Through the spring and early summer, moist conditions in paddocks and pastures are inevitable here in Minnesota. Moist environments not only cause horses to be muddy, but they also serve as a great environment for thrush development in hooves. Some owners will experience treating horses with thrush yearly and others will likely face it at least once in their horse’s life.
Thrush is a bacterial infection caused by the bacterium Fusobacterium necroporum. This bacterium naturally occurs in the environment; specifically in wet, muddy, or unclean living situation. The bacterium is an anaerobic species, meaning they thrive in dark environments with little to no oxygen. Once thrush develops in the hoof, it generally becomes established in the frog and the groves of the hoof first, often with a black appearance. In addition to the color, when the hoof is cleaned out with a pick, a foul odor will be present, tenderness will be appreciated throughout the frog, deep pockets will extend back to the heel bulbs, and poor frog definition will be seen.
Even in dry environments or in a clean stall, horses can still develop thrush. Thrush management is important year round. Here are a few tips to prevent thrush: keep the hoof balanced with regular trimmings from a farrier, clean the hoof out with a hoof pick regularly, and maintain an exercise program. Exercise promotes a healthy foot by providing good blood supply to the area.
Treatment of thrush depends on the horse and the severity of the episode. In more severe cases where the horse has a significant lameness or discharge from the hoof, a veterinarian should be called. For less critical thrush cases the hoof needs to be cleaned, infected tissue be removed, and treated with a product to clean and dry the infected area; these specific products can either be obtained over-the-counter or from a veterinarian. Some commonly used treatment products are Thrush Buster, Copper Sulfate, or iodine dilution; bleach should never be applied to the hoof due to the risk of harming sensitive tissue. Keep in mind that the use of dilute iodine can help treat thrush when packed with gauze, but iodine is inactivated when it comes in contact with organic material. If iodine is chosen for treatment, the hoof must be cleaned really well.
Overall, thrush can be a minor problem for owners to treat; however, if left untreated, this minimal issue can cause damage to the soft tissue of the hoof leading to lameness and loss of riding time. With the suggested prevention and a quick response to start treatment thrush episodes are typically short.