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What is White Line Disease in Horses

Mukulika Mukherjee
The white line disease is one of the most common hoof infections in horses. This Story talks about its causes, symptoms, and treatment.
Did you know that the white line disease can affect any horse, irrespective of its age and gender?
The hoof is the modified third digit of each of the four limbs in horses, which bears the entire weight of the horse. Thus, the hoof is very crucial to the health and well-being of the horse. Hooves are highly prone to infections because of the many layers.
The fact that a horse almost always remains standing, unless it is sick, means that it is one part of the horse's body that hardly gets any rest.
It is essential that you take proper care of the hooves and get your horse shod to protect damage due to wear and tear. White line disease is a result of fungus or bacteria affecting the middle layer of the inner hoof wall, which gradually spreads to the other layers of the hoof, eating away at it.
If left untreated, it can cause lameness. This infection is also known by other names, such as seedy toe, hollow foot, wall thrush, and stall rot.


The hoof is made up of 4 layers—the pigmented horn, non-pigmented horn, white line, and sole. While the white line contains live laminae tissue, the non-pigmented horn contains dead laminae tissue.
The hoof wall has three layers—stratum externum, stratum medium, and stratum internum. The hoof horn is located beneath the hoof wall, and the latter is attached to the laminae. The laminae attaches the hoof wall to the coffin bone. The coronary band is located at the top of the hoof wall.
The following are the symptoms of the white line disease.
  • Outer hoof wall sounding hollow on tapping
  • Poor consistency of hoof wall
  • Flattening of the sole
  • Tenderness in parts of the sole
  • Bulges in the hoof
  • Slower growth of hoof wall
  • A chalky and powdery white line


It is a condition that is caused by one or several microbes feeding on the keratin tissue of the hoof wall, and begins with a separation between the wall of the hoof and the sole. The microbes, commonly bacteria or fungi, enter the hoof through small cracks and fissures, including nail holes in the hooves of shod horses.
Even though the causes of white line disease are widely debated, here are a few of them.
  • Unbalanced feet
  • Insulin resistance
  • Improper hoof trimmings
  • Leverage due to overly long toes
  • Deformities in the hoof
  • Abnormal hoof angle
  • Trauma or injury to the hoof
  • Other hoof diseases, such as chronic laminitis
The rich feeds that we provide our horses with, are also to blame. Horses were never meant to feed on legumes, fruits, and molasses, anyway. It is important for horse owners to understand that these can adversely affect their horses. Instead, horses should be fed on free-choice, mixed-grass hay.
This can work wonders in preventing hoof diseases, including the white line disease. People believe that their horses would lose weight without adequate nutrition. The fact is that the diet of a horse should depend on the amount of work or exercise it does.
Eating nutritious stuff without engaging in any kind of exercise does more harm than good. Also, there seems to be a very strong connection between too much sugar in the diet and fungal infection in the hooves.

Diagnosis and Treatment

The white line disease causes damage to the stratum medium layer. There are other conditions that cause flares and chipping of tissue at the white line, and hence, true white line disease often remains undiagnosed. Laminitis, keratoma, and crumbling of the white line tissue due to dietary deficiencies are some of them.
Diagnosis involves tapping the hoof wall, which produces a hollow sound. Once the disease has reached its advanced stages, diagnosis is carried out using X-ray photography to assess the extent of damage.
There are different methods of treatment, depending on the severity of the infection. In some cases, the hoof wall covering the affected tissue is removed. Debridement is the removal of a part of the hoof wall that covers the affected tissue, and the amount of debridement required depends on the severity of the damage.
However, if detected at an early stage, treatment can be as simple as cleaning the debris from the affected area and applying antifungal ointments.
In most cases, the first step in treatment involves removal of the affected tissue. The second step involves application of topical antifungal solutions. The third step is to prevent relapse or recurrence of the infection.
This involves exposing the affected area to air and prevent exposure to excess moisture. In cases of severe damage to the hoof, a bar shoe or acrylic hoof patching is used to support the roof. The horse should be given zinc, methionine, iodine, and biotin supplements to accelerate hoof growth.


White line disease can be prevented with the following 3 steps: suitable changes in the environment, desired changes in the diet, and proper hoof care.
Here are some preventive measures for white line disease in horses. 
  • From an early age, the horse should be trained on landing heel first. This practice goes a long way in protecting the hoof.
  • The horse should be taken to a farrier on a regular basis for trimming and removing flares from the lower ⅓rd of the hoof.
  • From an early age, the horse should be trained on landing heel first. This practice goes a long way in protecting the hoof.
  • Get the hooves of the horse examined by a farrier every time you take it for trimming, because a farrier would be the best person to detect it.
  • Place a layer of small pebbles in the stalls to create a bedding. This will help keep the hooves dry and protect the horses from fungi and other pathogen that thrive in wet and moist conditions. Not only during the rains, but this can also help during the winter months when the grass is rendered wet by the dew.
  • Opt for a diet that is low in carbohydrates and fruit sugars. Too much carbohydrate causes imbalance in the metabolism of horses. You should restrict the use of sugar supplements, as too much sugar can lead to Metabolic Syndrome, along with hoof diseases, such as laminitis and white line disease, among others.

Possible Complications

If left untreated, the infection can travel up to the coronary band, causing the laminae to separate, which leads to the rotation of the coffin bone, which is one of the complications of white line disease.
In severe cases, where the coffin bone is affected, the horse might require a wall cast, which is nothing but a cast made of fiberglass that provides support to the foot.
In order to ensure proper management and treatment for the condition, you should seek the help of a veterinarian. The time of recovery depends on the extent of damage. It takes approximately a year for the hoof to grow from the coronary band to the toe.