mass and weight is two different things. what you call weight is actually known as mass. the weight of an object is the mass multiplied by the gravitational pull so the mass of a dog would typically be around 30 grams so if you put 30 in the whole of the mass of the dog column and then multiply 30 by the gravitational pull e.g. for venus you would do 30*0.9 so the weight would be 27