Disseminated bovine tuberculosis in a wild red fox (Vulpes vulpes) in southern Spain

A wild-caught, adult red fox (Vulpes vulpes) from Doñana National Park (southern Spain), in very poor condition, died during anesthesia. At necropsy, the submandibular, retropharyngeal, mediastinal, axillary, mesenteric, and popliteal lymph nodes were enlarged, and the right submandibular and mesenteric lymph nodes had hard, white-colored concretions (calcifications). Multiple white pinpoint foci were observed in the lungs, and abscesses were present in the left dorsal lung lobes. No lesions were seen in tonsils, liver, or spleen. On histopathology multiple tuberculous granulomas, with Ziehl-Neelsen-positive bacilli, were observed in the lung, and multifocal necrotic areas with calcification were present in the submandibular and mesenteric lymph nodes. Nucleic acid amplification from lymph node samples demonstrated the presence of mycobacteria belonging to the Mycobacterium tuberculosis complex. One strain was isolated by culture and identified as Mycobacterium bovis. The suspected route of infection was oral, probably after repeated scavenging of infected wild ungulate carcasses. This is the first report of generalized bovine tuberculosis (bTB) in a wild canid. This finding raises concerns about bTB as a disease risk for protected species, livestock, and humans in Mediterranean Spain.