Hoof crack

My gelding has a HORIZONTAL crack in his hoof. I have seen quarter cracks and vertical hoof cracks, but I haven't seen this before. It's a split about 1 inch long growing down parallel to the coronet. Is this something to worry about? Is there anything I can do to help it heal or keep it from splitting any more? Product reccomendations? I will get a picture when I can.

I'll wait for pics before commenting.

Actually this is a different horse. My mare is lame after a trim, and my farrier tells me that this is because the blood flow is increased in her hoof and she has more feeling sensation. I am a little scpetical, but this farrier comes highly reccomended. She says that my mare (Sierra) needs her hooves kept short so that there is less pressure on the nerves or something. If her hooves get too long, the blood flow will decrease and she will be less lame, but the healing will slow. I don't understand it, this is just what my farrier tells me.

The gelding, on the other hand, is totally sound. He has an old splint on his front leg that doesn't bother him, and this new weird crack on his front hoof....

Yes, cherriebark -- I read and re-read what I originally posted and then corrected myself... I did respond on your other thread about the mare.

A horizontal crack is usually an old abscess or "gravel" that blew or popped in the hairline. It can come and blow without your knowledge or the horse ever taking a bad step. A blow to the area while that section of hoof wall was growing can cause a weak section that cracks, and it's no big deal. As long as the hoof seems otherwise sound and it's relatively small, just don't worry about it. It will grow down the hoof wall, and then the only problem it's likely to pose is wanting to chip off as it reached ground level. Your farrier will address it as it approaches the ground, and it can make it hard to hold a shoe on while that section grows out. If the horse is barefoot, it's not an issue.
Your farrier is right, in that when shoes are removed or a trim is corrected, increased blood flow means the body starts healing little things it couldn't before and abscesses can be part of that healing process. If it happens a lot, though, I'd look into dietary issues, such as too much sugar or starch (grain, molasses, corn, certain grasses, etc).