my 3 year old spayed female labrador is underweight, however, I cant seem to get the weight back on her, she gets fed almost 1000g of food a day, sometimes leftovers and treats, however, I do try and space her meals over 2-3 feedings, this isnt always possible, she will really 'horse' down her food often puking it back up and eat it again (sorry, abit gross I know) I'm worried about her as my other dog is a 1 year old collie cross, she gets about 500g a day (it's dry food btw) and she's fine.
we take them both out for about an hour everyday for exercise, which includes playing ball, so possibly she's not takin in enough calories??