Two of the latest ideas making the rounds with dog lovers are:
1- Dogs shouldn't be allowed to exercise vigorously until they're well over a year old
2- Large breed puppies should be fed lower protein content food to prevent fast growth.
I'd think twice about believing these unquestioningly.
Research it on your own and give the most credence to opiniions that reference specific DOUBLE BLIND SCIENTIFIC studies to back those opinions up.
My personal belief is that while it is BAD for any puppy to be FAT, it is GOOD for them to eat food jam packed with top grade ingredients and high protein content (Yes I believe in high protein content). Also, the food should have little or no chemical additives or preservatives.
Mostly, I believe that eating super duper food in smaller quantities is much better than eating food deliberately concocted to have lower protein, vitamin and mineral levels.
Don't believe me, though. Read up on it yourself.
May I suggest the attached link?
Best of Luck on your Mum's dog.
Link