Cracks are symptoms of an imbalanced hoof situation. They will automatically grow out when the hoof starts to rehabilitate and changes its shape with the correct hoof treatment. The time period for this can vary greatly, depending on existing hoof deformations. Most cracks and splits are completely gone after the renewal of the hoof capsule, which takes about 11 months. If the coffin bone and its hoof continue to remodel after a year or the horse is forced to change load on the limb due to accompanying factors (e.g., osteoarthritis, tendon damage), the process takes longer. Constant changes in the hoof capsule have an impact on the hoof mechanics, which must be permanently controlled by the hoof specialist. The crack cannot grow out if the hoof shape is not rehabilitated yet. If the hoof has concomitant circumstances like defects in the bone structure, crena, keratomas or horn scars, then the journey can become challenging and long-lasting but not impossible. 

Case 1       Nora

Toe Wall Crack
right front hoof, lateral view
toe wall crack left front hoof
left front hoof, lateral view

6 months later:

right front hoof 6 months later
right front 6 months later
left front hoof 6 months later
left front 6 months later

Case 2    Tom Petty

toe wall split right front hoof
toe wall crack left front hoof

4 months later:

right front 4 months later
left front hoof 4 months later

7 months later:

right front 7 months later
left front 7 months later

Case 3       Rain

These toe cracks were very stubborn. Rain had been dealing with these cracks for years before I started. If a toe crack lingers on for such a long time, the coffin bone will be affected. A so-called 'crena' can develop, a notch in the coffin bone which makes it hard to treat a toe crack. A crena causes a gap in the laminae, the connection between hoof wall and bone. A crena will always occur in the front hoofs and exactly at the spot where the horse toes off, where the most pressure acts on the hoof, when the horse pushes the hoof off the ground. 

cracked hoof wall right front hoof
cracked hoof wall left front hoof
lateral view right front hoof

2 months later:

right front 2 months later
left front 2 months later
right front 2 months later

one year later:

right front 1 year later
left front 1 year later
right front lateral view 1 year later

Almost 2 years later:

right front almost 2 years later
right front 2 years later, after treatment
left front almost 2 years later, before
left front 2 years later, after treatment

Case 4     Quarter Crack 

Left Front. The crack completely separated the heel from the quarter wall. The solar picture shows the main load of that hoof is to find lateral, left in the picture. That heel is severely underrun, the bulb is being pushed upward due to the load and compression whereas the other side can flee from the center of pressure. The heel wall on that side is more slanted, the bar leans onto the sole, every horn part seems to be pushed to the side. 

Cause and effect

The flaring toe wall has completely lost its stability. The horn tubules are bent, start to crack. If not addressed properly, the heels will underrun even more. On the more loaded side, forces will collide. Underrun heel being pushed inside, rolls in while quarter wall bulges out. Toe wall starts to bent and moves forward, the quarter wall will inability start to crack. In this case, the problem hadn't been addressed in months. The crack became worse and worse. 

quarter wall crack, heel wall separated
quarter crack, solar view
medial view, left front

Medial side, same hoof. We can see how the toe on that inner side is in the way, makes it hard for the horse to break over. A second crack has developed right where forces collide again and work against each other. The quarter wall cause a huge lever, bulging up into the coronet. We see horizontal compression lines. That massive lever causes the horse to only use the lateral side with the heel crack even more. It cannot use the medial side at all.

Right Front. Two completely different deformed quarter walls. The main load of that hoof is lateral (left picture) as well. Therefore, the medial side is bulging out. The toe wall flares too but the hoof is in an overall better shape than the left one. The reason for that is simply that the horse has two different feet, different heel height. This is the steeper, smaller hoof which has a better heel alignment by nature and is used less than the parallel flat foot. The heels are more stable than on the left foot. 

right front, lateral view
right front, medial view

Directly after treatment. Disturbing factors have been eliminated, the toe tubules will grow down in a proper orientation, the horse will be able to use its toe better, ergo, the heel will rise and the crack grow out. 

left front hoof, right after 1. treatment
lateral view right front after treatment

right front

right front dorsal view after treatment
right front lateral view after treatment