Miliary tuberculosis in a captive smooth-coated otter (Lutrogale perspicillata) in South Asia (India)

Background Tuberculosis is rarely observed in smooth-coated otter. This report describes a case of tuberculosis in an Asian smooth-coated otter ( Lutrogale perspicillata ). A ten-year-old male otter that had been raised in a zoological garden was brought in for necropsy. Methods Detailed necropsy was performed. Acid-fast staining on impression smears, histopathology, immunohistochemistry and PCR were performed. Results Gross pathological examination showed multifocal variable sized (1 to 10 mm) white tubercle nodules disseminated over the surface of both lungs and the mesenteric lymph nodes. Tuberculosis was diagnosed by Ziehl–Neelsen staining for acid-fast bacilli on the impression smear from lungs, histopathology, immunohistochemistry and PCR. Histopathologically, no typical granuloma observed. The nodules showed mononuclear cells infiltration in peribronchiolar and perivascular areas along with congestion. Modified Ziehl–Neelsen staining was used to identify acid-fast bacteria in the necrotic foci. Molecular analysis by polymerase chain reaction and immunohistochemistry led to the detection of Mycobacterium tuberculosis complex (MTC). Conclusion Thus based on the cytology, gross, histopathology, IHC and PCR, the disease was confirmed as miliary tuberculosis in a smooth-coated otter.