The textbook “Diagnostic Pathology” is a study material for students, who acquired knowledge of general pathology and special organ pathology as part of their study of pathological anatomy. The book thus represents a basic literary source for the final part of the study of pathological anatomy. Its aim is to acquaint students with patho-morphological changes present during the most important diseases of different animal species. Equally, no less important part of the presented text is differential diagnosis of diseases, on the basis, of which students should be able to distinguish individual diseases when performing diagnostic necropsies.