Intracorneal Vacuoles in Skin Diseases with Parakeratotic Hyperkeratosis in Dogs: A Retrospective Light Microscopy Study of 111 Cases (1973–2000)

This retrospective study examined 111 cases of canine skin diseases associated with parakeratotic hyperkeratosis to identify the presence of intracorneal vacuoles. The study found that 33% of the cases had intracorneal vacuoles, with varying prevalence across different conditions: 31% in primary idiopathic seborrhoea, 56% in necrolytic migratory erythema, 26% in Malassezia dermatitis, 14% in zinc-responsive dermatosis, and 100% in both hereditary nasal hyperkeratosis and congenital follicular parakeratosis (CFP). Notably, large vacuoles (>5 µm) were exclusively observed in CFP. The presence of intracorneal vacuoles was significantly associated with a higher degree of parakeratosis (P < 0.001), indicating that these vacuoles were a common feature in many parakeratotic skin diseases in dogs, but large vacuoles were specific to CFP.