Case 1

Signalment

• 7 year old
• Male neutered
• Domestic short haired cat

History

• Fully vaccinated
• Sudden death at home
• No other clinical abnormalities

Gross Pathology

Hypertrophic cardiomyopathy (cat). Courtesy of T. Scase

The following data and pictures were taken at post-mortem examination:

Cardiovascular system:

• Heart has a globoid shape
• Ventricular wall measurements:
  • Interventricular septum; 12mm
    

    Hypertrophic cardiomyopathy (cat). Courtesy of T. Scase
  • Right ventricular wall; 3mm
  • Left ventricular wall; 10mm
• Pericardium is fatty, shiny and intact

No embolic thrombi were found in the abdominal aorta.

The other body systems were examined.
No further abnormalities were found.

Histopathology

Histology; hypertrophic cardiomyopathy. Courtesy of K. Hughes

Samples were taken for histological examination (Stained with H and E):

• The cardiac myocytes are multifocally widely spaced and infiltrated by streams of spindle shaped cells (fibroblasts).

Histology; Massons Trichrome. Courtesy of K. Hughes

Some sections were stained with Massons Trichrome:

• This confirmed the presence of large, multifocal areas of fibrosis within the inner third of the myocardium and extending to the endocardial surface.
• Multifocally the fibrosis surrounds individual atrophied myocytes.
• There is mural thickening (smooth muscle hypertrophy) of the intramyocardial arteries.

Diagnosis

The gross post mortem findings indicated a severe hypertrophic cardiomyopathy which was confirmed on histology.

The fibrosis seen is a common sequale to this type of disease. The hypertrophy in the ventricular wall limits blood supply to the inner third of myocardium. Reduced perfusion stimulates replacement of degenerate myocytes with fibrous tissue, extending into the endocardium.