Thrush, White Line and More

What's the difference between white line disease, thrush and yeast in between the heel bulbs?

Briefly we'll discuss the difference between these conditions and how to tell what is what.

Thrush is a bacterial infection that occurs in the tissue of the frog

This condition starts when bacteria penetrate the outer horn of the frog. As it progresses, the frog tissue deteriorates causing a very foul odor. In severe cases, the bacteria can reach the inner frog/frog stay causing pain and lameness. You may even notice blood on the end of the hoof pick when cleaning the frog and the horse will pull the hoof away as this area will be extremely tender. The formal name for thrush is fusobacterium necrophorum. It is a "gram-negative bacteria" that is commonly found in most stables in the ground. Excessive hoof length, contracted heels, or shod horses with a full pad are most likely to contract thrush. Hoof thrush is NOT the same thing as 'thrush' in the human. Thrush, in the human, is a fungal condition known as candida albicans. Thrush, in the equine is a bacteria, not a fungus.

Thrush only develops in horses with unhealthy frogs. A horse with healthy frogs, that lives in the worst environments one can think of, will rarely get thrush while a horse with unhealthy hooves and frogs can live in the most immaculate situation and will contract thrush simply because the frogs are not healthy.

Diet plays a major role in hoof health as does hoofcare. Hooves must be correctly trimmed and balanced and the horse must have an equine appropriate diet that feeds the immune system in order to retain healthy hooves.

Treatment of thrush can range from simple topical applications for a minor case to surgical debridement and extensive care for those cases that have progressed into the sensitive foot. 

White Line Disease (WLD) is a FUNGAL situation in which  fungal organisms eat away at the hoof particularly between the middle wall and the inner wall of the hoof

This type of infection usually occurs when there is poor hoofcare and the hooves are too long with flares, hoof cracks and poor horn quality. WLD commonly is not noticed until the horse is lame and the damage to the hoof is severe.  Because WLD eats into the hoof there may even be a displacement of the hoof capsule similar to founder.  

Again, as with thrush, diet plays a strong role in treatment of WLD, in fact treatment must take a systemic approach through diet in order for the hooves to recover and remain healthy. Topical anti-fungal applications are used in conjunction with systemics to help treat WLD.

Prevention of WLD includes proper diet that is low in simple carbs and sugars along with correct care of the hooves in terms of balanced trimming to allow for proper function of the hooves.

Yeast infections are caused by hooves that aren't balanced correctly  

The heels can become contracted forming a crevice between the heel bulbs. Yeast, being an opportunistic organism, will seek out damp, warm places to invade, just as thrush bacteria does, so those cracks between the heel bulbs provides the perfect hiding place for yeast.

(Photo Pete Ramey

Symptoms of yeast infection in the hooves are lameness, cracks in between the heel bulbs and a white cheesy-like secretion that smells rather like cheese. It often is present when thrush is also present in the hooves. A stubborn case of thrush may not be JUST thrush but also invasive yeast. Yeast THRIVES on dead bacteria so as the thrush is treated  without also treating for yeast, one is actually feeding the yeast. Yeast also thrives on sugars. Many times a mixture called 'Sugardyne" is recommended for treating thrush. As the sugar in the sugar/Iodine mixture kills off bacteria, if yeast is present in the heel bulbs, one is actually causing further issues with the hooves that will progress rapidly into a debilitating condition of increasing lameness. One MUST consider yeast to be an issue if hooves with thrush are not responding well to antibacterial treatments. Yeast is also a systemic issue and a healing diet is paramount in eradicating the yeast in the hooves. It is found that if there is yeast in the hooves then there is yeast within the rest of the horse's system causing a never ending cycle of problematic issues.

As with WLD and thrush, a diet of low to NO simple carbs (processed grains and feeds) will be a primary factor in the recovery of hooves with yeast issues.

Thrush, White Line Disease and Yeast are an ongoing issue in areas that are warm and wet much of the time. These hoof conditions CAN be prevented with an equine appropriate diet of complex carbs (plants and forages), a lifestyle that allows for plenty of exercise over varied ground/terrain and allowances for 24/7 self-grazing/feeding. They can also be prevented with proper hoofcare where the hooves are balanced and in correct form for the hooves-in-hand on the horse-in-hand.

Treatment for existing conditions of Thrush, White Line Disease and Yeast should consist of proper diet as well as applicable proper topical treatments that will address BOTH bacteria and fungus at the same time and combined with timely and exacting hoofcare. Providing an area where hooves can dry out will also go a long way towards the successful rehabilitation and recovery of thrush/yeast-ridden hooves.

 Gwenyth Browning Jones Santagate is the world-renowned author of "10 Secrets to Healthy Hooves" and "Natural Hoof Anthology" as well as a noted author for various international equine publications including The Horses Hoof, Equine Wellness, Natural Horse Planet as well as a contributing author for the 2001 United States Federal Mounted Border Patrol Training Manual. For the last 37+ years, she has maintained healthy hooves with natural trimming on thousands of horses and specialized in pathological rehabilitation hoof care for the last 18 years. She and her husband John keep a small herd of their own equine in NE Connecticut and continue to offer consults for horses in need. For further information please click here:


Gwenyth is available for freelance assignments, contract work and consulting.



Leave a comment

All comments are moderated before being published