I think it is the same as it is with humans. Just as some meds affect different ethic groups in different ways, I assume the same is true for dog- and cats. Even the fact that some cats have short or no hair (like mine) mean they would require differing types of treatment in some ways. But mostly, in deciding on anesthesia, weight and other meds and age and other variables are equally significant.
"There are two means of refuge from the miseries of life: music and cats" Albert Schweitzer