Etiologias da icterícia e diagnóstico diferencial prospectivo em 84 cães

Abstract

Icterus is a yellowish discoloration developed from the bilirubin deposition, in tissues abundant in elastin, due to its high plasmatic concentration. It occurs in metabolism changes or bilirubin excretion and it is classified in pre-hepatic, hepatic and post-hepatic. Pre-hepatic icterus is a result of intra- or extravascular hemolysis by infectious or immune-mediated forms. The hepatic jaundice is a consequence of extensive liver damage. Post-hepatic form is usually secondary to partial or complete bile duct obstruction in cholelithiasis or neoplasms. The aim of this study was to evaluate and classify different icterus causes in dogs necropsied between 2014 and 2017, associating macroscopic and histologic changes as well as ancillary tests. Eighty four dogs were analyzed macro- and microscopically and separated in groups of icterus causes; 22 (26,2 %) dogs had pre-hepatic icterus, 48 (57,1%) hepatic, 13 (15.5%) pre-hepatic and hepatic and one (1.2%) with post-hepatic icterus. The hematological exam detected moderate anemia with severe leukocytosis and thrombocytopenia. The biochemical exam detected azotemia in most of the dogs with high increase in the sera levels of the hepatic enzymes, as alkaline phosphatase (AP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT). Many factors were identified as the cause of icterus and the main factors were infectious agents (47/84), neoplasms (13/84), degenerative changes (12/84), chronic changes (6/84) and obstructive cause (1/84). The most frequent infectious causes were leptospirosis (40/84) and ehrlichiosis (7/84). Neoplastic causes include cholangiocarcinoma (5/84), hemangiosarcoma (4/84) and lymphoma (2/84). Degenerative changes were lipidosis (9/84) and glycogen (3/84) degeneration. Hepatic fibrosis (cirrhosis) (6/84) was the most frequent chronic changes and cholelithiasis (1/84) was diagnosed once as obstructive cause. PCR was performed to confirm Leptopira interrogans e Ehrlichia canis infections. DNA of Leptospira interrogans was amplified in 37 dogs, which four had coinfection with Ehrlichia canis. The classification and identification of icterus causes in dogs are very important due to the number of diseases with this alteration, frequently without ante-mortem diagnosis.