Horn gap
Under Horn columns cracks in the horse's hoof to be understood that parallel to the tubules of the supporting edge extend. At the beginning of their formation, while they are still small and inconspicuous, they are called wind cracks. One speaks of horn fissures only when they are so deep that they go through the entire hoof wall to the dermis .
causes
The horn capsule is in constant motion. It expands and narrows with every step. The elastic material is equipped to withstand this stress. Only when these movements become too large locally due to an unfavorable hoof shape do they become disconnected. The horn tubes of the hoof wall separate from each other locally. A wind crack occurs. But this separation of context weakens the cohesion of the horny tubes. Due to the notch effect that then occurs in this area, the area of the disconnection increases, in extreme cases until the horn wall is severed down to the coffin bone support.
Symptoms
There are three types of horn fissures:
Support edge gaps
These are the most common horn clefts. They start at the rim and tear or slowly wander up the hoof wall. In some cases they tear up the downward growing hoof to the same height. If the gap becomes larger or longer and tears up to the coronet, then a continuous horn gap develops.
Continuous horn columns
With such a horn cleft, the hoof wall is severed from the ground to the coronet.
Coronet columns
The fact that such cracks can also appear at the coronet margin shows that the cause of horn cracks is usually not an injury or damage, but rather tension in the hoof wall, which it cannot cope with. Often, horn fissures bleed at the coronet , because the separate areas working against each other injure the coronet . Horn is dead material. Once cut through, the horn wall cannot grow back together. Therefore, in the long run, an untreated coronet gap will always become a continuous horn gap.
Course of the disease and possible consequences
Since the cause is the tension of a deformed hoof wall, which has torn at the point of high local stress and is thereby additionally weakened, this defect will rarely repair itself. In less dramatic cases, the crack simply remains or, contrary to the horn growth, always tears up to the same point. If the crack becomes wider or if it arises in or reaches the coronet, so that the dermis is injured and begins to bleed, there is an acute need for action. Because the hoof wall is constantly moving, this injury can heal poorly or not at all. If scars develop in the coronet, then a weak point will always remain in the hoof wall at this point, or the hoof wall will remain permanently split at this point. Incurable pain and lameness are the result, sometimes so strong that the veterinarian euthanasia is recommended.
prevention
Ensure that the hoof is trimmed professionally, which creates the most even load conditions possible over the entire bearing edge, aligns the hoof position with the fetlock position and achieves a flat footing of the hoof as far as possible. Carefully clean and examine the hooves at regular intervals. If wind cracks appear, this is a sign of unfavorable tension in the hoof. Adjust machining so that these stresses and loads are minimized.
treatment
For decades, attempts were made to stop the classic bearing edge gap by means of a filed transverse groove, which was supposed to neutralize the notch effect. Compared to the metal nib of a fountain pen , the slit in the nib , which also widens when you write due to the pressure on the paper or narrows again when the pressure is released, would also tear open the nib further up the nib due to the notch effect without the round hole at the end of the slit. But because, firstly, the transverse groove would have to go through to the coffin bone support and, secondly, the notch effect would be canceled, but the tension still exists, this unsuccessful method has largely been abandoned. In the picture, in the case of a continuous, sometimes bleeding, chronic coronet fissure, an attempt was made to reduce the notch effect by deeply cutting open the hoof wall. Nowadays, most attempts are made to ensure that this area of the hoof wall can no longer move so much by means of shoeing and special trimming of the hoof, for example in such a way that the supporting edge at this point "floats" above the horseshoe due to a local shortening . Depending on the size and shape of the gap, additional measures are taken to stop the movement, one of which is the screwing on of stabilizing steel strips. Sometimes it is possible to close the horn gap or to ensure that the hoof wall grows back coherently. However, if it is neglected to influence the load situation at the same time, the gap continues after removing the special fitting. If it is possible to remove the unfavorable loads and tensions from the hoof situation through appropriate processing, then the crevices grow out without any shoeing.
In the case of chronic clefts in the horn, it is often not possible to create a permanently improved situation simply by shoeing the horse, since the horn-forming tissue of the hem band has been injured and scarred. At this point, only inferior “scar horn” is formed, which cannot withstand the normal loads on the horn capsule. Only a surgical intervention with removal of the scar tissue from the hem band will possibly achieve an improvement.
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Web links
Videos on the formation of horn fissures:
