A rancid odor is often present. In fact, the rancid odor is usually due to the secondary bacterial or yeast infections and the fatty acids that are produced by these microorganisms. Follicular casts are tightly adherent scales around the hair shaft. Common secondary findings are alopecia, pruritus, erythema, and pyoderma. However, most of the time these cases are complicated by a concurrent pyoderma or Malassezia dermatitis and it is difficult to establish the sequence of events.
Most cases are pruritic at time of presentation.
In establishing a diagnosis a few factors are important such as the breed, the age of onset, the response to previous antibiotic therapy and the exclusion of other more common diseases. A dog should never be diagnosed with a primary disease of keratinization without a complete diagnostic plan to rule out secondary causes of scaling. It is common to have cases in which several diseases are present at the same time thus it is important to have a logical and systematic approach. If the scaling resolves completely with antibiotic therapy, it is unlikely that a primary defect of keratinization is present. If scaling persists together with pruritus, it is more likely that a parasitic or allergic disease is present.