Hello! I have a whippet pup about 4 months old. I understand that between being a pup and the nature of the breed, Martin (my pup) will sleep quite a few hours of the day, but he has seemed to lose the pep in his step the past couple of days and his sleep seems less like happy naps and more like lethargy. He recently completed his vaccines and has started going to the pup park so he can run off leash and yesterday he barely even ran! Mostly just jogged around to meet the other dogs. He is usually a bit of a rough houser but yesterday he was also exceptionally calm. I'm hoping this is just him going through some phase or is worn out from too much play at the park earlier in the week. Any advice on whether I should I take him to the vet or wait a few days to see if he peps back up?