Shrink This Pattern

Can anyone help with ideas for decreasing the size of a sweater pattern? I have a pattern for a dog with a 16 inch chest. It doesn’t have any smaller size options. I want to decrease the size and use it for a dog with a 13.5 inch chest. Is it better to go down a needle size, use a thinner yarn, or try to remove stitches? If I remove too many stitches, the strap borders will end up touching each other.

You could start with thinner yarn and smaller needles. If you have some leftovers in a thinner weight, use that to get an idea of the gauge and calculate the size of the finished sweater.
That should work but if it’s still not enough, you could then alter the pattern stitch number with the thinner yarn.

I recently did this to a sweater pattern that was for a 1 year old size down to a new born size by changing the needles to two sizes smaller than required for original pattern size and went from worsted weight down to DK weight. I posted a picture of my grandson wearing the newborn size I made in a thread here.