February 2021

Thrush is a common bacterial infection affecting the horse’s hoof, more specifically the soft frog tissues and sometimes the heel of the foot. It usually starts in the frog clefts and can produce black smelly discharge. It can affect one hoof or all four at a time.

Hoof Diagram


Thrush can be caused by a consistent exposure to poor environmental conditions such as deep soiled bedding, deep mud or very wet pastures. If your horse’s hooves are not picked out daily, they will be more prone to developing thrush. Poor hoof conformation and horses with deep frog clefts, or imbalanced feet are also much more likely to develop thrush.

Clinical Signs

Horse Hooves 
It’s really important to check your horse’s hooves daily, so you get to know what’s normal for them and to make sure you spot any signs of thrush straightaway - it should be easier to manage if you catch it in the early stages. Common signs of thrush include:

  • Smelly dark discharge
  • Softening of the frog
  • Excess growth of frog tissue
  • Lameness in more severe cases
  • In severe cases the bacteria can cause damage to the frog creating open sores.




If left untreated a thrush infection can progress and affect the deeper structures within the hoof. It is important for the owner, farrier and vet to work together to provide the best outcome for your horse’s specific circumstance, however a general treatment plan should include:

  • The horse initially being removed from the muddy, wet conditions and as such stabling on clean, dry bedding may be required.
  • The horse’s hooves should be picked out carefully twice daily before scrubbing the frog and sole with an antibacterial solution, for example dilute iodine (highly acidic solutions should be avoided as these may kill off healthy tissue as well as the thrush). Once washed the horse should be stood on a clean dry concrete area to allow it to dry.
  • Any loose or dead frog tissue should be removed by the farrier or vet to allow air to reach the affected tissue.
  • Avoid treatments that coat or seal the sole and prevent air contact as the bacteria involved thrive in conditions with low oxygen levels.
  • Shoeing may be necessary if there is heel instability, foot imbalance or to improve air flow under the foot.

Seek further advice from your vet if the thrush, does not respond to treatment, is causing lameness or the tissues are bleeding.


Prevention is much better then cure and through following these simple steps you can help to prevent the underlying causes.

Hoof Picking

  • Inspect your horse’s hoofs and pick out daily. As a matter of good practice this should ideally be done twice a day
  • Avoid your horse standing in wet and muddy conditions for long periods – make sure they have somewhere dry to stand for at least part of the day
  • Adopt good grassland management by rotating fields to reduce poaching and put hardcore down in places where horses gather, such as gateways and water troughs. Fence off any particularly muddy areas
  • Maintain good stable hygiene with clean dry bedding
  • Regular trimming of hooves and frog by a farrier is important to maintain good hoof conformation and frog health


With thanks to VetPartners - Laura McGillycuddy BSc BVetMed MRCVS Cert AVP. Hampden Equine Veterinary Practice.


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