## Overview A heave line is the visible hypertrophy of the external abdominal oblique muscle that develops in horses with chronic severe equine asthma (formerly recurrent airway obstruction or heaves). It runs diagonally from the flank toward the elbow and reflects prolonged increased respiratory effort. The underlying disease is an allergic airway inflammation triggered by dust and mold. ## Causes Chronic exposure to airborne allergens causing bronchospasm and mucus accumulation. ## Diagnosis Clinical signs of chronic cough, nasal discharge, and increased respiratory effort, plus the heave line in advanced cases. Endoscopy and bronchoalveolar lavage support the diagnosis. ## Treatment Environmental management (soak hay, maximize turnout, reduce dust) is the cornerstone. Corticosteroids and bronchodilators control inflammation and spasm. ## Recovery and Prognosis The heave line may persist. Clinical signs can be well controlled with strict management, but the condition is usually lifelong. ## Prevention Minimize dust and mold exposure, especially in stabled horses.
visible diagonal muscle ridge on the flank; labored breathing with abdominal effort; chronic cough; nasal discharge; exercise intolerance
## Overview A heave line is the visible hypertrophy of the external abdominal oblique muscle that develops in horses with chronic severe equine asthma (formerly recurrent airway obstruction or heaves). It runs diagonally from the flank toward the elbow and reflects prolonged increased respiratory effort. The underlying disease is an allergic airway inflammation triggered by dust and mold. ## Causes Chronic exposure to airborne allergens causing bronchospasm and mucus accumulation. ## Diagnosis Clinical signs of chronic cough, nasal discharge, and increased respiratory effort, plus the heave line in advanced cases. Endoscopy and bronchoalveolar lavage support the diagnosis. ## Treatment Environmental management (soak hay, maximize turnout, reduce dust) is the cornerstone. Corticosteroids and bronchodilators control inflammation and spasm. ## Recovery and Prognosis The heave line may persist. Clinical signs can be well controlled with strict management, but the condition is usually lifelong. ## Prevention Minimize dust and mold exposure, especially in stabled horses.
visible diagonal muscle ridge on the flank; labored breathing with abdominal effort; chronic cough; nasal discharge; exercise intolerance