Trichographic features of hair from normal black Dobermann pinscher dogs

BACKGROUND: Dobermann dogs are predisposed to colour dilution alopecia and follicular dysplasia. Limited information is available regarding the trichographic features of normal canine hair shafts, including those from Dobermanns, with no studies of inter-observer agreement for canine trichographic features. OBJECTIVES: To characterize the trichographic features of normal black Dobermann hair shafts evaluating the following variables; gross appearance, primary versus secondary hairs, colour change, tip structure, curling, twisting, bending, cuticle changes (breaks, compression, loss or abnormal overlapping), fractures and variations in hair diameter. ANIMALS: Twenty client-owned, normal, black Dobermanns of different ages and genders. METHODS AND MATERIALS: A systemized trichographic evaluation of hair samples from five body locations, which were evaluated independently by two observers, and inter-observer agreement evaluation. Kappa statistics, positive and negative agreement were determined. RESULTS: Agreement between investigators ranged from 87% to 99% for each examined variable. Kappa statistics showed excellent (0.81-1.00) to substantial agreement (0.61-0.80) for all variables with the exception of moderate agreement (0.41-0.60) for cuticle compressions and variations in hair diameter. A novel finding of a "round hair tip" was made, which was more commonly found on the dorsal head. Colour change to the proximal hair shaft was more common on the thighs and flanks. CONCLUSIONS AND CLINICAL IMPORTANCE: Trichographic features of 500 hairs collected from 20 normal black Dobermann dogs are described. A previously unreported finding of round hair tips was seen. We describe a systematic approach for evaluating hair shafts that can be applied in future studies for both normal and abnormal Dobermanns, and potentially other dog breeds.