Development of pericardial mesothelioma in golden retrievers with a long-term history of idiopathic haemorrhagic pericardial effusion.

This report describes the development of pericardial mesothelioma in five golden retrievers with a long-term history of idiopathic haemorrhagic pericardial effusion (IHPE). These five dogs were treated with repeated pericardiocentesis for recurrent episodes of pericardial fluid accumulation; other than IHPE, all potential causes of this fluid accumulation were ruled out by the results of diagnostic imaging and cytology and bacterial or fungal culture of fluid obtained during pericardiocentesis. In three dogs that eventually underwent pericardiectomy, neoplastic lesions were not detected in any organs or tissues within the thoracic cavity during the surgical procedure, and the surgical biopsies were consistent with IHPE. In one of the three dogs, however, cytology of recurrent thoracic effusion revealed clusters of neoplastic mesothelial cells from 1 month after surgical intervention until death. The clinical course of the disease ranged from 30 to 54 months between the first visit and death, and on post-mortem examination pericardial mesothelioma was diagnosed in all five dogs. The clinical observations, together with the breed and age of the affected animals, suggested that the five dogs initially suffered from IHPE, which was then followed by the development of pericardial mesothelioma. It is possible that IHPE is associated with the development of pericardial mesothelioma in golden retrievers through a chronic inflammatory process.