May 29, 2020 4 min read

Thrush is the name that we tend to use for any type of fungal or bacterial infection of the horse’s frog. Its characterised by a foul-smelling and often white, grey or black sludgy residue in and around the frog and it can cause significant pain and tenderness in the area.

Most of us were taught from a young age to pick out the hooves daily and to be on the lookout for Thrush however many horse owners believe it’s just a hygiene issue or cosmetic flaw. However, Thrush can be a serious issue, causing mild to severe lameness, with the symptoms mimicking navicular syndrome. It can also cause a host of other problems for the horse, both within the hoof and throughout the rest of the body.

The horses' Frog is an extremely important structure within the hoof. Along with the other structures in the back half of the foot, it acts as one of the main shock absorbers, dissipating the energy from impact and protecting surrounding structures.

A healthy hoof will land primarily heel first and a healthy frog and heel area is essential for this critical function in the hoof. Any sensitivity in the area will cause the horse to alter the way he moves, and as a result, the hoof may begin to land toe first.

A toe first landing puts major stress and concussive forces through the rest of the hoof, bony column, joints, ligaments and muscles. This can lead to injury and long-term breakdown. It can also cause hoof wall flares, capsule rotation, hoof cracks, thin soles, bruising, sole and pedal bone damage and abscessing.

Therefore, a healthy and functioning Frog is very important!

Causes of Thrush


Wet and unhygienic conditions are a risk factor for Thrush; however, it can also occur in dry climates.

It’s important that your horse’s living conditions are free from manure and urine and that if they are living in wet conditions that they have some places to stand that are well-drained. This can be achieved with ag drains and through the use of gravel. Pea gravel is useful here as even sore horses will be able to stand comfortably in between 4-6 inches of soft round pea gravel and it’s also useful to exfoliate the hooves and frog and to condition the hoof tissue.


Bacterial and fungal infections tend to thrive in anaerobic environments so keeping your horses’ hooves clean, picked out and trimmed is important.

Any excessive flaps of frog tissue can be trimmed (by your expert farrier) to allow the air to get to the frog. However excessive frog trimming should be avoided at all costs and when in doubt its best to leave more on! Your horse will get sore very quickly if too much frog is removed, and it can also expose healthy frog tissue to infection by the bacteria and fungus that is already there.

The hooves should also be regularly trimmed and well balanced to encourage correct use, movement, growth and form of the hoof.


Almost all hoof problems have a huge nutritional component and Thrush is no exception! When the horse does not receive the critical building blocks that he or she needs to make and maintain healthy tissue, in this case, hoof and frog tissue, then the structures weaken and become diseased.

An excellent quality, high dose, trace mineral and vitamin supplement is KEY! Something like Missy’s Bucket is ideal as it also contains essential amino acids, methionine and lysine, Biotin for hoof health as well as the two biggest (and most deficient) Trace Mineral guns - ZINC and COPPER.

A diet consisting of low sugar, decent quality forage (pasture and hay) without additional Iron and balanced minerals is paramount.


Once the diet, environment and trimming have been adjusted to promote good hoof health, then you can look at topical treatments.

There are many different products marketed to treat thrush however some of them may not be your best choice due to the caustic and tissue-damaging effects that they have on healthy hoof tissue.

We need to try and focus on treatments that not only kill the fungus and bacteria but also support the healthy, living frog and hoof tissue! And underneath all that damaged, smelly goo is sensitive, live and sometimes very thin tissue.

First, clean the hoof well by scrubbing with a stiff brush and bucket of warm soapy water, choose an antibacterial hand or body soap for this purpose. Then apply the treatment of choice.

The treatment you choose needs to get to the deepest parts of the hoof and frog cracks for it to be effective. This can be achieved with soaking or by injecting the product into the area with a nozzled syringe or similar.

If soaking the following mixes work well in soak boots:

  • 50/50 mix of Apple cider vinegar and water for 30-45 minutes
  • Oxine AH (Chlorine Dioxide) - 120ml Oxine AH and 1tsp citric acid (for activation) diluted in 3.5litres of water – soak for 20 minutes only

Some topical treatments could include:

  • Zinc oxide cream mixed with copper sulphate or athletes foot cream
  • Anti-bacterial hoof powders or human tinea powder

A great place to start would be to:

  • soak once or twice a week,
  • then clean hooves daily and apply the topical cream

In summary, the three most important factors to get right to treat horse's with thrush in their hooves would be:

  • DIET: Give the body what it needs to build strong tissue and disease defence
  • ENVIRONMENT: Eliminate environmental causes
  • TRIM: Balance the hoot for good function and trim excess frog to expose the area to air

Once you’ve got the three bases covered, then go onto to the treatment's that include soaking and topical treatments.

Two additional thrush treatment resources:

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