I sent the dog somewhere really early on when I hooked up with the PI but I don't know where. Anyone go a tip for locating my dog?

try to remember which settlments you had at the time, try looking in them, if you've been to Fort Hagen, try there, check dog houses

Thanks for the tip Lovefool35, I'll give Fort Hagan a go as you suggest but it was too long ago and I've been too many place to try and predict. I'm just hoping I stumble across him one day because he was my favourite companion and the only one I've aligned with that I don't still have in my company somewhere

If you play on PC you cud simply use the console command to summon the dog to your location or teleport to him.

If you play on PC i recommend this http://www.nexusmods.com/fallout4/mods/7903/? It allows you to track companions with a misc quest marker. I started using it when I couldn't find Piper or Danse at the airport and came to find out they were in the area that was locked because I hadn't gone far enough in the BOS quest line yet.

Just go to your settlements and check each one. He loves sitting beside the doghouse kennels or just roaming around.

I came out of my place at Sanctuary yesterday and saw him just patrolling down the middle of the road. I thought it was a hairy version of Preston.

Also try Red Rocket Truck Stop. He may be back at home. Some people have even found him standing on a garage roof looking down at them.

Now I can't remember if Dogmeat comes when you ring the bell, if you're playing on PS4 or something then build the settlement bell at every location and ring to find out.