Suckling provides a well-defined and functionally significant context in which to study mammalian sibling competition and the possible consequences of this for long-term differences in individual behavior, physiology, and life histories. There have, however, been surprisingly few studies of suckling behavior, even in species as accessible as the domestic dog. In a first approach, we filmed the suckling behavior of 10 litters (47 puppies) of various dog breeds in their owners' homes during the first postnatal month before the start of weaning. The pattern of nipple use was very similar across litters but very different to that of the better-studied pig or cat. Puppies showed only weak preference for particular (central) nipple rows, they often switched nipples during nursing sessions and showed no evidence of teat consistency in which each littermate uses primarily one or two particular nipples. They also showed very little agonistic behavior that could be interpreted as contesting access to nipples. The present findings provide a reminder of the diversity of suckling patterns among altricial mammals and of the need for more comparative information to better understand the reasons for and functional significance of such differences.