This concise textbook of differential diagnosis was originally written for students and new graduates, and for the non-equine veterinarian seeking to become proficient in handling the increasing volume of equine work which is becoming available. A number of changes have taken place since the first edition was published, although the original purpose remains. This edition has been fully updated throughout - some sections, for example, lameness, have been completely rewritten to make it easier for readers to refer to any particular condition and to include more sophisticated modern diagnostic techniques. Ultrasonic techniques are included for the first time and there is a new section devoted to methods of pregnancy diagnosis. Several new conditions are introduced - pemphigus, Cushings syndrome and thyroid dysfunction, for example, and the section on skin diseases has been expanded.