There's no special food to give a spayed dog it's just that they are more prone to weight gain than an intact female because it will slightly decrease their metabolism. But, as Ellie May said, being a puppy she'll still need the extra calories for a while. Stick with the same food (if it's puppy formula you can decrease it but very slightly, unless of course she's currently on the thin side) and when she's ready to switch to an adult formula, start on the low end of the feeding guidines for her weight, and if need be adjust accordingly based on how she's doing weight-wise.
