My GSD is eating less

Question
Hi , i have a 6 month old GSD female who seems to have lost her appetite , up to a few days ago she was eating x5 400 grm tins of dog food and now shes eating around half of that.
She weighs 49 lb in weight and seems well in herself , she is also very slim in build , should i be worried or is it normal for  a GSD puppy to eat less as they get a little older

Answer
Yes it is normal to need to eat less after their growth slows.  That sounds like a lot.  You may want to be alert for other problems and take her to the vet if you see anything else.  

Your dog definitely should be narrower at the waist than the hips and chest. You should be able to easily feel the ribs, but not see them. Each dog is different. Standard recommendations are a good place to start, but each dog must have its food and exercise adjusted to its individual needs. Here is a link to a good illustrated guide, http://www.longliveyourdog.com/twoplus/RateYourDog.aspx