Meeting Abstract
P3.132 Wednesday, Jan. 6 Cardiovascular adaptations of Inuit sled dogs in response to seasonal changes in work load, temperature and feeding GERTH, Nadine; STARCK, J. Matthias*; Univesity of Munich (LMU); University of Munich (LMU) starck@uni-muenchen.de
Using ultrasonography and external heart rate monitors we have measured morphological and functional parameters of the heart of Inuit sled dogs living in traditional husbandry conditions in Greenland. We explored adaptive long-term and short-term responses of the cardiovascular system to changes in exercise, temperature and food supply. We compare measurements of same dogs in summer and winter when resting and fasting, resting and digesting, and working. Husbandry includes intermittent feeding during summer and adequate feeding in winter. In winter, the diameter of the aortic root was larger than in summer, whereas the dimensions of the left ventricle remained unchanged. We found substantial functional adjustments during winter: stroke volume (SV) was 28% higher, left ventricular ejection fraction (LVEF) was 11% higher, and fractional shortening (FS) was 7 % more intensive in the LO-dogs. We also explored short term responses to feeding and working in the dogs. In summer in resting dogs heart rates and cardiac output doubled when digesting. Elevated levels were maintained for 4 hours and slowly declined within 32 hours to fasting levels. When pulling a sledge in winter dogs maintained working heart rates of 200 bpm and cardiac output of 221.7 ml min -1 kg -1 compared to resting heart rates of 109 bpm and cardiac output of 114 ml min -1 kg -1. The Inuit sled dogs living in Greenlandic husbandry are an excellent model to study adaptations to seasonal changing conditions. The Inuit dogs adjust functionally rather than morphologically to the differing demands between the seasons and conditions. Besides long-term adjustments we also monitored dramatic short-term adjustments to digesting large meals and sustained work with doubled heart rate and cardiac output.
