White Line Disease in Horses

White line disease in horses is neither a disease nor involves the white lines on the bottom of the feet of horses. There are so many words in English that do not carry the exact meaning, and this is one.

So what does white line disease look like, and what exactly is it if it is not a disease?  

Horse in the paddock

What is White Line Disease in Horses?

White line disease (WLD) is a horse foot problem characterized by breaks and crevices in the non-pigmented area of the horse’s hoof. It occurs when there is a separation between the stratum medium (middle layer) and stratum internum (inner layer) at the non-pigmented junction. White horse hooves can affect shod or unshoed horses of any sex, age, or breed.

The inner part of the hoof is more clammy and moist than the outer part, which is hard and dry. Thus, it is much easier for the inner part to be colonized by microorganisms (bacteria and fungi) from the environment, causing the disease. The white line disease in barefoot horses occurs commonly.

The disease is also known as Onychomycosis (onycho = nail + mycosis = fungal infection). The disease involves the stratum internum and not the white lines on the bottom of the feet. It is locally known as yeast infection, seedy-toe, Candida infection, or hoof wall disease.

What Does Equine White Line Disease Look Like?

Having little breaks in the hoof is normal after a farrier has trimmed it. However, if there are still breaks and crevices after trimming the hoof to the right length, it indicates that white line disease might be setting in. It can happen on all four hooves or just one.

Signs of white line disease include 

  1. After tapping the hoof, the farrier identifies a cavity or space in the hoof.
  2. The farrier identifies a fine, powdered hoof wall instead of a hard one.

The Causes of White Line Disease in Horses

Since white line disease is not really a disease, it is difficult to pinpoint it to just a particular microorganism. Instead, various factors come into play regarding horse foot problems.

White line disease can be caused by:

Mechanical Stress Applied on the Hoof Wall

Mechanical stress on the hoof wall occurs when a lot of force is applied, especially to one hoof, as compared to the other. This can be in the form of sheared heels, arthritis, club foot, horseshoe nails pricking the hoof, long toes, poor conformation, and under-run heels.

Inflammation of the Laminae (Laminitis)

This occurs when blood seeps out of the damaged laminae in the hoof to the horn of the hoof. It creates inflammation, pain, and the perfect environment for microorganisms leading to white line disease. 

Allowing Horses to Stand for Long Periods in Feces

Horses are hindgut fermenters, which means they have bacteria in their hindgut to ferment their food and provide nutrients. Due to the proximity to the rectum, horse poop contains a bit of bacteria. Hence, allowing your horse to stand in its poop for a long time will let bacteria gradually eat away the hoof wall.

Dressing the Hoof With Harmful Materials Like Hydrogen Peroxide or Iodine 

This degrades the hoof and makes it very susceptible to microbial invasion.

Nutritional Imbalances

Every living thing needs nutrients in the right proportions to grow well. So does the hoof. Diets lacking or with little fiber, calcium, selenium, and/or phosphorus and diets high in vitamin D, starches, Vitamin A, and molasses can predispose to white line disease.  

White horses in the evening light

Treating Equine White Line Disease

Treating equine white line disease should not be a daunting task. A veterinarian can treat white line disease with a farrier in your region.

Firstly, the hoof is soaked and disinfected in a hoof soak. This kills the horn of the hoof and penetrates deep into the hoof. Allow the hoof to dry thoroughly. Then, cover the foot with an anti-microbial gel that penetrates through the cracks and stays on the hoof for a while to prevent the growth and spread of microorganisms in the hoof. 

Your veterinarian would recommend administering the anti-microbial gel at least twice a week. 

Now, attending to the main hoof issue is addressed. A farrier resects the hoof and cuts away the three hoof layers using a hoof knife to meet healthy hoof tissue. This cuts away all the infected parts of the hoof. The farrier then uses a drum sander to file and make the hoof area smooth, allowing the hoof to grow better and nicely.

The resected hoof is then supported with a special type of shoe to keep the body balanced, protect the hoof, and prevent it from bearing weight. It would be best if you kept the horse in a dry place and the hoof brushed daily to keep it clean. 

Every two weeks, the farrier should assess the hoof, and any part not looking clean should be marked with a dye marker and cleaned by the farrier or an experienced horse owner. Ensure the horse does not bleed during this process. 

The farrier re-examines the hoof every four weeks until healing is complete, and as much as possible, you should try to keep the hoof and the stable bedding dry. 

Thrush vs. White Line Disease (Difference)

Even though thrush is a bit similar to white line disease, it should not be confused or mistaken for each other, as there are apparent differences. 

Trush is a fungal and bacterial infection of the frog (yup, it is part of the hoof of horses). It has a pitch-black discharge, like tar, and a foul odor. The white line disease, however, is an infection of the hoof’s inner wall caused by various factors. 

Is Equine White Line Disease Painful?

Most diseases, in their initial and mild states, are hardly painful. So it is with white line disease. The mild forms are not painful and usually go unnoticed unless a farrier is attending to the hoof. 

The sign that screams for attention is lameness, and this occurs when much damage to the coronary band or laminae is affected, causing extreme pain leading to lameness. 

Hoof Dressings That Proliferate Equine White Line Disease

Like pouring acid harms the skin, so do various chemicals harm the hoof and make it easier to get white line disease. Hoof dressings like hydrogen peroxide, a mixture of sugar and iodine (sugardine), engine oil,  hoof oil, iodine, formalin hoof dressings, purple spray, and Stockholm Tar are culprits. These are poor for hoof growth, making them dry, brittle, and susceptible to white line disease.

Can You Ride a Horse With White Line Disease?

Yes, you can, but it is not advisable. If your horse is not already lame, mechanical stress caused by riding can make the disease worse. It is also dangerous for both the horse and the rider as the horse might lose balance and throw the rider off. It might also predispose the horse to lameness.  

Resected Hoof Regrowth Time

A skilled farrier performs a hoof resection by cutting off the entire three segments of the hoof using a hoof knife. This removes the infected parts, creating a healthy section for the hoof to heal and grow.

The anchor of white line treatment is hoof resection; like every part of the body affected, a resected (cut) portion takes a while to regrow. A healthy, well-fed horse should regrow the hoof from the hairline to the ground in about 10-12 months. It should take about six to eight months to regrow the sides (quarters) of the hoof and an additional three to four months for the heel to regrow. 

Domestic Horse in the ranch

Prognosis and Recurrence

If left untreated, white horse disease will eat up the hoof wall, making the animal lose its stability. A horse that responds to medication and hoof regrowth early has a good prognosis, making a full recovery.

After hoof resection, it is not all rosy yet. The hoof should be constantly monitored and trimmed to remove any further infection. This is important because white line disease can recur. 

The Word’s Out!

For your horse to live healthy and comfortably, you need to identify the leading cause of white line disease and tackle it. Protect your horse’s hooves by involving a skilled farrier and a veterinarian in your stable. This way, you can enjoy a healthy and comfortable life with your horse.