Thrush In Horses - What Causes It And What To Do About It
Updated: Feb 2
Are you even a horse owner if at some point in your life you haven’t mentioned your horse’s thrush problem to a ‘none horsey’ person, and they’ve sniggered or made a hilarious joke? Although we’ve probably all laughed along, and nodded in agreement, it is a really frustrating and in some cases serious condition in horses.
So what is thrush? Well, thrush, in horses, is degeneration of the frog with a secondary bacterial infection that usually starts in the central and collateral groove of the frog. Many factors can cause the frog to degenerate including high exposure to wet pasture ground, soiled bedding, and poor hoof hygiene. Once the frog starts to degenerate it allows bacteria to enter, causing an infection: thrush! Once the infection has started it causes the borders of the frog to die. Unfortunately, it gets worse. The frog doesn’t naturally shed very well so the dead tissue is a perfect home and food source for the bacteria. It allows moisture and dirt to be stored in and under the dead tissue, making it a haven for bacteria. It's the all-you-can-eat buffet of the bacterial world. It’s a knock-on effect because the bacteria gradually eat away at more and more layers of tissue. It’s a bit like lighting a match and throwing it into a waste paper bin, once the match is burning the spread is inevitable unless you put it out.
The first symptom of thrush is commonly a foul odour, with more severe cases noting a thick black or white discharge in the grooves of the frog. The frog is sometimes soft with some separation between various parts of both the frog itself and the sole of the hoof. This is sometimes misunderstood as excessive growth of the frog tissue and often gets missed as a symptom of thrush. More severe cases can result in more severe issues such as open sores and lameness.
There is hope though. We can stop the knock-on effect just like we could extinguish the fire in the waste paper bin. Environment is a key factor in treating thrush; horses should be bedded on clean dry bedding and long periods of exposure on wet pasture avoided until the infection has cleared up. Farriers can trim back the dead tissue where possible, which will reduce the bacterial spread by taking away its main breeding ground and food source. Topical treatments such as sprays and powders can be applied to kill the bacteria and should be used daily until the infection has cleared up. Some products can also be used as a preventative treatment so if you have a horse who's particularly thrush prone, prevention is better than the cure. There are lots of different ones on the market so it’s important to research your chosen product and see how it works and how it is applied. A good hoof balm is also a handy tool to have for any horse, particularly when trying to prevent thrush. Some can be applied to the sole of the hoof to act as a barrier against the wet and keep the frogs strong and healthy, but again, do your research before you apply, as some are full of cheap fillers that can be drying on the hoof!
There is a lot of evidence linking thrush, especially reoccurring cases, to confirmation of the hoof but realistically you can only work with what you have! If the frog is close to the ground or the groves of the frog are narrow or deep dirt and moisture are more likely to get trapped in there. Once it gets in the match has been struck so degeneration begins. Regular hoof maintenance is essential and a qualified farrier is key to managing any hoof issue. The reality is however that if they have thrush it needs clearing up before the fire spreads and it becomes severe.
Amber Sellers: BscHons Biomedical Science