Often referred to as White Line Disease, seedy toe is a very common condition in horses all over New Zealand but almost unheard of in some parts of the world. In most cases, seedy toe does not cause lameness and can be eliminated effectively with careful management.
What it is
The white line, which can be seen on the solar surface of the hoof, is the area between the hoof wall and the sole. It is a very fine area (often around 3-5mm wide in an average sized horse) and contrary to its name, is often yellowish in appearance. Seedy toe is a combination of fungi and bacterium which compromises the white line of the hoof.
Seedy toe enters the area of the white line at the ground surface and will endeavour to escalate upwards, causing deterioration of the white line as it goes.
Symptoms
Seedy toe can often, but not always, be identified by a small fissure or crack in the outer hoof wall when the hoof is on the ground. This crack will be caused after the seedy toe has gained an established hold of the area and tracked up the hoof. As the white line has been compromised, the resulting weakness of the hoof wall allows it to crack near to the seedy toe.
Underneath, a cavity will be apparent which is often packed with black necrotic material. Your vet or farrier may carefully probe the cavity to determine how far it extends up and around the hoof.
In more advanced cases, the hoof wall may sound hollow when tapped. This indicates a cavity and can offer a very rough guide of how much of the hoof may have been affected.
Causes
We most commonly see incidences of seedy toe during the wetter months of the year – and the weeks following. With the hoof softer and the ground wetter, the ability for dirt and debris to enter the hoof (in particular penetrating the white line) increases significantly.
Allowing the hooves to become overgrown and the toes to become long places exceptional force on the hoof wall. This will often stretch the white line at the toe area as the hoof wall stretches in a forwards direction. This stretching of the white line is a great opportunity for the seedy toe to enter the hoof.
Treatment
The most effective method of treatment for minor cases involves the complete removal of the seedy toe and exposure of the affected area to the elements. Seedy toe is anaerobic and thrives in a dark, moist environment such as the white line. Removing the seedy toe and removing the contributing factors is key to the successful treatment.
Treating with a specialist product such as White Lightning may be recommended to assist with the elimination of the causative bacteria and fungi; and using repeated applications, as a preventative measure for re-occurrence.
For more severe cases of seedy toe, a vet should be involved to advise about xrays, heart bar shoes (providing support to the bony column), especially so when the sensitive structures of the hoof are penetrated during the removal of the seedy toe and/or hoof wall. The vet may also administer drugs as they see necessary.
The condition should be assessed following treatment on an on-going and more frequent basis.
If identified at the early stages and the correct approach to removal is followed, most cases will be successfully eliminated efficiently without any lameness or further problems.
Farrier Blog 
Have you any thoughts on why NZ has a high incidence of seedy toe and other parts of the world dont?
Hi Janna,
I’m in little doubt that the environmental conditions are the most significant contributor. The climate and ground conditions in particular.
But if we saw an improvement in the general standard of hoofcare from owners and those responsible for horses I think there would also be a reduction in the severity of the cases we do see. Leaving the hooves too long in between trimming/shoeing (which is not uncommon in NZ) encourages problems of the white line including seedy toe. A long toe can stretch the white line which encourages foreign objects (including fungus and bacteria) to enter the foot at this area.