Seedy toe or white line disease, as it is sometimes called, is an infection ofthe horse hoof caused by the yeast genus candida.

To gain a better understanding of seedy toe a knowledge of the anatomy of the hoof ishelpful.

Layers Of The Hoof
The first layer is the part we see every day - the hoof wall. This is hard insensitivetissue similar to the tips of your fingernails.

Inside the hoof wall is the second layer - known as the white line. Anyone who has watchedclosely a horse being trimmed or shod and looking at the sole after trimming would havenoticed a quite visible white line just inside the perimeter of the hoof and basicallymirroring the shape of the hoof wall. The white line is softer and more flexible than thewall. It is also insensitive tissue and basically exists to provide a juncture between thehoof wall and the third layer of the hoof, the sensitive laminae.

The third layer which is known as the the sensitive laminae is highly sensitive, vascular(blood carrying) tissue which provides nutrients and blood to the internal structures of thefoot.

The hoof wall and the sensitive laminae interlock, with the white line in between, bondingthem together.

In a normal healthy hoof micro-organisms cannot gain entry to hoof tissue. However when thestructure of the hoof wall is compromised, for any number of reasons, varying degrees ofinfection can occur.

Common Causes
1. In my experience the most common cause of breakdown in hoof wall integrity is allowing ahorse's feet to grow overlong. Apart from the obvious fact that long feet are pre-disposedto chipping, splitting or cracking, long toes significantly delay hoof break-over (theaction of the foot when walking) creating a lever arm effect on the foot. This in turncreates a shearing force between the hoof wall and the sensitve laminae weakening andstretching the bond between the two. In my opinion, this stretching creates microscopicgaps in the laminae allowing undesirable organisms access to the foot. Imagine the feelingwhen you bend back a fingernail.

2. Horses feet absorb moisture. This causes the hoof to expand when wet, contract when dry.Typical South Eastern Australian Springtime weather commonly sees continual periods of wet,followed rapidly by periods of dry. This climate sees the hoof exposed to repeated periodsof expansion and contraction. This also can contribute to weakening the bond between thehoof wall and the laminae. Exacerbarting this problem, is that it appears that candida genusis most active in warm moist conditions.

3. Other less common causes can include:
• acute trauma
• abscess formation that introduces infection
• a case of laminitis that causes tears in the laminae
• sole or toe bruising near the white line where dried blood provides growth nutrients forthe candida organism

Long Term Effects Of Seedy Toe
If left untreated seedy toe can have serious long term effects. I have seen cases where thehoof has become infected to the point that over half of the hoof wall has literally rottedand peeled off exposing the sensitive laminae. This has caused acute lameness for severalweeks. These worst case scenarios seem to leave scar tissue on the sensitive laminaeresulting in a permanent weakness in the hoof.

In extreme cases the organism can penetrate to the pedal bone possibly causing bone ersionor infection.

Prevention
I have found the best results for prevention of seedy toe are a regular (5 to 6 weeks)trimming program in order to keep the hoof wall short and prevent cracks appearing throughshearing forces.

Where possible try to provide your horse relief from extended periods in wet enviroments. I am frequently asked about the use of hoof oils and conditioners and whether they help. Inmy opinion (i stress this is only an opinion) the short answer is no.

Treatment
In most cases seedy toe shows significant improvement with aggressive trimming andshortening of the toe. Generally two to three (regular!!!) trimming cycles is enough to cutthe majority of the infection away.

In more severe cases the hoof wall will need to be resected (cut away) in order to get tothe origin of the infection. Generally after resection the area is treated daily with atopical agent in order to kill any remaining pathogens. My personal favorite is iodine as ihave some reservations about the use of harsher agents such as peroxides so close to livetissue. Again i stress that is just an opinion.

Resection is a tricky job and i recommend you find an experienced and qualified masterfarrier to undertake the task.

Recovery
In nearly all cases, with proper treatment and regular trimming, horses recover fully fromseedy toe without any lasting side effects.

Visit Shane Ellis MasterFarrier

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