MARINE MAMMAL SCIENCE, 30(1): 272–281 (January 2014) Published 2013. This article is a U.S. Government work and is in the public domain in the USA. DOI: 10.1111/mms.12037 Nitric oxide in the breath of bottlenose dolphins: Effects of breath hold duration, feeding, and lung disease LAURA C. YEATES, 1 KEVIN P. CARLIN, MARK BAIRD, STEPHANIE VENN-WATSON and SAM RIDGWAY, National Marine Mammal Foundation, 2240 Shelter Island Drive, Suite 200, San Diego, California 92106, U.S.A. Abstract Breath analysis, including measurement of nitric oxide (NO), is a noninvasive diagnostic tool that may help evaluate cetacean health. This is the first report on the effects of breath hold duration, feeding, and lung disease on NO in dolphin exhaled breath. Three healthy dolphins were trained to hold their breath for 30, 60, 90, and 120 s and then exhale into an underwater funnel. Exhaled NO values from 157 breath samples were compared among three healthy dolphins by breath hold time and after fasting and feeding. Exhaled NO values were also measured in two dol- phins with pulmonary disease. NO in dolphin breath was higher compared to ambi- ent air; healthy dolphins had higher NO concentrations in their breath after feeding compared to after overnight fasting; and there were no significant differences in exhaled NO levels by breath hold duration. A dolphin with Mycoplasma-associated pneumonia and chronic gastrointestinal disease had higher postprandial exhaled NO levels compared to healthy controls. This study demonstrates, contrary to previous publications, that dolphins exhale NO. Given the high standard deviations present in exhaled breath NO values, future studies are needed to further standardize collec- tion methods or identify more reliable samples (e.g., blood). Key words: bottlenose dolphin, exhaled breath analysis, lung disease, nitric oxide, Tursiops truncatus. Breath analysis has been used previously to better understand dolphin and sea lion physiology (Ridgway et al. 1969, Ridgway 1972, Ponganis et al. 1993). These stud- ies have included measurements of oxygen, nitrogen, and carbon dioxide after dives and various breath-hold times, and methods have been developed to readily collect exhaled gas either underwater or at the surface. As such, breath analysis may be useful to non-invasively assess marine mammal health. Nitric oxide, a potential biomarker of health and disease, can be readily found in the exhaled breath of animals and humans (Gaston et al. 1994, Schedin 1997, Falke et al. 2008). Endogenous nitric oxide (NO) is found in many types of organisms, including vertebrates, bacteria, and fungi, and it is considered a universal biological messenger and regulator (Rhoads and Bell 2012). NO is endogenously produced 1 Corresponding author (e-mail: laura.yeates@nmmfoundation.org). 272