Lung Inflammation Associated With Clinical Acute Necrotizing Pancreatitis in Dogs

Although dogs with acute necrotizing pancreatitis (ANP) can develop respiratory complications, there are no data describing lung injury in clinical cases of ANP in dogs. Therefore, we conducted a study to characterize lung injury and determine if pulmonary intravascular macrophages (PIMs) are induced in dogs with ANP (n = 21) compared with control dogs (n = 6). Two pathologists independently graded histologic sections of pancreas from clinical cases to characterize the severity of ANP (total scores of 3-10) compared with controls showing histologically normal pancreas (total scores of 0). Based on histological grading, lungs from dogs with ANP showed inflammation (median score, 1.5; range, 0-3), but the scores did not differ statistically from the control lungs (median score, 0.5; range, 0-2). A grid intersects-counting method showed an increase in the numbers of MAC387-positive alveolar septal mononuclear phagocyte profiles in lungs of dogs with ANP (ratio median, 0.0243; range, 0.0093-0.0734, with 2 outliers at 0.1523 and 0.1978) compared with controls (ratio median, 0.0019; range, 0.0017-0.0031; P < .0001). Only dogs with ANP showed labeling for von Willebrand factor in alveolar septal capillary endothelial cells, septal inflammatory cells, and alveolar macrophages. Toll-like receptor 4 and interleukin 6 were variably expressed in alveolar macrophages and septal inflammatory cells in lungs from both ANP and control dogs. Inducible nitric oxide synthase was detected in alveolar macrophages of dogs with ANP only. These data show that dogs with ANP have lung inflammation, including the recruitment of PIMs and expression of inflammatory mediators.