Sand crack

[fl68]

Has anybody any experience with sand cracks.
We recently took on a loan horse which is absolutely perfect for my daughter, however after two weeks of riding her she went lame snd we noticed a small amount of blood on her coronet band . After further investigation I found a sand crack running down the inside of her hoof, it was well hidden and the owner said she didn't know it was there. (She was on full livery).
I had my farrier look at it and he said a heart bar should fix the problem as it will take the pressure off that area. He thinks that the crack has been there for a long time. She had the shoe fitted last weds but is still lame. She only has one bar shoe on and one normal. My farrier thinks this shouldn't effect her. Has anybody any experience with this?.
I've put her on box rest for a week in the hope that she's foot sore from the farrier.
I'm just not sure where to go from here I'm wondering if this us going to be a long standing issue?. If so she will have to go back. Such a shame as she's perfect x

I’d personally have a farrier with some specialist knowledge in remedial work have a look. That definitely isn’t the worst I’ve seen but it’s hard to tell from the photo if there is any concave areas around jt. Did they discuss stapling it at all?
I generally find they are caused by an imbalance to the hoof and poor diet. The latter is much easier to address than the former!

I'm surprised just the show has been suggested, I'd expect some direct treatment of the crack as well or it will likely contribute split as it grows down. The shoe presumably is only treating the lameness (or not as the case may be). Definitely second someone specialised in remedial shoeing. Ask your vet for recommendations. If you have a equine hospital or dedicated specialist equine vet even better as they will work collaboratively with farriers in more complex cases and know who's best at what.