What is thrush?
Thrush is an anaerobic bacteria and fungus found in the intestinal tract of hooved animals, such as horses. “Anaerobic” means that it grows and thrives in the absence of oxygen.
Once thrush gets into a horse’s foot, it attacks the frog, central sulcus, and collateral sulci.
Although thrush is a somewhat common condition, it shouldn’t be underestimated, and immediate treatment is recommended to prevent the infection from spreading to sensitive tissue.
Thrush-infected hooves will show a thick, black tar like substance that has a very specific foul-smelling odor.
The frog will have a rough appearance as well as looking ragged and unhealthy.
Thrush usually begins as a mild “infection’ and travels into the collateral sulci and the central sulcus and eventually to the entire frog.
If not treated and prevented properly deepseated thrush will attack the sensitive frog, which will create bleeding when the frog is cleaned and lameness may be present.
How bad can it get?
While thrush may appear suddenly, the initial stage of infection is fairly superficial and easy to treat. If ignored, on the other hand, thrush can quickly become a serious issue.
The following images are examples of what different stages of a thrush infection may look like.
Causes
The most common misconception about thrush is that it is caused by mud and/or wet conditions.
As mentioned in the beginning of this article, thrush is a bacteria that is present in the horse’s intestinal tract. Thrush, therefore, cannot be caused by a horse simply stepping in mud.
Thrush is caused by the horse stepping in manure, thereby introducing the thrush bacteria and fungus to his feet. If the conditions are wet, then the mud will seal the manure into the sulci of the frog.
Horses with deep sulci and narrow heels more commonly develop the disease. High heels with deep sulci can be found in club-footed horses, horses with high heels, contracted feet, and chronic founder. Deep sulci can pack with manure, creating the perfect environment for thrush.
Deep sulci will not self-clean when the horse moves around as easily has a horse with shallow sulci. Thrush may affect only one foot or multiple feet.
Thrush is not contagious.
Treatment
Because thrush is an “anaerobic” bacteria, it will immediately die once it is exposed to air.
The first and most efficient line of treatment, therefore, is a consistent and thorough hoofpicking regimen to expose the bacteria to oxygen as often as possible.
This will kill the bacteria and prevent manure and mud from packing the feet for extended periods of time, which allows the infection to spread faster.
Having your hoof care provider clean and treat the thrush in your horse every 6 to 8 weeks, will not resolve the thrush condition, nor prevent continued problems.
Your veterinarian and hoofcare provider may also recommend a topical thrush treatment. Remember that a sporadic application of thrush treatment is unlikely to resolve the issue: consistent and thorough hoof cleaning will still be required, as well as a regular application of thrush treatment according to label instructions.
If the thrush infection has advanced enough to cause lameness, extended hoof soaking in medicated solutions and/or medicated hoof wrappings may be in order.
If the central sulcus is involved, there is often a split that travels from the central sulcus up, between the bulbs and develops a deep fissure. These feet must be soaked and cotton gauze is used to “floss” between the bulbs with the medicated solution.
The fissure can be deep enough to allow sand from an arena to work its way up, causing irritation and lameness.
Contraindications
The use of boots, especially if plastic-lined, is not recommended while the horse is at rest and not being worked. Boots create a warm, moist environment with very little airflow that is perfect for thrush to thrive in. If the goal is to provide protection to a sensitive thrushy hoof, medicated wrappings are a better option.
Do not be lured into using “homemade” recipes’ for the treatment of thrush. Caustic chemicals can spill onto the coronary band and have disastrous effects on your horse’s feet. Horses can slough their hoof capsule when aggressive treatment of caustic chemicals are used. Purchase products that are safe and designed to treat thrush.
Prevention
When dealing with thrush the best offense is a good defense. The area the horse live in should be regularly cleared of manure and kept as dry as possible. Thrush is a horse husbandry problem not prevented by your hoof care provider.
Proper hygiene of the environment and of the feet is essential.
Feet infected with thrush should be cleaned, picked and medicated daily.
Key Points
Thrush is a degenerative, anaerobic bacterial/fungus infection of the frog.
Thrush is caused by a horse stepping in manure and feet not regularly picked.
Thrush is not created by mud only, but by manure packed into a foot.
Horses that continually walk in manure will be more likely to develop thrush.
Without treatment thrush my attack the sensitive frog, creating lameness.
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