Research Communications of the 27(th) ECVIM-CA Congress: Intercontinental, Saint Julian's, Malta, 14th to 16th September 2017

Disclosures: No disclosures to report. Chronic pancreatitis (CP) is common in the English Cocker Spaniel (ECS), and is characterized histologically by duct destruction, interlobular fibrosis and dense periductular and perivenous lymphocytic aggregates. These changes are characteristic of human autoimmune pancreatitis type 1, part of a steroid-responsive, multi-organ syndrome, newly recognized as IgG4-Related Disease (IgG4-RD). Human IgG4-RD affects one or several organs, often showing a predominance of IgG4+ plasma cells histologically, with an IgG4+/total IgG+ plasma cell ratio >40%. This study investigated whether ECSs with CP and inflammatory disease in several organs show an increase in IgG4+ plasma cells within affected tissues. Histological sections of pancreas (n = 12), liver (n = 10), kidney (n = 12), salivary gland (n = 4), anal sacs (n = 9), and conjunctiva (n = 2) were obtained from 37 ECSs with idiopathic chronic inflammatory disease affecting those tissues. Control samples were identified from 18 agematched dogs of other breeds with chronic pancreatitis (n = 6), chronic idiopathic hepatitis (n = 2), chronic nephritis (n = 6), anal sacculitis (n = 5), chronic sialadenitis (n = 2) or chronic conjunctivitis (n = 1). Eleven ECSs and 6 control dogs presented with disease in more than one organ. Immunohistochemistry was performed for canine total IgG and IgG subclasses (IgG2, IgG3, and IgG4). Normal tissue sections were labeled as controls. The number of plasma cells was counted in three high power fields (9400). The number of IgG4+ cells and the percentage of total IgG+ plasma cells were compared between groups using Mann-Whitney U tests.