White Line Disease

One of my client’s poor pony is suffering from white line disease. We think it’s been a long time brewing because each time the pony has been trimmed by the farrier he’s been footsore for a few days. Anyway, what seemed to be an abscess a couple of months ago didn’t clear up and then the vet diagnosed white line disease. A new farrier later, and he’s making progress. Unfortunately, due to the rate of growth in the hoof, any problems with the hoof wall takes months to recover.

I don’t know much about white line disease, so I’ve done some reading up on it. When you pick up the foot, you can see the white line where there sole meets the outer hoof wall. Damage to this area allows fungus and bacteria to get between the sole and hoof wall, which causes them to separate. Infection then spreads up the hoof towards the coronet band, destroying the hoof wall and making the horse very lame. White line disease usually affects the toe and quarters of the hoof. As the hoof deteriorates it takes on a chalky, crumbly, soft, white texture.

There are numerous different types of fungi which can be involved in white line disease, which makes treatment harder, especially as some spores cannot be eradicated, which means that some types of white line disease cannot he treated, only managed.

Because the hoof wall is made of dead cells, like our finger nails, the damaged area cannot regrow as skin would around a wound. Instead new, healthy hoof has to grow down from the coronet band which can take up to six months. Which is why you can see ridges on hoof walls following a change in diet or health.

White line disease sets in if the hoof wall is weakened, or if the hoof wall starts to separate from the laminae due to poor trimming and balancing of the foot. It begins with small cavities in the hoof wall, or seedy toe, which a good farrier should pick up on and take appropriate steps to prevent the disease spreading.

Farriers will shoe horses with white line disease with bevelled shoes to bring the breakover point further under the foot which takes the pressure off the toe area, and supports the compromised area. Shod horses are more likely to develop white line disease because of the mechanical pressure of the metal shoe against the hoof wall can literally tear the hoof wall away from the foot.

Treatment of white line disease involves removing the infected hoof wall, and then keeping the area as clean as possible. Horses usually need box rest, especially if lame, and to keep the foot as clean as possible, using an iodine or alternative solution. Once healing is established and the ground conditions are favourable – dry and mud free – the horse can begin light work because movement improves circulation and increase hoof growth.

There is a risk of laminitis developing as a secondary infection if a lot of the hoof wall is debrided and the bones of the hoof are less supposed so the laminae becomes detached. By supporting the bars and frog of the shoe you can reduce the risk of laminitis developing.

Caught early, white line disease is easily managed, but in more severe cases special shoes, boots or cast are needed for several months in order to provide enough support to the structure of the hoof while the healthy hoof grows down. Farriers measure the lesion upon treatment so that the next time they trim the foot they can establish if the rate of hoof growth is exceeding the tearing of the hoof wall. If this is the case then the hoof will recover as long as it’s kept free from further infection by keeping it disinfected, dry and open to the air to discourage the fungi from thriving.

You can try to prevent the onset of white line disease by feeding biotin containing supplements to improve the quality of the hoof wall, and having the hooves trimmed and well-balanced regularly. The farrier should keep an eye on old nail holes, old abscess sites and quarter cracks. Other than that, good hoof hygiene and care is paramount at preventing white line disease, and catching it early. Horses kept in a more artificial environment – stabled with less turnout – and those in extreme conditions (very wet or very arid) are often more prone to developing white line disease.

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