White line disease is a condition in which the inner [hoof wall](/anatomy/horse-hoof-anatomy) separates from the sole at the white line, allowing opportunistic fungi and bacteria to invade the non-pigmented horn. It can undermine large sections of the hoof wall and, in advanced cases, compromise the stability of the hoof capsule. The condition is often secondary to poor hoof quality, chronic [laminitis](/conditions/laminitis), or irregular farriery. ## What it is The white line is the junction where the insensitive laminae of the hoof wall meet the sole. When this area separates, it creates a space that traps moisture and debris, allowing fungal and bacterial organisms to proliferate. The organisms digest the horn, causing it to become powdery, cheesy, or hollow. Over time the separation can extend up the wall and around the foot, weakening the attachment between the wall and the [coffin bone](/anatomy/coffin-bone-distal-phalanx-p3). While the name suggests a fungal infection, bacteria are often involved as well. The condition is frequently seen in horses with previous laminitis, thin or brittle hoof walls, or inconsistent trimming schedules that allow the white line to stretch. ## Signs and symptoms - Visible separation at the white line on the solar surface - Chalky, powdery, or cheesy material in the separated area - Hollow sound when the hoof wall is tapped with a hammer - Undermining of the hoof wall that may extend from the toe into the quarters - Hoof wall that feels unstable or flexible when pressure is applied - Lameness if the separation becomes extensive or reaches sensitive tissue - In severe cases, abscess formation or further wall detachment ## Causes and risk factors White line disease is usually secondary to another problem that weakens the white line attachment. Common predisposing factors include chronic or repeated [laminitis](/conditions/laminitis), poor hoof quality and nutrition, irregular or infrequent trimming, excessive moisture, and mechanical stress from long toes or flared walls. Horses with thin soles or previous white line defects are more susceptible to recurrence. ## How it is diagnosed Diagnosis is made by visual inspection of the solar surface and careful probing of the white line. A farrier or veterinarian will often use hoof testers and may take radiographs to assess how far the separation extends and whether it has affected the coffin bone attachment. In some cases, resection of the undermined wall is needed both for treatment and to fully evaluate the extent of the damage. ## Treatment and management Treatment focuses on removing all undermined and infected horn, stabilizing the remaining hoof wall, and addressing any underlying causes. This usually involves careful hoof wall resection by a skilled farrier, followed by regular cleaning and application of antifungal or antibacterial agents. Supportive shoeing or glue-on shoes are often used to protect the foot while new horn grows down. Managing any concurrent [laminitis](/conditions/laminitis) or metabolic issues is critical for long-term success. ## When to call the vet Contact your veterinarian or farrier if you notice significant separation, lameness, or signs of abscess formation. Extensive white line disease can lead to instability of the hoof capsule and secondary laminitis if not addressed promptly. Deep or rapidly progressing cases should be evaluated professionally. ## Prevention Prevention centers on maintaining strong, well-balanced hooves through regular professional trimming, good nutrition, and prompt treatment of any underlying issues such as laminitis. Avoiding prolonged exposure to excessive moisture and keeping the feet clean also helps reduce risk. Horses with a history of white line disease benefit from more frequent farrier visits and careful monitoring. ## Frequently asked questions **Is white line disease contagious?** No. It is not contagious between horses. It is an opportunistic infection that occurs when the white line is already compromised. **Can white line disease cause laminitis?** Severe cases that undermine large areas of wall can increase stress on the laminae and potentially contribute to laminitis, especially in horses already at risk. **How long does it take for white line disease to heal?** Healing depends on how much wall has been lost. New healthy horn must grow down from the coronary band, which can take 6 to 12 months for the toe area. This information is for educational purposes only. Always consult with a licensed veterinarian for diagnosis and treatment of your horse.
Visible separation at the white line on the solar surface; chalky, powdery, or cheesy material in the separated area; hollow sound when the hoof wall is tapped with a hammer; undermining of the hoof wall that may extend from the toe into the quarters; hoof wall that feels unstable or flexible when pressure is applied; lameness if the separation becomes extensive or reaches sensitive tissue; in severe cases, abscess formation or further wall detachment
White line disease is a condition in which the inner [hoof wall](/anatomy/horse-hoof-anatomy) separates from the sole at the white line, allowing opportunistic fungi and bacteria to invade the non-pigmented horn. It can undermine large sections of the hoof wall and, in advanced cases, compromise the stability of the hoof capsule. The condition is often secondary to poor hoof quality, chronic [laminitis](/conditions/laminitis), or irregular farriery. ## What it is The white line is the junction where the insensitive laminae of the hoof wall meet the sole. When this area separates, it creates a space that traps moisture and debris, allowing fungal and bacterial organisms to proliferate. The organisms digest the horn, causing it to become powdery, cheesy, or hollow. Over time the separation can extend up the wall and around the foot, weakening the attachment between the wall and the [coffin bone](/anatomy/coffin-bone-distal-phalanx-p3). While the name suggests a fungal infection, bacteria are often involved as well. The condition is frequently seen in horses with previous laminitis, thin or brittle hoof walls, or inconsistent trimming schedules that allow the white line to stretch. ## Signs and symptoms - Visible separation at the white line on the solar surface - Chalky, powdery, or cheesy material in the separated area - Hollow sound when the hoof wall is tapped with a hammer - Undermining of the hoof wall that may extend from the toe into the quarters - Hoof wall that feels unstable or flexible when pressure is applied - Lameness if the separation becomes extensive or reaches sensitive tissue - In severe cases, abscess formation or further wall detachment ## Causes and risk factors White line disease is usually secondary to another problem that weakens the white line attachment. Common predisposing factors include chronic or repeated [laminitis](/conditions/laminitis), poor hoof quality and nutrition, irregular or infrequent trimming, excessive moisture, and mechanical stress from long toes or flared walls. Horses with thin soles or previous white line defects are more susceptible to recurrence. ## How it is diagnosed Diagnosis is made by visual inspection of the solar surface and careful probing of the white line. A farrier or veterinarian will often use hoof testers and may take radiographs to assess how far the separation extends and whether it has affected the coffin bone attachment. In some cases, resection of the undermined wall is needed both for treatment and to fully evaluate the extent of the damage. ## Treatment and management Treatment focuses on removing all undermined and infected horn, stabilizing the remaining hoof wall, and addressing any underlying causes. This usually involves careful hoof wall resection by a skilled farrier, followed by regular cleaning and application of antifungal or antibacterial agents. Supportive shoeing or glue-on shoes are often used to protect the foot while new horn grows down. Managing any concurrent [laminitis](/conditions/laminitis) or metabolic issues is critical for long-term success. ## When to call the vet Contact your veterinarian or farrier if you notice significant separation, lameness, or signs of abscess formation. Extensive white line disease can lead to instability of the hoof capsule and secondary laminitis if not addressed promptly. Deep or rapidly progressing cases should be evaluated professionally. ## Prevention Prevention centers on maintaining strong, well-balanced hooves through regular professional trimming, good nutrition, and prompt treatment of any underlying issues such as laminitis. Avoiding prolonged exposure to excessive moisture and keeping the feet clean also helps reduce risk. Horses with a history of white line disease benefit from more frequent farrier visits and careful monitoring. ## Frequently asked questions **Is white line disease contagious?** No. It is not contagious between horses. It is an opportunistic infection that occurs when the white line is already compromised. **Can white line disease cause laminitis?** Severe cases that undermine large areas of wall can increase stress on the laminae and potentially contribute to laminitis, especially in horses already at risk. **How long does it take for white line disease to heal?** Healing depends on how much wall has been lost. New healthy horn must grow down from the coronary band, which can take 6 to 12 months for the toe area. This information is for educational purposes only. Always consult with a licensed veterinarian for diagnosis and treatment of your horse.
Visible separation at the white line on the solar surface; chalky, powdery, or cheesy material in the separated area; hollow sound when the hoof wall is tapped with a hammer; undermining of the hoof wall that may extend from the toe into the quarters; hoof wall that feels unstable or flexible when pressure is applied; lameness if the separation becomes extensive or reaches sensitive tissue; in severe cases, abscess formation or further wall detachment