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Thrush and Horses

Posted by John Belcher on
Thrush and Horses


For any horse owner that doesn’t know what Thrush is, here’s a brief description for you:  

Thrush is a degenerative bacterial (Fusobacterium necrophorum) and fungal (Spherophorus neaophorus) infection of the central and collateral grooves of the frog. It is typically caused by standing in moist areas such as very damp, dirty stalls, bedding and/or wet grounds. This bacterium is aggressive and invasive, causing destruction to the frog. If left untreated this can cause destruction to the frog and expose the deeper tissues. 

Thrush results from anaerobic bacteria being trapped in moisture, creating a fungal infection that slowly eats away at the horse's hoof tissue in the frog area, the sulcus, causing damage to the soft tissue structures of the horse's foot.  


The diagnosis is quite cut and dry (no pun intended): there will be a foul, almost rotting odor within a deep crevasse that shows a dark bacterial infection on either side of the frog. When pressure is applied to the frog, there can be a reaction of pain or general discomfort and may even cause swelling in the lower part of the leg, whether front or hind. 

Most of the time Thrush will create some mild discomfort, but if treated quickly it rarely worsens. If left untreated, the thrush can eventually make its way into the sensitive areas of the frog, causing some bleeding from the frog with much higher levels of pain in the foot, creating a much more difficult treatment plan for negating the thrush and any damage that may have been caused to the hoof in general. 

Long heel conformation encourages the development of deep narrow frog sulci, which are more prone to the development of thrush, especially if environmental conditions are right.  If the horse has an imbalanced foot in the lateromedial (inside-outside) plane then this also predisposes the horse to thrush. 

Preventative Measures 

Use a wire brush to clean mud or other moist debris such as manure, etc. each day to keep the area clean.  

If your horse resides in a facility that is low ground with a lot of standing water that creates a moist environment of mud, you can use a topical preventative consisting of anti-bacterial and anti-fungal essential oils and/or a pack of balm with a wrap or boot to protect the frog from many hours standing in this environment that is less than healthy for the foot in general. 


There are many products for Thrush, preventative and treatment wise, most contain chemicals and synthetics that horses can be quite sensitive to.  As with all holistic health, preventative is the way to go.  Obviously a clean, dry stall and grounds (field and turnout) are the best prevention but the land may not be able to be dry 12 months of the year and turn out is hugely important for good health overall.  

healthy hoof

    Hoof with Thrush                         Healthy Hoof

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