As puppies are born with very low immunoglobulin concentrations, they rely on passive immune transfer from ingested colostrum to acquire a protective immunity during the first few weeks of life. The purpose of this study was to describe the timing of gut closure in canine neonates. Twenty-two Beagle puppies received 3 ml of standardized canine colostrum at 0, 4, 8, 12, 16 or 24 h after birth using a feeding tube. Blood immunoglobulins G (IgG, M and A) were assayed 0, 4 and 48 h after colostrum ingestion. IgG absorption rate was significantly affected by the time of colostrum administration, and the IgG concentrations in puppies serum 48 h after administration were significantly higher when colostrum was ingested at 0–4 h of age than at 8–12 h or 16–24 h (1.68 ± 0.4, 0.79 ± 0.07 and 0.35 ± 0.08 g/l, respectively; p < 0.001). In the canine species, gut closure seems thus to begin as early as 4–8 h after birth and to be complete at 16–24 h. Consequently, this phenomenon appears to occur earlier in puppies than in most other species.