When you lift your horse’s hoof for picking, you notice a black, almost mold-like gunk accompanied by dark fluid. Perhaps it’s already eaten away part of the frog. The smell is horrendous.
We’ve been there, fellow equestrian. Say hello to thrush. If you are a horse owner, this is probably not your first encounter with this common hoove infection.
But if it is your first time, not to worry: Thrush is highly treatable if caught early.
Read on to learn all about thrush: what it is, what causes it, and how to treat it, to get your galloper back to feeling the fresh breeze flowing through their mane.
Thrush: The Basics
Thrush is a bacterial or fungal infection in horses that occurs on their hooves. It’s focused around the frog, which is that V-shaped section in the center of the hoof. The grooves that you pick are called “sulci,” and bacteria love to collect deep inside them.1
The bacterial culprit carries the grandiose name Fusobacterium necrophorum,1 and despite sounding like a wizard spell, it’s anything but magical. In humans, it’s primarily known as the bacteria behind Lemièrre’s syndrome, but it can cause a variety of different conditions like meningitis and abscesses. In horses, it causes hoof thrush.
This common bacteria thrives in moist soil and feces and hitches a ride on your horse’s hooves when given the chance.1, It makes its home in the sulci and begins causing symptoms soon after.1,3
Symptoms of Thrush
Thrush is typically easy to diagnose by examining the hoof. The most well-known symptom is a runny, black discharge with a distinctive rotten smell.1,3
Other horse thrush symptoms include:
- Dark, necrotic areas around the frog1,3
- Hoove sensitivity or tendernessve sensitivity or tendernes1
- Gaps in the hooves1
The most severe case of thrush usually appears in the central sulcus, the groove that runs down the middle of the frog. This can cause a gash that destroys the integrity of the hoof and begins eating its way into sensitive tissue.4 That’s why you want to catch thrush as early as possible.
Thrush is sometimes confused with canker, another hoof condition. The difference is that while thrush eats away at the hoof, canker grows like a tumor.4 If you’re not sure which infection your horse has, ask a farrier or veterinarian for advice.
Causes of Thrush
Bacteria are tricky organisms, and try as we might to keep our horse’s stables and surroundings clean, sometimes they inevitably make their way into places they’re not invited.
That said, caretakers must do their part as much as they can to help prevent bacteria from festering, by providing a clean, dry living space for horses along with plenty of exercise.
The two main factors that can lead to thrush are:1,3,4
- Wet or unsanitary living conditions
- Lack of exercise
While thrush is commonly associated with unkempt living spaces, even the most pampered ponies can become infected if they aren’t exercised often. Likewise, your horse can get a workout every day and still get thrush if they go home to muddy stalls.1
Since bacteria thrive in moisture, it’s no wonder why damp and dirty floors can lead to infection. But what does exercise have to do with anything?
The answer lies in the anatomy of your horse’s hooves.
Hooves Are Self-Cleaning
No, you can’t throw out your hoof pick, but equine hooves do have a pretty neat way of cleaning themselves. Hooves are concave, but the bone at the base of their foot actually presses down as they walk, causing them to flatten out against the ground.1,4
This mechanism helps to push out debris. A thrush infection can be a sign that this cleaning mechanism isn’t working properly, and all the gunk your horse walks through is getting stuck in their hooves.1,4
There are several possible culprits behind this malfunction. It could be due to:
- An abnormality in the hoof caused by improper trimming.3
- A leg injury might cause the horse to limit the amount of weight they are putting on the hoof, so the cleaning mechanism stops working.4
- Hoof pads with medicated sole packs that have been applied incorrectly can cause moisture to become trapped.4
- Some horses have deeper clefts in their soles, creating more room for bacteria to gather.4
The most common cause of thrush, however, is lack of exercise.1,3,4 Since hooves are cleaned as the horse walks, a horse that does less walking gets less cleaning.
If the worst happens and you pick up your horse’s hooves to see (and smell) that runny black fluid, you’ll need a treatment plan. Most thrush infections are treatable at home and experienced owners typically don’t need to call a vet for backup.1 But if you’re a new horse owner, or if the infection is severe, you’ll probably want professional help.4
Call a veterinarian if you notice any of the following severe symptoms: 1
- Blood or pus emanating from the infection
- Bumpy, granulated tissue called proud flesh
- Lameness or symptoms of such
If the infection is minor and on the surface of the hoof, you’ll most likely be able to treat it fairly quickly. Here’s how to treat a horse with thrush:
#1 Clean Out Your Horse’s Living Space
Step one is to remove all wet or soiled flooring from the horse’s living area and replace it with clean, dry flooring. The bacteria came from these moist materials, so they need to be removed before there’s any chance of curing the infection.3
#2 Debride the Infected Hoof
Next, you’ll need to get rid of the necrotic areas through a process called debridement. This involves cutting away the infection so it stops growing. In minor thrush cases that don’t involve sensitive tissue, experienced owners can sometimes handle this themselves by carefully trimming off black areas of the hoof.1,3,4,5
If the infection has buried deep into the hoof where it can cause your horse discomfort, or if you notice any of the signs listed above, you’ll likely need a veterinarian or other trained specialist. They can also help you decide on a treatment plan that works best for your horse.4
#3 Treat the Infected Hoof
The last step is to banish the remaining bacteria by soaking the hoof in a medical treatment like Hoof Soak. Fill a bucket or hoof boot with water and mix in the powder, then keep the hoof submerged for 40 to 60 minutes.
You should start to see the water change color as the infected material purges from the hoof. If the infection is persistent, you can repeat this process in about 2-4 weeks.1,3,4,5
For less serious infections, you can try a lighter treatment in spray form like Vetericyn Hoof Care. This formula can be applied daily if necessary. It includes a blue dye, so you can tell at a glance if it’s still present and working to protect the hoof.
In some super severe cases, the thrush eats away so much of the hoof that chemical solutions would reach raw, sensitive areas deep in their foot that aren’t typically exposed to the elements. If that’s the case and chemical soaks aren’t an option, sometimes a vet can make a paste of antibacterial tablets and spread it on the hoof before bandaging it up.4
#4 Prevent Tetanus
Tetanus is a particularly nasty bacterium that can infect horses through wounds on the soles of their feet.5 Once inside, it unleashes neurotoxins that attack the horse’s nervous system, which can be fatal. Because thrush creates wounds on the soles of the hoof, a severe thrush infection can lead to a tetanus infection.5
Fortunately, there’s an effective way to prevent tetanus: keep your horse up to date on tetanus vaccinations.6 If a horse that is unvaccinated or has an unknown medical history suffers from a severe thrush infection, they should be administered a tetanus antitoxin as soon as possible.5
Ultimately, the best way to prevent thrush and its unpleasant symptoms is by proactively caring for your horse and their daily health.
Here are some ways to prevent thrush infection:
- Exercise your horse – Make sure your horse is getting a regular workout.1,3,5
- Clean their hooves regularly – While regular horse hoof cleaning is important, it’s especially vital for horses that spend most of their time in a stall.4 If your horse can’t be turned out every day for health or weather reasons, clean their feet more often than usual.
- Give their hooves plenty of love – Have your horse’s hooves trimmed and shod properly.1,3,5 If you’re having recurring infection issues, talk to your farrier about using a different shoeing technique.3
- Keep their homes tidy – Bacteria love mud and feces and all things moist, and they’re rooting for you to let the scum pile up. Keep your horse’s living areas as clean and dry as possible so our nasty foe Fusobacterium necrophorum has nowhere to hide.1,3,4,5
- Change their bedding frequently – Change out your horse’s bedding regularly, and swap straw for materials that collect less moisture, like wood chips.4
Trot Toward Healthier Hooves with Vetericyn
If you find that your horse has developed a hoof thrush infection, don’t panic. Educating yourself with this essential knowledge is the first step to treating this case and preventing future ones.
The next step (or trot) is to gather safe and effective hoof treatment. Vetericyn can help with that.
When thrush strikes, Vetericyn’s Horse Mobility line can get your horse back on track (or trail, or arena). Our Hoof Care spray penetrates the hoof to draw out exudates faster than other treatments and leaves a barrier to help prevent future problems. For deeper or more advanced infections, purge hoof-eating microbes for good with Hoof Soak.
So when your horse needs hoof help, turn to Vetericyn.
- The Horse. The Lowdown on Thrush. https://thehorse.com/119138/the-lowdown-on-thrush/
- PubMed. Fusobacterium necrophorum, an emerging pathogen of otogenic and paranasal infections? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4184658/
- Merck Vet Manual. Thrush in Horses. https://www.merckvetmanual.com/musculoskeletal-system/lameness-in-horses/thrush-in-horses
- US Equestian. Hoof Help: Thrush. https://www.usef.org/media/equestrian-weekly/hoof-help-thrush
- VCA Hospitals. Thrush in Horses. https://vcahospitals.com/know-your-pet/thrush-in-horses
- VCA Hospitals. Tetanus in Horses https://vcahospitals.com/know-your-pet/tetanus-in-horses