Hopefully this helped, so let us know in the comments if you have any questions. Losing Dogmeat can make you distraught, but never fear.
Red Rocket would likely be a better pick than Sanctuary, but some of the other settlements are even smaller, making it easier to find Dogmeat once you need him again. If you find this annoying and don’t want to keep doing it over and over again you might want to start sending Dogmeat to a smaller settlement when you don’t want him by your side. There are a few of these, so just do a run around the outside of the town, including at the very end of the cul-de-sac, to locate them all. There’s no telling which one of the dog houses Dogmeat decided to make his home, so be sure to check them all if you are really having trouble finding him.
He will almost always be near one of these, whether hanging out inside or wandering nearby. The key to finding Dogmeat in Fallout 4’s Sanctuary is to look for the red dog houses found in many of the backyards.