Contracted Heels in a Horse

The foot in the first two images (Figure 1 and 2)  belongs to a horse with chronic heel pain. As a result of the chronic pain, the horse's heels are severely contracted and the base of the frog has atrophied (shrunk). In Figure 2, the width of the frog is highlighted by the blue line and the length of the frog is in yellow. Normally, the width of the widest portion of the frog is 2/3 of the total length of the frog (Figure 3).

Figure 1

Figure 2

 

Figure 3

In Figure 5 and 6, a normal foot demonstrates the normal ratio between the length of the base of the frog and the over all length of the frog.This is in stark contrast to the foot in Figures 1 and 2. Normally, a horse's foot lands heel first and transfers the ground forces from the base of the frog/digital cushion thru the body of the frog. As such, the frog and digital cushion play and important role as a shock absorber.  If the base of the frog is abnormally atrophied OR the frog is NOT making contact with the ground, the ground forces are transferred to the sole and wall of the foot creating a scenario for pain over the sole and bars of the foot. This may result in further heel contracture and continued foot pain!!

Figure 4

 

Figure 5

 The development of contracted heels and an atrophied frog can be due to poor conformation and/or chronic heel pain. The chronic pain prevents the horse from fully loading the heel region and engaging the frog properly.One of the most common conditions that results in heel contracture due to chronic heel pain is in horses with navicular syndrome. Unfortunately there is no magic treatment or shoeing that will significantly reduce heel contracture in these horses. In addition, once the base of the frog atrophies as in Figure 1, it is not likely that a normal frog will ever develop. Regardless, it is important to determine if these horses have heel pain and to treat accordingly. In my experience, shoeing these horses with a full pour-in pad or a frog-support pad is key to promote normal engagement of the frog. In addition, maximizing the "break-over" will allow these horses to land heel first yet shorten the time spent weight bearing over the heel region and thus reduce heel pain. An example of such a shoeing is in Figure 6. This shoe is known as a "Roller-motion" shoe which has maximum break-over built into the toe region of the shoe. In addition, a medium-grade pour-in pad has been included for the entire length of the frog.

Figure 6

Thin Soles in a Horse!!

The radiographs below in Figures 1-3 belong to a middle-aged QH gelding that presented for severe lameness. The gelding was recently trimmed by the farrier and had a history of mild to moderate foot pain.
On presentation, the gelding was very sore when asked to walk on a firm surface and was not willing to walk in a tight circle! There were NO pounding digital pulses however firm pressure, via my finger tips, over the sole region resulted in a strong pain reaction by the gelding. Radiographs were taken and severely thin soles were diagnosed in both front feet (Figure 1 and 2). The actual thickness of the sole was difficult to measure due to the thinness but was approximated at 2-3mm (Figure 3). Less than 5mm of thickness essentially corresponds to 1 swipe with the hoof knife!!

Figure 1

Figure 2

Figure 3

In Figure 4, there is a radiograph of a normal horse's foot. The sole depth at the toe region is approximately 15-20mm. In my experience, when the sole thickness is less than 10mm, there is increased likelihood of foot pain from concussion with the ground. Thin soled horses are at high risk for sole bruising and sub-solar abscess development. Unfortunately, some horses are "naturally" thin soled due to poor genetics and MUST be managed with shoes. The corrective shoeing is simple and may include a rim pad, leather pad , or soft pour-in pad. I strongly recommend radiographic evaluation PRIOR to any foot trimming to determine the sole thickness of horses that have a history of chronic foot pain!

Figure 4

Sub-solar Abscess in a Horse!!

Figure 1

The radiograph in Figure 1 is of a horse's hind foot. This gelding has been suffering from chronic laminitis/founder for over 1 year. When I first examined this horse, there was nearly zero sole depth between the coffin bone and the bottom of the foot. In addition, the coffin bone was reduced in size due to gradual degradation (pedal osteitis) of the coffin bone. The pedal osteitis developed due to the chronic pedal bone rotation that is evident in Figure 2 (non-parallel red lines). It was decided that a deep digital flexor tenotomy combined with appropriate shoeing may help stabilize the foot and promote sole growth. Over 4-6 months after the surgery, the gelding's sole depth increased significantly, indicating normal hoof growth and he was more comfortable on this limb.

Figure 2

Recently, the gelding's lameness worsened and he was non-weight bearing when examined. A lateral radiograph was performed (Figure 1-3). A large, radiolucent area (red circle) was noted in the toe region of the foot with a track that appeared to be traveling toward the coronary band (Figure 3). These findings are consistent with a large, sub-solar abscess! 

Figure 3

The shoe was removed and a large "hole" was noted at the apex of the frog that extended into a cavity with the circumference of a golf ball! The abscess appeared to be draining however it involved a significant amount of space between the bottom of the sole and the coffin bone. After removing the shoe, the foot was soaked in a warm epsom salt solution and then was "packed" with a strong disinfectant. The gelding's lameness improved within 24 hrs however he remains lame at the walk. His return to soundness will take some time and most likely require a specialized shoe known as a hospital plate. Recurrent foot abscess formation is a common problem among chronically foundered horses and highlights the importance of regular trimming/shoeing plus radiographic examination!

Figure 4

White Line Disease and Laminitis in a Horse!

Figure 1

 The radiograph in Figure 1 is that of a middle-aged gelding that presented for intermittent foot pain. One year prior, the gelding had developed a high fever of unknown origin (presumed viral). During the weeks that followed the high fever, the gelding was slow to walk in small circle and on concrete surfaces. Over several months, the gelding's lameness improved however he was consistently tender immediately after being trimmed by the farrier.  There are 2 disease processes identifiable in Figure 1. The first is chronic laminitis or founder.

Figure 2

 In Figure 2, the yellow lines correspond to the dorsal hoof wall and the dorsal aspect of the coffin bone. Normally, these lines are parallel to each other such that a horizontal line drawn across them would yield equal angles (angle A and angle B). However, when the coffin bone has "rotated" from its axis then the angles will differ as they do in Figure 2. Hence, the radiographic finding is consistent with laminitis (founder) and subsequent coffin bone rotation. This condition appears to be chronic, evidenced by the "flaring" of the tip of the coffin bone seen in the blue circle in Figure 3. This flaring often corresponds to small fractures of the tip of the coffin bone secondary to increase concussive forces over the toe region of the foot. The red arrow highlights the extremely thin sole which measured less than 5 mm!  Ideally, the sole depth at the tip of the coffin bone should measure between 10-15 mm in thickness.

Figure 3

 The second disease process noted in these radiographs is White Line Disease. This is evidence by the gas lucency traveling up the dorsal hoof wall (yellow arrows in Figure 4). The lateral radiograph is only 2 dimensional hence it is impossible to predict if this gas lucency is right down the middle of the hoof or if it wraps around the medial and lateral aspect of the hoof. Regardless, the gas lucency corresponds to separation of the hoof wall from the underlying tissue. White line disease may be the primary problem or secondary. In this case, it is likely secondary to the chronic founder/laminits however in primary cases, it can cause coffin bone rotation and result in laminitis. This condition results from the accumulation of dead/decaying material that slowly works its way from the sole surface up the hoof wall. The offending organism is believed to be in part anaerobic bacteria that thrive in a low-oxygen environment and produce gas that can be seen on a radiograph. Excessive gas accumulation may result in hoof wall separation from the coffin bone and coffin bone rotation.  Treatment involves aggressive removal (hoof wall resection) of ALL dead and decaying hoof wall to expose the offending organisms. Hoof wall resection along is very effective in treating this condition but it is typically paired with soaking the foot after resection in a variety of solutions to kill off the offending organisms.

Figure 4

Often, the early signs of white line disease can be detected at the time of hoof trimming and appear as a shallow crack at the toe region. The opposite foot of this horse had the very beginnings of white line disease evidenced by a small amount of gas lucency noted at the very tip of the hoof (Figure 5). When identified at this early stage, the condition is easily managed with regular balanced 4-pt trimmings by the farrier. Successful  management of white line disease is best accomplished through a farrier-veterinarian team effort. The farrier is the most important part of the team since they will be doing 99% of the work. The veterinarian will provide the radiographic studies to verify that adequate exposure of the diseased foot is accomplished.

Figure 5

Laminitis in a horse!!

 The following radiographs are from a gelding that has been lame for nearly 1 year. The gelding has been treated for laminitis/founder and despite efforts by the farrier and veterinarian, the gelding's conditions has worsened. He is non-weight bearing on one forelimb at the time of my exam. The right front foot is imaged in Figure 1 and the left front foot in Figure 2. In Figures 3 and 4 the palmar angle (angle "A") is measured in both front feet. The palmar angle corresponds to the angle that the bottom or palmar surface of the coffin bone makes with the horizon. In both front feet, the palmar angle measures approximate +23-25 degrees. Normally, the palmar angle may range between zero to +5 degrees. Abnormal palmar angles may be negative or greater than +7-8 degrees. However, even though the right and left front feet share the same palmar angle, it is for two very different reasons!

Figure 1 (Right front)

Figure 2 (Left front)

Figure 3 (Right front)

Figure 4 (Right front)

The most likely causes for an increased palmar angle include coffin bone rotation and coffin joint contracture. The difference between these two conditions is key to making the correct diagnosis. In the case of laminitis, the coffin bone rotates under the influence of the deep digital flexor tendon and due to a lack of attachment between the coffin bone and the lamina (i.e. laminitis). In Figure 5, the degree of coffin bone "rotation" is estimated based on the difference between angles "A" and "B". Normally, the hoof wall (red line over "A")  is parallel with the coffin bone (red line over "B"). When these two lines are parallel, the angles equal each other and there is zero degrees of coffin bone rotation. Therefore, the problem with the left front limb in Figure 5 is laminitis and secondary coffin bone rotation.

Figure 5 (Left front)

The right front foot has zero degrees of coffin bone rotation however the palmar angle is the same as in the left front foot. This due to coffin joint contracture and is the definition of a "Club foot". In Figure 6, the lines corresponding to the hoof wall and coffin bone are parallel and as such angle  "A" equals angle "B". Figure 7 diagrams the concept of coffin joint contracture that results in an angle of contracture (angle "A"). Typically, a club foot or coffin joint contracture does not result in non-weight bearing lameness but rather a life long commitment to proper shoeing and trimming. In this case, first glance of the radiographs might be deceiving because both front feet have an abnormal palmar angle, but it is the left front foot with the coffin bone rotation and life threatening laminitis! The deep digital flexor tendon was transected in the left front limb and follow-up radiographs will follow!
To be continued......

Figure 6 (Right front)

Figure 7 (Right front)