Alopecia is a common presenting problem in dogs. It is often assumed that there is an endocrine cause. However, while hypothyroidism, hyperadrenocorticism and hyperoestrogenism are frequently found there are many other conditions that result in alopecia. It is therefore important to recognise and understand the different patterns of canine alopecia. This helps clinicians formulate an appropriate differential diagnosis list, which can then be used to determine the most appropriate tests. For example, multifocal alopecias are only rarely associated with endocrinopathies and endocrine tests are not normally indicated. Symmetrical and diffuse hair loss is typical of an endocrinopathy, but other causes include follicular dysplasias, pattern baldness, telogen effluvium and anagen defluxion. Understanding the clinical signs in detail can help the investigation by prioritising tests and avoiding unnecessary testing. Finally, there are some rare causes of endocrine alopecia that are difficult to diagnose using basic endocrine tests.