1.I got my picture from pexels.com and I took this 2 photo from pexels.com.
2.I drag this two images to the computer and open it on adobe.
3. Then in the tool I selected Rectangular Marquee too and selected the face of the horse-> click edit on the top and copy
4. Then paste it on the dog-> then click layer on the top-> layer mask and hide all
5. I used brush tool to reveal the face of the horse, but you have to know where the face of the horse.