[Pigmentation disorders in the nasal vestibule of horses with nasal discharge]

The nasal vestibule of numerous horses is pigmented. In the ventral part of the nasal vestibule, this pigmentation is often disturbed resulting in a clearly depigmented area. As nasal discharge passes this area, our study aimed at the practical quantification of the depigmented area in the nasal vestibule of horses and the analysis of its relation to nasal discharge and other parameters.This study included 74 horses (59 warmblood horses, 15 ponies) with pigmented nasal vestibule. When a depigmentation was found to be present in the ventral part, this area was photographed and quantified by use of a software. In addition, we recorded the horses' general parameters including the presence of nasal discharge (amount, consistency, basal microbiology).The median area of depigmentation was found to be larger in warmblood horses than in ponies (1.6 cm² in total for both nasal vestibules vs. 0.5 cm²). Separate evaluations of the warmblood horses indicated a clear association with age and presence of nasal discharge at the time of inspection. In this regard, the depigmentation was increased with higher age and with the presence of nasal discharge (1.4 cm² in horses without nasal discharge vs. 2.5 cm² in horses with nasal discharge, each with a positive age correlation). Ponies only showed a clear dependency on nasal discharge (0.1 cm² in ponies without nasal discharge vs. 1.3 cm² in ponies with nasal discharge, and no age correlation). Further dependencies could not be identified.Increasing age of horses and nasal discharge contribute the depigmentation in the ventral part of the nasal vestibule. Therefore, an estimation of the degree of dermal depigmentation in this area seems to be useful to acquire further information concerning airway disorders with nasal discharge.