Management of Traumatic Injuries to the Hoof Capsule

Management of Traumatic Injuries to the Hoof Capsule Written and presented November 2005 by R.F. (Ric) Redden, DVM

Foal Injuries One of the most common injures to the foot may occur hours to days from birth. Mares occasionally step on their foal's foot while it is recumbent, often causing serious damage to the hoof capsule, soft-tissue and digit. Traumatic wall injuries demand immediate attention and thorough first-aid care.

Exam and Debride Many times the wall will be separated from the underlying laminae and sole corium. It is very important to determine the extent of damage and note if any of the germinal centers have been disrupted. The coronary papillae are of great concern, as they are responsible for tubular horn growth.

A frequently asked question is, "Should the wall be sutured back on in places where it has been pulled away?" This question has two answers. When the papillae remain inserted in the coronary groove, it is best to leave the wall. The exception is when the traumatized laminae become septic. If the papillae have been displaced from the coronary groove, it is best to remove the corresponding section of wall. Attempting to suture the wall back in place disfigures the papillae, which results in disfigured horn growth, delayed healing and the creation of a bacterial reservoir beneath the detached wall.

Radiographs are always indicated with traumatic foot injuries, as fractures are common and often very extensive. When taking radiographs, remember that a foal that is only a few hours or days old requires a very low MAS due to low foot mass and density of the bone. Creating a soft-tissue exposure chart for foals of varying ages is helpful, as over-exposure is often a common problem.

General Rules for Caring for Injured Foal FeetRemove all horn that has been detached from the dermis.Remove all bone fragmentsPreserve the coronary papillae and gently direct them downward into the natural direction normal tubules grow.Use firm but very forgiving compresses over all exposed corium to prevent exorbitant granulation.Use a mild iodine solution (less than 2%).Avoid any and all caustic agents that are often used to dry the foot.Protect the fragile vascular bed.Application of a light, short-limb cast that incorporates the foot can also be helpful. Pin casts for severely damaged feet can offer a more favorable healing environment.

Iatrogenic Wall Avulsions It is quite common to have foals that walk on their toes at birth. Most respond well to Tetracycline, bandaging, splinting and/or casting depending on the severity of the deformity, size and strength of the foal. Applying a very aggressive toe extension shoe as an aid to stretch the deep digital flexor tendon (DDF) can case catastrophic damage to immature laminae. The result is partial and/or full wall avulsions.

If this occurs, debride and bandage the exposed dermis. Protect the digit from being fully loaded by applying a pin cast. Short-limb, bi-valve casts can be easily changed and are useful once the pins are removed. The sole and laminae will cornify within days. New horn wall will grow from the coronary plexus and will totally replace the hoof wall over the course of a few months. Protecting the digit from load is the key to obtaining a functional, healthy hoof capsule. Normally, the new hoof will not be as healthy and tough as the original one, but most cases will have a good prognosis for use as brood animals.

Joint Ill Associated Avulsions Joint Ill involving the coffin joint may occur with contracted cases and go undetected in the early stages of splint and cast application. Foals apparently have a high pain threshold and often do not demonstrate an initial pain response to coffin joint sepsis. Therefore, extensive damage can occur. Damage can include PIII fractures and wall avulsions.

Septic coffin joints demand emergency treatment, as the cartilage, collateral ligament and tendon attachments can quickly lose their connections and slough, leaving the bone totally detached. The author reports having three cases that required complete removal of PIII. Two of these cases regrew a large majority of their respective coffin bones, and both patients lived to raise several foals. The remaining case presented at 17 days old with multiple fractures of PIII and a fully detached wall. Wall and the fragmented PIII were removed, and the digit was protected with a cast until the hoof capsule regrew around PII. Last contact with the patient was at age two.

Fractures Many different types of fractures have been previously described. The scope of this paper is not to describe in detail the etiology and treatment of various fractures, but to help point out the most commonly encountered fractures and useful treatment protocols.

Parietal Fractures Parietal groove fractures occur commonly in foals (AAEP 1987). The precise location and size will vary considerably. Normally, the medial wing will be the predominant site; occasionally the lateral wing will also be involved. It is not uncommon to find all four feet with fractures of various sizes. These areas were once thought to be separated ossification centers. However, the work of Dr. Andy Kaneps concluded that separated osseous bodies were in fact fractures.