I wouldn't worry about it. You can't force feed and if she's eating some, she's probably getting enough. The recommendations on the bag are always way over-estimates. Most vitamin supplements are pointless for dogs... they get what they need through their food, there's no need to worry about balance when feeding an AAFCO kibble.
You could also start scheduled feeding. Free feeders are often pickier and since they know the food is always down, they become more sparse about eating it. I know that's how Jackson was. Now that he's on a schedule (he gets kibble mixed with wet in the morning) and then around 5pm, I pour the rest of his kibble into his bowl and he eats it dry within the hour. He now knows it's only down at certain times and really seems to enjoy dry food, like he never did before. He was super picky before.
Also, Jackson is 16lbs and extremely active and never eats more than 3/4 cup per day. Even that is pushing it. Generally speaking he gets 2/3 cup per day, sometimes less. If he seems hungry, I will feed him more or if he gets a super active day. But on a lazy day, he gets 1/2 cup and on a very very active day he will get up to 3/4 cup. If Callie is mostly just around the house, then I doubt she needs more than 1/2 cup and is probably self maintaining pretty well. |