If you have a horse with chronic heel infection it is the result of a larger underlying problem.
The frog needs to be completely resected or cut out to find the root problem. The heels are the point where the infection is discharging, not the root problem.
Just treating the heels will not solve the true issue. Your horse might have what we call sheared heels this is made worse by the foot landing heel first on either the medial or lateral sides of the heels.
If this happens then the heel shift or shears and if the frog is compromised by thrush; the two halves are unstable and will shear with every step. This can cause heel pain or tripping. Stabilizing the hoof is paramount to healing this condition along with treating the cleft in the frog with Outlaw Thrush Stuff. Stabilizing the hoof with a bar shoe or even a wide web shoe will help stabilize the hoof and the medial lateral instability. The most important thing to do is balance the hoof so it lands flat on the ground, not one side hitting first and rolling over.
A good farrier will be able to help with balancing the foot. Stopping the shearing in the hoof will allow the hoof to grow out healthy and strong. To recap on how to treat sheared heels and thrush: