It is a similar infection to thrush, at the difference that it will attack a very particular point at the toe, and generally starts from the white line, but can deteriorate the wall too, leading to cracks.
The origine of Seedy Toe is not the gravel coming in and creating a space where the infection can spread. It is the other way around: the white line wasn’t perfectly tight and “invited” the gravel to come in.
So Seedy Toe can and should be topically treated to prevent further deterioration. However, if you do not fix the cause for a non tight white line, you’ll always have the same problem.
WHAT ARE THE MAIN CAUSES?
Causes frequently are:
– mecanical, wall too long, creating separation between wall & sole
– nutritional problem, the feed not being properly adapted to the horse’s need leads to weakened laminae (internal part of the white line to simplify), thus wall separation
Now, you’ve fixed diet, trim, and you’re aggressively treating. It is clean and free from infection but a hole is still there. That could be a larger than usual toe crena, potentially leading to keratoma (see below for exemple). Only X-rays would confirm.