Learn About White Line Disease in Horses

 

Oddly enough, white line disease (WLD) does not directly involve the white line of your horse’s hoof. That makes sense, right? Instead, this insidious foot infection likes to find some separation of the hoof wall and set up shop there. Cracks are a way for this bacterial and fungal infection to invade the hoof tissue. Interestingly enough, white line disease starts as a bacterial infection, and then the fungi come along and take over. So, treatment for white line disease involves both types of organisms.

 

Table of Contents

 

Anatomy

Causes and contributing factors

Treatment for white line disease – topicals and resection

White line vs. thrush

Prevention

Dietary considerations

Lameness and laminitis

jump to videos and shopping

 

 

 

Horse hoof anatomy

 

• The hoof wall has three layers: the stratum tectorium, the stratum medium, and the stratum lamellatum.

 

• The stratum tectorium is the outer layer of the wall. This protective layer is a physical barrier to the inner layers.

 

• The stratum medium, also called the tubular horn, is the middle layer. It is the thickest and has many parallel cylinders, known as horn cylinders, that stretch from the coronary band to the edge of the hoof.

 

• The stratum lamellatum connects the stratum medium’s horns to the outer covering of the distal phalanx (coffin bone). These sensitive tissues are joined to the stratum medium, making a mostly united hoof wall.

 

• The white line is where the sole of the hoof and the hoof wall meet. It’s the edge of the unpigmented stratum medium and the ends of the laminae. There’s also a bit of pigmented wall included as well. This is why the white line isn’t actually white – it’s usually a shade of yellow.

 

• The white line marks the boundary between sensitive and insensitive portions of the foot.

 

Read more about hoof anatomy here, and this article has great illustrations of anatomy made simple.

 

Colors may vary.

 

Where does white line happen in the hoof?

 

• White line disease grows in the stratum medium and the laminar horn of the hoof wall. You may also hear it called seedy toe. Sometimes, the only hint you see is some little cracks at the edge, where tiny bacteria seeds can enter the hoof.

 

• You will typically see white line disease during a farrier’s visit, which is very close to the white line after your farrier has trimmed the area. The white line is pretty hard to see on an untrimmed hoof. There might be a crack in the toe or quarter area, or you might see some hoof wall separation or a bit of chalky debris where the solid hoof wall should be. There is often a little toe crack that can’t seem to grow out.

 

• It is futile to narrow down a specific cause of WLD. Over a dozen fungi and bacteria have been identified that contribute to white line disease. Each case will be different, and each case will respond differently to treatments.

 

• We know that air and light do wonders to kill white line disease.

 

Causes of white line disease in horses

 

Bacteria and fungi

 

• These obnoxious microbes create the actual WLD in horses by residing in the hoof wall. Without light or air, they breed and burrow into the wall. It’s wild that microorganisms can take down a creature as large as a horse, but they can.

 

• A horse with poor hoof quality, cracks, nail holes, or other defects has made the perfect home for pathogens. Once they move in, the affected area can quickly grow as the bacteria and fungus multiply.

 

Contributing factors to WLD that are mostly out of your control

 

• Genetics – horses are going to horse the way their DNA tells them, and sometimes, weak hooves are on the menu.

 

• Poor conformation – largely tied to genetics, conformation can be altered with farrier work. Poor conformation can lead to tiny cracks that offer a welcome mat to bacteria and their invasive friends. Long toes, a club foot, and a less-than-healthy hoof horn are opportunities for WLD.

 

• Space aliens – it’s possible, but not probable.

 

Things you can influence

 

• Injury to the hoof wall or sole – bruising, cracks, quarter cracks, and trauma can happen to the hoof. Even an abscess, those painful pockets of infection that pop out, can create an opening for white-line disease. Abscesses can exit the hoof around the sole or at the top in the coronary band, known as gravel. 

 

• Living conditions – even horses living in pristine conditions can develop white line. It’s truly impossible to avoid bacteria. There is no straight line between your horse’s environment and the development of problems.

 

• Farrier care – the hoof balance is essential, as is looking for and treating cracks early. If your horse is shod, the only time to look for cavities near the white line is when the shoes are removed and the hooves are trimmed.

 

• Wet/dry cycles – some horses do better with constantly changing moisture on the hoof. It is common for horses in wet conditions, like dew and mud, to develop cracks as the hooves cycle between moist and dry.

 

• The type of footing your horse stands on may encourage cracks. Is abrasive footing more likely to create cracks? Perhaps.

 

• Your horse’s exercise routine matters, as this is part of their overall health and well-being. And this included natural movement during turnout!

 

• Diet – hoof health starts with nutrition. A forage-based diet is best for horses, but it must be balanced to supply vitamins, minerals, calories, fats, and other nutrients to provide proper nutrition. Biotin is a vitamin that supports the metabolism of amino acids, which make up proteins in the body and are closely related to hoof health.

 

More on abscesses here.

 

See this little crack growing upwards? Time to open it up to allow fresh air in.

 

Treatment for white line disease – from topical meds to resection

 

• Address tiny cracks and openings immediately for horses of any age. Being present with your farrier as they trim the hoof is always a good idea, and if you are particularly minded, taking photos after trimming can help you track hoof health, especially between the borders of the inner and outer hoof wall.

 

Your veterinarian and farrier can devise a plan if you suspect white line disease.

 

• Some cracks can be opened while small, allowing the all-powerful oxygen in. Your farrier may want to scoop out the hoof wall around the crack with a hoof knife, allowing air and topical medications to find the source. 

 

• If the infection seems more significant, get x-rays of the hoof. Pockets of infection will show up on radiographs. White line can extend up the entire hoof wall, and you may not know the extent until x-rays are done. 

 

• Even without cracks, WLD can happen. Your horse’s hoof may sound hollow when thumped, as the infection has eaten away from the inside out. This detection method is largely subjective, and not as reliable as actual diagnostics – like x-rays. 

 

• Radiographs also give your veterinarian and farrier a map to start opening up the infection. In some cases, large sections of the wall need resection. X-rays give your farrier an actual map to remove only the necessary parts of the wall.  

 

Can we trust our horses to not make a mess while soaking?  No. 

 

Soaking the hoof and shoeing

 

• Many commercially available soaks exist, although your vet will have the best recipe for your area. Clean Trax is widely available and has a good reputation. Mix this formula with water and let your horse’s hoof soak in a bag for up to an hour.

 

• A change in shoes can support the frog and bars if the wall is damaged too much, either from the disease itself or from a resection of the hoof wall.

 

• As only time will grow back the hoof, having your horse on a well-balanced diet is essential for healthy hoof growth. Support healthy growth with good footing, lots of turnout, and appropriate exercise, too.

 

More about hoof resection

 

• You, your vet, and your farrier must develop a shoeing plan to combat this disease.

 

• Sometimes, the outer hoof wall needs to be removed to allow air in. You will get an up-close view of the hoof wall’s inner layers, and your heroes may lose some hoof functionality. The wall will be weakened along that area, and they will likely need more support from shoeing.

 

• Using supportive shoeing is critical in the healing process. A horse’s foot needs continuous pressure to grow evenly and correctly, and therefore, a horseshoe needs to compensate for the resected bits. However, using composite or fillers is only sometimes best, as heat-activated materials may push the microbes further into the foot.

 

• Also, there needs to be enough hoof left to adhere to a shoe.

 

• Cleaning the resected hoof is best done with a wire brush to debride the area manually. Yes, you read that correctly. This won’t hurt, and has been shown to be more effective than topical solutions when the hoof is clean and dry.
•  
• Topicals are also helpful as dye markers to track healing. Your farrier and vet should show you how to do this daily.

 

• And then do your best to keep your horse moving and dry!

 

Read more about resection and treatments after resection here.

 

A crack that has been opened and notched to try and prevent further cracking.

 

White line vs. thrush 

 

• Like white line disease in horses, thrush is a hoof infection primarily composed of bacteria and fungus. But, thrush lines in and around the frog, not the wall. Topical treatments for the two usually overlap, as the anaerobic microbes don’t need oxygen.

 

• Interestingly enough, like WLD, thrush happens to horses that live in pristine and perfect conditions. It’s not just mud and manure! Researchers have discovered that movement is critical for horses with thrush, as this flexes and extends the frog, making exposure to the elements more thorough and improving hoof health. This creates a less hospitable environment for bacteria to flourish.

Preventing equine white line

 

• Sometimes, you can’t prevent infections, but you can reduce their likelihood and catch things early. Here are some things to consider:

 

• Your horse’s farrier care should be appropriate for their hooves. The oddly standard “8 weeks” is often too long; many horses fare much better with a 5-week schedule. And the hoof won’t undergo such a drastic change if the cycle is shorter.

 

• Track your horse’s hoof health with photos or a physical record. Look for cracks and how they progress or grow out.

 

• Let your horse move more. More appropriate exercise, more turnout, more herd time. Just more movement.

 

The big one – keeping your horse’s hooves dry.

 

• This can seem impossible, but you can try plenty of things.

 

• Try shifting turnout schedules to avoid dew.

 

• Use bell boots to cover the hooves and keep them drier than otherwise. Hopefully.

 

• Use a protective moisture barrier on the sole and hoof wall. This barrier will wear off, but it’s better than nothing.

 

Lots of potential for WLD here with these cracks.

 

Dietary considerations like copper and zinc supplements

 

• Feed your horse to prevent and heal white line. Start with forage, and then look at vitamins and minerals. Your equine nutritionist is the best resource for this.

 

• Calcium, phosphorus, biotin, zinc, copper, and amino acids are all needed in the correct quantities. What your horse gains from pasture, hay, and supplements may be too much or too little, varying by region.

 

• For example, genetically identical horses eating the same diet but living across the country from each other will differ in their dietary needs. The pasture in New England does not have selenium, while it does in other parts of the country. Also, where a horse’s hay is grown matters, as the hay takes up the selenium from the soil.

 

• Adding supplements can help balance the diet, so long as you don’t feed too much of something.

 

Can white line cause lameness or laminitis?

 

• Yes, unfortunately. Damage to the wall translates to decreased support in the hoof, and lameness may be a side effect. Inside the hoof, the laminae can fail because of this reduced support. Catching white line disease in horses early is your best defense, and involving your vet and farrier for treatment and progress is always a good idea.

 

For more about the signs of laminitis, read this.

 

Videos about treatment for white line disease in horses: 

Hoof anatomy and how white line happens

 

More about white line

 

Preventing white line disease in horses 

 

 

Stock up here for your horse supplies! As an Amazon Associate, I earn from qualifying purchases, but it’s ZERO extra cents to you.  You can also visit my Amazon storefront here:  PEG storefront.

Thank you!