Examination of horses with cardiac disease

Examination of Horses with Cardiac Disease

Introduction

A thorough medical history and clinical examination are essential components for the cardiac evaluation in horses. Given that cardiac issues are relatively uncommon in equines compared to other species, it is vital to recognize symptoms early, as clinical signs often manifest only when significant heart dysfunction is present. Potential cardiac diseases may come to attention via routine checks performed during vaccinations or prepurchase evaluations, as well as through specific complaints raised by horse owners. Recognizing the presenting signs is crucial for guiding differential diagnoses.

Key Points

• Comprehensive clinical examinations remain indispensable despite advancements in technologies such as echocardiography. This approach allows for a better understanding of cardiovascular problems within the entire context of the animal’s health.

• Signalment (including breed, age, and sex) provides valuable context for identifying potential cardiac issues, as predisposing conditions can vary among demographics. For example, congenital heart defects may commonly present in certain breeds.

• Proficient auscultation skills are essential for clinicians and improve with consistent practice; additional ancillary tests, such as blood pressure measurement and laboratory evaluations, can offer further insights into the cardiovascular health of the equine.

Signalment and History

Importance of Signalment

Understanding signalment is critical, as different breeds and ages exhibit predispositions to specific cardiac diseases. Noteworthy examples include:

• Aortic Regurgitation: More prevalent in young horses, often noticeable during veterinary checks.

• Ventricular Septal Defects (VSD): Frequently identified in Welsh Section A ponies, highlighting genetic predispositions.

• Congenital Lesions: Certain breeds, such as Arabian horses, have demonstrated marked predispositions for specific heart abnormalities.

• Fistulae: Friesian horses are particularly susceptible to developing aortopulmonary fistulae.

• Stallions: More prone to aortic root fistula development, warranting careful monitoring.

Documenting key background facts along with any presenting symptoms is crucial, particularly if recent abnormal findings arise during assessments.

Clinical Evaluation

The clinical evaluation process must be thorough, encompassing nuances of the whole cardiovascular system and relevant body systems. Evaluating clinical signs, such as dyspnea, weakness, and collapse, should always be contextualized within the understanding of cardiac disease:

• Dyspnea: Consider whether this symptom aligns more closely with cardiac congestion or indicates a primary respiratory issue.

• Peripheral Edema: Notable as a significant indicator that suggests the possibility of congestive heart failure.

Clinical Findings

Peripheral Circulation

Observations regarding peripheral circulation are essential:

• Mucous Membranes: These are critical indicators of overall vascular health; color changes, such as pallor or cyanosis, can signify compromised cardiac function.

• Pulse Assessment: Evaluating pulse characteristics (rhythm, rate, and subjective pulse pressure) aids in assessing cardiac output. Weak pulses may indicate low-output heart failure, while bounding pulses are typically associated with aortic regurgitation.

Central Venous Pressure Assessment

Jugular vein examination provides insights into right atrial pressure:

• Jugular Vein Filling: Normal filling typically reaches approximately one-third up the jugular furrow. A heightened response serves as an indicator of potential congestive heart failure.

• Pulsation in the Jugular Vein: Reflects variations in atrial filling pressures during the cardiac cycle, assisting in the assessment of right heart function.

Cardiac Auscultation

Cardiac auscultation is a critical component in forming differential diagnoses.

• Key Considerations:

  • Heart Rate: Measured at rest (normal range is 28–40 bpm); consistency should be maintained across assessments.

  • Heart Sounds: Attention should be given to normal heart sounds (S1, S2) and their association with murmurs and rhythms, which may indicate underlying cardiac conditions.

  • Regular Rhythm Assessment: Essential for identifying arrhythmias, requiring ECG confirmation for accurate diagnosis.

Arrhythmias and Murmurs

Understanding different types of arrhythmias is fundamental in veterinary cardiology:

• Common Findings: The most frequent finding during auscultation is the second-degree AV block; however, atrial fibrillation may be identified by an irregularly irregular rhythm, warranting ECG evaluation for confirmation.

• Murmur Classification:

  • Physiologic Murmurs: Often related to normal blood flow; typically soft and brief.

  • Pathologic Murmurs: Indicate abnormal blood flow dynamics often resultant from cardiac structural issues:

    • Valve Regurgitation: Commonly leads to murmur generation due to leaky valves.

    • Stenosis: Less frequently seen but may occur in congenital heart defects.

    • Abnormal Communications: Congenital or acquired anomalies leading to turbulent flow and consequent murmurs.

• Distinguishing Murmur Types: Short murmurs suggest mild pathology; longer, continuous murmurs may indicate major structural issues and require comprehensive diagnostics, including blood tests and specialized veterinary evaluations, especially if linked to aortic regurgitation.

Blood Pressure and Laboratory Evaluation

Blood Pressure Measurement

Recent advancements have led to increased emphasis on blood pressure measurement in veterinary practice:

• Measurement Methods: Blood pressure can be measured directly (invasive) or indirectly (non-invasive). Indirect methods usually suffice for standing horses but can sacrifice accuracy.

• Pulse Pressure Assessment: Correlates with specific conditions, including aortic regurgitation, which may significantly influence prognosis.

Laboratory Tests

Routine evaluations in hematology and biochemistry may show minimal alterations in horses with cardiac issues. However, certain specific markers, such as cardiac troponins, have demonstrated diagnostic potential:

• Continued research is warranted to better understand the implications of myocardial damage through these biomarkers, providing further insights into equine cardiac health and athletic performance impacts.

Conclusion

Techniques and a comprehensive understanding of equine cardiac evaluations are critical for effective diagnosis and management of cardiovascular diseases in horses. Advancements in diagnostic techniques necessitate thorough initial assessments coupled with ongoing follow-ups using tools such as echocardiography, blood pressure evaluations, and laboratory tests to ensure best practices in the field of veterinary cardiology.