Some years ago Purina ran ads for Puppy Chow with the jingle
Puppy Chow for a full year,
Til he's full-grown.
It had a catchy little tune that's currently chasing itself around my brain.
I know this was an ad designed to sell Puppy Chow, but it's actually not the worst advice in the world for feeding puppies. Dogs actually mature at different rates, corresponding to their size, and a year is a pretty good average for a medium-sized dog. The giant breeds may not be completely mature until they're two years old.
What brought this to my mind was that tonight, for the first time in quite a while, I had to loosen Gordo the Wonder Puppy's adjustable collar. He's ten months old now and he's still growing, but the rate has really slowed. He's getting pretty close to his adult height and weight and he's maturing mentally, too. He's markedly better behaved and much less destructive, although he's still fond of tipping over the recycling bin and picking out some box or plastic container to chew on. That's kind of OK with me, so he doesn't get into much trouble over it. He seems to prefer rawhide to cardboard these days and the tipping is getting less frequent.
I really don't know how the medications he takes for his epilepsy are affecting his growth. Epilepsy is uncommon in puppies, so the vet isn't really sure, either. We recently halved the dose of the Keppra. This has made Gordo a litle less somnolent and a little more frisky, and he hasn't had a seizure for almost two months. He also hasn't had any of the little neurological "episodes" that he'd been having. I'm really pleased with how he's doing, in fact.
Anyway, to get back to the Puppy Chow, when he was about seven months old, Nutro discontinued the lamb and rice puppy food and I started trying new brands. This was when we discovered that he's allergic to some ingredient in other foods. It's probably a protein, because allergies usually are, and it's not a grain, because he's allergic to not just one, but two, count them, two super-expensive super-premium dog foods made with no grain at all. It's also not chicken, which is really good because he loves those dried chicken breast strips as treats and inducements.
Anyway, I was having a real problem finding puppy food he could eat and I called the breeder about this. She told me that she put all her puppies on adult Nutro at six months. Well, that made life easy and now Gordo is eating adult lamb and rice food. So much for the jingle.
 This is my way of saying I have no idea when, although I think it was probably after about 1972, when we got our first collie. I can remember other advertising jingles, too, which says a lot about their staying power. Some of them are from the '50s and the products are long gone, but the jingle lingers on.