedentary (Thorncroft, Wormell, & Price, ). This age‐sex class also tends to be heavier, and exhibits a higher frequency of cardiomyopathy (Dickson et al, ; Killick et al, ). We therefore expected that older, dominant male Livingstone's bats would fly less than older female bats, but that a sex difference would not be apparent in younger bats (Phase 2).…”