White Line Disease/Fungal Infections

Have you ever come across a grey, crumbly spot on the hoof wall when picking out the hoof? Then watch out, because that could be “White Line Disease”!

How White Line Disease develops

White Line Disease (“WLD” for short, or in German “Erkrankung der weissen Linie”) is a fungal infection of the hoof, often with bacterial involvement. The name is misleading, however, because the infection does not actually affect the white line, but the inner part of the hoof wall (the unpigmented layer of the wall horn). There, dermatophytes (keratin-eating thread fungi) settle and destroy the horn material. What remains is grey, mealy crumbly material that can easily be scratched out.

A healthy hoof is normally resistant enough not to give these fungi a chance. But as soon as the hoof is weakened, entry points for bacteria and fungi easily form. This is often the case when the white line is no longer intact and harmful organisms can thus 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 be caused mechanically, by bacterial infestation or by problems in the nutrient supply. The most common causes include the following points:

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

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

Treatment

For the effective elimination of White Line Disease, on the one hand the causes must be eliminated, otherwise the fungal infection will keep recurring. On the other hand, the existing fungal infestation must be removed. For this it is necessary to completely remove the affected horn areas, i.e. cut them out as part of professional hoof trimming. If the infection has already spread over a large area behind the wall, a large part of the hoof wall may need to be removed. This can look scary, but is unfortunately necessary to dry out the infection. If the removed area was very large, the hoof capsule may become too unstable and an artificial reconstruction may be necessary. Artificial horn is then applied to the affected area and helps to compensate for the missing wall.

If the fungal infestation is not yet so large, an attempt can first be made to preserve the outer part of the wall and only cut out the affected area in the inner layer. However, the hole that is created must then be treated thoroughly so that bacteria and fungi cannot become re-established.

All products with a fungicidal effect and ideally also an antibacterial effect are suitable for this. These include common household remedies (e.g. vinegar, propolis, chlorine cleaners), hydrogen peroxide and gentian violet. But beware: 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 can also make sense to plug it with cotton wool or wool that has been soaked in vinegar, propolis or gentian violet beforehand. There are also special clay-based pastes (“Hoof Clay”) that also work against bacteria and fungi and with which the cleaned holes can be sealed.

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