A foal born with club feet or a young, growing horse which develops the condition can be both a mystery and a problem for the owner and the veterinarian in charge of treatment. The condition can be mysterious because many factors might be involved in its onset. It is a serious problem because unless the mystery of origin is at least partially solved, treatment might not elicit the desired results.
PHOTO COURTESY RIC REDDEN, DVM
Grade 1 club in a mature foot. Note the even growth rings.
There are both congenital and acquired causes of flexural deformities. They can range from uterine malposition to injuries after birth, and from genetic defects to improper nutrition. Not to be overlooked as a cause for acquired flexural deformity is pain. In fact, some researchers believe that chronic pain is the most common cause of an acquired deformity.
Pain can arise from physitis, osteochondrosis, degenerative joint disease, or soft tissue wounds and infection. When severe pain occurs, the horse might seek relief by not flexing the leg in normal fashion. This causes the deep digital flexor tendon to contract, and the horse winds up walking on its toe or knuckling over at the fetlock joint.
Nutritional errors are implicated in flexural deformities in much the same way that they are in physitis and osteochondrosis. Overfeeding, for example, can result in abnormally rapid growth, trauma to cartilage, and mineral imbalances. While overfeeding can be implicated in some cases of deformity, underfeeding or an improper diet can result in malnutrition, which also can be a factor.
Signs of flexural deformities vary widely in newborn foals. Some cannot stand, some attempt to walk on knuckled-over fetlocks, and still others are able to stand, but knuckle at the fetlock or knee. Sometimes afflicted foals improve spontaneously, while other foals--some of which might have appeared normal at birth--become progressively worse.
In cases of acquired flexural deformities, sucklings and weanlings three to 12 months of age might exhibit a rapid onset and walk around on their toes with their heels off the ground. In other cases, a slower onset is characterized by a "boxy" hoof with an elongated heel and dished toe. Physitis frequently is evident in these animals. Generally both forelimbs will be involved, but it is not unusual for one leg to be worse than the other. Walking on the toe, if allowed to continue, can result in toe abscesses, which bring on additional pain and a worsening of the condition.
When older animals--those which have reached yearling to two-year-old status--acquire flexural deformities, they often are more difficult to treat than younger foals.
In all cases, treatments vary from the sophisticated to the simple. The most basic of treatments if nutrition is a factor is simply changing the diet. Other treatments range from specially constructed shoes and braces to proper trimming.
For a more detailed look at flexural deformities, we turn to Gayle W. Trotter, DVM, MS, Diplomate ACVS, Professor of Surgery at Colorado State University. Trotter frequently has spoken on and written about the subject. One of his papers, "Flexural Deformities," was published in the 1997 proceedings of "Lameness in the Horse: An In-Depth Short Course for the Horseman," which was presented by the Equine Sciences Department at Fort Collins.
Trotter made these comments in introducing the subject in his paper:
"These (flexural) deformities are commonly referred to as contracted tendons, even though true tendon contracture is unlikely the cause of the problem. However, with flexural deformities, the soft tissue structure on the palmar (forelimb) and less commonly plantar (hindlimb) are affected such that the bones align in varying degrees of flexion. The true cause and method of development of flexural deformities remain unknown, although horses with acquired deformities often share similar factors to those associated with the developmental orthopedic disease complex.
"Generally, flexural deformities are divided into congenital and acquired types. Congenital deformities are present at birth, and acquired deformities develop at some stage of the growing period. Acquired deformities manifest differently depending on the age of the horse."
Trotter says that many causitive factors can be involved in congenital deformities. In addition to intrauterine positioning, they can include ingestion of certain toxins by the mare (such as locoweed or hybrid Sudan grass), collagen cross-linking defects, equine hypothyroidism/goiter, and unidentified predisposing genetic factors.
Rarely is there a simple cause and effect. Multiple factors can be involved in a given case.
Problems And Treatments
Let us now take a look at some specific congenital flexural deformity problems as outlined by Trotter, along with some suggested treatment protocols:
Digital Hyperextension--Many foals are born with flaccid flexor tendons, such that their toes elevate off the ground during weight-bearing. Most of these deformities are minor and self-limiting. Normally, correction occurs during the first two weeks of life as muscle and tendon tone improve. In more severe cases, the foal might walk on the bulbs of the heel or on the pastern, which can result in soft tissue abrasion injuries.
Treatment can include temporary heel extensions. The youngster might need to wear such a device until muscle and tendon tone improve.
Ruptured Common Digital Extensor Tendon--This condition might be congenital or acquired. The cause is unknown. Affected foals have characteristic swellings over the tendon sheath at the dorsolateral aspect of the knee. Foals also appear slightly bowlegged, and they tend to knuckle over at the fetlock when walking and appear over at the knee when standing.
One of the most effective forms of treatment is application of a temporary splint to prevent knuckling over; however, the gait abnormality in these cases is often self-limiting.
Congenital Carpal Deformities--These deformities often are severe in extent, and frequently involve only one limb. Manual correction often is impossible. Many cases have sufficient contracture of the carpal joint capsule and ligaments to prevent correction, even after transection of all carpal flexor tendons. For less severe forms, splinting is effective.
Congenital Flexural Deformities of the Foot and Fetlock (the traditional club foot)--The young horses afflicted with this form of deformity either stand on the toe or knuckle forward at the level of the fetlock. In some cases, the deep digital flexor tendon is involved, and in others, it is the superficial flexor tendon. Sometimes both are involved. Palpation of the tendons is used to identify involvement.
If the foal can stand and the limbs can be extended manually into a normal position, the prognosis is favorable with the use of splinting. More severe forms might require check ligament desmotomy.
Desmotomy (which is cutting or transection) of the check ligament is performed just below the knee. The goal is to lengthen the affected tendon without compromising the tendon tissue in any way. The inferior check ligament encompasses and lightly supports the deep digital flexor tendon. By transecting or cutting through the ligament, the tendon is released and lengthened by several centimeters. Normally, this is all that is required to allow the heel to rest normally on the ground. The transected area quickly heals and the foal can live a normal life. Horses which have had inferior check ligament desmotomies have gone on to successful racing and other athletic careers. The concern one might have in future use of the animal would come in the breeding shed. As mentioned earlier, it is possible that genetics figure into the equation. If that is the case, using the afflicted horses as a breeding animal could produce a continuation of the problem in the offspring.
More recently, reports Trotter, the use of oxytetracycline has been advocated for some of these deformities.
Acquired Flexural Deformities
We now turn to a discussion by Trotter of acquired flexural deformities. He introduces the subject this way:
"There are many potential causes for acquired flexural deformities, and those factors important in the development of osteochondrosis are also the same factors that are important here. Flexural deformities seem to occur most commonly in fast-growing individuals, and often those that are on a high plane of nutrition. Other factors that can be involved include pain, which results in the flexion withdrawal reflex and an altered stance. The source of pain could be OCD, joint infection, physitis, or some other form of acute trauma. If the altered stance is maintained, a flexural deformity will result. The cause(s) of these deformities seem to be multifactorial, with nutrition and rapid growth being factors that are commonly present."
There also is conjecture that overfeeding of the mare during gestation can be involved in flexural deformities.
"There tends to be two age groups that develop acquired flexural deformities," reports Trotter. "Deformities of the distal interphalangeal (coffin) joint are usually at one to four months of age, whereas deformities of the metacarpophalangeal or fetlock joints are usually at 12 to 14 months of age. This age relationship is thought to be related to the effects of the accessory or check ligaments of the deep digital and superficial flexor tendons, respectively, and the fact that limb growth at the distal limb is largely completed by three months of age, but continues at the level of the carpus or knee for a much longer period.
"There is no evidence to suggest that true contracture or shortening of tendons occurs, but the check ligaments may restrict passive elongation of their respective flexor tendons during periods of rapid bone growth at the more distal or proximal locations. In the case of the deep digital flexor tendon, a flexural deformity affecting the foot will be the end result, as this tendon attaches to the distal phalanx or coffin bone. With involvement of the superficial flexor tendon, the deformity will appear at the fetlock joint and is very difficult to deal with.
"Affected foals have varying degrees of a more upright or clubbed foot appearance. In less severely affected foals, a dished appearance to the dorsal hoof wall will appear over time due to the mechanical influences placed on the foot. In more severely affected foals, the heel will not contact the ground. Very severely affected foals will walk on their dorsal hoof wall."
Step number one in the treatment process involves the diet of the mare and the foal. If the foal is very young, it might be necessary to restrict the diet of the mare so that milk production can be limited.
Trotter also recommends that exercise be controlled. Some exercise is beneficial, but it might be harmful if the foal is allowed to roam freely in a pasture. With less severely affected cases, he says, a toe extension can be taped or glued to the foot or a special glue-on shoe with a toe extension can be applied.
Treating Club Feet
For an in-depth look at treatment of the traditional club foot, we now turn to Ric Redden, DVM, an equine foot specialist from Versailles, Ky. He begins with his explanation of what is involved in the club foot syndrome, then goes into detail on his approach to treatment.
"A club foot," he says, "results from a deformity associated with a contraction of the deep digital flexor muscle. Club feet are characterized by irregular horn growth, usually of the front feet, with one foot being involved more often than both. The condition appears to have a genetic linkage, and nutrition seems to play a role as well. The horn capsule develops a high heel due to excessive growth, and the hoof angle becomes much higher than normal. The horse may develop a dished foot. Club feet are seldom seen as a congenital deformity, but are acquired, ranging from one month to 12 months of age, with three to five months being more common."
Treatment of club feet, Redden says, depends on the severity of the deformity. To assist in devising a treatment plan, Redden classifies the severity on a scale of Grade 1 through Grade 4.
Here is his description of the four grades:
Grade 1--The feet appear mismatched, with the hoof angle of the affected foot being three to five degrees greater than the opposing foot. There is a characteristic fullness at the coronary band due to slight luxation of P2 (short pastern bone) and P3 (coffin bone).
Grade 2--The angle of the hoof is approximately five to eight degrees greater than the opposing foot. Growth rings are wider at the heel than at the toe. The sole will protrude slightly below the wall at the toe, and the bulbs of the heel appear thickened. The heel of the foot will not touch the ground when trimmed to a normal length.
Grade 3--The hoof wall is dished and the growth rings are twice as wide at the heel than the toe. The impression of P3 on the sole can be seen clearly just forward of the apex of the frog. The sole shows signs of direct weight bearing as it will be bruised in many cases. The coronary band protrudes well out over the face of the anterior wall. Radiographs of P3 reveal lipping and demineralization along the apex.
Grade 4--The upper portion of the hoof wall angle is 80 degrees or more, and the foot becomes heavily dished along the lower wall depending upon the horn thickness and quality. The coronary band at the heel is the same plane or higher than the coronary band at the toe. The sole supports the weight of the bony column as it is well below the ground surface of the wall. Radiographically, the apex of P3 will appear rounded due to extensive demineralization and may show several degrees of rotation.
"Treatment," says Redden, "is traditionally directed toward realigning the hoof-pastern axis by lowering the heel and preventing further wear of the toe. Application of a tip shoe is often used as a treatment to prevent excessive wear of the toe. The tip shoe is used in conjunction with lowering the heel. Extended toe shoes are also often used to gain immediate results. But, caution is advised with all methods that are directed toward mechanically stretching the deep digital flexor tendon.
"It is my experience that only Grade 1 and a small number of Grade 2 cases are likely to respond to this treatment. This is because the hoof and coffin bone are more vulnerable to the added stress of abnormal weight bearing than the deep flexor is to the increased tension. The posterior three-quarters of the foot is suspended in mid-air by the contracted deep flexor; therefore, the toe of the foot supports the entire weight of the limb, causing a multitude of problems that could become a threat to the health of the foot. The abnormal stress of direct load to the toe of the foot causes dishing of the horn wall, reduction of anterior horn growth, bruising of the sole, excessive heel growth, demineralization of the apex of P3, and frequent toe abscesses that may cause considerable lameness and full thickness toe cracks. These problems seem insignificant on the foal, but often diminish the racing potential of young horses.
"To avoid unfavorable side effects of lowering the heel, such as a dished horn capsule and rapid demineralization of P3, it is imperative to evaluate the response obtained from the first session of heel lowering within 10 days. Grade 1 and a select few of Grade 2 cases may hold their own or improve with this treatment. However, some will progress at a steady rate to a higher grade with continued heel lowering. This starts a vicious cycle that threatens the future soundness of the animal. It is difficult in the early stage of the syndrome to give an accurate prognosis regardless of treatment as we do not understand the initiating cause nor the severity of the trigger mechanism."
Treatment of Grades 2, 3, and 4, according to Redden, is directed toward improving the anterior-posterior balance to re-establish a normal load equilibrium between the deep flexor and ground surface of the foot. Those horses which develop Grade 1 and Grade 2 clubs over several weeks normally are quite easy to manage, he says. Others might be explosive in nature and quickly progress to a Grade 3 or 4.
No matter what the treatment approach taken, Redden says, it should be directed toward protecting the toe from excessive wear and reducing the major force at play--the deep flexor. This protection will reduce the incidence of toe abscesses and is helpful in maintaining a more normal hoof and pastern axis.
"With the advanced grades," he explains, "the center of load is transferred to the toe and the heel is basically unloaded. Even if it slightly touches the ground, little, if any, load is carried on the inside of the heel area. Continued lowering of the heel increases the load at the toe and prevents normal heel loading that is vital to protect the white line, sole, and apex of P3 from the excessive pull of the deep digital flexor. The dished foot is the result of the excessive pull and absence of heel loading. The weight of the horse simply bends the toe.
"It is recommended that all club feet be examined and trimmed (if indicated) every two to three weeks as heel growth and toe loss are excessive in 30 days and this forces the farrier to make drastic changes in the hoof angle with each trim. Frequent trims are necessary to evaluate accurately the progress of treatment and to make appropriate changes if the foot is not responsive to lowering of the heel."
Redden explains the use of the special Dalric shoe for club feet this way:
"A safe procedure to help identify the lower grades is to trim the heel to a normal length and set it down just behind the opposing foot. If the heel is not touching the ground surface, then a Grade 2 or better can be given this foot. Mechanically raising the heel reduces the continuous pull of the deep digital flexor. Adding twice the height to the shoe of the space under the heel allows the heel to become weight bearing and the deep digital flexor will relax. Use of the Dalric B1-B2 shoe with heel attached has produced consistent favorable results with Grades 1 and 2, and a few low Grade 3.
"Caution is advised when using any shoe on foals, as prolonged use can retard development of the foot. The all-adhesive shoe prevents problems associated with nailing."
To be successful in treating club feet regardless of grade, he explains, the technique must be designed to address specifically the mechanical demands of the foot.
"Trying to group club feet under one general heading, with a common means of treating them," he says, "promotes mass confusion and seldom offers favorable results. This is very serious business and the most minute detail can make or break you. Experienced professionals that deal frequently and successfully with club feet have broken my scale down even further. Instead of four basic classes, it is quite easy to use 12 as a standard scale. Training the eye for detail and having a thorough understanding of the anatomy and physiology of the foot certainly have their merits in treating club feet."
Redden said he uses a four-point trimming technique for all Grade 1 and Grade 2 club feet, with variations as indicated. For Grades 3 and 4, more drastic options are required.
"Basically," he said, "the four-point technique calls for pushing the heels back to the widest point of the frog, starting at the apex of the frog, not the toe. Then I rocker the toe to obtain breakover just in front of the point of the frog, approximately one-half to three-fourths inch in young foals. The goal is to leave as much foot mass as possible. All club feet have a tendency to sole load. The area just over the coffin bone is normally calloused and tough. Leave it. Do not disturb it. If you push the heels back without bringing the breakover back under the foot, the tendon is tighter and counter-productive.
"When favorable results are obtained in 10 to 15 days, I stay with the four-point technique, trimming every two weeks. Favorable results offer a thick sole with each trim, good toe growth, and less heel growth. If the hoof angle decreases on its own due to the sole and toe growth, you have solved your dilemma. If your farrier must take off heel and back up the toe with every trim, you are not maintaining status quo, but losing ground. Note: the breakover is under the toe and is perpendicular to the long axis of the frog. The toe is not square; just the breakover. I refrain from backing up the toe from the front to the four-point, as it merely weakens the frog arch and only gains one-fourth to one-half inch break-over--not nearly enough to mechanically reduce tendon pull.
"Step 2 is used when your Grade 2 does not hold or fails to improve. I use the same technique as just described and apply a Dalric raised heel shoe with Advance Cushion Support arch support. The goal is to load the heel and unload the sole and apex. The heel must be pushed back before raising to accomplish this goal. Raising the heel 15 degrees significantly reduces tendon pull and offers good results for Grade 2 and low Grade 3.
"Strong Grade 3 and Grade 4 club feet require Option 3. Here, the heels are backed up, creating a ventral angle of three to five degrees with the load surface. A toe extension shoe is applied-nail on or glue-on-and the inferior check ligament is surgically severed. I prefer to de-rotate the digit with the shoe applied just prior to surgery. Shoeing the foot immediately after surgery does not work well for the farrier and increases the risk of bruising the surgical site. Shoeing several days or weeks after surgery often reduces the overall results as the check begins to heal the moment it is cut and adhesions develop within days that prevent the heel from dropping to the desired level. I maintain the foot in a toe extension shoe for two resets. Basically, what you have achieved in two months is your end product as the check is healed at that time.
"Strong Grade 4 clubs require Option 4. Here, we begin with the same approach--trim, obtain three to five degrees on the ventral angle, short toe extension, and a heel extension shoe (one to 1 1/2 inchs). Then, I surgically sever the deep flexor tendon at midcannon. Cutting the check ligament in these cases seldom offers enough laxity for favorable results. The heel extension supports the limb and holds the toe down while the tendon heals. Stall rest for two months, hand walking for two months, then turnout in a small paddock for two months are called for during the recovery period. Keep the leg bandaged with a very firm cotton wrap for two to three months. The tendon is quite strong in six months, and most all of my cases have gone on to perform successfully for most all sports, other than racing. One thing is certain--they are much sounder with a thick spot on the tendon than they are with a Grade 4, beat-up foot that is a farrier's nightmare for the life of the horse."
His approach, Redden says, is not a cure-all, but it has been effective in a great many cases and is far more beneficial than merely lowering the heel of a club-footed horse.
About the Author
Les Sellnow is a free-lance writer based near Riverton, Wyo. He specializes in articles on equine research, and operates a ranch where he raises horses and livestock. He has authored several fiction and non-fiction books, including Understanding Equine Lameness and Understanding The Young Horse, published by Eclipse Press and available at www.exclusivelyequine.com or by calling 800/582-5604.
POLL: University Equine Hospitals