Instructions from Peterpaul Forcher as a PDF file: https://www.origamiseiten.de/forcher/scottish.pdf
(‘Auf der Rückseite ebenso’ is German for ‘on the back side as well’ and the instruction at step 26 tells you to undo the steps 25 and 24 before proceeding with step 27.)
The head was a bit tricky when I folded it for the first time, and even though this is my third time folding this, I somehow can’t get this dog’s back quite right… you can see the square sticking out and the tail is not quite aligned as well, but maybe you guys can do better than me :)
I would also suggest using at least 20x20 cm paper - I simply used regular white A4 printer paper where I cut off a square with the size of 21x21 cm and the resulting dog is roughly 8 cm long and 7 cm high. If you don’t want to fold a Westie but a Scottish Terrier, just use all-black paper :)