Comparison of abomasal luminal gas pressure and volume and perfusion of the abomasum in dairy cows with left displaced abomasum or abomasal volvulus

Objective - To compare abomasal luminal gas pressure and volume and perfusion of the abomasum in dairy cows with a left displaced abomasum (LDA) or abomasal volvulus (AV). Animals - 40 lactating dairy cows (25 with an LDA and 15 with an AV). Procedure - Abomasal luminal gas pressure and volume and pulse oximetry values for the caudal portion of the dorsal ruminal sac and abomasal wall were measured during laparotomy. Abomasal perfusion was assessed on the basis of abomasal O₂ saturation (pulse oximetry) before correction of the LDA or AV. Abomasal perfusion was also assessed after correction of the LDA or AV by measuring venous O₂ saturation in the right gastroepiploic vein and calculating the abomasal oxygen-extraction ratio. Results - Abomasal luminal gas pressure and volume were higher in cattle with an AV than in cattle with an LDA. Abomasal O₂ saturation was lower and abomasal oxygen-extraction ratio higher in cattle with an AV, compared with values in cattle with an LDA. In cows with an AV, lactate concentration in the gastroepiploic vein was greater than that in a jugular vein, whereas no difference in lactate concentrations was detected in cows with an LDA. Abomasal luminal gas pressure was positively correlated (r, 0.51) with plasma lactate concentration in the gastroepiploic vein and negatively correlated (r, -0.32) with abomasal O₂ saturation determined by use of pulse oximetry. Conclusions and Clinical Relevance - Abomasal perfusion decreases as luminal pressure increases in cattle with an AV or LDA.