California Riding Magazine • January, 2009

Hoof Abscesses
What causes a hoof abscess,
and what you can do to help heal it.

by Dr. Kim Sergent

Your horse is dead lame very suddenly. One day she’s fine and the next she is not eating, doesn’t want to move and can’t put her foot down. Panic sets in. Thinking the worst you call your veterinarian.

Your veterinarian is surprisingly calm, looks for swelling, heat and pain in the limb. Feeling around the pastern and coronary band and pushing on the sole with a pair of hoof testers, your vet announces that the most likely culprit is a sole or hoof abscess not a broken leg (thankfully, fractures are rare). Whew! The hoof testers are used to localize the pain to a portion of the sole (the horse will flinch if there is pain). If located, your vet will dig with a hoof knife in the spot and try to drain the abscess. This makes the horse more comfortable quite quickly. Sometimes there is no pain response and the vet is unable to locate the abscess. This can occur because the abscess is too deep or the sole too dry and firm for the hoof testers to help.

So what is the purpose of feeling the pastern and coronary band? The pastern has two large vessels (the palmar digital arteries) that are on either side of the back of the pastern. In the case of an abscess these vessels will be “bounding” or pulsing hard, so it gives us a clue that there is inflammation in the foot. The coronary band is felt since many abscess break out in that area as they travel up the hoof wall through the soft tissues (most commonly in the heel or quarters) and there may be a bulge, soft spot, heat or pain located. Other symptoms can include mild swelling in the lower limb or decreased appetite. Since many of the symptoms can be related to laminitis or tendon trauma it is best to have your vet sort it out.

Once the diagnosis is made, your veterinarian can guide you how to help draw the abscess out or treat it if it is pared out. Cleaning the foot, sometimes a good soak in warm water and Epsom salts, a poultice and a wrap are all that is needed. Occasionally bute and/or antibiotics are given depending on the situation.

What Causes an Abscess to Develop?

What is a sole abscess and how do they develop? An abscess is simply a cavity filled with pus. The pus consists of white blood cells, cell debris, fluid and bacteria. An abscess will take a few days to develop from the time of infection. Within the hoof there is no ability to swell, so, much like a blood blister under your fingernail, the pressure builds up to the point of pain until it is relieved. There are several reasons that abscesses develop:

  1. Insufficient sole depth causing bruising which develops into a seroma (not really an abscess technically because it is an accumulation of serum, but behaves the same).
  2. Excess sole in a area creating bruising (see #1) or trapping bacteria and creating an abscess.
  3. An improperly placed shoeing nail which introduces bacteria and creates an abscess.
  4. Laminitis causes a weakened/damaged white line which allows bacteria in and creates an abscess. Also separation of the lamina can cause a seroma (a collection of serum).
  5. Penetrating wounds (most commonly nails) introduce bacteria and an abscess results.
  6. Most commonly we see abscesses several days after a recent trim and rain. Trimming exposes fissures or cracks in the sole, moisture widens the fissures allowing bacteria to enter. The cracks close up when drying occurs and the bacteria is now trapped causing the abscess to appear several days later.

So if you see your horse holding up a limb, pointing a toe and unwilling to come for dinner ... don’t panic ... but do call your veterinarian!

For more info call All County Equine Services (A.C.E.S.) at 619-659-3532 or visit www.acequine.com.