{"id":3206,"date":"2026-05-11T12:00:00","date_gmt":"2026-05-11T16:00:00","guid":{"rendered":"https:\/\/www.farrierproducts.com\/blog\/?p=3206"},"modified":"2026-05-11T15:57:53","modified_gmt":"2026-05-11T19:57:53","slug":"managing-white-line-disease","status":"publish","type":"post","link":"https:\/\/www.farrierproducts.com\/blog\/2026\/05\/managing-white-line-disease\/","title":{"rendered":"Managing White Line Disease"},"content":{"rendered":"

By Travis D. Burns, CJF, TE, EE, FWCF and Lauren Trager, DVM <\/em><\/p>\n

White line disease (WLD) is a pathology that has long frustrated farriers, veterinarians, owners, and other members of the equine profession.<\/h2>\n
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Fig. 1 \u2013 Cases of WLD are often first noticed by farriers during routine trimming\/shoeing visits. An area of separation in the hoof wall that is filled with dirt\/debris is noted.<\/p><\/div>\n

WLD is described as a progressive hoof wall separation originating at the solar surface of the hoof and migrating proximally. It is thought to be the result of opportunistic keratinopathogenic organisms invading the non-pigmented stratum medium. The separation does not affect the stratum internum or dermal tissues.<\/p>\n

Historically, WLD has been referred to by many other terms, including seedy toe, hollow hoof, hoof rot, onychomycosis, etc. Even though \u201cwhite line disease\u201d has become the commonly utilized term for this disease, it is a misnomer as the disease process does not actually affect the white line of the horse\u2019s hoof capsule. Therefore it is this author\u2019s opinion that the equine community should begin to use the term \u201cwhite zone disease\u201d or another term that describes the anatomy affected (non-pigmented stratum medium\/white zone).<\/p>\n

The cause of WLD has long been debated. Although several theories have been described, none have been proven. The current theory of WLD etiology as described by O\u2019Grady, Moyer and others is that opportunistic, keratinopathogenic microorganisms invade the non-pigmented stratum medium of the hoof wall following an initial separation caused by a mechanical stress or weakness, trauma, abnormal or excessive moisture exposure, or some combination. 1,2 These organisms degrade the keratin in the hoof wall exacerbating the separation. Furthermore, dirt and debris typically fill the separation, acting as a mechanical wedge forcing the wall apart.<\/p>\n

Although WLD has been reported all over the world in many different environments, the highest incidence of WLD appears to be in areas with exposure to high moisture\/humidity. It affects horses of all ages, breeds, sex, and type. Many factors appear to predispose horses to WLD that include but are not limited to: poor environment, repetitive cycling of the hoof from wet to dry conditions, various hoof wall distortions, flexural limb deformities, chronic laminitis and weak\/brittle hoof walls resulting from genetic or nutritional abnormalities.<\/p>\n

Cases of WLD are often first noticed by farriers during routine trimming\/shoeing visits. An area of separation in the hoof wall that is filled with dirt\/debris is noted (Fig. 1). When removing the dirt\/debris with a hoof knife or curette, an area of undermined hoof of varying degree is revealed. After the dirt\/debris is removed, portions of white\/grey powder like hoof wall are typically seen before reaching a healthy margin. There can be rather large areas of separation filled with dirt\/debris despite maintaining a healthy appearance of the outer hoof wall (Fig. 2).<\/p>\n