From Equine Disease Quarterly, funded by Lloyd’s of London Underwriters, Brokers, and their Kentucky Agents

The skin is one of the largest organs of the body; however it rarely receives the attention given to many of the other organ systems. Examination of the skin is much like that of many organs, requiring a detailed history of the problem. This is followed by visual inspection and direct palpation by region: face, neck, chest, abdomen, legs, mane, and tail.

It is important point to define the types of lesions observed, with crust or scaling, papule, pustule, vesicle, bulla, wheal, macule, and nodule being among the most common.

Skin diseases are often grouped into categories that cause these specific lesions and a differential diagnosis is pursued from that category. For example, crusting skin diseases may be due to fungal agents (dermatophytes or ringworm), bacterial infections (dermatophilus or "rain scald"), or immune-mediated disorders (pemphigus foliaceous). Nodular skin diseases may lead the examiner down a different track such as sarcoid, allergic collagenolytic granulomas, or other tumors involving the skin