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Symptoms:
For reasons as yet unknown (which hasn't stopped all manner of wild speculation), occurrences of what has become known as White Line Disease (WLD) are on the rise. Twenty-five years ago, a hoof care professional may well have never encountered an incidence of this condition. Today, those in the hoof care industry might well encounter two or three cases per year, while those who specialize in therapeutic care often see this on a monthly basis. Unfortunately, despite the increased occurences, equine practitioners have not been highly motivated to focus research efforts in this direction--probably because the disease rarely causes lameness except in severe cases. Likewise, the farrier community, which has not traditionally engaged in research activities, has done little systematic work on this problem. White Line Disease, also known as "hoof wall disease," "onychomycosis," "foot rot," and "hollow hoof," is caused by micro-organisms which produce enzymes and endotoxins that break down protein and collogen in the hoof wall, destroying the wall at the stratum medium (the area of connectivity between the sensitive and insensitive laminae). It is believed that no single organism causes the condition; instead, several different fungi and bacteria are at work, with each organism breaking down the hoof wall in a different manner and providing metabolites for other organism(s). Because of this symbiotic relationship, wherein each organism lives independently yet benefits from another's presence, the condition manifests differently in virtually every situation. While the micro-organisms which cause this condition will not normally invade a healthy hoof wall, they are opportunistic in nature and will invade a stressed or traumatized hoof, taking advantage of anything from a nail hole or a bruise to a seedy toe. As with most problems or diseases of the hoof, the condition is exacerbated by compromised circulation, wet or unhealthy conditions, and imbalanced or poorly maintained hooves. The condition usually initiates in the quarters of the hoof and works forward to the toe area. In its early stages, WLD usually evidences in the quarters of the hoof, generally appearing as a white, gray, or black crumbly area, with a consistency similar to grated parmesean cheese. Externally, the hoof will occasionally show signs of stress and breakage, and it will often become challenging to keep shoes attached even when the nails have been appropriately started in the white line of the hoof. At this stage, WLD can often be arrested through good maintenance practices: keeping the hoof balanced, clean, and dry; encouraging circulation through turn-out and exercise; and applying appropriate medications (see attached list). Although applying an affixed pad is occasionally suggested at this point, my experience has been that this traditional approach usually proves counter-productive in this situation since WLD thrives in an aneroebic (dark, wet, unoxygenated) environment. In its more advanced stages, WLD will actually undermine the hoof capsule. Often, a visual inspection of the outer wall and ground surface of an affected hoof will reveal no apparent abnormalities; a cavity may not be visible until the hoof is trimmed. Even then, it may appear as only a small opening, but it will often open into a large cavernous area, revealing that much of the hoof capsule has been undermined and compromised. Once the condition reaches this point, it's more than the nuisance of icky looking, shelly walls and shoes that are difficult to keep on. In fact, at this stage, there's a potential for intermittent lameness and, worse, a potential for remodeling of unsupported internal structures. The general consensus among experts remains that resecting the lesion (no matter how small it initially appears) offers the best hope for successful, reasonably quick treatment. Once the diseased hoof wall has been entirely removed and debrided, the area should be left exposed to the open air and treated with an appropriate medication (see attached list). Although some farriers and practitioners recommend keeping the hoof trimmed and not shod, this decision must be weighed carefully for several reasons: 1) with significant deterioration (and subsequent separation/detachment) of the hoof wall, internal structures may need to be supported, 2) with significant loss of ground surface (from deterioration or resection), the bony column should be supported. Whether the concern is internal separation or external ground surface, I tend to lean toward recommending the use of an appropriately fitted heartbar shoe to avoid secondary laminitis / PIII rotation. Because we're talking about removing a significant amount of hoof wall, the treatment period is often protracted, and - frustrating as it may be - re-infection is always a possibility. Treatments:
Medications:
Supplements:
These will not treat or arrest WLD; however, it's possible that they'll promote healthy new growth after treatment.
Shoeing Approaches:
Problematic Shoeing Approaches:
Maintenance:
Further Resources: Cohen, Jonathan and Peacock, Robert. "Update on Hoof Wall Disease." Anvil Magazine, vol. xx / #5 (May 1995), 94-95. Gallenberger, Michael R. "Fingernails vs. Horse Hooves." American Farriers Journal, vol. 20 / #7 (Dec. 1994), 58-61. O'Grady, Stephen E. "Chronic Foot Soaking." American Farriers Journal, vol. 22 / #5 (Sept./Oct. 1996), 51. Shakalis, Richard and Pautienis, M. John, "Taking the Mystery out of White Line Disease." Anvil Magazine, vol. xx / #5 (May 1995), 90-93. "White Line Disease Mysteries." American Farriers Journal, vol. 21 / #3 (May/June 1995), 27-30. Watson, Marilyn. Poisioning Leads to Hoof Wall Disease" American Farriers Journal, vol. 21 / #2 (March/April 1995), 60-61.
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