Cardiomyopathy syndrome in Atlantic salmon (CMS) – Histopathology

CMS in ventricle of Atlantic salmon showing severe myocarditis of spongy layer. Note that the compact layer (on the left) is largely unaffected.

Cardiomyopathy syndrome (CMS) is a severe cardiac disease affecting Atlantic salmon characterized by prolonged periods of usually low-level mortalities. The disease was first recognized in farmed Atlantic salmon in Norway in 1985 and subsequently in farmed salmon in the Faroe Islands, Scotland and Ireland. CMS is a transmissible disease that has been causally linked to the Piscine Myocarditis Virus (PMCV), closely allied to the Totiviridae. CMS usually causes mortality in adult or maturing fish after 12 to 18 months in seawater, resulting in substantial economic...