Scoliosis in a Tiger Salamander (Ambystoma tigrinum) Associated with Encysted Digenetic Trematodes of the Genus Clinostomum

A group of 202 tiger salamanders (Ambystoma tigrinum) was brought into captivity due to habitat destruction. Half of these animals died, over two mo, showing generalized hemorrhages compatible with an infectious disease, but an etiologic agent was not determined. Encysted metacercarial stages of trematodes within the skeletal musculature, coelomic cavity, and subcutaneous space were additional necropsy findings. One salamander had scoliosis and multiple skin nodules. A radiograph showed no skeletal abnormality to explain the scoliosis; however, numerous round nodules were more radiodense than the surrounding tissue. A presumptive diagnosis of generalized trematodiasis was made, yet the salamander did not improve after a course of praziquantel and subsequently died. Necropsy revealed massive, encysted trematode infection. Histologic examination revealed marked multifocal intramuscular, subcutaneous, and coelomic trematodiasis with associated necrosis and inflammation. Based on gross morphology, the trematode was identified as a member of the genus Clinostomum.