carting with bernese mtn dogs

Hi - We have a 5month old Bernese mtn dog. This is our second berner.
I would like to learn to cart. Anyone with experience or someone that can give me some advice on getting started?
We didn't cart with our first girl because family life was priority and after things settled down - she didn't seem very interested in learning a new skill - berners can be very stubborn.

 

I could be very fun. You need to start training them when they are fully developed. If yo start now while they are growing. You can blow their hocks and knees out. Not to meantion putt strain on undeveloped muscle tissue and stunt their growth. It can also cause bowed leggs and tendons.


Precious is fixing to be two. We just started harnessing her up and letting her drag a 20' tow chain around. I think it weighs roughly 35-40lbs...
We recently stopped wieght pull training due her pregnancy scare...

Kabuki is still growing. So we haven't started letting her pull wieght. She's only 9 months...

 

I haven't put a harness on our little 5 month old guy yet for some of the reasons you have mentioned. I have read that it is a good idea to start putting a harness on them and attaching something very light in weight (about 5pounds) behind them to get them used to the feeling of something behind them.
Where did you get your harnesses?
I saw instructions on the internet - I might make one out of webbing to start but I wouldn't want to use anything I made for the guy to use pulling a cart. I don't want to risk any injuries.
Our old little girl loved to run as a puppy (from more of a herding line) and we had some problems with panno. This new guy is more of the typical couch potato type.
Why did you wait until two? Is Precious a berner?