If your horse has a thrush infection, you will usually notice the odour first. A closer inspection will reveal a black, oozing discharge, or perhaps just the beginnings of it, noted by some blackness in the grooves around the frog. This is an infection -- in fact, the Clyde Vet Group Equine Hospital's website notes that a thrush infection can include both bacteria and fungus. Commercial treatments are effective but are usually harsh and can damage healthy tissue. You can make treatments for preventing and treating thrush that are effective and gentle.
Keep a spray bottle filled with apple cider vinegar handy and apply it to the hoof. Apple cider vinegar, or ACV, is a mild and effective way to treat thrush if you apply it every day. You can also use it as a foot soak. If your horse is on stall rest, or is in a wet environment for long periods of time, use it once or twice a day to prevent thrush. One advantage of ACV is that it can treat the thrush without destroying healthy frog tissue.
Apply tea tree oil to the frog area. Tea tree oil is a natural anti-fungal that you can use to treat thrush. One Iron Horse Farm Owner Tom Tower, of Dripping Springs, Texas, applies it with a dropper but you can also keep it in a spray bottle. You can also mix it with alcohol, such as vodka or vegetable glycerine. Apply it directly to the infected area, then cover the foot with a large sock or baby diaper. Apply at least twice per day.
Mix triple antibiotic cream and athlete's foot cream in a syringe. Clean the frog, and then use the syringe to direct this mixture into the sulcus --- the crack in the centre of the frog --- as well as any other cracks in the frog.
Scrub the hoof with dish soap and warm water, and apply zinc oxide on the frog and near the cracks. The zinc oxide protects it from urine. This is helpful for mild cases, as well as prevention, particularly for horses that are on stall rest and stand in urine-soaked shavings or hay.
Scrub the hoof and frog with a dish soap for cases just forming or before applying a treatment. You can purchase vegetable glycerine from several online suppliers, particularly companies that sell herbs.
If thrush is an ongoing problem for you, clean hooves daily, and talk to your veterinarian about the way your horse's hoof is trimmed to see if that is contributing to the problem.