2007 Volume 18 Issue 4 Pages 137-144
This study observed the fluctuation of total hemoglobin (tHb) and reduced hemoglobin (dHb) concentrations as a direct reflection of hemodynamics under the hoof wall with near infrared spectroscopy (NIRS). NIRS observation of the laminar layer under the pigmented hoof walls was performed without sedation or invasion on five clinically normal horses. NIRS indexes relating to the concentration change of tHb (tHbindex) and dHb (dHbindex) in tissue were recorded at 2 Hz and evaluated over 0.004 Hz in spectral power. Each NIRS index fluctuated spontaneously and continuously from 0.01 Hz to 0.05 Hz. Over 10 times difference of total power was shown in fluctuations of each NIRS index. Nevertheless, a significant positive correlation was observed between NIRS indexes. In the geometrical distribution of the power spectra from 0.0078 Hz to 0.5 Hz, the sub-band power of the dHbindex dominated the tHbindex in sub-bands with central frequencies of 0.011 Hz and 0.022 Hz. This was interpreted as characteristic of the hemoglobin oxidation-reduction (redox) fluctuation common to forelegs of both sides. NIRS observation based on the second time scale and adapted by spectral analysis was able to evaluate qualitatively the characteristics of spontaneous kinetics of hemoglobin redox regardless of a lack of quantity, suggesting the ability to provide virginal vital signs under hooves.
