Acid-base and blood gas studies in horses. I. A comparison of capillary and arterial blood samples for the estimation of acid-base values in horses.

SUMMARY Arterial and capillary blood samples were collected simultaneously from 12 horses and analysed by the Astrup micromethod to determine pH, Pco2 and (HCO3). The convenience and accuracy of the capillary samples were compared with that of the arterial samples. Mean differences between arterial and capillary values were: + 0·009 ± 0·0194 for pH, — 0·38 ± 2·83 mm.Hg for Pco2, and + 0·46 ± 1.76 meq./L. for (HCO3). It was concluded that the accuracy of the capillary samples was acceptable for clinical investigation only in the case of pH, but not for Pco2 or (HCO3).