As he does not have an excessively long neck this is an interesting achievement. How to resolve it?
We'll begin by working him a little in front or above the bit, sending him forward and setting a good rhythm from the get go. Then we'll encourage him to take the reins and stretch over his back and out down in front, without putting his head too low i.e. not below the knee - he must learn to take the contact and to take his part of it consistently. This requires a very good seat from the rider and is best done first at the working trot posting. He is also being worked in shoulder fore, shoulder in and counter flexed to the outside to supple his neck and his sacroiliac.
The horse also lacks gaskin development indicating that he is not carrying himself properly behind, and he is pushing forward rather than lifting forward. At his stage of development he is built higher behind than in the front, a common issue with Andalusians. In fact the ANCCE breed inspectors ( the much revered and appreciated Spanish Andalusian registry) actually prefer a higher croup than wither. As a dressage rider we know we are fighting a 'downhill' battle with this type of conformation. But again, correct work will help. As the horse learns to take his own weight backward and to lift correctly, through frequent transitions, lateral work and counter flexion in all gaits, his sacroiliac region will strengthen and his ability to carry will improve.
It is essential that the horse not be overworked during this period. The work must be kind and not overly enthusiastic or the horse will become tired. This is hard work for them. Thankfully this horse has good hocks and no 'wobbling' in his fetlock or hock joints. That would require a different approach. We use frequent walk breaks in an active but uncluttered or unfettered walk i.e. not interfering all the time as a rider but just allowing the horse to move forward, are beneficial. It is important that even when walking on a long rein the horse be required to be 'out there' in front, taking the rein contact softly as he covers the ground, relaxed across his top line.
How will you know when you are back on the right track and can move on in his work? The wither will essentially 'pop'. You will go to re-stick ( re-measure with a measuring hand stick) your horse and find he has grown an inch or two. His gaskin will be evenly developed and bulging nicely when the horse is viewed from behind. Look for the horse to show even amounts of bulge on each hind leg. Any difference is an indicator of incorrect work or unsoundness. And the neck will be soft, the muscles rolling and rippling as he works. The sacroiliac will be soft and supple and the horse will easily bend around each of your legs as requested instead of 'blowing off' your leg, avoiding bend, stiffening against the bend, shoving shoulder out of alignment etc. In many years of buying both young and proven international Grand Prix horses, that look from behind tells you everything. Don't get me started on that topic.
When working your horse through this transition to correct work be aware that if you are 100% certain you are riding the horse correctly and he still cannot access the correct contact you may need to have a chiropractic exam. So often young horses are tied up then they panic or struggle for one reason or another, and pull vertebrae in the neck. This is a reason we never tie foals. My pet hate is the cross tied horse for the farrier.. again, don't get me started. It is also a reason we don't use cross ties, but if you must, be sure they are velcro breakaways. The emergency snaps are not good. I have seen them hit a horse in the face, or pull off at the wall and be dragged behind and around the horse during his panic, I have also known one friend to lose fingers trying to unsnap them.
Will update as this young lad with so much potential progresses. As Greta Grillo, German dressage team rider once said, " He didn't ask to be in my yard. Taking care over his training is the very least I can do." Ditto here at WVH. Every horse is an individual and so is every rider, and they must be treated as such with much respect.