Humans speak to dogs using a special speech register called Pet-Directed Speech (PDS) which is very similar to Infant-Directed Speech (IDS) used by parents when talking to young infants. These two type of speech share prosodic features that are distinct from the typical Adult-Directed Speech (ADS): a high pitched voice and an increased pitch variation. So far, only one study has investigated the effect of PDS on dogs' attention. We video recorded 44 adult pet dogs and 19 puppies when listening to the same phrase enounced either in ADS or in PDS or in IDS. The phrases were previously recorded and were broadcasted via a loudspeaker placed in front of the dog. The total gaze duration of the dogs toward the loudspeaker, was used as a proxy of attention. Results show that adult dogs are significantly more attentive to PDS than to ADS and that their attention significantly increases along with the rise of the fundamental frequency of human' speech. It is likely that the exaggerated prosody of PDS is used by owners as an ostensive cue for dogs that facilitates the effectiveness of their communication, and should represent an evolutionarily determined adaptation that benefits the regulation and maintenance of their relationships.