What is white line disease and what can I do about it?

Hoof Nutrition Intelligence is a twice-a-month web segment that is designed to add to the education of footcare professionals when it comes to effectively feeding the hoof. The goal of this web-exclusive feature is to zero in on specific areas of hoof nutrition and avoid broad-based articles that simply look at the overall equine feeding situation.

Below you will find Part 2 of the latest question and answer installment that you can share with your footcare clients.

Q: What is white line disease and what can I do about it?

By Kentucky Equine Research staff

A: Hooves bear incredible pressure, especially when asked to withstand the rigors of modern equestrian endeavors. Despite their natural strength, all hooves are susceptible to breakdown based on a combination of mechanical stressors, environment, secondary health problems and conformation.

For many horses, a weakening of hoof integrity occurs just in front of the white line in the portion of the wall known as the stratum medium. Since the band of stratum medium nearest the white line is not pigmented, this is where the separation of hoof structures causes problems.

While white line disease is a common vernacular used by professionals, it is a misnomer. The problem actually springs from the disease of the adjacent tissue, not within the white line itself. Separation at the stratum medium gives opportunistic bacteria or fungi the chance to proliferate and cause infection. Over time, the infection progresses deeper into the hoof toward, but never into or beyond, the coronary band.

No single cause has been implicated in the onset of white line disease. Mechanical stressors, including misguided farriery work or poor conformation, as well as the weight-bearing problems they bring about, could initiate wall separation. Others have suggested moisture might be a contributing factor, as excessive moisture softens hoof tissues, giving pathogens access to hoof tissue, which potentially wind up as an infection.

On the flip side, dry hooves often develop cracks, which may allow pathogens to invade any fissure between the hoof wall and sole.

When white line disease first sets in, few changes in the hoof occur. Aside from slight crumbling near the white line, a powdery area may occasionally arise just behind the white line, pointing toward the frog. This area may stay small or may gradually widen. This slight change is often missed by horse owners, though careful farriers will notice it.

Alterations to the sole in terms of tenderness and shape may also take place. Growth of the hoof wall might slow, and disintegration of the wall could occur. When diseased wall is tapped gently with a farrier’s hammer, a hollow sound often results.

As the disease advances, the junction between the wall and the sole will widen, soften and often discharge a chalky powder. Lameness usually occurs once the disease has progressed to the point of severe damage and possible rotation of the coffin bone.

In addition to an examination by a farrier, assessment by a veterinarian, including high-quality radiographs, will help determine the extent of damage to the foot and will reveal any changes to the coffin bone. In addition to damage assessment, radiographs serve as useful guides in the trimming and shoeing of affected horses.

Treatment of white line disease usually begins with the removal of affected hoof wall followed by therapeutic shoeing. Because debridement of the hoof wall interferes with the weight-bearing capacity of the entire hoof, a shoe is typically applied for support, though the type of shoe depends on the degree of damage.

Daily cleaning of the debrided hoof should be performed and topical medications can be applied as directed. However, medications are often unnecessary after successful debridement and routine cleaning.

Since the affected hoof should remain as dry as possible, attention should be paid to stall cleanliness and turnout situations. Only turn out the horse once the dew has dried and only when the paddock or pasture is free of mud.

Since an exact cause of white line disease cannot be pinpointed, prevention revolves around scrupulous care of the hooves through daily inspection and cleaning, professional farriery and high-quality nutrition. If white line disease occurred in part because of weak hoof walls, biotin supplementation may help. High-quality hoof supplements contain biotin and an array of other hoof-building nutrients.

Kentucky Equine Research is a nutrition consulting company located in Versailles, Ky.

Click here to read part 1 of the April 15, 2020 installment of Hoof Nutrition Intelligence: What role does zinc play in hoof quality?

Click here to read more installments of Hoof Nutrition Intelligence.