White Line Disease/Fungal Infections

Have you ever come across a grey, crumbly spot on the hoof wall while picking out the hoof? Watch out, because it could be "White Line Disease"!

How White Line Disease develops

White Line Disease (WLD for short) is a fungal infection of the hoof, often with bacterial involvement as well. The name is misleading, however, because the infection doesn't actually affect the white line itself, but rather the inner part of the hoof wall (the unpigmented layer of the wall horn). Dermatophytes (keratin-eating filamentous fungi) settle there and destroy the horn material. What remains is grey, mealy, crumbly material that can be easily scraped out.

A healthy hoof is normally resistant enough not to give these fungi any chance. But as soon as the hoof is weakened, entry points for bacteria and fungi easily arise. This is often the case when the white line is no longer intact, allowing harmful organisms to penetrate deep into the hoof. Dermatophytes love dark, damp and warm places – the hoof therefore offers them the perfect environment.

Entry points into the hoof wall

Channels into the hoof wall can arise either mechanically, through bacterial infestation or through problems in nutrient supply. The most common causes include the following:

• Laminitis: the connection of the white line becomes detached and the fibre layer is often significantly widened
• Nutrient over- or undersupply: the horn can become brittle or too soft due to imbalances in nutrient supply (especially an incorrect calcium-phosphorus ratio, selenium excess or too much starch feeding)
• Cracks/splits in the hoof wall due to leverage (unbalanced hooves, misalignments, overdue or incorrect trimming)
• unhygienic housing conditions
• holes in the hoof wall from nails

In practice, the cause is often not clear-cut but rather a combination of several factors that ultimately lead to fungal infestation of the hoof wall.

Treatment

To effectively eliminate White Line Disease, the underlying causes must be addressed, otherwise the fungal infection will keep recurring. At the same time, the existing fungal infestation must be eliminated. This requires completely removing the affected horn areas, i.e. cutting them out as part of professional hoof trimming. If the infection has already migrated extensively up behind the wall, a large portion of the hoof wall may need to be removed. This can look alarming, but is unfortunately necessary in order to dry out the infection. If the removed area was very large, the hoof capsule may become too unstable and artificial reconstruction may be required. In that case, synthetic horn is applied to the affected area and helps to compensate for the missing wall.

If the fungal infestation is not yet extensive, one can also initially try to preserve the outer part of the wall and only cut out the affected area in the inner layer. However, the resulting hole must then be treated thoroughly so that bacteria and fungi cannot settle there again.

All agents that have a fungicidal effect and ideally also work antibacterially are suitable for this. These include common household remedies (e.g. vinegar, propolis, chlorine cleaners), hydrogen peroxide and crystal violet. But be careful: chlorine and hydrogen peroxide are irritating and volatile substances. You must therefore apply them quickly and make sure they do not come into contact with sensitive skin areas.

Depending on the size of the hole, it may also make sense to pack it with cotton wool or wool that has previously been soaked in vinegar, propolis or crystal violet. There are also special clay-based pastes ("Hoof Clay") that also work against bacteria and fungi and can be used to seal the cleaned holes.

Author: Nathalie Kurz

>> Sources

https://thehorse.com/113282/the-frustrations-of-white-line-disease/ https://www.epauk.org/about-equine-podiatry/articles/white-line-disease/ https://www.huf.ch/hufpilz.html https://www.barhufteam.ch/white_line_disease.html https://www.der-hufspezialist.de/whiteline-disease