Nocardiosis in domestic ferrets (Mustela putorius furo).

Abstract

Nocardia spp are ubiquitous, gram-positive, variably acid-fast, branching and beaded filamentous, facultative intracellular bacteria that are resistant to phagocytosis and can cause localized or systemic disease in a variety of mammals, including humans, as well as in birds, fish and reptiles. Seventeen pet domestic ferrets (Mustela putorius furo) were diagnosed with nocardiosis by several methods including cytological evaluation, histopathology, Ziehl-Neelsen staining and polymerase chain reaction (PCR). All except two ferrets were 2 years old or older at the time of clinical presentation. Clinical findings included anorexia, weight loss, lymphadenomegaly, splenomegaly, masses/nodules in internal organs, hindlimb weakness or paresis, vomiting, dyspnoea, central nervous system signs, diarrhoea, abdominal pain and coughing. Anaemia, leucocytosis, neutrophilia, hypoalbuminaemia and hyperglobulinaemia were frequent. All ferrets had granulomatous or pyogranulomatous inflammation involving most commonly the lymph nodes, spleen, lungs, liver and adipose tissue. Intralesional acid-fast, branching filamentous bacilli were detected in 15 of 17 ferrets. PCR for the 16S rRNA gene of Nocardia spp was positive in 13 of 15 ferrets, including the two that were negative by acid-fast staining; of these two ferrets, one had intralesional coronavirus antigen. BLASTn analysis of eight sequences revealed six different Nocardia spp, including N. globerula, N. seriolae and N. donostiensis, that have rarely been reported to cause disease in humans and terrestrial animals. Antibiotic treatment (most commonly trimethoprim-sulfamethoxazole alone or in combination with clarithromycin and marbofloxacin) was followed by a marked improvement in several patients, although relapses were frequent. Six ferrets had concurrent neoplasia as a potential predisposing factor. Nocardiosis should be included in the differential diagnosis of granulomatous/pyogranulomatous inflammation in ferrets, particularly in those over 2 years of age.