This study aimed to determine the distribution of diseases causing fever in dogs in France. Dogs with fever were reviewed and 50 dogs were retrospectively assigned to disease groups. Fever profile and intensity, the time taken to reach a diagnosis, and inflammatory status were compared among groups. Almost half the dogs (48%) were diagnosed with non-infectious inflammatory diseases. No final diagnosis was reached in 14 dogs, 13 of which belonged to owners who did not wish to pursue the investigations. No association was found between disease group and the intensity of fever, fever profile, or serum C-reactive protein concentration. Cytological examinations were most frequently found to be the most important determinant for diagnosis (55.7%). This study confirms the predominance of non-infectious inflammatory diseases as causes of fever. Neither clinical nor biological factors were found to be predictive of disease group.