240 permanent teeth from 8 different dogs aged 1, 3, 8, 10, 15 years, were used for an anatomic study. The teeth were cleaned, their root canal system was stained with dye, then the teeth were decalcified and cleared to determine the root canal anatomy. The apical root canal anatomy in dogs can be described as a "sprinkler-rose" anatomy: at the tip of the pulpal canal, the canal is divided in numerous narrow channels radiating peripherally through the dentin and the cementum and ending in numerous apical foramina on the cementum surface. This architecture constitutes a very complex apical delta.