You slowly realize that you probably took your dogs tail as you were so focused on it. If that were true, you had to test it on something else. As you look out the window of your second story apartment, you notice a few subjects. A blue jay flies on one of the trees. This was your chance.
You than assumed focus on the bird. In particular, you focus it's wings. You stare at it's wings extremely carefully, trying not to take off focus from it moving around. Again, a flash covered your eyes and you collapse to the floor. You wake to your dog again. You still see it doesn't have a tail unfortunately so it wasn't a dream. But that's not all that changed. You try getting up pushing your arms from the floor... Only their blue and white wings now. You look out the window and the same bird has your own human arms.
Falling back down in surprise, you see your test has indeed worked and you now have bird wings and a dogs tail.