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Multiple atrial dysrhythmias in a horse
Journal of the American Veterinary Medical Association
|October 15, 1980
Summary
A 5-year-old Quarter Horse experienced various atrial dysrhythmias unresponsive to common treatments. Postmortem examination revealed atrial lesions characterized by myocytolysis and fibrosis, suggesting a potential underlying cardiac pathology.
Area of Science:
- Cardiology
- Equine Medicine
- Veterinary Pathology
Background:
- Atrial dysrhythmias are common cardiac arrhythmias in horses.
- Treatment of equine atrial dysrhythmias can be challenging, with variable responses to medications.
- Understanding the underlying pathology is crucial for effective management.
Observation:
- A 5-year-old Quarter Horse gelding presented with multiple atrial dysrhythmias, including paroxysmal atrial tachycardia, atrial fibrillation, and atrial flutter.
- Initial treatments with quinidine and propranolol failed to restore normal sinus rhythm.
- Digoxin therapy temporarily re-established sinus rhythm but was followed by a recurrence of atrial dysrhythmia.
Findings:
- Necropsy revealed multiple pale areas in the atria and interatrial myocardium.
- Histologic examination identified myocytolysis and replacement of cardiac tissue by fibrous connective tissue in these lesions.
- These findings suggest a degenerative or inflammatory process affecting the atrial myocardium.
Implications:
- The atrial lesions may represent the primary cause of the refractory atrial dysrhythmias in this horse.
- Further research into the etiology of such myocardial lesions in horses is warranted.
- This case highlights the importance of thorough postmortem examination in diagnosing complex cardiac conditions in equine patients.