Canine atopic diseases, including those with skin lesions, have been described for many years. Unfortunately, early descriptions often failed to establish definitive guidelines for considering a patient atopic, and criteria for diagnosing atopic dermatitis (AD) have varied from author to author. Larger case-series published from the 1960s to the 1980s suggested that the most common clinical manifestation of AD was pruritus, particularly of the face, ears, paws, extremities, and/or ventrum. It is not always clear that testing to eliminate other differential diagnoses was always carefully performed on patients in early reports; therefore, some descriptions could include patients affected with diseases other than or in addition to AD. Points of consensus regarding clinical manifestations of AD in case-series include the presence of pruritus beginning at a young age, possibly seasonally; and a prominent lesional involvement of the face, extremities, axillae or ventrum. Conflicting information on breed and sex predispositions is present, perhaps representing regional or temporal variability. Clinical reports vary, in regard to the description of lesions seen in dogs with AD. This reflects a possible confusion with lesions of secondary complications, and highlights the fact that the existence and nature of primary lesions of canine AD are not truly known.