Q: My 18-year-old Quarter Horse/ Thoroughbred cross is prone to having thrush in his right hind hoof. I keep the area as clean as possible with no success. Although it’s a mild case, it never quite goes away. Why does it affect only one of his feet? Could my farrier be the problem? What could be possible causes? My horse wears front shoes only. He is ridden six days a week at lower-level dressage. 

Janet Rodriguez 

Fayetteville, North Carolina

James E. Gilchrist 

A: Thrush is a condition thought to be caused by an anaerobic bacteria or fungus that is found naturally in the soil and thrives when given the proper environment. It thrives on damp, moist areas in the equine foot, such as the frog, clefts and sole, which can pack with mud, manure and debris. Clinical signs of thrush are a distinct foul odor in the foot, a black, tarry substance and/or sensitivity to hoof-picking. Horses can become lame from thrush, but it is uncommon in the early stages of the condition. If left untreated, the organisms can invade the sensitive tissues of the foot, leading to more serious problems. If the condition worsens, consult your veterinarian and farrier. 

Environmental management and proper foot care are crucial in the prevention of thrush. It is not uncommon for thrush to occur in only one foot. The occurrence of thrush in one hind foot can be linked to the horse standing in his urine spot in the stall. Keep his stall and bedding clean and dry. Lime can be added to the urine spots in the stall to neutralize the acid in the urine. There are several effective commercial topical treatments available on the market for treatment of thrush. I use several products dependent on the case. When the frog is trimmed freshly, I pack the clefts with what’s known as “sugardine,” a homemade mixture of sugar and povidone iodine that acts as a drawing agent. Topical penicillin has also been a treatment of choice for some of my cases. I advise you to consult with your veterinarian and farrier for their recommendation. Most importantly, clean your horse’s hooves routinely, accompanied by regular trims by your farrier.

James E. Gilchrist was the official farrier for the 1996 Olympic Games, the U.S. Dressage Team in Rome, Italy, in 1998 and in Winnepeg, Canada, in 1999. Owner and president of Palm Beach Farrier Service, Inc., he lives in Wellington, Florida, with his wife, Dr. Kimberly Snyder, and his toddler, triplet boys.