White line disease of the horse’s hoof


You might guess that it’s some sort of hoof issue that involves the white line of your horse’s hoof. Well, sort of. Technically, white line disease doesn’t reside in the white line.  Because WHY make sense?  

PS – there are videos at the end of this article showing hoof anatomy and white line disease tips and prevention. 


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  • Let’s discuss horse hoof anatomy first. When you examine the hoof wall, there are three layers of the hoof wall, the stratum tectorium, the stratum medium, and the stratum lamellatum.


  • Where the sole of the hoof and the hoof wall meet is the white line. It’s made up of the edge of the stratum medium, which doesn’t have pigment and the ends of the laminae. There’s also a bit of pigmented hoof wall included as well.


freshly trimmed hoof showing white line and hoof wall

Colors may vary.


Where does white line happen?


  • White line disease hangs out 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 hoof’s edge, and that’s where tiny seeds of bacteria can enter the hoof.


  • You will typically see white line disease during a farrier’s visit, very close to the white line. There might be a crack in the toe or quarter area, or you might see some hoof wall separation, or there’s a bit of chalky debris where the solid hoof wall should be. There is often the little toe crack that just can’t seem to grow out.


  • To narrow down a specific cause of white line is largely futile. There have been over a dozen identified fungi and bacteria that contribute to white line disease. Each case is going to be different and each case will respond differently to treatments. It is known that air and light do wonders to kill white line disease.


Causes of white line disease in horses


  • Genetics – horses going to horse the way their DNA tells them.  


  • Conformation – largely tied to genetics, conformation can be altered with farrier work.  Less than ideas conformation can lead to those tiny cracks that offer a welcome mat to bacteria and their invasive friends. 


  • Living conditions – even horses living in pristine conditions can develop white line.  It’s truly impossible to avoid bacteria. 


  • Farrier care – the balance of the hoof is important, as is looking for cracks.  If your horse is shod, the farrier visit becomes even more important to inspect under the shoe. 


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


  • Injury to the hoof wall or sole – bruising, cracks, quarter cracks, all sorts of trauma can happen to the hoof.  Even an abscess that pops 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, which is known as gravel. 


  • Wet/dry cycles – some horses do better than others with constantly changing moisture on the hoof.  


  • Type of footing he stands on – abrasive footing may be more likely to create cracks?  


  • Exercise routine – and this includes turn-out.  


  • Diet – hoof health starts with nutrition. 


small vertical hoof crack

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


If you suspect white line disease, your veterinarian and farrier can come up with a plan.


  • Some cracks can be opened up while they are small – this allows the all-powerful oxygen in. Your farrier may want to scoop out the hoof wall around the crack, which allows air and topical medications to find the source – hopefully. 


  • If the infection seems larger, it’s often a good idea to do some 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. 


  • There may be no cracks to give something away, instead, your horse’s hoof may sound hollow when thumped as the infection has eaten away from the inside out.  This method of detection 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 hoof wall need to be removed.  X-rays give your farrier an actual map to remove only the necessary parts of the hoof.  


Soaking an infected hoof may also help.


  • There are lots of commercially available soaks, although your vet will have the best recipe for your area to try. Clean Trax is widely available and has a good track record.  This is a formula that you mix with water and soak the hoof – for up to an hour.  


  • A change in shoes might also help, to support the frog and bars if the hoof wall has too much damage, either from the disease itself or from a resection of the hoof wall.


  • As only time will grow back the hoof, it’s important to have your horse on a well-balanced diet to provide for optimal hoof growth.  Support healthy growth with good footing, lots of turnout, and appropriate exercise, too.


vertical hoof crack that has line above it

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


In some cases of white line disease, a horse may develop laminitis.


  • Damage to the hoof wall translates to decreased support in the hoof, and the laminae can fail. The best course of action is one of quick intervention, working with your farrier and veterinarian to prevent worsening of white line disease into lameness or laminitis.




Videos about white line disease in horses: 

Hoof anatomy and how white line happens


More about white line


Preventing white line disease in horses 


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Cavallo Simple Hoof Boot for Horses, Size 3, Black

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$17.99 $14.45 ($3.61 / Fl Oz)
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Handson Ergonomic Hoof Pick
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This is the strongest hoof pick available!

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Thank you!