In Arizona, monsoon often brings struggles with thrush in the hooves of many horses. In other parts of the country, where the weather is damp year round, thrush might be a constant concern.
We can recognize a serious case before we even lift the hoof, by detecting the awful smell just by the horse walking near us. Certainly, we can see it once we do have the hoof in our hand; the frog is usually the center of infection and thrush is often evident in an unhealthy central sulcus when it is deep and sensitive, instead of shallow and resilient. It will also follow along the collateral grooves. If allowed to continue unchecked, the infection can grow so ferocious that it can spoil the entire corium of the frog, cause the digital cushion to become diseased, and even harm the deep flexor tendon where it attaches to the coffin bone. You’ll only have these feeble slivers of nonfunctional frog and your horse will exhibit increased sensitivity, especially in the heel area of the hoof. Eventually, this can result in complete lameness.
There is an ongoing debate as to whether thrush is a bacterial infection (Sphaerophorus Necrophorus) or a fungal one (Candida Albicans) and I’m sure it can be either one or the other or both…but what we do know, is that it is an unwanted intrusion to our horses’ hooves and we need to be diligent in preventing it!
In my experience, healthy barefoot horses rarely suffer thrush at all. So, let’s talk about why that is!
First and foremost, movement. Some of this can still apply to a well shod horse, but it applies most completely to a barefoot horse. There is strong evidence that horses who are stabled and prohibited in their freedom to move on varied terrain for much of their day, often battle thrush more than others who are allowed ample space to roam. With the freedom to walk, trot, and gallop over a clean environment, as horses were designed to do, the hoof is constantly being worn and cleaned of collected debris and dead tissue. Obviously, when we confine them to a stall or small corral, without opportunities to exercise regularly and especially if clean conditions are not maintained, we cancel the hoof’s ability to preserve itself naturally. But even with nearly immaculate husbandry practices and an adequate turnout setting, thrush can still be a problem for some hooves.
This is where we leave the symptoms behind and go straight to the root cause: hoof contraction. A hoof that is contracted is a hoof that will have poor circulation. A hoof with poor circulation will have slow growth. A hoof with slow growth will have excess horn on which thrush will feed. And the whole thing is a vicious cycle! Overgrown and impacted bars are probably the most common culprit of inhibited circulation in our horses’ hooves—the bars and how to correctly see and trim them, seems to often be the most misunderstood element of all. Of course, there are various cases of bar neglect, with some quickly healed by a correct trim and others taking a bit more time. In severely neglected bars, they are actually forced upward and inward, inside of the hoof. This action basically causes everything else to also compress and pinch, such as the frog corium. Of course, increased pressure is put on the palmar digital artery too and it cannot function as it was intended. All this limitation creates the perfect opportunity for thrush to enter and thrive, further compromising the already compromised hoof.
Minor thrush can be easily combated with daily rinses of apple cider vinegar. Keep the crevices of the hoof as clean and open to oxygen as you can. Often, if I encounter a serious case, I will use a few drops of iodine complex to treat. But this is a very concentrated treatment and while it does work well, we should not have to not rely on it! We must treat the cause, not only the symptoms! Or you will be emptying thrush treatments every month because you are still providing the perfect environment for bacteria and fungus and thrush is a destructive opportunist. I only use iodine treatments to help a client along initially, but the real and lasting treatment is in the trim!
For a more detailed explanation of what causes thrush and also more information on the fundamentals of barefoot trimming I have come to recommend, please visit the websites for Hoof Help Online and The Horse’s Hoof.
Pictured is a beautiful and healthy frog!