In cases of cardiac failure in dogs, what is the immediate action for a dyspneic dog with a murmur and ventral lung edema?

In cases of cardiac failure, a dyspneic dog presenting with a murmur and ventral lung edema indicates a significant pulmonary congestion, likely due to heart failure. The immediate action should be to relieve the respiratory distress and fluid accumulation. Performing thoracocentesis is particularly effective in this scenario because it allows for the removal of excess fluid in the pleural space if pleural effusion is contributing to respiratory distress. By reducing the pressure in the thoracic cavity, thoracocentesis can facilitate breathing and improve oxygenation.

Additionally, while providing supplemental oxygen is crucial in supporting the dog’s breathing and ensuring adequate tissue oxygenation, it does not directly address the underlying issue of fluid accumulation that is impairing respiratory function. Administering diuretics can help manage fluid overload, but their effects are not immediate; they take time to work. Starting intravenous fluids is counterintuitive in cases of cardiac failure where fluid overload is often a problem. Therefore, thoracocentesis is typically the most urgent and effective immediate action to alleviate respiratory distress in this specific context.