Objectives: To investigate the possibilities and limitations of arthroscopy to detect flexor enthesopathy in dogs and to distinguish the primary from the concomitant form. Materials and methods: Fifty dogs (n = 94 elbow joints) were prospectively studied: dogs with primary flexor enthesopathy (n = 29), concomitant flexor enthesopathy (n = 36), elbow dysplasia (n = 18), and normal elbow joints (n = 11). All dogs underwent an arthroscopic examination of one or both elbow joints. Presence or absence of arthroscopic characteristics of flexor enthesopathy and of other elbow disorders were recorded. Results: With arthroscopy, several pathological changes of the enthesis were observed in 100% of the joints of both flexor enthesopathy groups, but also in 72% of the joints with elbow dysplasia and 25% of the normal joints. No clear differences were seen between both flexor enthesopathy groups. Clinical significance: Arthroscopy allows a sensitive detection of flexor enthesopathy characteristics, although it is not very specific as these characteristics may also be found in joints without flexor enthesopathy. The similar aspect of both forms of flexor enthesopathy and the presence of mild irregularities at the medial coronoid process in joints with primary flexor enthesopathy impedes the arthroscopic differentiation between primary and concomitant forms, requiring additional diagnostic techniques to ensure a correct diagnosis.