cats also need to have fatty acids in their foods, something dog food is void of, (called arachidonic acid). also the vitamin A source for the canine and feline is different. Canines can convert the carotenes found in fruits and vegetables, due to their biochemical processes, into vitamin A, where felines cannot do this and must have their source already preformed in animal sources.
so yes, as stated, felines CAN eat dog food, however it is not recommended, as dog food does not meet all their nutritional needs, and ultimately, in the long run, it is more harmful than helpful.