Morphological features of coronary arteries and lesions in hearts from five species of sharks collected from the northwestern Atlantic Ocean

EVALUATION OF HEALTH PARAMETERS IN COWNOSE RAYS ( RHINOPTERA BONASUS) HOUSED IN A SEASONAL TOUCH POOL HABITAT COMPARED WITH AN OFF-EXHIBIT HABITAT

Cownose rays ( Rhinoptera bonasus) are commonly displayed in zoo and aquarium touch pool exhibits; however, there is a gap in our understanding of how these practices might impact the health of these animals. The aim of this study was to evaluate and compare selected health parameters in cownose rays housed in a seasonal outdoor exhibit touch pool system with abundant public contact and an indoor off-exhibit holding system with minimal human contact. All animals underwent physical examination, ultrasound, cloacal wash and cytology, and blood collection for complete blood counts, point-of-care blood analysis, plasma protein electrophoresis, and plasma cholesterol electrophoresis in May and October 2014. Physical examination, ultrasound, and cloacal wash cytology findings were all unremarkable for both groups of animals. Significant differences in health parameters among animals by location and time point were few and included decreased heart rate ( F = 12.158, P = 0.001), increased lactate ( F = 6.838, P = 0.012), and increased low-density lipoproteins ( F = 19.961, P = 0.000) in touch pool animals over time. Based on these results, cownose rays inhabiting a touch pool exhibit and an off-exhibit system remained in comparable planes of health based on routine diagnostic modalities with few differences in measured health parameters.

The bulbus arteriosus of the holocephalan heart: gross anatomy, histomorphology, pigmentation, and evolutionary significance

This study was designed to determine whether the outflow tract of the holocephalan heart is composed of a myocardial conus arteriosus and a non-myocardial bulbus arteriosus, as is the case in elasmobranchs. This is a key issue to verify the hypothesis that these two anatomical components existed from the onset of the jawed vertebrate radiation. The Holocephali are the sister group of the elasmobranchs, sharing with them a common, still unknown Palaeozoic ancestor. The sample examined herein consisted of hearts from individuals of four species, two of them belonging to the Chimaeridae and the other two to the Rhinochimaeridae. In all specimens, the cardiac outflow tract consisted of a conus arteriosus, with myocardium in its walls and two rows of valves at its luminal side, and an intrapericardial bulbus arteriosus shorter than the conus and devoid of valves. The bulbus, mainly composed of elastin and smooth musculature, was covered by the epicardium and crossed longitudinally by coronary artery trunks. These findings give added support to the viewpoint that the outflow tract of the primitive heart of the gnathostomes was not composed of a single component, but two, the conus and the bulbus. All rabbitfish (Chimaera monstrosa) examined had pigment cells over the surface of the heart. The degree of pigmentation, which varied widely between individuals, was particularly intense in the cardiac outflow tract. Pigment cells also occurred in the bulbus arteriosus of one of the two hearts of the straightnose rabbitfish (Rhinochimaera atlantica) included in the study. The cells containing pigment, presumably derived from the neural crest, were located in the subepicardium.

Arteriosclerosis in the ventral aorta and epicarditis in the bulbus arteriosus of Atlantic salmon (Salmo salar L)

Spontaneous mortality of seemingly healthy, farmed Atlantic salmon (Salmo salar L) is an increasing problem in Norwegian aquaculture. In this study, we present a morphological study of the previously undescribed syndrome of arteriosclerosis of the ventral aorta and epicarditis of the adjacent bulbus arteriosus found in farmed Atlantic salmon, with wild-captured fish as a control group. Both the ventral aorta and epicardium are vital for correct arterial compliance and vascular resistance in the respiratory capillaries of the gills. We discuss the possible implications of ventral aorta arteriosclerosis and epicarditis for blood vascular health and in particular for the increasing frequency of spontaneous gill bleeding in farmed salmon. As both these conditions primarily occur in farmed salmon, we suggest that they should be considered pathological.