I arrived at the barn late in the day. It was almost feeding time, and the horses were inside. As I walked through the open barn door I smelled it – the unmistakable stench of thrush.

Studies claim over 90% of domestic horses have an active infection in their feet. That may seem high, but at least 90% of horses I encounter have a form of thrush – some mild, some severe – and the smell in this barn agreed with the statistics.

Thrush is at epidemic proportions in our horses yet no one seems to notice! It’s so common it’s either not recognized or is perhaps accepted as normal. Every barn has bottles of chemical treatments on hand for their never-ending battle against thrush. Wouldn’t it be great to never have to smell, see, or worry about it again?

Does your horse have thrush?
Quite possibly, the answer is “yes”. Thrush is a very common anaerobic bacterium found in the soil, and is everywhere horses are kept. It thrives in damp environments like stall floors, over-crowded or ill-designed outdoor pens, run-in sheds, and loafing areas. The land becomes saturated with high concentrations of urine and manure. As this decays, thrush grows like mold in a Petri dish. Add to this equation the other epidemics of improper foot form and high sugar feeds, and you create the perfect environment for thrush infections.

How do you know it’s thrush?
Thrush does not always have a textbook presentation of black oozing “goo” with a horrible smell. While this is an advanced form (trench foot), there are moderate forms (athlete’s foot) that can wreak havoc on hoof health and negatively affect your horse’s body and behavior as a whole.

In early stages, thrush begins as a flaky sole with shiny black areas along the wall-sole connection. Thrush can affect the frog in the collateral grooves and/or central sulcus, the bulbs, the white line, and even the sole. It is similar to foot rot in cattle or sheep. In many cases, it is not uncommon for secondary infections like “greased heels” and “rain rot” to be present.

• What do you see? When cleaning and inspecting your horse’s feet, are they the picture of health with a clean distinction between parts? The ideal foot will have wide, thick, calloused, uniform frogs that blend into wide, smooth heel bulbs – smooth, shiny soles – and clear white line connections. Or maybe you see some warning signs of a foot susceptible to thrush: chalky, flaky sole – tattered, black frog – deep crevices that trap manure and bedding.

• What do you feel? Does the foot clean easily, almost as if it’s cleaning itself? Is the sole hard and shiny, or chalky and sticky? Is there soft black material in deep cracks and grooves? When you press on the frog, is it strong and super firm like a rubber stall mat, or is it weak? Does it give easily to pressure, like raw meat?

• What do you smell? Naturally kept and trimmed hooves simply don’t smell, or perhaps have the mild odor of fresh manure or damp clean earth. Does your hoof pick come away smelling foul – like an overused chemical toilet at the country fair? That’s “trench foot” thrush. Common, but not normal.

What can you do?
The first thing is to recognize that thrush is a symptom! It is not something a horse can “catch” or come up with in one day. Several factors predispose your horse to thrush. A horse presenting thrush is in chronic stress with a compromised immune system, from one or more of the following:

• The shape of the foot itself. The trim has a lot to do with whether or not a horse is likely to get deep-seated thrush or an easily rectified temporary/ seasonal condition. Overgrown or conventionally trimmed and shod feet are more likely to develop thrush due to unnatural hoof shape and poor circulation. A good barefoot trim creates a self cleaning foot, and promotes blood flow and function, which helps eradicate thrush.

• A high sugar or concentrate diet. This encourages the growth of thrush – like acne of the foot. Too many horses are over-supplemented with processed feeds/grains and other “additives”. A staple diet of free choice grass hays improves health and strengthens the immune system.

• Lack of movement. Stalled horses or those in small turnouts are at a much higher risk of developing thrush. Urine is very concentrated, moreso if the horse is fed grain/concentrates. Bedding soaks up the caustic urine and returns it to the foot. This shows up in the sole as an orange or cantaloupe color. We call this “urine burn”, and it is usually accompanied by black, ragged, narrow frogs, dull, flat heel bulbs and a foul smell. Enhanced natural movement with a correct barefoot trim ensures better circulation, and with attention to footing and feeds, thrush will become a thing of the past.

Thrush cannot exist in a healthy functioning foot – no matter how wet it is outside! Natural horses handle wet seasons with their built-in protection of a strong immune system. Their healthy feet have a thin shellac-like coating, which helps the foot self-clean and maintain proper moisture balance.

The ultimate goal is to keep thrush from developing. By treating now and taking new management approaches, you may never have to deal with this problem again. Prevention is the key!

Lisa Huhn has six years of post secondary schooling in equine and animal sciences and has studied and practiced natural horse care for 20 years, with Equinextion natural hoof trimming since 1995. Lisa developed, tested and implemented the protocols for the Equinextion Therapeutic Performance Trim and now travels North America teaching clinics and giving lectures to vet schools and other equine organizations on natural horse keeping, health care and trimming. Located in Ontario, Canada, Lisa owns and operates an equine rehabilitation and training center. For more information on the Equinextion Associate Trimmers program and certification courses, visit www.equinextion.com

Anne Louise MacDonald is the author of five books, and has worked with Equinextion since 2004.