When are crackles typically heard in a canine?

Crackles, also known as rales, are abnormal lung sounds that are typically associated with the presence of fluid in the airways or alveoli, which can occur due to various pulmonary conditions such as pneumonia, congestive heart failure, or pulmonary edema. In canines, crackles are most commonly heard during inspiration.

This is because as the dog inhales, air is drawn into the lungs, and when it passes over or through fluid-filled areas, it produces the characteristic popping or crackling sound. These sounds indicate that there may be underlying issues affecting the normal air exchange in the lungs and can signal the need for further investigation or medical intervention.

While crackles can be influenced by the respiratory cycle, they are distinctly identifiable as a sign of pathology during the inspiratory phase, correlating with the movement of air through compromised lung tissue.