Normal Lung Sounds:

• Normal lung sounds are quiet breath sounds

Abnormal Respiratory Sounds:

• Animals with upper respiratory tract disease can have increased sounds from the nasal passages, pharynx, or trachea. These sounds can be referred to the lower airways and mask pulmonary parenchymal sounds.
• Pulmonary crackles can be ausculted due to fluid in/around the airways – this can be secondary to cardiac failure (left sided) or inflammation.
• Pulmonary wheezes are due to abnormal airway diameter (e.g. bronchitis or asthma conditions).
• Friction rubs are not common in small animals. These are scratchy sounds that change with respiration and are due to fibrin present on the pleural surfaces of chest wall, lungs, or pericardium