Pulmonary Hypertension Induced in Dogs by Hypoxia at Different High-Altitude Levels |
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| Authors: | Glaus TM Hässig M Baumgartner C Reusch CE |
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| Institution: | (1) Division of Cardiology, University of Zurich, Winterthurerstr. 260, CH-8057 Zurich, Switzerland;(2) Department for Small Animals, University of Zurich, Winterthurerstr. 260, CH-8057 Zurich, Switzerland;(3) Division of Herd Health, Department of Large Animals, University of Zurich, Winterthurerstr. 260, CH-8057 Zurich, Switzerland |
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| Abstract: | Chronic natural hypoxia at 2300 m altitude induces mild pulmonary hypertension (PH) in healthy dogs. The influence of more severe hypoxia on the same group of dogs was evaluated by re-examining such dogs at 3500 m, after they had regularly exercised at this altitude level for half a year. Despite severe hypoxaemia at 3500 m (P
aO2 52±5 mmHg), none of the dogs developed erythrocytosis, and their PCV at 3500 m (48%±4%) did not differ from that at 2300 m (49%±4%). There was a tendency towards an elevated systemic BP, with a significant increase in diastolic BP (105±13 mmHg at 3500 m versus 98±17 at 2300 m). Tricuspid regurgitation (TR) was detected in 7 dogs at 3500 m compared to 8 dogs at 2300 m. The mean TR V
max was significantly higher at 3500 m, and all 7 dogs had systolic PH at 3500 m (33.6–54.8 mmHg), when PH was defined as TR V
max  2.8 m/s, i.e. a peak pressure gradient >30 mmHg. Hence, in dogs, increasing altitude and the concomitant hypoxia result in a progressively more pronounced PH and an elevated systemic BP. Intermittent severe hypoxaemia of around 50 mmHg may not cause erythrocytosis in healthy dogs, even over a prolonged period. |
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| Keywords: | blood pressure dogs erythrocytosis exercise high altitude hypoxia pulmonary hypertension tricuspid regurgitation |
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