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Treating White Line Disease
Natural Angle, Volume 3 Issue 2 · by Dave Farley, CF APF

“White line” disease is a problem that is affecting all breeds of horses. It can be an absolute nightmare to deal with. It knows no boundaries. I have seen it in many areas of the United States and in all breeds. I have seen it in barefoot as well as shod horses and it occurs in the best barns as well as the worst.

In Fran Jurga’s new book, Understanding the Equine Foot, it is mentioned that until recently there was no name for the microorganism that causes this cancerous like invasion of the hoof wall. According to Jurga, Dr, Chris Pollitt (a research scientist at the University of Queensland in Australia) has named them keratinolytic microorganisms. He describes them as aggressive organisms of unknown origin. Unfortunately, no one knows for certain whether the microorganisms come from dirt, water, or even air. We only know that it seems to thrive in warm, moist environments.

If you notice a hoof that has a separation that does not want to grow down, beware. It may be shelly in appearance from the outside and you may have difficulty keeping solid clinches in that area. The exterior wall may even fall out when rasping and clinching. When the hoof is dry you may notice a chalky appearance in the area of separation. These are all signs of this aggressive disease.

If you look at a hoof with these problems you will notice that the separation is in the hoof wall itself, just outside the white line. You will also notice that the problem may only affect one foot. It may begin with problems in one or two areas you nail in, but soon the problem is magnified as we help the spread by attempts to get solid nails. We create more openings for the movement of the disease. On improperly balanced feet or horses with conformation faults the hoof wall often suffers even more separation resulting in difficult flares, long toes (seedy toe), and underrun heels that crush and become hollow. The hooves are soon falling apart, losing all consistency.

It soon becomes obvious that we have a serious problem. When it is in the early stages the temptation is to patch the weak wall with various repair materials. In fact, by patching we are enhancing the environment in which white line thrives. Moisture is trapped below the repair material and no oxygen reaches the affected area.

Treatment of this disease requires complete debriding of the affected area. Be careful not to damage the white line itself. Remove only the outer wall that is cracked, shelly or undermined. Once the area is debrided treat with a product like merthiolate or Fungadye. Life Data is also coming out with a product for treating white line disease. Keep the feet dry and treat daily. Severe cases may require pulling the shoes and putting the horse on stall rest.

Don’t patch at this time. Allow the hoof time to grow down and replace the affected areas. I use clipped shoes and even heartbars to support the wall which has been weakened. There are various hoof supplements on the market that can help speed up the process of growing new, healthy wall.

Once you’ve exposed the hoof and cut away the affected area your owners need to do all they can to keep the feet as dry as possible. Horses that are in wet, muddy areas seem to be affected more frequently than those in dry environments. Good, basic hygiene means the feet have to be picked regularly and given regular hoof maintenance. Stalls have to be cleaned well and should be disinfected and kept as dry as possible. The environment is involved in most of the cases I have seen.

It is a difficult, if not impossible, problem to diagnose in the very earliest stages. If you have any suspicions that you may be dealing with a white line problem treat it immediately. The longer you go before treatment the more damage you will have to contend with.

1. Muddy, wet conditions seem to increase
likelihood of white line disease.

2. This foot was patched without debriding and
treating for white line first. Notice that wall is
undermined on both sides.

3. On another foot, this lateral view shows an
area that has been debrided. Clipped shoe
to help hold.

4. Medial side of same foot - you have to take
out all the infected area.

5. Use your hoof knife to pare away weak,
undermined wall.

6. Be careful not to damage white line.

7. Hoof debrided before applying shoe.

8. Clipped shoe applied after debriding.

9. In some cases you can use your nipper
to start removing wall that is undermined.

10. In some cases you can use your nipper
to start removing wall that is undermined.