Evaluation of the pathogenesis of vagus indigestion in cows with traumatic reticuloperitonitis

OBJECTIVE--To evaluate the functional importance of impaired reticular contractions attributable to inflammatory adhesions in the pathogenesis of vagus indigestion in cows with traumatic reticuloperitonitis (TRP). DESIGN--Case control study. ANIMALS--42 dairy cows with TRP were compared with 10 healthy control cows. Cows with TRP were assigned to 3 groups: cows with uncomplicated TRP (n = 15), cows with TRP and a disturbance of digesta passage through the reticular-omasal orifice (TRP-AD; n = 17), and cows with TRP and a disturbance of digesta passage through the pylorus (TRP-PD; n = 10). PROCEDURE--Cows were evaluated, using routine clinical methods, biochemical analysis of blood and ruminal fluid samples, exploratory rumenotomy, and postmortem examination. RESULTS--Damage of thoracic and abdominal parts of the main vagal branches were not evident in cows with TRP. Parareticular inflammatory adhesions were more extensive in cows with TRP-AD and in cows with TRP-PD than in cows with uncomplicated TRP. Reticular motility was decreased in cows with TRP-AD and TRP-PD, compared with cows with uncomplicated TRP and control cows. In contrast to cows with uncomplicated TRP and cows with TRP-AD, the abomasum was impacted with large amounts of long fibrous material in most of the cows with TRP-PD. CLINICAL IMPLICATIONS--We believe that disturbances of digesta passage in cows with TRP represent distinct stages of a common pathogenetic course. The primary disease mechanism was a disturbance in particle-separating processes in the reticulum/rumen attributable to mechanical inhibition of reticular motility that was the result of extensive inflammatory parareticular adhesions.