Hoof Abscess

A hoof abscess is the result of a bacteria infection in the hoof. The infection results in the buildup of pus in the area of infection. As the outside of the hoof is rigid, this buildup of pus within the hoof results in increased pressure on the sensitive structures within the hoof, causing both damage and pain. Usually the pain associated with the hoof abscess is due almost entirely to this pressure from the buildup of pus, with the actual infection itself causing relatively little discomfort. This pain continues until one of the following happens:

  • Breakage of hoof. The pressure builds until it causes a break in the hoof, through which the pus drains and releases pressure. The location of the break will depend on the location of the infection and any nearby weak points within the hoof, as the pus is naturally pushed along the path of least resistance. Depending on circumstances, this can be out the sole of the hoof or through the hoof wall itself.
  • Surgical relief. A common part of hoof abscess treatment is to make a small hole near the location of the infection and associated pus. This allows the pus to drain out, thereby relieving pressure on the hoof.
  • Cure. If the abscess is minor, the horse's immune system may cure the infection before pressure builds to the point where it breaks through the hoof. In this case, the body will gradually absorb and dispose of the pus, returning the hoof to normal (no pus, no infection, no pressure).

Symptoms

The most obvious and common symptoms for hoof abscesses is a reluctance to put weight on the affected hoof, due to the associated pain. The horse may stand with the affected hoof held up, or with minimum weight on it. If forced to walk, it will tend to adjust its gait so that the affected hoof is weight bearing for the minimum amount of time, resulting in an abnormal gait. In some cases the horse might walk on the toe of the hoof rather than with the hoof flat.

In some cases, the infection can result in other symptoms such as: warm hoof or leg, slight fever, swelling of the leg, increased digital pulse. A veterinarian will often test for the presence of an abscess using a hoof tester (a blunt pincher) to apply moderate pressure at various points on the hoof (especially the sole of the hoof). A painful response at a specific point not only helps to confirm the diagnosis of an abscess but also to identify its location.

Note that any of these symptoms on their own could be due to a variety of causes. For example, holding a hoof in the air for short periods is normal behavior for a horse (they often do this, alternating legs, to rest the legs). Likewise, a painful or warm hoof can be due to other causes, such as laminitis. However, a veterinarian will examine the pattern of symptoms to determine if a hoof abscess is the probable diagnosis.

Treatment

A hoof abscess should always receive medical attention and should normally receive medical treatment. An untreated abscess risks the following problems:

  • Extreme Pain. The pressure on sensitive structures by a hoof abscess is almost always extremely painful for the horse. Even though the evidence of injury may be relatively small, one needs to be aware that the pain can be quite extraordinary and it would be cruel not to relieve it.
  • Hoof Damage. Although pressure does not always build to the point that it causes a break through to the outside of the hoof, it is fairly common for this to occur. Depending on how and where this break occurs, substantial damage to the hoof can result. In addition, the damage makes another opening, through which dirt and bacteria can enter, causing further infections. Even if the pressure does not result in damage to the exterior of the hoof, it can cause internal damage.
  • Unusable Horse. A horse with an abscess cannot reasonably be used for its normal functions until the abscess is cured. An untreated abscess takes much longer to heal, especially if there is secondary damage. Prompt treatment allows the horse to return to normal duties and activities much sooner.

Hoof abscesses are almost always treated with antibiotics. The objective of the antibiotics is to cure the infection as quickly as possible, allowing the hoof to heal naturally. Curing the infection also stops the production of pus, thereby preventing hoof pressure and associated issues (pain, hoof damage).

It is also common to make a hole in the hoof, near the abscess, to allow the pus to drain. The purpose of this is to reduce internal pressure on the hoof, preventing possible hoof damage and relieving pain. If the abscess is mild, the veterinarian may decide not to make a hole, for two reasons. Firstly, in mild cases, the pressure is not great and will be quickly reduced through antibiotic treatment, so surgery is not necessary. Secondly, making a hole not only damages the hoof (although much less than allowing the pus to make a breakage itself), but this hole is a potential source of another infection.

Hoof abscess are often associated with holes in the hoof. In some cases this is the cause of the abscess (e.g., the horse stepped on something sharp, which punctured its hoof and allowed bacteria to enter). In other cases it is a result of the abscess (e.g. the pus pressure resulted in a hole in the hoof or resulted in the need for a surgical hole to be made). In either case, a hole can allow further dirt or bacteria to enter, causing further infection. To prevent this, the holes need to be covered (by bandages and/or compresses) until the holes have closed and healed, to prevent such infection. In addition, antibiotic treatment is normally continued until the holes have closed, to minimize the risk of such infections. In some cases, a horse boot may also be used to help keep the hoof clean. A horse boot is also sometimes used to take pressure off the affected part of the hoof (especially if the abscess or wound is in the sole), possibly with pads placed inside the boot to control which part of the hoof is weight bearing. If pastures are wet (especially if they are muddy), the veterinarian may advise keeping the horse confined to its box so that any wounds are kept clean and dry until they close.

A poultice is sometimes applied to the hoof, to help draw out the infection and pus.

Note that treatment should be started as soon as possible, as early treatment results in a quicker and easier cure, resulting in less pain for the horse and probably less veterinary expenses.

Causes

A hoof abscess is caused by bacteria. The bacteria can enter the hoof in a number of ways, such as:

  • Through a wound or puncture (e.g. if the horse steps on a hard object, which pierces the sole)
  • Through cracks, fissures or defects in the hoof
  • Through a softened hoof (e.g. if the horse is standing in wet conditions for a long time), allowing sand or dirt to enter the hoof, carrying bacteria in
  • As the result of an incorrectly placed horseshoe nail
  • As the result of separation of the hoof (e.g. due to extreme laminitis)
  • Through softened or damaged tissue, resulting for an impact (typically to the soft sole or soft part at the top of the hoof)

Prevention

As hoof abscess are caused by hoof defects or damage (see above) which allows bacteria to enter, the best prevention is to avoid such defects and damage. This is basically down to good hoof care:

  • The horse should not stand for long periods in wet conditions, which make the hoof overly soft and liable to injury.
  • The horse should not be ridden over sharp or excessively rough terrain. If it is to be ridden over terrain which can damage the hoof, then horse shoes and/or horse boots should be used for protection.
  • The hoof should be properly trimmed. If it is shod, a good farrier (blacksmith) should be used.
  • Cracks, fissures or other defects in the hoof should be promptly treated and corrected. Depending on the cause, correction may involve different trimming, corrective shoeing, or food supplements.
  • Prevention of illnesses which can damage the hoof (such as severe laminitis) is important.

If a hoof is damaged, consider consulting with your veterinarian if any preventive action should be taken. For example, in the case of a puncture, it may be appropriate to administer preventive antibiotics, clean the wound and bandage it to prevent dirt entering.