The objective of this study was to determine whether: (1) lysozyme supplementation would influence coat quality in dog and (2) coat quality improvement would be related with haematological parameters, fur composition and faecal quality. Eight dogs were divided into two groups and fed a diet supplemented with 0.2% lysozyme. Blood samples were analysed for haematological and haematochemical parameters. Coat quality was assessed using near infrared spectrometry (NIRS) and through a three-point scoring system. Fur copper and zinc concentrations were analysed. Faeces were scored using a five-point scale, and faecal concentration of short-chain fatty acids was analysed. Coat quality changed significantly with lysozyme treatment as assessed by NIRS analysis and was improved according to a three-point visual scale. Plasma total protein, creatinine, blood urea and plasma chloride were lower after a two-month lysozyme dietary supplementation period. Faecal valerate was higher after the supplementation period. Lysozyme supplementation would lead to an improvement of coat quality, which could be related to modification of gut microflora in dogs.