Atypical systemic mycobacteriosis in Hermann's tortoises (Testudo hermanni)

Background: Hermann's tortoise (Testudo hermanni) is a near threatened species found throughout southern Europe. Captive breeding of endangered species is subject to health risks, such as the stress of captivity and ambient conditions that may favor the emergence of infectious diseases. An episode of systemic atypical mycobacteriosis was investigated in six Hermann's tortoises from a captive population. The symptoms appeared in the form of anorexia, weakness, and lethargy, with inflammatory and edematous lesions of the hind limbs and tail. Four of the affected tortoises were euthanized and necropsied. Methods: Blood samples and joint aspirates were obtained for assessment. Euthanasia of four affected animals was performed. Postmortem examination included necropsy, histopathology, and mycobacterium detection by culture and polymerase chain reaction (PCR). In the other two animals, only hematology and blood biochemistry was carried out. Results: Hematological and blood biochemistry analyses gave inconsistent results. In joint aspirates, mononuclear cells with phagocytozed bacillary structures were observed. Ziehl-Neelsen stain revealed the presence of acid-fast bacteria. Granulomatous lesions were observed in liver, lungs, spleen, heart, muscle, kidney, and ovaries. Culture and identification were positive for mycobacteria and molecular sequencing led to the identification of Mycobacterium nonchromogenicum. Conclusions and clinical relevance: Although mycobacteriosis is rare in reptile collections, strict hygienic and prophylactic measures in species of high ecological value must be performed, especially if the animals are to be used for reintroduction projects.