A new approach to diagnosis is described based on behavioural signs of which some twenty are listed. Fixation licking, starting at the rump and asymmetrical sitting are among signs added to the existing commonly accepted ones such as ‘scooting’. Normal anal sac fluid is defined as almost clear, slightly yellow in colour, and abnormal material is described in varying forms of coloured pus. Predisposing factors are suggested such as diarrhoea and diets leading to soft bolus. The bacterial flora involved is defined consisting of micrococci, diphtheroids, Escherichia colt, Salmonella, Streptococcus faecalis, Clostridium welchii, Staphylococcus, Pseudomonas and Proteus. Moreover, it is suggested that some unresponsive skin conditions are prolonged through a secondary effect of anal sacculitis.