Diagnostic imaging is a key component in the care of companion animal patients. In recent decades the available imaging modalities have expanded from conventional radiography to include ultrasonography, computed tomography and magnetic resonance imaging and all are employed on a daily basis in both general and specialty veterinary practice. The transition from film screen radiography to digital radiography has transformed veterinary practice by making diagnostic radiography quicker, easier and cheaper and facilitates rapid transmission, sharing and interpretation of images. The Atlas of diagnostic imaging of dogs and cats provides a broad overview of diagnostic imaging of companion animals for students and general practitioners. Interpretation of diagnostic images is a visual science, and images are presented throughout the textbook to illustrate normal anatomy, species differences, anatomic variation and common pathology. Radiography remains the most commonly employed diagnostic imaging modality in both general practice and specialty practice and the textbook provides a thorough review of the use of this imaging modality for all body systems. As ultrasound is now widely employed in general practice, this imaging modality is also covered in detail, particularly where it complements diagnostic radiography. Computed tomography and magnetic resonance imaging are also discussed to show how these imaging modalities can supplement radiography and ultrasonography and where they are superior. In addition to the images included in the textbook, scanning the QR codes in the book or going to https://vetdiagnosticimaging.edrapublishing.com, there are also linked online video files which more clearly show normal physiologic function and dynamic pathology.