Diagnosis and treatment of cardiac arrhythmias.

The research article discusses the frequency of cardiac arrhythmias (irregular heartbeats) in horses, detection methods, as well as treatment options. Specifically, the authors provide a thorough investigation into the types of diagnosis and antiarrhythmic therapy given for these conditions.

Cardiac Arrhythmias in Horses

• The authors begin by noting that horses are more likely to have cardiac arrhythmias than any other domestic animal species. The main clinical symptom associated with such irregularities is exercise intolerance, making physical activity challenging.
• The arrhythmias can be characterized by fast or slow heart rate, long pauses between beats, additional sounds, or abnormal heart sounds which are usually detected via auscultation during a physical examination.

Diagnosis of Cardiac Arrhythmias

• To confirm these irregularities, the authors state that an electrocardiogram (ECG) is used to definitively diagnose the type of dysrhythmia present.
• Apart from the ECG, other laboratory and cardiac function tests are also utilised to find out the cause and determine the significance or severity of the arrhythmia.

Treatment of Cardiac Arrhythmias

• Antiarrhythmic therapy is recommended when clinical signs directly related to the arrhythmia are noticed, if the arrhythmia compromises hemodynamic parameters (the physical factors that contribute to overall cardiovascular function), or if the ECG shows abnormalities that could result in more severe arrhythmias.
• The frequently used cardiovascular drugs are digoxin and quinidine. Digoxin is mostly prescribed for supraventricular arrhythmias (those that originate in the atria or atrioventricular node), especially those characterised by fast heart rates.
• Quinidine, on the other hand, is effective for short-term treatment of both ventricular and supraventricular arrhythmias. However, caution is advised due to the potential for toxic side effects.

Arrhythmias Due to Vagal Tone

• The study also touches on horse cardiac arrhythmias due to vagal tone, such as sinus arrhythmia, sinus block, sinus arrest, sinus bradycardia, wandering pacemaker, first and second-degree AV block. These are usually found in resting horses, considered normal and generally do not require treatment.