Is Taenia crassiceps Cysticercosis a Threat to Dogs? Description of Macro- and Microscopic Lesions in a Dog. Case Report and a Review of the Literature

<i>Taenia crassiceps</i> is a cestode capable of causing severe and atypical cysticercosis in accidental intermediate hosts, including domestic dogs. Here we report a fatal disseminated <i>T. crassiceps</i> infection (cystiscercosis) in a 4-year-old castrated male German Shepherd from Poland that had been undergoing long-term prednisone therapy for Addison's disease. The dog developed multiple soft subcutaneous nodules containing numerous asexually proliferating cysticerci. Necropsy revealed extensive dissemination of larvae throughout the subcutis and the thoracic and abdominal cavities, accompanied by serosanguineous effusions, necrosis, and chronic inflammatory lesions. Histological examination demonstrated cestode larvae with a scolex bearing two rows of hooks, consistent with <i>T. crassiceps</i>. Immunosuppression and endocrine alterations, including chronic glucocorticoid treatment and low levels of testosterone, likely promoted rapid asexual proliferation of larvae. A literature review shows that although dogs are definitive hosts of <i>T. crassiceps</i>, immunosuppressed individuals may also serve as accidental intermediate hosts. Early cytological evaluation of subcutaneous nodules may facilitate faster diagnosis and treatment decisions. Given the zoonotic potential of <i>T. crassiceps</i> and the increasing number of European cases, this parasitic infection should be considered in the differential diagnosis of subcutaneous nodules in immunosuppressed dogs. The presented case underscores its epidemiological relevance within the One Health framework.