If The Infection Migrates
Many times the painful tract can be located, but drainage cannot be established at the sole-wall junction. In this case, the infection is deep and may have migrated under the sole or wall away from the white line. Again, under no circumstances should an opening be created in the adjacent sole. This seldom leads to the abscess, generally leads to hemorrhage and may create a persistent, non-healing wound with increased potential for bone infection.
Instead, a small channel can be created on the hoof wall side of the white line using a small pair of half-round nippers. The channel is made in a vertical direction following the tract to the point where it courses inward. Drainage can usually be established using a small probe in a horizontal plane. Preferably this is done at the onset of lameness, before the infection ruptures at the coronet.
If left untreated, a hoof abscess will follow the path of least resistance along the outer margin of the dermal tissue and eventually rupture at the coronet forming a draining tract. Many horse owners actually consider this to be an acceptable practice and wait for this to take place. From a humane standpoint, this practice often extends the amount of time the animal experiences severe pain.
Rupture at the coronet also leads to a permanent scar under the hoof wall. This tract leading to the coronet may result in a prolonged recovery from the abscess, a chronic draining tract, repeated abscesses and a full-thickness, hoof-wall crack. Every effort should be made to establish drainage on the solar surface of the foot.
Abscess Or Infection?
Please be advised that the following comments are the author's opinion and do not reflect the position of the American Association of Equine Practitioners (AAEP) or any other veterinary medical organization.
Members of the veterinary and farrier professions have debated the topic of who should treat hoof abscesses for ages. If we go back and consider how an abscess is formed, it is a cavity filled with exudate surrounded by a thin fibrous membrane.
The cavity of the abscess could be thought of as an extension of the entry tract located in the hoof capsule. Therefore, when a farrier follows a tract through the sole-wall junction and creates a small opening into the cavity of the abscess, he or she may not be invading dermal tissue.
There is no hemorrhage or pain involved with this process. It could be considered much the same as removing a splinter from under the skin in a person. In this context it would appear justified for a farrier to drain an abscess and initiate the aftercare described previously.
Again, it could be argued and/ debated whether this is the practice of veterinary medicine. Furthermore, it would be prudent and in the farrier's best interest to inform the horse owner at the onset as to his or her intention of draining the abscess, to give the owner the option of contacting a veterinarian and explaining to the owner that hoof abscesess can and often do persist to a point where veterinary intervention would be necessary.
On the other hand, when an infection is present from a puncture wound in the sole or a "close nail," the treatment should be a joint venture with a veterinarian.
To establish drainage in this case, a larger opening may need to be created and sedation may be necessary, dermal tissue will need to be invaded and possibly debrided, there may be hemorrhage and medications such as antibiotics and anti-inflammatory drugs will need to be prescribed.
If a farrier were to treat an established infection in the hoof, it would be practicing veterinary medicine and the farrier could be held liable.
Prevention is achieved through proper hoof care and centers on promoting a strong, solid sole-wall junction (white line) that resists penetration by debris. Hoof abscesses are less likely to occur when a solid sole-wall junction (white line) is maintained.
Excessive toe length increases the bending force exerted on the toe, leading to a widening and weakening of the white line. Other conditions that cause mechanical breaks or weakness in the continuity of the white line are hoof capsule distortions (long toe-under run heels, excessive toe length, heels too high or a club foot, sheared heels), hoof wall separations (white line disease, seedy toe) and chronic laminitis. Excessive moisture or dryness may also contribute to weakness in the white line.
To prevent abscesses, it is important that the foot be trimmed in a manner that accentuates a strong healthy foot. A few basic principles can be used when trimming to create a strong foot and strengthen the white line.
First is the creation of a good heel base where the bars are preserved and the heels are trimmed to the base of the frog, or as far back as possible. This increase in ground surface allows a substantial amount of weight bearing to occur in the palmar portion of the foot. Sole is only removed adjacent to the white line to identify excess hoof wall that should be removed. It is not necessary to concave the sole as this occurs naturally.
The toe is trimmed appropriately and backed up from the dorsal surface (front) of the hoof wall, such that a line drawn across the widest part of the foot will be in the middle of the foot.
This assures that there is no excessive toe length. In some cases, fitting the shoes hot may be helpful to seal the sole wall junction. The use of hoof hardeners (Keratex) and bedding the horse on shavings or sawdust may be useful to harden the feet during extremely wet weather or when the horse is being washed frequently, such as during horse shows.
During dry weather, a hoof dressing, such as a combination of cod liver oil and pine tar (mixed in a ratio of 3:1) painted on the entire foot, may help to soften the hoof capsule.
Preventing indirect penetration through the white line is therefore dependent on providing adequate protection to the underlying sensitive structures. The hoof capsule has a natural ability to provide such protection and it is imperative that we strive to enhance these strong features through proper trimming. Excessive removal of protective horn is a common practice, as emphasis is often placed on eye appeal instead of functional strength.