You can't... (unless you put it in a full bath and measure the displacement, but lets not get ahead fo oursleves...)
If your dog does not like the scales, you could always hold your dog and stand on them, then subtract your weight.
I would measure it with a ruler.
a ruler
a ruler!
A ruler
A ruler.
A ruler :/
A ruler would do the trick.
A yardstick or ruler!
No. Balances measure weight. To measure a stick, you would use a ruler or similar measure.
You would use a ruler and measure in millimeters or centimeters.
A ruler or tape measure.
If you are measuring it's length, a ruler is adequate