It all depends on the severity of the crack.
My lease mare has a vertical crack on the surface. I asked my farrier when he trimmed hooves a few weeks ago and he showed me that the crack doesn't actually go into the hoof wall to where it would be causing any type of issue. She still has 3/4 of an inch before it would even start to cause any type of issues. She has the crack because of of dry it was awhile back. No biggie for her, but I can't speak for your horse unfortunately.
"The greatest pleasure of a dog is that you may make a fool of yourself with
him and not only will he not scold you, but he will make a fool of himself too."