The crooked horse

Reite dein pferd vorwärts und richte es gerade.
(Ride your horse forwards and make him straight)
Gustav Steinbrecht

As most humans are right handed, most horses are stronger in one side, usually on the left.
If so, the muscles in the left side of the horse are slightly shorter and stronger.
The left hind will be flexed more and carrying more of the horses weight, and the horse often prefers the left canter.
The rider can feel this crookedness through uneven contact with the reins (more contact on the left rein), or through displacement of the shoulder or hips, i.e the horse is not travelling straight.

My horse Fame has a tendency to travel with the hind slightly inwards on a circle to the left, a slightly travers position.

As a right-handed person is stronger in the right hand, the problem here originates with the horse being stronger in the left leg, it carries more weight.
Being a dressage rider my goal is to make my horse as ambidextrous as possible as a crooked horse never can move intirely in balance.
I have to address the problem by strengthening Fame's right hind leg.
Fame has to increase the pushing power of her left hind leg and the carrying power of her right hind leg.
I have to get her to take more contact on the right rein.
By using my left leg more, Fame will increase the pushing power of the left hind leg, and I will also get more contact in the right rein.

Now, one of the bearing principles in dressage riding is to always correct the shoulder into the motor, the hind quarters.

As Fame is travelling slightly bent in travers position (haunches-in) on a circle to the left, I try and position her in a shoulder-fore position instead.
I also work on the shoulders-in on the left rein on the longside of the arena. It is very important to soften on the inside, left rein and instead have the horse stepping up to a contact on the outside rein.
Another possibility is to work with renvers, but as we lose a bit of impulsion here still, I find it easier to work with the shoulders in.
Travers and shoulders-in to the right is also good, as it strenghtens the carrying power of the right hind.
The work we do with counter canter also helps.
Straightening the horse is a never ending story.