Horse Foot Health


Factsheet - ISSN 1198-712X   -   Copyright Queen's Printer for Ontario
Agdex#: 460/10
Publication Date: 03/12
Order#: 12-019
Last Reviewed: 03/12
History: Replaces OMAFRA Factsheets Horse Management: Foot Care, Parts 1 and 2, Order No. 88-073 and 88-074. The original Factsheets were authored by Dr. Bob Wright, retired Veterinarian-Disease Prevention Equine and Alternate Species, OMAFRA.
Written by: Development of this Factsheet was coordinated by Tania Sendel, Veterinary Science and Policy Unit, OMAFRA, Guelph, with input from Dr. Jeff Thomason, University of Guelph, and farriers Kevin Alcock, Randy Luikart and Dave Dawson.

Table of Contents

  1. Proper Care
  2. Daily Check
  3. Routine Cleaning and Maintenance
  4. Regularly Scheduled Trimming and Shoeing
  5. Treatment of Foot Diseases and Injuries
  6. Introduction to Foot Anatomy
  7. Useful Tips

Proper Care

To prevent lameness in horses, it is critical to routinely care for and properly manage their foot health. Foot care needs teamwork, and the team should include the owner, any caretakers, a professional farrier and a veterinarian.

Make tending to your horse's feet as much a part of the daily routine as feeding and watering. Note that some elements of foot care should not be attempted by laypeople. This Factsheet includes recommendations on when to consult a farrier or veterinarian.

An introduction to basic foot anatomy - the structures and their names - is included for reference at the end of this Factsheet.

Figure 1.  Diagram of the hock/knee, pastern, fetlock and hoof from the side.

Figure 1. Basic structure of the foot - front (left) and hind (right) limbs are similar.

Text Equivalent of Diagram

Daily Check

Check the horse's legs and hooves every day for changes such as new scrapes, cuts or lumps, and run your hands down over the cannon bones and pasterns to feel for unusual lumps or hot spots (Figure 1). Also look for cracks or chips in the hoof. Refer observable lameness or any injuries or defects that look or feel severe to a veterinarian.

Routine Cleaning and Maintenance

Disease organisms concentrate where animals are confined. These organisms may cause external infections (thrush, for example), which, if left unattended, may become internal infections. Clean the feet of horses kept in a stall or small pen daily.

Hoof cleaning includes use of the hoof pick to remove large embedded debris, starting from the heel toward the toe, being especially careful to clean the commissures on each side of the frog and the cleft of the frog itself (Figure 2). Use a fine-bristled wire brush and a mild soap solution for cleaning the remainder of debris on the sole, frog and hoof wall. Take care not to damage the periople with too much pressure from the wire brush.

Figure 2.  Diagram of the bottom of the foot, showing parts.

Figure 2. Bottom of the hoof.

Text Equivalent of Diagram

Be sure to check for and remove gravel or other foreign objects that could be lodged in the natural depressions of the sole. A nail, gravel, stick or other object can work into the foot and cause an abscess or lameness. Objects have been known to exist in a horse's foot for extended periods of time before emerging at the heel or along the coronet. These emerging objects are very painful and are often accompanied by massive infections requiring medical attention, so prevention is preferable.

Environmental conditions can significantly impact moisture content in the hoof, affecting its strength and flexibility. In consistently dry conditions, hooves should maintain healthy moisture levels, since most moisture needed for a healthy hoof comes from within. In consistently wet conditions, the moisture content level of the hooves is likely to be high. However, alternating wet and muddy conditions promote rapid drying of the hoof wall.

Both extremes of dry or moist hoof walls are weak and likely to crack or split. Dry hooves will have limited expansion and contraction, and moist hooves will be soft and unable to withstand hard impact. Therefore, it is desirable to somewhat match hoof moisture content to ground conditions (moist in wet conditions, dry in dry conditions).

Regularly apply a hoof dressing containing a natural conditioner such as lanolin or aloe. A dressing that is not a petroleum derivative can be massaged into the coronet, the frog and the sole, as well as on the hoof wall. The dressing helps keep the sole pliable and eliminate dead tissue around the frog and heel. Massaging the coronet also stimulates growth of a healthy new hoof wall.

Use a petroleum-based dressing to repel water, if needed. A petroleum base is best used before bathing, especially for a shod horse. Water can cause expansion in the hoof wall, pushing nails outward. When the hoof dries again, the clinches holding the shoe will have been loosened. A farrier can further advise on proper cleaning and maintenance if needed.

Regularly Scheduled Trimming and Shoeing

Have the horse's hooves trimmed on a regular schedule, by a qualified farrier. A bad trim can cause lameness. Only allow someone who has had sufficient training to trim the horse's hooves.

The main goal of trimming is to retain a healthy shape and length of the foot. The trimming should keep the bottom of the hoof level, and maintain the inside and outside walls at equal lengths.

The frequency with which hooves need trimming will depend on several factors, including:

  • age - growth may be faster in younger horses
  • season - growth may be faster in warmer months
  • health - growth may be faster in healthier horses with better nutrition and exercise
  • footing - wear may be faster in horses that are kept or exercised unshod on hard or abrasive surfaces

Base trimming schedules on each horse's individual needs. Averages are provided in Table 1 for reference.

 

Table 1. Average Hoof Trimming Schedules
Status
Frequency
Unshod and not in work
8-12 weeks
Unshod and in work
5-7 weeks
Shod
5-6 weeks

The hoof wall should be trimmed with nippers to remove excess length, then rasped to smooth and level the bottom. Rasping is done evenly from the heel to toe (or toe to heel, depending on preference) with each stroke, to prevent uneven areas along the hoof wall.

The primary purpose of trimming the sole is to keep the horse's weight bearing on the hoof wall rather than on the sole, since sensitive structures just above the sole are easily bruised if allowed to come in contact with the ground. In fact, removing too much sole can result in bruising, abscessing and even laminitis. Only the dead, flaky tissue should be trimmed, leaving the remaining solid and moist sole intact. Trimming the sole secondarily serves to remove bacteria associated with the excess dead material.

The frog should contact the ground with each step, and so is trimmed only enough to remove dead tissue and to provide a uniform and adequate fissure along the junction of the sole and the frog.

After the bearing surface has been rasped to a level surface of proper length, the edges of the wall should be rounded if the horse will not be shod. This helps prevent chipping and peeling.

The trimming should maintain the proper angle of the hoof wall in relation to the ground and the angle of the pastern. When possible, the angle of the hoof wall should approximate the angle formed by the shoulder and the pastern, which is usually 45°-54°.

Leaving shoes on too long changes the angle of the foot relative to the pastern and can cause lameness. Also, as the hoof grows larger, the walls at the heels will overlap the shoe. When a shoe presses on the bars, corns can develop. Regular trimming and shoe re-setting are essential to avoiding these problems.

Loose, old or overgrown shoes must be removed to avoid injury to the horse. First, the farrier straightens or removes the nail clinches with a clinch cutter or rasp in order to protect the hoof wall from being damaged when the nails are removed. Shoe pullers are then applied under the shoe at one heel and pushed slightly away from the bottom of the foot toward the toe. This manipulation is then performed on the opposite heel, always working toward the toe, then repeated, until the shoe is completely free. Or, instead of shoe pullers being used for the entire process, they can be used just to lift the shoe off slightly, after which the nails are pulled out individually.

Note that prying the shoe off sideways is always avoided because of the risk of damaging the hoof wall by twisting the nails, injuring the horse's tendons and possibly spraining the foot.

Many owners consider whether to leave their horse barefoot. The primary guidelines for making the decision to remove or leave off shoes are that the hoof does not wear excessively rapidly and that lameness does not occur from injuries within the hoof. Horses that are not worked heavily can thrive with bare hooves, and even some that are in heavy work can do well without shoes. Evaluate each case individually in consultation with a farrier. The feet of a barefoot horse should be inspected frequently, to avoid issues with excessive wear or injury.

As with trimming, shoeing should be left to a farrier unless you have had sufficient training. You are strongly advised never to attempt corrective shoeing. The following section is for your information only.

Corrective Trimming and Shoeing

Some conformation and movement problems can be addressed at least partially through correct trimming or shoeing, particularly when a horse is young and still developing. Although some corrections may be successful at any age, other corrections are more effective or only effective at a younger age. Regardless, these practices are best left to the farrier.

Some problems that may be addressed through corrective trimming or shoeing:

Buck knees (over in the knees). The knee has a forward deviation.

Calf knees. The knee deviates backward, placing excessive strain on ligaments.

Forging. The toe of the hind foot overtakes and strikes the bottom of the front foot of the same side, at the moment the front foot pushes off the ground.

Interfering. The horse strikes any part of the inside of one limb with the inside of the foot or shoe of the opposite foot.

Scalping. The toe of the front foot hits the hind foot of the same side, at the coronary band or higher.

Sickle hocks. When viewed from the side, the leg from the hock down is too far forward.

Toe in (pigeon-toed). When viewed from the front, the toes point toward one another.

Toe out (splay-footed). When viewed from the front, the toes point away from one another.

Treatment of Foot Diseases and Injuries

Leave treatment to the veterinarian, who will consult with the farrier if necessary. The following information is intended simply as a guide to common causes of lameness, most of which will need professional intervention.

Common Causes of Foot Lameness

There are many types of lameness and many causes. An accurate diagnosis is necessary to determine the appropriate treatment or shoeing requirements. Diagnosis may be made based on physical examination, and by using nerve blocking tests, radiographs, ultrasound imaging or magnetic resonance imaging. Treatments may include rest, correct trimming and shoeing, anti-inflammatory drugs, bandaging, cold hosing, acupuncture, shock wave therapy and even surgery.

Figure 3.  Detailed cut-away drawing from the side, showing internal parts of the hoof, pastern, fetlock and knee.

Figure 3. Side view of foot below the knee, showing internal detail.

Text Equivalent of Diagram

Bowed Tendon
The deep digital flexor tendon, soft digital flexor tendon and suspensory ligament (Figure 3) are liable to injury due to being overworked. The injury will be accompanied by swelling felt as a bowing of the skin over the tendon. Tendon repair is a lengthy process, often requiring rest. Consult your veterinarian if your horse is lame because of a bowed tendon.

Splints
Splints occur when the ligament holding a splint bone (Figure 4) becomes inflamed by overwork or the bone is fractured by a kick. Usually the inflamed area becomes hot and swollen for several days, but the heat should subside within 2-3 weeks. The swelling may remain, but this will be new bone binding the splint to the cannon and is of no consequence.

Figure 4.  Diagram of the hoof, fetlock, pastern and knee, from the back.

Figure 4. Rear view of front foot.

Text Equivalent of Diagram

Stone in the Foot
Stones often lodge between the shoe and the frog, causing considerable discomfort. This occurs suddenly and usually while at work, particularly on a gravel road. Remove stones immediately before further damage can occur.

Bruised Sole
Bruises are caused by direct injury to the sole by stones, irregular ground or pressure from a shoe. Rest and correct shoeing are usually all that is needed. If the sole is unresponsive, seek veterinary assistance.

Corns
Corns are the result of sole bruising between the bar and the hoof wall. This is most often the result of poorly fitted shoes or waiting too long to re-shoe the horse. Dry (uninfected) corns are treated simply by relieving the pressure. Remove the shoe, clean the foot thoroughly and reapply a properly fitted shoe, or rest without shoes if possible. Infected corns will appear moist and be draining serum or pus. In these cases, obtain veterinary assistance.

Pricked Foot or Puncture Wounds of the Foot
Puncture wounds of the hoof are common and can cause severe lameness that may lead to permanent disability or death if not properly treated. As with any wound that allows bacteria to enter the body, there is a serious threat of infection, necessitating veterinary care to prevent serious consequences, such as tetanus.

Often the site of puncture is very difficult to find by visual examination; a hoof knife, hoof testers and/or radiographs can be used to locate and evaluate the injury. In case of a large penetrating object, such as a nail, radiographs are essential for determining the extent and depth of injury.

An abscess (a pus-filled cavity) can develop in as little as two days following the initial injury. The outcome of a foot puncture depends on the area of the foot affected, the type of puncturing object and whether secondary infection occurs. If the puncturing article remains embedded, do not remove it; call the veterinarian to determine the extent of the wound before removal. In all cases, early veterinary care is essential to evaluate the damage done and prevent further damage from occurring.

Hoof Cracks
Hoof cracks that originate at the ground surface are common in hooves that are not trimmed frequently enough or are very dry or very moist. Hoof cracks that originate near the coronary band are caused either by injury to the coronary band or excessive uneven pressure of an imbalanced hoof. Severe lameness can be produced if bacteria enter the cracks and gain access to the sensitive structures of the foot, causing infection.

Cleaning and treating the crack, followed by proper trimming and shoeing, can alleviate the condition until the hoof wall grows out. It can take as long as a year to grow out a crack that either starts at or reaches the coronet. The application of hoof repair material (such as acrylic or epoxy) to the hoof wall can also produce excellent results when applied by a competent farrier or veterinarian. Often, hoof cracks can be prevented by proper maintenance.

Thrush
Thrush is a condition resulting from bacterial penetration into the external surfaces of the hoof. The bacteria produce a foul odour and black or grey exudates, and the area becomes spongy in texture. If allowed to go untreated or to enter the sensitive structures of the hoof, serious lameness can result and extensive treatment will be necessary.

Proper cleaning and trimming of the foot along with proper sanitation will remove the topical cause of the infection. Treat affected horses by cleaning and trimming the foot and disinfecting it with a phenol or iodine solution. The foot can also be packed with a copper sulphate solution.

Eliminating the bacteria completely is not the goal, since normal levels of bacteria serve to loosen dead excess sole and hoof. However, treatment of thrush as described above, as well as managing environmental moisture, can help achieve healthy bacterial levels on the hoof.

Laminitis
Laminitis is an inflammation of the laminae that attach the hoof wall to the coffin bone. The causes of laminitis are varied and in many cases obscure. Founder is a stage of laminitis where the laminae have become weakened to the point that the coffin bone is no longer bonded to the wall and rotation or sinking of the bone occurs.

Metabolic syndromes are the most common cause of laminitis. Obese, overfed and under-exercised horses are at the highest risk. Carbohydrate overload in the hind gut can trigger laminitis in horses with compromised metabolic systems.

Other causes can include:

  • direct trauma that causes massive bruising, such as from working or landing on hard surfaces (often called road founder).
  • retained placenta after foaling.
  • injury in another limb leading to mechanical stress on the main supportive limb during a lay-up.
  • poisonous plants such as black walnut or red maple.
  • any disease that spikes a horse's temperature for a prolonged time.

Regardless of the cause, the signs of laminitis will be similar. In the early or acute stages, the hoof and coronet will be hot, and the horse will often sweat and be reluctant to move. A digital pulse may be detected just above the fetlock beside the deep digital flexor tendon. Because the front feet are usually the most severely affected, the horse will be camped out in front (front feet out in front of the body) and camped under behind (hind feet well under the body) in an attempt to remove weight from the front feet. In cases where all four feet are affected, the horse will stand under himself both in front and behind as though he were attempting to balance on a barrel.

In advanced or chronic cases of laminitis, uneven hoof wall growth (which can be seen as ridges) occurs, and the sole drops (the sole's arch decreases). In severe cases, the coffin bone will protrude through the sole. The afflicted horse may spend most of the time lying down. A foundered horse will exaggerate its attempts to land heel first while in motion.

Treatment of early laminitis will vary depending on the cause. Whenever a horse is suspected of having laminitis, call a veterinarian and farrier immediately and keep the horse quiet and the foot iced to control swelling until the professionals arrive. Ask the veterinarian if there is any first aid they would like you to do prior to their arrival.

Prevention is the best defence:

  • Maintain a proper diet for the horse's exercise regime.
  • Ensure all nutritional requirements are being met by consulting a nutritionist.
  • Do blood tests on overweight horses.
  • Avoid excessive work on hard surfaces.
  • Save the placenta after foaling for veterinary inspection.
  • Avoid pastures containing poisonous plants.
  • Apply preventive shoeing to horses that have developed a prolonged fever.

Not all cases of laminitis end favourably. However, advances in treatment have increased the survival rate and usefulness of survivors. Good veterinary care, farrier service and management by the horse owner often results in a horse that can return to service.

Navicular Syndrome
Navicular syndrome is a lameness of the front feet caused by injury to or stress upon the navicular bone or surrounding soft tissues. It is a very common lameness, particularly in breeds that have genetic defects in conformation. Defects in conformation such as upright pasterns and straight shoulders and/or small feet impair the shock absorbing mechanisms of the front legs and predispose the horse to navicular issues. Similarly, long toes, causing strain during break-over or heavy use on hard ground will increase the probability of navicular lameness.

Affected horses are usually lame in both front feet. Because of the pain, they will alternately "point" or advance one front foot at a time to remove the weight from it and thus reduce the pain. In the early stages of the lameness, resting the horse can make the symptoms disappear, but when returned to work, the horse will soon become lame again. A mechanical issue is usually to blame and coffin bone/pastern alignment is essential to lessening the damage. Diagnosis is often difficult, but radiographs, nerve blocks and experienced professionals will be helpful. Corrective shoeing, pain killers and neurectomy (cutting the nerves to the back surface of the foot) can prolong the useful lifespan of the horse.

Introduction to Foot Anatomy

Proper care requires an understanding of the structure of the foot and the functions of its various parts. The term "foot" in its proper anatomical sense refers to the leg from the knee or hock down to the hoof. The term "hoof" refers to the horny structure at the tip of the digit, and the bones and soft tissue structures within it. The major external parts of the foot include the knee, cannon, pastern and hoof, while the hoof itself includes the hoof wall, coronet, sole and frog. The major internal structures of the hoof include bones, cartilages, tendons and connective tissue.

Bones and Tendons of the Feet

From the knee (carpus) and hock (tarsus) down, the fore and hind feet are anatomically quite similar. Each has a cannon bone and splint, long and short pasterns, a coffin bone and hoof, and a number of large tendons.

Cannon Bone and Splint Bones
The cannon bone (third metacarpal) is a sturdy, straight bone that is strong enough to bear the weight of the horse. Attached to its posterior surface are two splint bones that are the remnants of metacarpals (second and fourth). The splints participate in the knee or hock joint, but taper down to disappear well above the fetlock.

Coffin Bone
The coffin bone (third phalanx or pedal bone) is the bottom-most bone of the leg. It provides the shape of the foot base by being attached to the inside of the hoof wall and resting lightly on the sole and frog, which provides the stability necessary to bear weight.

Long and Short Pastern
These are the first and second phalanx and are equivalent to the first and second bones in your middle finger.

Navicular Bone
The navicular bone (or distal sesamoid bone) is a small rounded bone to the rear of the joint where the second phalanx articulates with the coffin bone. It serves as a fulcrum and bearing surface for the deep flexor tendon, which flexes the foot as it progresses through a stride. The navicular bone is under constant stress, so its mechanical balance and breakover point are crucial to its health.

Proximal Sesamoid Bones
These are two small, triangular bones buried in soft tissue on the posterior aspect of the fetlock. They are important in guiding the large tendons, which pass over their surface.

Tendons and Ligaments
Running down the posterior aspect of the foot are some large tendons and ligaments that are important springs that the horse uses to cushion shock and save energy while it is running. Below the skin is the superficial digital flexor tendon, which lies over the deep digital flexor tendon. Deepest of all is the suspensory ligament, which is a muscle that acts like a spring.

The suspensory ligament runs from the back of the knee (or hock) to attach to the sesamoid bones. It gives off small branches that are visible circling to the front of the long pastern. The deep digital flexor tendon arises as a muscle behind the forearm bone (radius) passing down the back of the leg all the way to the coffin bone.

The superficial digital flexor tendon also arises as a muscle, passing as a tendon behind the cannon bone to insert on either side of the joint between the long and short pastern.

External Structures of the Hoof

Hoof Wall
The hoof wall is made of a horn-like material that grows downward from the coronet (at the hairline), made stronger by parallel fibres called tubules. On the ground surface, the hoof wall is thicker at the toe than at the quarter and heel.

The hoof wall is coated with a varnish-like surface that aids in maintaining moisture within the hoof wall. The "varnish" is applied by the periople, which is the soft tissue at the hairline that goes white when wet. It is like the cuticle on a fingernail, and its cells grow down with the hoof wall, dying as they go, to become the varnish layer on the wall.

The hoof wall should be dense, straight and free from rings (ridges) and cracks. The wall has, on average, 25% moisture content, but this varies greatly as the result of environmental conditions. The main functions of the hoof wall are to provide a weight-bearing surface not easily worn away and to protect the internal structures of the hoof from the forces of impact and movement.

Bars
The bars are a continuation of the hoof wall, running along the side of the frog and forming the heel. These bars act as springs to hold the semi-circular shape of the wall together. They should be level with the sole, forming a ramp from the tip of the frog up to the heel. Straight vertical bars form a strong spring, while less angled bars result in a slightly weaker, more flexible structure.

Coronet
The coronet, or coronary band, is the source of growth for the hoof wall. It is directly above the hoof wall and protected by a thick layer of skin and dense hair. A healthy hoof will grow about 1 cm per month. A change in the rate of growth of the hoof can be caused by a change in exercise, feed, moisture content, health status and condition of the animal. Injury to the coronary band can result in irregular growth of the hoof wall and can develop into a permanently unsound hoof wall.

Sole
The sole of the foot, like the hoof wall, is a horn-like substance that protects the sensitive inner portions of the foot, but slightly softer. It should be firm, slightly concave, of uniform texture and thicker in the toe and heel areas. The sole, as the foot is on the ground, should form a dome-like structure, providing support and strength to the hoof wall. The horse has no feeling at the exterior sole surface; however, the inner sole can feel differences in ground surfaces and temperature. Horses with a lower dome ("flat-footed") more often experience bruising on hard surfaces or stone-covered areas. A higher dome or "deep cup" in the sole can hold more dirt, resulting in more bacteria and little to no frog function.

Frog
The frog is located between the heels, forming a "V" into the centre of the sole. The frog is a spongy, flexible pad and is a weight-bearing surface, being the intermediate organ between the plantar cushion and the ground. The frog is differentiated from the sole of the foot by two lines called commissures. Commissures are deep crevices beside the frog, bordered by the bars on the outer edge. The condition of the frog is a good indicator of the health of the foot, where the healthy frog has sufficient flexibility, expansion and ground contact to facilitate the circulation of blood and the absorption of shock throughout the foot.

Internal Structures of the Hoof

Plantar Cushion
The plantar cushion is a sensitive, rubbery structure above the frog within the hoof. Its shape and density aids in shock dissipation and circulation by expanding and contracting.

Sensitive Laminae
The sensitive laminae form a layer of tissue containing many blood vessels that service the rest of the hoof. This tissue also serves as a means of attachment for the hoof wall and the coffin bone - it is tightly interlocked with the horny laminae on the inner hoof wall. The white line is external evidence of the sensitive laminae. As supportive bonding structures, the health of the laminae can be a great indicator of unusual imbalances or diseases of the hoof.

Useful Tips

  • Begin foot care when foal is only a few days old, certainly within 3 weeks.
  • Exercise foals to allow natural wear.
  • If foal is kept in a stall, rasp down hooves every 2-3 weeks.
  • Clean soles and clefts of frog frequently, including before and after exercise.
  • Do not pare out sole, just clean.
  • Do not trim away healthy frog unless there is clearly an excess.
  • Keep foot straight with angle of pastern.
  • Rasp sharp edge of hoof wall to make bearing surface smooth and rounded to remove chipping potential.
  • Do not rasp outside wall.
  • Rasp in such a manner that the hoof wall remains flat with rounded edges.

There are many useful resources on foot care and maintenance. Ask your farrier, veterinarian or tack shop owner for recommendations.


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca