I found this cake on Pinterest. The design, like many others like it is unique. Can someone tell me how this was designed. Was it done with an icing tip?

Looks to me like the design was slightly piped on a sheet cake to give some demention to the dog,  then covered w/piping from a small round or star tip (star fill-in method).

It could also be a buttercream transfer. Look on you tube and watch a video of buttercream transfer. You can find a picture of a dog similar to one above and print it up and do buttercream transfer. They are really simple to do!! I have done only one of a power ranger once for a little boy in my neighborhood a couple of years ago. He was really happy with it.

I agree with @kakeladi design piped on a sheet cake then covered with a small round tip. A LOT of work! good luck if this is how you do it!

I have done buttercream transfers, and they are more smooth looking rather than the dots

I think they're beads piped similar to a shell border.  Looking at the top part of the hat portion that's what it looks like to me.  Probably a small round tip like a 3 or 4.