Help My Horse Has Chronic Thrush, and I Don’t Know Why.

I hear the phrase “Chronic Thrush” a lot. I also hear “reoccurring” and “constant thrush .” I also hear I have tried everything, and nothing helps, or it keeps coming back. Is it the horse? Is it some metabolic issue? Is it in his pedigree? His farrier? It probably isn’t any of those things. It is something much simpler than that. It is probably YOU.
First, you must understand what thrush is and what causes it. Thrush is a condition caused by Fusobacterium necrophorum. Fusobacterium necrophorum is a bacterium that lives in the soil. It is anaerobic, so it lives without oxygen. This is important. We will come back to this later. It is a common bacterium, and it is present in soils all over the world. All bacteria need a few things to live. The first is moisture. Without water, nothing can live for long, so wet, muddy soils are the perfect place for these bacteria to grow. So, you may ask if my field is contaminated with thrush-causing bacteria. Well, yes, but treating the whole field would probably do more harm than good.
How can Fusobacterium necrophorum, a microscopic germ that my horse has come in contact with his whole life, cause so much trouble? Well, the reason is quite simple, and this is where you come in, you are allowing the bacteria to thrive where he lives, where he spends most of his time, and worst of all, in his hoof. I understand the rainy season, and I understand that the hose keeps popping out of the trough. I realize that water collects around the feed tubs, etc. The problem is that a horse standing in wet conditions all the time is not good for him. We don’t let children eat candy for dinner because it is bad for them. We shouldn’t let our horses stand in wet or filthy conditions all day for the same reason.
When the hoof is submerged or coated in bacteria-filled mud for prolonged periods, the bacterium can colonize the hoof. This is often done within the deep recesses of the sulcus and frog area. Even if your horse moves around a lot, chances are the mud stays caked in those areas. A mud-caked sulcus is going to lack oxygen (remember, anaerobic) and stay damp. The moisture makes the hoof soft, and the protected crevices of the hoof allow the bacteria to gain a foothold and look for cracks or fissures to enter the hoof wall.
So now that we know what causes thrush, where it comes from, and how it infects our horses’ feet, what can we do to stop it from happening and reoccurring? Let’s start with where your horse spends most of his time. I understand the rainy season, I do, but if your horse is turned out in a bog all day, you may have to rethink that choice. Feeders can be moved to dryer areas, and hay can be placed on higher ground or at least moved around so one area doesn’t get beat up where puddles start to form. Do you muck out the run-ins ever? Are the run-ins elevated so water doesn’t pool in them? If your horse is brought in, is his stall clean? Is it dry? Does he have clean bedding? Moisture in a hoof can be a blessing, but too much can cause all kinds of problems. In the case of thrush, and I will add White Line Disease here, it can be a disaster.
So, other than managing your paddocks better, what else can be done? My background is in racehorses, Standardbreds, to be exact. In my many years of training, I have only seen minor cases of thrush, and I have never seen a case of white line disease in a racehorse. Why is this? How is this possible when WLD is the most common hoof problem? It is simple: racehorses are stabled, their stalls are picked out every day, and most importantly, their feet are cleaned every morning before they exercise and again before they are put away for the day. Racetrack grooms will rinse their feet out while they are giving a bath, and when they put them away for the day, the feet are cleaned for the second time, and a hoof oil or conditioner is rubbed or painted on and often, they are packed with poultice, or some other hoof packing. The hoof packing is medicated, and it keeps the hoof moist (not damp), clean, and sanitized.
After reading that, you are now saying this guy is nuts. I can’t possibly clean my horses’ feet out twice a day. I agree it isn’t practical for everyone to provide that level of care, and it can make you a little OCD ask a racehorse trainer. What can be done, though, is to use more common sense when dealing with cases of thrush or with horses that are prone to thrush. Whereas cleaning their feet out multiple times a day is excessive, keeping them on dry footing or providing an area with dry footing is not, especially around feed and water buckets if they are kept out. Bringing them in every few days to clean and examine the hoof and using a product like our “Thrush Thrash” as a preventative also isn’t. Having the farrier cut out any area that is starting to look like thrush is taking hold and opening up the sulcus to eliminate pockets and trimming back the frog also isn’t. Stalled horses that are in training or being ridden often should have their feet cleaned and inspected daily, at least to see if they smell, to see if anything is lodged in them, and if the shoes are on properly.
When dealing with any horse, think about how the horse would live in the wild. Would he stand in a bog all day, stand in his and other horses’ manure all day? Probably not. If we keep horses in unnatural conditions, we have to take measures to counteract these circumstances.

Thrush Thrash