Abstract

Myopathies are found in many species ranging from mammals to fish. A bilaterally symmetrical myopathy was observed in a collection of seahorses at the Toronto Zoo since 2004. All myopathy lesions are localized in the nuchal region of the axial musculature. Under light microscopy, the lesions are characterized by hypereosinophilia, myodegeneration and necrosis of myofibers with a variable degree of inflammatory cell infiltrate and regeneration. These lesions were suspected to be of a nutritional etiology due to the symmetrical presentation and absence of a pathogen. A number of dietary supplements and methods of feed administration were attempted to address the problem. Upon implementation of a supplementation program in the population of affected seahorses in late 2004, mortalities associated with myopathies declined over the next months and finally disappeared in 2005. Two separate incidents in 2006 and 2009 resulted in prolonged periods without dietary supplementation and the subsequent return of characteristic lesions. Evidence to date suggests that the myopathy observed was due to a nutritional etiology.

Acknowledgements

The author would like to thanks the Toronto Zoo and the Endangered Species Fund for support and funding of this research.