Transconjunctival oxygen index in healthy awake dogs

Transconjunctival oxygen tension (PcjO2) has been used clinically in human beings and experimentally in dogs to evaluate tissue perfusion and to estimate arterial O2 tension (PaO2); however, normal values in awake healthy dogs have not been reported. In this study, transconjunctival oxygen tension and arterial oxygen tension were measured once a week in 6 healthy conditioned dogs (15 to 28 kg) for 8 weeks. The conjunctival oxygen index (PcjO2 index = PcjO2/PaO2) was calculated. Mean PcjO2 index for all dogs was 0.47 +/- 0.08 (X +/- SD). The variability of repeated measurements on the same dog and between dogs was evaluated. A difference (P less than 0.05) in PcjO2 index among dogs was evident, and although there was not a difference in the same dog over time, there was a high coefficient of variability.