How does thrush affect the health of the hoof?

Posted July 9th, 2013

Denise A. Gorondy, DVM

"Thrush is by far the most common infection of the equine foot. Thrush is caused by an infection with anaerobic bacteria, typically Fusobacterium necrophorum. This bacteria, which thrives in a moist, dark environment with little to no oxygen present, is typically found in animal feces and normal soil samples. The condition of thrush arrives when bacteria create an infection in the foot of the horse. Typically, thrush is found in either the sulci (the grooves on either side of and in the middle of the frog) or the central sulcus (the cleft between the heel bulbs). Occasionally, the thrush can extend into the sole region of the foot.

Symptoms of thrush include foul odor, black discharge, soreness and/or bleeding in the frog region, deep pockets or fissures within the frog or heel bulbs, and deterioration of the consistency and integrity of the frog.

Historically, it was suggested that horses developed thrush due to being housed in sub-standard environments. Although this is likely a contributing factor, the amount of regular exercise a horse gets also influences the potential development of thrush. Exercise is very important in maintaining appropriate circulation and oxygenation of the foot. A horse that exercises regularly in deep or muddy conditions is less likely to develop thrush than a non-exercised horse that stands still all day in shavings provided the horse receives regular and appropriate foot care. Regular foot care includes proper trimming and balancing by the farrier and routine hoof picking.

The average case of thrush can be treated effectively by horse owners with application of any of the over the counter astringent based thrush treatment products. If the central sulcus of the frog is affected, purchase small cosmetic cotton pledget or cotton balls and saturate the cotton with thrush treatment product. Push the saturated cotton into the bottom of the central sulcus with a hoof pick. The cotton must be advanced to the bottom of the crevice in order for the medication to contact the source of the bacterial infection. The presence of the cotton also opens the crevice which allows oxygen to penetrate the affected tissues. Continue daily changing of the medication saturated cotton for approximately 7 days, or until the condition resolves.

More severe cases of thrush that involve lameness, bleeding from the frog, purulent discharge, or advanced deterioration of the frog or sole tissue should be evaluated by a veterinarian."

Three Oaks Equine Veterinary Services
318 River Road West
Manakin Sabot, Virginia 23103
threeoaksequine.com

Veterinary Notes for Horse Owners

A manual of Horse Medicine on Surgery
- Published by Arco Publishing Inc. New York 1877-1984

  • States: "Treatment for thrush simple measures such as the application of an astringent and antiseptic dressing should be used to ensure that the frog is subjected to reasonable pressure so that its functional activity may be restored. This dressing has stood the test of time."