Unusual case of pyogranulomatous hepatitis of suspected infectious etiology in a 3-year-old Labrador retriever dog.

A 3-year-old spayed female Labrador retriever dog was presented with clinical signs of lethargy, vomiting, hyporexia, and increased respiratory effort. An exploratory laparotomy was conducted and a liver biopsy submitted for histopathologic evaluation revealed moderate multifocal coalescing pyogranulomatous hepatitis. Clinical signs, hematological parameters, and liver histopathology suggested an infectious etiology, such as leptospirosis, mycobacteriosis, or fungal infection. Polymerase chain reaction (PCR) and immunohistochemistry (IHC) for leptospirosis were negative. The infectious etiology was not identified, but leptospirosis may have played a role in the disease.