BIOLOGICAL CONSEQUENCES OF HYPOXIC STRESS ON WORKING DOGS - EXPEDITION LICANCABUR-CHIENS-DES-CIMES - CHILE APRIL 1996

Scientific litterature provides numerous informations concerning the b iological effects of altitude hypoxia in Humans, but none in dogs. The aim of the present study was to consider search and rescue ions worki ng at an altitude of more than 5 000 meters, without any acclimatation period, as a model for cellular hypoxic stress. All racing dogs, and especially sled dogs, are facing a high level of metabolic stress, inc luding cellular hypoxia related to vasoconstriction problems and/or la ck of oxygen transportation to deep muscle cells. The ''Licancabur - C hiens des cimes'' expedition was organized in april 1996 in Chile; the main reason for this choice is that tie volcano Licancabur (Atacama d esert, north of Chile) culminates at 5 980 meters in altitude and can be reached, for its lower part (4 600 meters) in less tha 24 hours aft er leaving. France. This allowed the expedition to be in high altitude without any acclimatation time, enhancing the biological effects of a cute altitude hypoxia. Members of the expedition were : 5 search and r escue teams from the Paris Fire Department (military unit); 5 search a nd rescue reams from the Carabinieros de Chile (military unit); 1 MD, 1 Vet (authors) and 2 dog behaviour specialist from La Sorbonne Univer sity Paris; 12 other people in charge of the pratical organization, in cluding specialized guides. To study the effects of nutrition on the h ypoxic stress related modifications, the jogs were divided into the gr oup : 5 dogs received a standard dry food, non premium maintenance typ e; 5 dogs received a high stress diet basicly designed for racing sled jogs, a premium 35/25 dry food, supplemented with vitamins E and C, a nd with omega 3 fatty acids. Observations and blood samples have been realized at the following levels of altitude : sea level; 2 300 meters (San Pedro de Atacama); 4 500 meters (base camp); 5 750 meters (maxim um altitude reached). At each level of altitude the dugs have been wor king by having to search 2 victims in local Inca ruins, before beeing sampled. Blood sampled have been imediatly centrifuged. and frozen, ex cept for the quantities necessary to on site analyses. Back to Paris, the following parameters have been analyzed : membran resistance to li poperoxydation in tertiobutylperoxyde; blood free fatty acids; blood a lkanes; blood vitamins E and C; plasma cortisol; plasma antioxydant tr ace elements. The results of the present protocole clearly demonstrate the interest of an antioxydant supplemenation in such hypoxic conditi ons. They also show that stamina in acute hypoxia is a good spontaneou s model for cellular oxidative stress, also involved in elderness proc ess, in some cardiovascular pathologies, in tumors proliferation and i n... sport physiologic. On a pratical point of view we were also able to better understand and prevent in the future the consequences of acu te mountain sickness in working dogs. Following the first expedition w ill be other ones already scheduled and starting in 1998, on top of th e Aconcagua in Argentina.