Pancreatitis Is an Important Feature of Broilers Suffering from Inclusion Body Hepatitis Leading to Dysmetabolic Conditions with Consequences for Zootechnical Performance.

The aim of the present study was to further unravel the pathophysiologic mechanisms of inclusion body hepatitis (IBH). In a first trial, the susceptibility of specific-pathogen-free (SPF) broilers to fowl aviadenovirus (FAdV) infections was investigated. Regardless of viral dose, route of infection, and susceptibility to disease on day 1, the 3-week-old SPF broilers showed resistance to IBH, with no mortality being recorded throughout the experiment. In a second trial, SPF broilers were orally infected at 3 weeks of age with a FAdV-E strain, and their digestive and metabolic processes were monitored. The birds' performance decreased from 7 days postinfection (dpi) onward, and hepato- and pancreatomegaly were found at necropsy at 4, 7, and 10 dpi and at 7 dpi, respectively. Clinical chemistry revealed transient hyperlipasemia at 4 dpi and hyperglycemia from 4 dpi onwards, with 25% of infected birds showing glycemia levels suggestive of diabetes mellitus. Histopathology findings included typical adenoviral hepatitis in the liver, while in the pancreas, inflammation characterized by multifocal infiltrations of lymphocytes, together with shrinkage of acinar cells, loss of acinar arrangement, and hyperplasia of islet cells, was noticed. Additionally, the pancreatic tissue had tendentiously lower levels of enzyme activity, and in the ileum, the digestibility of fat was significantly impaired. Hence, our data reinforce the concept of age-related resistance to experimentally induced IBH. Additionally, we demonstrated that FAdV-induced pancreatitis in broilers interferes with the digestive process and evolves into a dysmetabolic condition that resembles diabetes, affecting the health and zootechnical performance of birds, and therefore providing an important component of IBH pathogenesis.