This dog sweater is for a 10 to 12 pound dog with measurements as follows:

Around the neck (below the collar) 12 inches
Around the chest (widest part) 18 inches

Knit loosely to accommodate the body and possible shrinking after multiple washes.

I use scarp yarn that I have left over from other projects, so there is no need to buy yarn just to make this sweater.

Have fun with colors and textures. My pattern show all the sweater that I have made so far using this pattern.
The idea is to make it warm and comfy for you bundle of joy. But also sturdy enough to withstand tug, pulls and frequent washing.

Gauge is not that important, but if you must have a gauge here it is:
6 stitches per 2 inches in worsted or DK weight using a size 8 US needle.