Fatal Acute Thyroiditis in a Giraffe (Giraffa camelopardalis) Associated with Clostridium perfringens Type A: A "Local Proliferation-Systemic Intoxication" Pathogenic Model.

This report presents the first case of fatal acute thyroiditis associated with Clostridium perfringens type A in a captive giraffe (Giraffa camelopardalis) and describes findings consistent with the proposed "local proliferation-systemic intoxication" pathogenic model. A 5-year-old female giraffe in Hebei Province, China, presented with diarrhea, emaciation, and sudden death. Necropsy revealed marked thyroid enlargement, intestinal mucosal hemorrhage and shedding, and pericardial effusion. C. perfringens type A was isolated from thyroid tissue, and molecular analysis detected the presence of the α-toxin gene (cpa). Immunohistochemistry detected α-toxin antigen immunoreactivity in thyroid, lung, liver, and cardiac tissues. Histopathological examination showed severe disruption of thyroid follicular structures and inflammatory cell infiltration, alongside α-toxin immunoreactivity in multiple organs, including the lungs, liver, and heart. Based on the observed pathological and microbiological findings, we hypothesize a possible pathogenic scenario in which intestinal barrier disruption may facilitate bacterial dissemination and subsequent thyroid colonization. This report expands the known clinical spectrum of C. perfringens infections and provides insights into possible atypical clostridial pathogenic mechanisms in non-classical host species.