Clinical and Histologic Description of Lykoi Cat Hair Coat and Skin

Abstract

Hair and skin abnormalities of domesticated animals are readily identified and are biomedical models for ectodermal dysplasias. The hair coat of the Lykoi cat, a new cat breed, is a dramatic phenotype and has not been clinically or histologically described. Dermatoscopic examination was performed and skin biopsies were collected from seven Lykoi cats and seven dermatologically normal domestic shorthair (DSH) cats. All skin structures were examined on longitudinal and transverse sections. Immunohistochemistry for CD3 and Cytokeratin 8/18 was performed for comparison with DSH cats. Dermatoscopic images were compared. Lykoi had a significant reduction in average numbers of follicles per hair follicle group as compared to DSH cats, 14.7 ± 2.9 and 23.4 ± 5.4, respectively. Median (range) numbers of hairs per hair follicle group were 1.3 (0.4–5.7) and 18.8 (10.6–26.6), respectively. Mean (± SD) hair follicle depth was 0.95 mm ± 0.15 and 1.14 mm ± 0.21 for Lykoi and DSH cats, respectively. Mean (± SD) primary hair shaft diameters were 39 μm ± 0.029 and 47 μm ± 0.011 for Lykoi and DSH cats, respectively. Mean (± SD) total sebaceous gland area per hair follicle group was 19,937.7 pixels ± 10,254.9 and 9,833.7 pixels ± 5,784.5 for Lykoi and DSH cats, respectively. Unlike DSH, Lykoi had mild to severe perifollicular to mural lymphocytic infiltration in 77% of observed hair follicle groups, and follicles were often miniaturized, dilated, and dysplastic. The Lykoi has a unique feline phenotype that may serve as a novel dermatological biomedical model.