13 Sebaceous adenitis
CASE HISTORY
The relevant history in this case was as follows:
• A 2-month history of scaling and partial alopecia over the dorsal trunk, and also scaling over the concave aspects of the pinnae.
• The dog had been moderately pruritic, particularly in association with the development of the papular lesions over the face.
• The dog was fed a good quality, complete dried fish and potato diet with occasional packeted wet food and fresh chicken, and given only water to drink.
CLINICAL EXAMINATION
There are substantial variations in the clinical appearance of sebaceous adenitis between breeds.
Feline sebaceous adenitis is a rare disease characterized by multifocal annular areas of alopecia, scaling, crusting and follicular casts. Pruritus can be absent to marked, and tends to be more severe if there is secondary pyoderma.
The physical examination was within normal limits.
Examination of the skin revealed:
• Well-demarcated areas of alopecia, slight erythema and hyperpigmentation over the periocular skin, bridge of the nose and muzzle (Fig. 13.1).
• Generalized partial truncal alopecia with fine adherent scaling and yellow-coloured follicular casts involving groups of adjacent hair shafts (Figs 13.2 and 13.3).

Figure 13.1 Sebaceous adenitis. Alopecia over the periorbital skin and adjacent to the nasal planum.

Figure 13.3 Sebaceous adenitis resulting in partial alopecia and discolouration due to follicular cast formation.