Microscopic lesions in the hearts of aged horses and mules.

The research paper conducts an in-depth study of heart diseases in older horses and mules, with the major findings including various forms of heart changes and conditions such as arteriolosclerosis, myocarditis, myocardial fibrosis, and others.

Research Methodology

• The researchers examined the hearts of 23 older equids, which comprised 18 horses and 5 mules.
• The examination was done histologically, which involved studying the microscopic anatomy of the heart tissues to identify any diseases or abnormalities.

Major Findings

• The major findings of the histological examination included several types of heart diseases and conditions, including arteriolosclerosis (hardening of the small arteries), and intimal bodies in small muscular arteries.
• Other conditions such as myocarditis (inflammation of the heart muscle), myocardial fibrosis (scarring of the heart muscle), fatty metamorphosis of myocardial and Purkinje fibers (fatty changes in heart and conduction cells), myocytolysis (breakdown of heart muscle cells), and mucinous degeneration of myocardium (blue staining, gel-like changes in heart muscle) were also identified.

Less Frequent Findings

• Less commonly identified diseases included chronic fibrotic valvulitis (long-term inflammation and scarring of heart valves), acute myocardial necrosis (sudden death of heart muscle cells), sarcosporidiosis (protozoal infection affecting the muscle tissue), and hemosiderosis (excessive iron build-up in the body).
• A single case each of malignant melanoma (cancer), cartilaginous metaplasia of the I-V septum (transformation of cells in the wall dividing the lower chambers of the heart), mineralization of connective tissue in the I-V septum (hardening of tissues in the heart wall), and an aneurysm of the left ventricular apex (swelling in the lower left chamber of the heart) were also found.

Correlations

• In some instances, the researchers were able to make correlations between pathological findings (diseases detected at the tissue level) and clinical findings (symptoms and signs observed in the animals).
• Purkinje fibers, which are essential for the conduction of electric signals within the heart, were found in both atria (upper chambers) of the heart, indicating potential conduction abnormalities.