Myocardial degeneration and fibrosis

Etiology:  There are several factors thought to predispose rats to this condition including chronic myocarditis or myocardial ischemia.  Age and the concomitant development of chronic progressive nephropathy may also contribute.

Incidence:  Incidence is common, especially in SD rats.  Older males are more commonly affected.

Clinical Signs:  Usually there are no clinical signs.

Pathology:  Grossly, there may be multifocal grey lesions in the left ventricle.  Histologically, there is myocardial atrophy, necrosis and collagen deposition (fibrosis) with interstitial infiltration with mononuclear cells [3].

Diagnosis:  Diagnosis is made based on histopathologic findings.

Myocardial degeneration and fibrosis

3.            The Laboratory Rat, ed. M.A. Suckow, Weisbroth, Steven H., Franklin, Craig L.2006, 30 Corporate Drive, Suite 400, Burlington, MA 01803 Elsevier.