By: Katie Jones, CVT
Horse hoof walls consist of three layers; “White Line disease” occurs between the middle and inner layer.
Characteristics: Progressive hoof wall separation.
- Affects horses of all ages, sex, or breed.
- One or more hooves can be infected at one time.
Causes: It is mainly caused by damage to the junction between the adjoining layers. This damage between the middle and inner layers causes an invasion of opportunistic bacteria to the area. The infection will typically spread from the toe up the sides of the hoof but doesn’t infect the coronary band which supplies the hoof with needed nutrients. This gradually breaks down the strength of the wall and causes the horse to become very lame.
- Over grown feet and an improperly balanced hoof. The improperly balanced hoof (due to over-growth) can lead to a mechanical separation of the hoof due to the greater break over. The more damage that is done to the sole/wall junction and the exterior protection, separation becomes more extensive. The hoof of the horse is similar to the human finger nail; once it is damaged it cannot heal, it must grow out to form a healthier hoof to replace the damaged one.
- Environmental conditions. Excessive moisture softens the foot, allowing easier entry of debris into the hoof separation. Examples of moist conditions include: Continual bathing, damp shavings in stalls, or moving from a damp stall to a muddy pasture.
Clinical Signs: Lameness is not always present. Lameness is typically not observed until there is extensive mechanical loss between the laminae and the inner hoof.
- Hoof testers may not detect any discomfort.
- Early detection will be most commonly seen by a farrier during routine hoof care.
- Slow hoof growth, poor constancy of hoof wall, a bulge on the coronary band above the affected area, or a hallow sound when the hoof wall is tapped with a hammer (should only be done by your veterinarian).
- The veterinarian will note a wider separation in the sole/wall junction and it will be softer, as well as having a chalky texture.
- Drainage could be present if the cavity is large enough.
- Radiographs can be informative in determining the damage done to the inner hoof structures. The extent of the hoof/wall separation and possible rotation of the coffin bone can both be appreciated with a radiograph. These same radiographs can be used to guide a farrier in his trimming and shoeing.
Treatment: Directed at correcting the cause of the separation and treating the infected area. Treatment options are also based on the severity of infection in the hoof.
- If heavily infected: Debridement of the affected hoof will need to take place and it will need to be kept clean during the healing process.
- The infecting bacteria are sensitive to air and light, so it is important the area doesn’t become clogged during the healing process.
- Special shoeing recommendations are usually prescribed. The foot is typically trimmed with a mild toe-rock to improve the break over, while still being able to support the frog and bars of the hoof with a shoe.
- Supplements including Biotin to promote hoof growth.
- Movement is very beneficial for improving the blood circulation to the hoof. If the horse is not painful when moving, it is recommended to do hand walks and/or turnout.
Commitment from the owner regarding a continued treatment schedule is necessary until all signs of the disease has been eliminated and the hoof wall has completely grown out. This disease can be treated and resolved with good management. Treatment of White Line Disease is generally successful, but can be time consuming waiting for the hoof to grow out and replace the damaged area (up to a year). Consult with a farrier and veterinarian if any concerns regarding white line disease arise.