Since publication of the third edition in 2004 there have been important advances. Several endocrine disorders, such as feline acromegaly and hyperaldosteronism, have risen in importance. The use of diet and novel insulins in diabetic cats, and new drugs such as trilostane and methimazole, which were briefly mentioned in previous editions are now considered routine. In addition, the genetic risks associated with many disorders have been elucidated. * A new chapter presents the principles of interpreting endocrine test results and discusses how test performance is assessed in relation to diagnostic confidence. * The central section on glands and their diseases is presented in a standard format -- detailing physiology, aetiology, clinical features, diagnosis and treatment - to aid information retrieval. * The final section has been rewritten to focus on solving clinical and clinicopathological abnormalities with an endocrine dimension.