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What is Thrush in Horses? Thrush Causes and Treatments

What is Thrush in Horses? Thrush Causes and Treatments
Photo by Jonathan Bean / Unsplash

You start to clean your horses’ hooves before a lesson and realize that there is a foul odor that seems to get worse as you pick away debris. Many times, this odor is the tell-tale sign of thrush, or, what is scientifically known as nonproliferative pododermatitis. Your horse may not seem to be in any pain, however if left untreated, thrush may continue to affect your horse to the point of creating lameness in serious cases. Before getting to treatments, it is important to consider what causes thrush in the first place.  

Thrush Causes 

When looking at a horses’ hooves, you will find an area in the middle of the hoof shaped like a triangle, which creates the upside-down “V” shape in the horses’ hooves that many use as a guide when hoof picking. This triangle is known as the frog of the hoof and is an important area that helps to distribute weight as the horse moves. The frog also functions as a self-cleaning mechanism helping to remove excess debris; every time a horse takes a step, the frog will expand, pushing out lodged material that doesn’t belong.  

Thrush is often associated with unsanitary conditions but that is not necessarily the case for many horses who contract thrush; thrush may survive due to many different types of moisture paired with debris that is unable to be discarded by the frog. Conditions that may contribute to thrush are:  

  • Prolonged periods in stalls  
  • Prolonged periods in paddocks or lots that are muddy or have excess feces 
  • Lack of exercise for prolonged periods of time  
  • Irregular hoof conformation  
  • Excess moisture (May be due to frequent bathing or weather conditions) 

Thrush as a bacterial disease heavily affects the frog’s function; by weakening the frog, it becomes smaller in size and becomes unable to utilize its self-cleaning properties. This then allows the bacteria to continue to eat away at the horses’ hoof, creating more damage. If left untreated, thrush may cause lameness and more serious issues such as white line disease.  

Thrush Treatments 

Call the Farrier  

According to recent studies, such as a study posted by the Scientific Eminence Group titled “Remedial Hoof Trimming: A Curative Measure for Thrush”, one of the fastest ways to help rid of thrush is contacting a farrier to trim the horses’ hooves. In this study, horses in Group A were given a treatment of copper sulfate, povidone powder, and zinc oxide in a 1:1:1 ratio, while horses in Group B were given this same treatment as well as a hoof trimming. The study showed that horses in Group B were able to heal from thrush faster, where the median recovery time in Group B was 8.5 days compared to Group A, who had a median recovery time of 11 days. The frog size in horses in Group B was also shown to increase, suggesting horses in Group B had healthier frog health after receiving a trim and treatment.  

The Virginia Therapeutic Farriery also mentions that horses experiencing thrush should have their hooves trimmed in such a way that the heal of the hoof should be trimmed down to the base of the frog to promote better frog growth and reduction of thrush. Their article mentions that, if possible, it is best for a horse with thrush to go barefoot, however, if a horse needs to be shod, they may wear a straight bar shoe.   

Administer Medication 

The Virginia Therapeutic Farriery mentions that the frog may be cleaned by soaking in Epsom salts, followed by with daily cleaning by using antiseptics or astringents. Some examples of these include vinegar, iodine, rubbing alcohol, or any of the items used in the previously mentioned study (copper sulfate, povidone powder, and zinc oxide).   

If Necessary, Call the Vet 

If your horse is experiencing lameness and/or is not showing any signs of improvement after seeing a farrier and having consistent application of treatment, it is best to consult your vet to make sure the thrush gets resolved and that there are no other conditions contributing to your horses’ discomfort.  

Thrush Prevention 

Thrush may be common and can affect even the most well cared for horses, however there are some preventative measures you can take to prevent thrush from developing: 

  • Cleaning your horses’ hooves regularly: removing debris that the frog is unable to remove can help to avoid frog disfunction.  
  • Exercising your horse regularly: movement helps to promote a healthy frog, allowing it to function properly. 
  • Ensuring clean living environments: thrush is often caused by exposure of the hooves to bacteria from manure and urine, so make sure that your horses’ primary living areas are cleaned often. 
  • Using dry bedding in stalls: using dry bedding such as shavings will help to prevent thrush as it decreases the moisture that thrush thrives from. 
  • Making sure your horses’ legs are dry before returning them to their main living area after water exposure 

References 

“Equine Thrush: A Closer Look.” Equine Podiatry | Dr. Stephen O’Grady, Veterinarians, Farriers, Books, Articles, www.equipodiatry.com/news/Equine_Thrush_A_Closer_Look.html. Accessed Nov. 2024.  

Patel, Abhishek. “Remidial Hoof Trimming: A Curative Measure for Thrush .” ResearchGate, 2021, https://www.researchgate.net/publication/366167867_Remidial_Hoof_Trimming_A_Curative_Measure_for_Thrush_Publication_Dates_Corresponding_Author. Accessed 2024.  

Rice, Jennifer. “Thrush in Horses.” PetMD, 2023, https://www.petmd.com/horse/conditions/skin/thrush-horses. Accessed 2025.