[Enjknsua]

WOW! impressive!
on another forum someone took pictures of there great dane puppys growth from 8 weeks upward into adult hood week by week and holy cow! the growth is incredible!!

and it always made me wonder "is growing that quickly ever painful to a dog?"

That's probably me. If you YouTube Zephyr Growing you should find it. This is his growth:

2 months: 24lbs 15"
3 months: 40lbs 19"
4 months: 56lbs 23.25"
5 months: 71lbs 26"
6 months: 90lbs 28.5"
7 months: 102lbs 29.75"
8 months: 115lbs 31"
9 months: 120lbs 31.5"
1 year: 127lbs 32.5"
2 years: 133lbs 33"

My new dane pup averages 4lbs a week. He was 25lbs at 8 weeks, 30lbs and 18" tall at 10 weeks, 42lbs and 21.5" at three months and 60lbs and 26" at four months last Thursday. He grew an inch between Saturday and yesterday. He's right in the middle of average for weight, but very tall for his age. It's normal for male Danes to gain 5 pounds a week.
Here's the average dane growth chart:
http://www.chromadane.com/ht&wt.htm