Get dimensions with module bge

I want to get and print the dimensions of my object with bge module and I definitely don’t find it!
I just find for having the position like this:

import bge
cont = bge.logic.getCurrentController()
object = cont.owner
initial_position = object.position

I had tried
initial_dimension = object.dimension
and initial_position = object.size
but I had an error message all the time

Someone have a solution? I don’t want to work with bpy module