
Excess weight and lack of exercise can also make a dog weak in pastern so causing them to stand down and ten to two as also when young likely to be still narrow, or if older and the ribs are broad may even toe in, so There is no one reason.
If there is bowing in the bones and not just poor posture then a vet needs to be consulted as sometimes there is damage to the growth plates causing one bone or side to grow at a different rate to the other.
There are so many parts to the front Assembly. shoulders, upperarm, the leg bones themselves, then the pasterns and their relative strength, length and angles, feet, and also the breadth and depth of the chest.
Many of these parts also develop at different rates during growth., so may go through phases of being less than ideal, but come good at maturity.