Made it larger for my Jack-Chi 20lb pup.

Rows 1-8 are the 1st button hole to the next
repeat 1-8 until you’re close to the legs

The first few rows need to fit from tail to ribs. I Cast on 30 and knitted 10 rows of ribbing to start. I also did a bit of shaping to round out the butt area so when I started the button section I had 36 stitches.
Basically knit your knits and purl your purls. If your KorP 2tog you do what ever the 2nd stitch is. i.e.: row starts with a Knit you would do a p2tog because the purl is your second stitch. :)

I’m in the process of doing another one and will try to take better notes.