Horse Side Vet Guide ®

Equine Health Resource

Black, Smelly & Pasty Material in Sole or Frog, Thrush

Code Orange - Call Your Vet at Their First Available Office Hours

Code Green - Contact Your Vet to Obtain Useful Advice & Resources

Code Orange - Call Your Vet at Their First Available Office Hours

  • If you notice lameness in addition to this sign.

Code Green - Contact Your Vet to Obtain Useful Advice & Resources

  • Even if the horse does not appear to be lame to you.
  • To discuss your equine's general health and management.

Normal, healthy, barefoot equine hooves are dry and hard,and they often have some debris trapped in the sole and frog. A small amount of smelly, pasty material in the depths of the grooves may be normal. However, if hooves become overgrown, and especially in chronically moist conditions, fungus and bacteria grow in the crevices creating a black, smelly paste known as thrush.

Horses that are stalled and those that get little exercise have more problems with thrush as well as other hoof and lameness-related problems than horses that move regularly. The hoof’s self-cleaning mechanism requires movement. Horses whose hooves do not clean out normally because they have underlying lameness issues and so don’t exercise develop thrush too.


Inspect your horse’s feet routinely, daily if possible. Pick debris from sole and sulci, the clefts (or grooves) in the foot located on either side of the frog. Remove as much of this debris as possible.

Assess your horse’s general health with the Whole Horse Exam (WHE), paying particular attention to whether or not you notice lameness, and whether there is digital pulse or heat in the feet. Share your findings and concerns with your vet and your farrier. Talk to your farrier about trimming excess tissue away to allow the tissues access to air. If thrush is developing, you may need more regular removal of this excess tissue. Thrush medications like dilute bleach and copper sulfare may be helpful, but are not a substitute for removal of excessive sole and frog.

Your vet will ensure that thrush is not associated with lameness. They will consider the development of thrush with respect to overall health and management, and provide methods to reduce the problem. If there are underlying reasons for the development of thrush (underlying lameness), then they will deal with that.

What Not To Do

Do not use strong, irritating substances without first removing overgrown and under-run sole and frog.

Topical solutions may help, but not without proper hoof care and removal of overgrown hoof.

Author: Doug Thal DVM Dipl. ABVP


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