Abstract

There is no gold standard diagnostic test for cardiovascular disease in dolphins, so we may be failing to diagnose heart disease. On the other hand, in humans, blood tests can be used to diagnose and determine the severity of cardiovascular diseases. Human atrial natriuretic peptide (hANP) has low species specificity, and although there are already reports on the homology of dolphin ANP, the possibility of its clinical application has not been examined.¹ hANP is a peptide hormone that is released from atrial myocytes into the bloodstream by stimulation of myocardial stretch when the blood volume in the atria increases excessively.² This hormone has a natriuretic effect on renal tubular epithelial cells and a vasodilatory effect on vascular smooth muscle in peripheral blood vessels, thus causing a general hypotensive effect and reducing the capacity load of the atria.³ For this reason, it is used in the diagnosis and assessment of the severity and treatment of cardiac diseases in humans and dogs.⁴ We studied hANP in normal bottlenose dolphins with the goal of establishing a reference value for hANP.

Eight healthy bottlenose dolphins, females (4–33 years old). Husbandry staff used a butterfly needle to draw blood from the fluke vein of the caudal fin, and the plasma was quickly frozen and measured by the chemiluminescence immunoassay (CLEIA) method. We measured each individual’s plasma more than three times and calculated the mean value. The mean value of No. 1 was 85.4 pg/ml, the maximum value was 97.0 pg/ml and the minimum value was 79.1 pg/ml, which was high when compared to the mean value of Numbers 2 through 8. The mean value of dolphins Numbers 2 through 8 was 41.5±10.54 pg/ml, the maximum value was 61.0 pg/ml and the minimum value was 30.24 pg/ml. It is reported that the mean value of hANP in healthy humans is 20±7 pg/ml and that in dogs it is 16 pg/ml. It has been reported that hANP levels are significantly elevated during heart disease, 3–10 times higher than normal in humans and 2–12 times higher than that in dogs. All the dolphins examined in this study had no clinical signs of heart disease, such as exercise intolerance. However, from the results, it is highly possible that No. 1 is suffering from a heart disease. Therefore, we would like to examine the heart sounds of No. 1 to confirm the presence of arrhythmia and heart murmur in the future. Based on the above, we consider the mean value of 41.5±10.54 pg/ml of hANP obtained from No. 2 through 8 to be in the normal range and suggest using it as the reference value of hANP. Cardiac examination by blood test is easier than auscultation and echocardiography. In this study, we established a reference value for hANP, which is expected to be useful in clinical practice in the future.

Literature Cited

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