Although an uncommon condition, keratoma formation beneath the horse’s hoof wall or sole can cause lameness, recurrent abscesses and damage to the laminae and coffin bone.
Because of the potential for serious medical consequences, keratoma diagnosis, removal and treatment requires either the close collaboration between farrier and veterinarian or the involvement of a veterinarian skilled in farriery.
This article presents the conclusion of a clinical case involving a keratoma patient treated by equine veterinarian and certified journeyman farrier Raul Bras in the podiatry clinic at Rood and Riddle Equine Hospital in Lexington, Ky. The patient, a 2-year-old Thoroughbred gelding, a future racing prospect, was referred to Bras for a defect in the dorsal hoof wall of the left hind with recurrent abscesses at that site and in the sole and mild, intermittent lameness.
Through examination and radiographs, Bras found that the horse had two keratomas (Figure 1 Above) in the left hind foot. Two masses, one at the lateral toe (Figure 2) and one directly below P3 in the region of the sole lesion (Figure 3), can be seen in radiographs. Keratomas classically show up on radiographs as a radiodense (white) circle or semi-circle outlined by a radiolucent (dark) margin. The presence of both the cylindrical keratoma under the dorsal hoof wall and the spherical keratoma beneath the sole presented a problem for Bras.
The previous article (which can be read at www.americanfarriers.com/ff/0914) tracked the surgical removal of the cylindrical keratoma in the dorsal hoof wall and stabilization of the foot following surgery. The horse did even better than expected after the first surgery, never showing any lameness. As the foot began to grow out from that surgery, Bras scheduled the removal of the second mass.
This keratoma was a spherical knot of abnormal tissue located under the sole, directly distal to P3 (Figure 3).
Removing The Second Keratoma
Bras performed this surgery in the same manner as the previous resection, with the horse standing and under local anesthesia from an abaxial block. The sole over the mass was pared away, and the abnormal tissue was surgically scraped and peeled out of the foot (Figure 4).
Although this keratoma appeared well-demarcated on X-ray, Bras says that wasn’t the case.
“A lot of times, you have well-defined abnormal tissue,” he says. “The one in the sole wasn’t as obvious as I thought from the X-ray.”
Bras also was concerned by the fact that the mass had left a defect on the solar surface of P3. He believes this defect was because of prolonged pressure of the keratoma against the bone.
The horse once again surprised Bras after the surgery.
“I was pretty aggressive with the solar keratoma,” he says. “I wound up scraping a little bit against healthy bone in order to remove all of the abnormal tissue. The next day the horse was sound.”
Therapeutic Shoeing Plan
Because an extensive amount of hoof wall was resected during the first surgery, the hoof capsule required stabilization. Bras applied a SoundHorse Technologies Sigafoos Series II glue-on shoe with a fiberglass cuff that encapsulates the entire perimeter of the foot for stability. He customized the shoe by cutting out the areas over each keratoma, bracing the dorsal hoof wall defect with an aluminum band, and using a removable treatment plate over the sole.
Bras says he used “a similar shoe with a treatment plate so I can access the bottom and top” after the second surgery.
Fabricating and applying the shoe can be labor intensive. Bras strongly advises that farriers become familiar with the shoe and practice fabricating it before taking on a case and trying to apply one.
“For someone who fabricates them only once in awhile, it can easily take more than an hour,” he says. “For someone who does them on a regular basis, it could take 30 to 45 minutes per shoe.”
Because the surgery was considered to be clean and uncompromised, Bras did not start the horse on antibiotics. However, he did put it on a short course of phenylbutazone to address the inflammation following surgery.
The horse was kept stalled for a few days for observation. Since it was sound the day after surgery, “we dropped the anti-inflammatories right away.” As there was no lameness, stall confinement lasted less than a week.
“We began hand-walking right away,” Bras says, “then they moved the horse to a small turnout, and now it’s back outside.”
Just as he did after the removal of the first keratoma, Bras employed the same Sigafoos shoe after the second surgery. However, this time, he also used a treatment plate to keep the surgical site free of dirt and debris (Figure 5).
Given that this horse “is really growing a lot of foot,” Bras anticipates that the solar defect may be filled in within 4 months. In most cases he would expect a similar lesion to take a minimum of 6 months to completely fill. However, in the roughly 4 months since the first surgery, the dorsal wall defect almost has completely grown down (Figure 6).
Although the dorsal hoof wall defect is growing down without complications, Bras thinks “this horse is always going to have some scar tissue, because it was so invasive.”
While horses can return to full function after successful removal of a keratoma, Bras is a bit more cautious when predicting this patient’s future.
“I have to be careful and say that considering how compromised the horse has been,” Bras says, “it could have further issues.”
The question, Bras says, “Is the horse going to have further complications from the scar tissue because it sets up dead space that could cause abscesses to routinely appear?”
However, he notes that the horse “has proved us wrong the entire time,” by having a more complicated condition than anticipated and by responding to surgery without any hint of lameness. So, Bras says, the possibility remains that the horse “could run well.”
He anticipates that the horse will remain in his care at least for another two to three more shoeings, about 2 to 4 months, to ensure no complications arise throughout the healing time.
A number of potential complications and concerns can accompany keratomas, Bras says, including:
- Damage to the laminae or bone.
- Post-operative infection.
- Rotation of P3 in the affected foot.
- Supporting-limb laminitis.
- Incomplete removal and recurrence of the keratoma(s).
In order for treatment to be successful, an accurate diagnosis is necessary — usually by radiograph, but sometimes through biopsy or MRI — and complete removal is critical. If any portion of the keratoma is left behind, it will reoccur.
Infection prevention can be accomplished through packing the defect, systemic and/or regional antibiotics, and by keeping the site clean at all times. Pain is generally managed with non-steroidal anti-inflammatories, such as phenylbutazone.
The remaining hoof capsule should be stabilized and the compromised area unloaded during the regrowth period.
This case was unusual because of both the young age of the horse and the presence of two keratomas. There was no history of injury or other potential cause, Bras says.
Keratoma cases provide an excellent opportunity for close collaboration between veterinarian and farrier.