Using Standing CT Imaging to Find Abscesses in Equine Patients
What is an abscess?
“Hoof abscesses occur when bacteria get trapped between the sensitive laminae (the tissue layer that bonds the hoof capsule to the coffin bone) and the hoof wall or sole. The bacteria create exudate (pus), which builds up and creates pressure behind the hoof wall or sole. This pressure can become extremely painful.” -Dr. Brian Fitzgerald
Most horse owners associate the cause of hoof abscesses with extremely wet or dry conditions. Moisture in the environment can soften regions of the foot and make it easier for bacteria to get trapped inside, likewise, extremely dry conditions can cause brittle cracked feet to become exposed to bacteria. However, hoof abscesses can also be caused by:
Debris: This is called a “gravel” abscess which is caused by a small piece of debris getting jammed into a weakened spot in the white line or corn area of the hoof. If debris manages to penetrate beyond the hoof wall, bacterial invasion into the soft, sensitive tissue (corium) inside the hoof will follow.
Figure 1: Chronic abscess and bone cyst like lesion of the coffin bone. CT image taken with the Equina by Asto CT.
“Hot” Nail: A misplaced nail can be the cause of an abscess when the nail is driven inside the white line and penetrates the soft tissue within the hoof capsule.
Close Nail: A close nail is a nail that is driven into insensitive horn, but displaces hoof material in a way that affects the function of the hoof.
Chronic Laminitis and Pedal Osteitis: Horses with laminitis or founder can experience abscessing due to septic pedal osteitis (coffin bone infection). The coffin bone of the laminitic horse gets progressively more damaged with each episode.
Acute Laminitis: Horses in the acute stage of laminitis can suffer from abscessing from internal injuries taking place within the hoof capsule.
Seedy Toe: Horses with chronic laminitis and fungal infections are also likely to have chronic abscessing in the toe. Certain laminitic cycles can result in a malformed, scarred or damaged horn that is prone to infection.
Trauma: Horses with coffin bones that have been damaged from trauma such a bruising or fractures can abscess if the injury leads to infection.
Keratoma: A keratoma consists of a benign tumor of keratin or horn-producing cells. The keratoma will grow between the coffin bone and the hoof wall causing distortion of the hoof wall, recurrent foot abscesses, and laminitis.
Abscesses are a common occurrence in horses. Chances are if you have horses you have already experienced treating an abscess or will be treating one in the future. The majority of time abscesses can be healed with minimal treatment, but as we see in the case studies below, sometimes it takes more aggressive treatment.
Figure 2: Mark the Clydesdale shown with several hoof wall debridement’s and resections.
Case Study One
Mark is a nine-year-old Clydesdale gelding who had a long history of chronic abscessation and white line disease in his left front foot. Dr. Diego De Gasperi stated that “We don’t always scan horses with white line disease, but we started to scan horses with chronic draining tracts from abscesses or more severe white line disease like Mark. We found that scanning these horses has been extremely helpful for us and our farriers to figure out how far back the draining tract goes or how far back we have to debride the hoof walls.” Mark had several hoof wall debridements and resections and is currently doing well (shown in figure 2).
View the video of Mark’s CT images: Click Here
Case Study Two
Figure 3: CT images of the keratoma , the markers placed below the hoof crack, and the hoof wall resection.
This 12-year-old thoroughbred had a history of a right front limb lameness and chronic abscesses. Dr. Diego De Gasperi states, “We scanned this horse to confirm the presence and extent of the infection. We see the infected foot with a crack and our markers placed below to help us understand the location and extent of the lesion; this helped us prepare for surgery.” The next day the hoof wall was resected, and the mass was confirmed to be a keratoma. Figure 3 shows an extensive hoof wall resection with two methyl bars across the hoof wall defect and adhesive on each side to stabilize the foot. Prognosis is good for a full recovery assuming the entire keratoma was removed at the time of surgery.
To view the full case study, click here.
We hoped you learned a thing or two about abscesses and found our case studies interesting. For more info on how CT scanning can help diagnosis lameness, which will help define the optimal treatment, send us an email at information@astoct.com.