Aims This study aimed to evaluate the impact of immunoglobulin Y (IgY) in a diet on the systemic health and the gastrointestinal tract (GIT) of dogs. Methods and Results Sixteen healthy 11-month-old Beagle dogs were distributed at random (eight animals per treatment) in two treatments groups: control (0 g kg(-1) IgY) and test (2 g IgY per day). The animals were evaluated on days 0 and 40 for a complete blood count (CBC) and biochemical profiles (ALT, ALP, creatinine and urea). Faecal samples were collected from days 35 to 40 to measure nutrient digestibility, faecal characteristics, sialic acid, intestinal microbiota composition and microbial metabolites. The CBC, biochemical profiles, apparent nutrient digestibility and faecal characteristics did not differ between the two treatment groups (P > 0 center dot 05). Dog faeces that received IgY were characterized by lower sialic acid and n-valeric concentration, as well as an increase in n-butyric concentration, in contrast to dogs fed a diet without IgY (P < 0 center dot 05). The other microbial faecal metabolites did not differ between the two treatment groups (P > 0 center dot 05). There tended to be an increase in the copy number of Clostridium cluster XIVa (Clostridium coccoides group) in the IgY group in contrast to the control group (P = 0 center dot 07). The other bacteria analysed did not differ between the treatment groups (P > 0 center dot 05). The colonic pH in the IgY group was lower than in control group (P < 0 center dot 05). Conclusions The addition of IgY in the diet of healthy dogs maintains the microbial balance and has an interesting effect on microbial metabolites. Significance and Impact of the Study The use of IgY, antibodies produced by laying hens, in animal feed is an alternative for the prevention and treatment of intestinal diseases in companion animals.