My mare Freyja has the exact same injury, although on a rear hoof. Believed to be caused by a fence incident when she was quite young, she had been unsound on her feet the majority of her life when I got her.
It's taken nearly a year, but she has now been riding sound for almost 4 months. She will probably never be sound for HEAVY riding, but pasture sound and for light riding she is. It took good nutrition, keeping the foot CLEAN AND THRUSH FREE
, and CONSTANT TRIMMING
to get her where she is now. Not to mention a good amount of sound advice and some guidance I got from Loosie there.
I trim every 4 weeks
on that mare without fail. I keep her in a dry environment. I added only a very marginal hoof supplement to her diet, I think hoof supplements do only limited work in terms of healing a hoof like that - it's really coming down to addressing the root problems of good nutrition and FREQUENT
hoof care. Thrush invading the crack was the biggest problem I faced due to the fact her rehab was in the middle of winter.
The hoof does grow out with a "flaw" there from the coronet, but it stays together and uncracked now, and she moves solid on it. I stopped riding her for 8 months.
Here was Freyja's foot in the beginning (actually this is after her 3rd or 4th barefoot trim...she still had a lot of hoof to come off at the time, but we had started with full slipper feet as well). I'll have to get a recent picture to show you where it is now.
My advice to you - listen to Loosie, the girl knows her stuff. Get your horse trimmed WAAAAY more than you are doing now, and stop riding until the structure has time to heal together!