Canine idiopathic pulmonary fibrosis (CIPF) is a chronic, progressive, interstitial lung disease affecting mainly middle-aged and old West Highland white terriers. Other dogs, especially terriers, have been diagnosed with the disease. The cause is largely unknown, but it is likely to arise from interplay between genetic and environmental factors. CIPF shares several features with human idiopathic pulmonary fibrosis. This article summarizes the current literature; describes the findings in physical examination, arterial blood gas analysis, bronchoscopy, bronchoalveolar lavage, diagnostic imaging, and histopathology; compares the canine and human diseases; gives an overview of potential treatments; and discusses biomarker research.