White line disease is characterised by a separation of the inner hoof wall at the white line. This separation can be caused by mechanical stress, environmental conditions, toxicity (such as selenium) and laminitis. Bacteria and fungi can invade the area of separation and result in infection, which is commonly called seedy toe.
Seedy toe is more common in wet, humid areas but can occur in hot, arid conditions. Excessive moisture softens the foot and allows for easier entry of dirt and debris into an existing separation which can lead to a secondary infection. Alternatively, excessively dry hooves can form cracks or separations in the hoof wall allowing for invasion of bacteria.
Mechanical stress can be placed on the hoof wall by excessive toe length, poor hoof conformation, such as long toe-under run heel, clubfoot or sheared heels and these stresses can lead to separation. Chronic laminitis causes alterations in blood supply to the hoof and will lead to separation at the sole/wall junction. Seedy toe can also occur following foot abscesses.
Seedy toe is often identified by the farrier. Treatment of seedy toe involves cutting away the hoof wall overlying the area of
(hoof resection) and protecting the foot with therapeutic shoeing. A shoe needs to be applied to protect and stabilise the hoof wall and prevent the horse using the sole for weight bearing. It is essential to correct any abnormal hoof conformation which may have contributed to the hoof wall separation. After hoof resection the hoof wall is left to grow out with regular trimming of the affected area. The feet should be kept as dry as possible and the horse should be reshod monthly during recovery.
The type of shoe required and method of attachment depends on the extent of the damaged hoof wall. If the area is small the hoof can be shod normally. The toe is normally involved, thus it is recommended to move the break-over back behind the toe to reduce the load on the hoof wall. If the resection is extensive and/or rotation of the coffin bone is present a heart bar or egg bar shoe can be used to stabilise the foot. This type of shoe provides support to the heel area and allows some weight bearing to be transferred to the frog. Glue on shoes may also be used in selected cases. Acrylic repair should be avoided if possible as this can weaken the hoof wall and encourage reinfection. To prevent recurrence the feet should be examined carefully daily and any abnormal areas regularly cut away. Careful shoeing to balance the foot correctly is essential.
Oral hoof supplements are recommended to strengthen the hoof wall. Soft, crumbly feet will be predisposed to the development of seedy toe. Biotin has been shown to significantly improve hoof horn quality in horses. In a study by Josseck et al (1995), untreated horses showed soft white lines and crumbling, fissured horn at the hoof wall border, compared with good hoof condition in horses treated with biotin for 9 months. Biotin supplementation has also been shown to increase hoof horn growth by 15% (Reilly et all 1998).
A dose rate of 15-25mg of Biotin daily for an adult horse has been shown to improve hoof quality after 8-15 months of supplementation (Geyer and Schulze 1994). Zinc and methionine supplementation has been shown to improve hoof quality and reduce hoof abnormalities (Moore et al 1989). The combination of biotin, zinc and methionine is recommended for improving hoof quality (Huntington and Pollitt 2005) and to lessen the risk of seedy toe developing. Retread contains biotin, zinc and methionine and can be used to improve or maintain hoof condition.
Josseck, H., W. Zenker, and H. Geyer. 1995 Hoof horn abnormalities in Lipizzaner horses and the effect of dietary biotin on macroscopic aspects of hoof horn quality. Eq. Vet. J 27.3: 175-182.
Reilly JD et al 1998 Effect of supplementary dietary biotin on hoof growth and hoof growth rate in ponies: a controlled trial. Eq Vet J 26: 51-7.
Moore, C.L., Walker P.M. and Winter, J.R., 1989. Zinc methionine supplementation for dairy cows Trans. Ill Acad. Sci 82, 99-108
Huntington, P. and Pollitt, C. 2005 Nutrition and the Equine Foot [online]. Available
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