How Do Horses Get Thrush & What Is The Best Treatment: Tips & Myth Busters For Horse Thrush
By Elyse Schenk
August 21, 2020
Phew! What’s that smell? While picking your horse’s feet, a foul odor lingers, accompanying an oozing black slime and a hideous decay of hoof tissue. Thrush strikes again.
Example of a horse hoof with thrush post-trim from a farrier. Image courtesy of David Hallock, CJF, ASF, AWCF.
What is thrush?
Thrush is a common, relatively non-threatening bacterial and fungal infection found mainly in the sulci—the central groove of the hoof—and regions adjacent to the frog. However, if left chronically untreated, infection and inflammation can spread to cause more debilitating cases of lameness.
Notorious for its putrid smelling dark discharge, the odor will likely be your first indication of the disease. Hoof tissue sloughs and peels away from the infected regions, leaving a dark, jagged, flimsy appearance of the normally firm and shallow grooves. You’ll notice unusually deep crevasses surrounding the frog as the bacteria erodes the area. The deeper the erosion and separation, the more pain and irritation the condition causes your horse.
Thrush is embedded in the deep cracks on both sides of the frog. Image courtesy of Rannveig Lien. Image courtesy of David Hallock, CJF, ASF, AWCF.
How do I treat my horse’s thrush?
The diseased tissue has got to go. Decaying tissue and limited exposure to oxygen enables thrush to thrive, so a successful and speedy treatment must include the removal of rotting hoof material. This may require farrier intervention for a thorough and careful job. Otherwise, go ahead and scrape out as much “gunk” as possible!
Once the diseased tissue is excised, thrush is easy to tackle with widely available antiseptic products. Various types of bacteria known to cause thrush are eliminated by formalin and iodine-based products, such as Mustad Thrush Buster. The general recommendation is to clean and treat the infected areas twice a day until the foot is healed.
Thrush is almost always treatable on your own but contact your veterinarian if your horse is showing signs of lameness. Also, if the disease seems incessant and recurring, determine what is contributing to the condition in order to eliminate the source and prevent the disease in the future.
A severe case of thrush in the central sulcus. Image courtesy of David Hallock, CJF, ASF, AWCF.
How can I prevent thrush?
The main contributing factor to thrush is improper hoof care, particularly poor frog health. Many people underestimate the role of a properly trimmed hoof in preventing thrush. Hoof conformation matters to ensure enough heel pressure to activate the frog’s self-cleansing properties. When pressed, a frog releases trapped dirt. This necessary natural cleaning process is hindered by overgrown or unbalanced feet, a long toe, clubfoot, or contracted heels—all of which prevent the frog from bearing sufficient weight. Without enough weight, the frog will shrink over time, and the surrounding grooves will deepen, trapping dirt and bacteria. With particular attention to proper hoof shape and frog health, thrush is unlikely to occur, even if your horse lives in muddy conditions!
Secondarily, limit your susceptibility to the disease by frequently picking your horse’s feet. Removing manure removes risk for thrush to develop. Make it a habit to pick feet before and after turnout. Utilize the bristle portion of your Corro Easy-Grip Hoof Pick / Brush Combination to gently but efficiently remove mud from the sensitive regions surrounding the frog.
Of course, limited manure and urine exposure will make it more unlikely for thrush-causing bacteria to attack. Sanitary conditions should always be a priority for this reason (and many others).
Image 1: Horse hoof shows a compromised frog ready for thrush to grow
Image 2: The deep central sulcus shows the depth that thrush can go to in the heels
Image 3: Locations where thrush can flourish in
Common Myths About Thrush
1) Damp footing causes thrush.
A horse with healthy, properly formed and trimmed feet won’t be vulnerable to the bacteria present in muddy footing. Likewise, if the wet ground is mostly void of manure and urine, the bacteria concentrations will be too low to pose any risk to your horse.
2) You shouldn’t ride a horse who has thrush.
If your horse appears sound, exercise will actually help keep the foot clean. Frequent concussion of the frog will push out debris and initiate healthy frog growth.
3) Bleach is an appropriate thrush treatment.
Although considered a traditional remedy, be weary of bleach, as it is harsh on sensitive hoof tissue. A diluted bleach solution may be safe, but talk to your veterinarian first.
Here is a picture of what would be considered a nice healthy frog post trimming. No flaps or pockets for thrush to hid in and the frog itself is healthy/robust. Image courtesy of David Hallock, CJF, ASF, AWCF.