If you cannot see images at all on my site click here for an explanation
Farrier Wisdom
Medical Index
First Posted: Aug 2006
Sep 12, 2012

White Line Disease

by Debora Johnson

Image: Copyright HorseHints.org
White Line Disease

There are many names for white line disease. It has been referred to as foot rot, hoof wall disease, hollow hoof, stall rot, and onychomycosis. Basically what happens is invaders (pathogens) break down the protein and collogen that make up the hoof wall. They usually enter the hoof through a compromised spot. Trauma, abscess formation, sole or toe bruising, nail holes, and fissures could be enables for these opportunistic invaders. Enzymes and endotoxins are produced by these invaders which cause the hoof wall at the stratum medium to deteriorate. The stratum medium is the area that connects the sensitive and insensitive laminae. It is believed that both bacteria and fungi work together for this destruction to occur.

In the beginning stages of white line disease, one may notice a gray, black or white line that looks chalky or flaky on the ground surface of the hoof. Breakage and/or cracking of the hoof wall may occur. When advanced, white line disease can undermine the hoof structure. When trimmed, often a cavity or deep cavern can be seen showing that much of the hoof wall has been destroyed. It looks like an empty shell. At this point it is often difficult to attach a shoe. The horse may become lame or even worse- there can be rotation of the coffin bone. If possible an egg bar or heart bar shoe might be used depending on where the underlying structures have been compromised.

It is important to stop white line disease in its early stages. It should be treated quickly and aggressively. The hoof must be balanced, have correct angles, be clean, and dry. The offending micro organisms flourish in a wet and dark environment. It is important to have the hoof exposed to the air. Medication such as merthiolate is often effective. There are many other preparations on the market that may be recommended by your vet or farrier. Removing the compromised hoof wall is often recommended. Depending on the severity of the white line disease the treatment time can be long. It takes approximately ten months to one year for the hoof to grow out. Biotin mixtures are frequently recommended, not as a cure, but to help the new hoof growth to be strong and healthy.

This is a thumbnail sketch of white line disease. It is meant to help the horse owner identify white line disease and avoid major problems. If you suspect your horse may be starting with this problem, contact your vet and your farrier immediately.

Note: Bill Baker, DVM, of Equine Associates in Hawkinsville, Ga., discussed the disease and its treatment at the recent Bluegrass Laminitis Symposium, held Jan. 25-28 in Louisville, Ky.
Fighting White Line Disease

"...This ugly mess called white line disease might not be a big deal initially, but left untreated it can undermine large amounts of your horse's foot (or feet), resulting in lameness and instability of the coffin bone within the horse's foot. Bill Baker, DVM, of Equine Associates in Hawkinsville, Ga., discussed the disease and its treatment at the recent Bluegrass Laminitis Symposium, held Jan. 25-28 in Louisville, Ky.

'White line disease doesn't seem to occur without some sort of mechanical stress (such as long toes or hoof damage from previous disease or injury),' he began. 'The only known certainty (about its cause) is that a breach in the hoof wall has to occur for the disease to occur. (Opportunistic bacteria and/or fungi then invade the defect and begin destroying hoof wall from the inside, starting at the bottom and working their way up.) There is no breed, age, or sex predisposition to this disease. It occurs in anything from Minis to drafts, donkeys, and mules. It may invade one foot or all four feet. Most cases are diagnosed with physical exam findings,' he went on. "'ou see a small breach or crack in the hoof, explore it a little with a hoof knife and find cheesy, soft, white horn. You explore further and find that lots of wall is undermined. That soft white horn is why it's called white line disease, although that's somewhat of a misnomer because it affects the white inner part of the stratum medium layer of the wall (just outside the white line). It doesn't really affect the zona alba (white line) at all.' ..." "...Baker summarized this disease and its treatment with the following comments:
  • There is no clear pathogenesis for white line disease, but there has to be some mechanical stress in the hoof wall for this to occur.
  • The best treatment starts with supporting the foot. Do not resect without a plan for support!
  • Exposure appears to be the best treatment. Apparently whatever's causing this likes a low-oxygen environment.
  • No medicines on the market have been proven effective.
  • Research is much needed for this disease.
  • Treatment is effective if early and aggressive."

For More Information:

White Line Disease in the Hoof An excellent article.
White Line Disease Diagnosis and Treatment An excellent article.

Farrier Wisdom
Medical Index