Here are the key differences between the two types:
Physiological Heart Murmur
Cause: Physiological murmurs are caused by normal turbulent blood flow in a healthy heart. They may be due to increased blood volume during exercise or excitement.
Characteristics of Murmur: They are generally soft and low-pitched.
They may vary in intensity with heart rate and often disappear or change characteristics with exercise or stress.
They are most common in young, trained horses.
Location and Timing: They are often best heard on the left side of the chest, over the area of the left ventricle.
They occur during systole (when the heart contracts).
Impact on Performance: They do not usually affect the horse’s performance.
They are not associated with clinical signs of heart disease.
Diagnosis: They are usually diagnosed by auscultation (listening with a stethoscope) and do not require additional treatments.
Echocardiograms and electrocardiograms can be used to confirm that there are no underlying abnormalities.
Pathological Heart Murmur
Cause: Pathological murmurs are caused by structural abnormalities in the heart, such as valve defects, cardiomyopathies, or septal defects.
Characteristics of the Murmur: They tend to be louder and have a higher pitch or harsher tone.
They may be continuous or present in both systole and diastole.
They do not change or disappear with exercise or stress.
Location and Timing: They may be heard in different areas of the chest, depending on the valve or structure affected.
They may occur during systole, diastole, or both, depending on the type of defect.
Impact on Performance: They may be associated with signs of heart failure or reduced performance.
They can cause lethargy, exercise intolerance, or even collapse in severe cases.
Diagnosis: They require further evaluation, including echocardiograms, electrocardiograms, and possibly other advanced studies such as angiography.
Treatment depends on the underlying cause and may include medical management, exercise restriction, or surgical interventions in severe cases.
Summary The main difference between a physiological and a pathological heart murmur in sport horses is that physiological murmurs are benign and do not affect the health or performance of the horse, while pathological murmurs indicate a structural abnormality of the heart that can affect the health and performance of the horse. A careful veterinary evaluation is essential to determine the type and cause of the murmur and to establish appropriate management.
