Ok, I have two large breed puppies and I have heard that large breed puppies should be fed the large breed puppy formula for longer than their first year. Is this true? And if it is how do I know when to stop feeding them? My vet just sort of gave me this blank stare and said "oh, it depends on the breed." He didn't tell me anymore though. Some people have said 18 months and some people have said a full 24 months.