Pulmonary atelectasis in a young dog with Cor pulmonale: clinical and radiographic follow-up.

Pulmonary atelectasis is a disease characterized by the collapse of the pulmonary alveoli, leading to partial or total loss of function in the affected lung, and is mostly described in older dogs. It occurs due to chronic inflammatory and obstructive processes such as pneumonia. In infants who do not feed directly from the mother, it is common to develop aspiration pneumonia due to inhalation of a milk replacer.