Contents 1. Introduction - Structure and function. 2. Approach to the case. 3. Diagnostic tests. 4. Bacterial skin disease. 5. Fungal skin disease. 6. Viral, rickettsial and protozoal diseases. 7. Parasitic skin disease. 8. Endocrine and metabolic skin disease. 9. Otitis externa. 10. Allergic skin disease. 11. Immune mediated skin disease. 12. Alopecia. 13. Nutritional skin disease. 14. Congenital and hereditary skin diseases. 15. Pigment abnormalities. 16. Psychogenic skin disease. 17. Keratinisation defects. 18. Miscellaneous skin diseases in the dog. 19. Miscellaneous skin diseases in the cat. 20. Environmental skin diseases. 21. Neoplastic and non neoplastic tumours