What you see. The starting point for addressing any equine health related issue is your observation.


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


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.

  • 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.

your role


What To Do

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 sulfate may be helpful, but are not a substitute for removal of excessive sole and frog.

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.

your vet's role

Most importantly, I consider the development of thrush with respect to overall health and management. Are there underlying management conditions that need to be changed? Is there an underlying health or lameness concern that must be addressed first?

Once these questions are answered, I am willing to discuss treatments to eliminate or reduce thrush and prevent its reappearance.

In most cases, no matter the cause, I use a hoof knife to remove under-run, dead, thrushy tissue from the sole, sulci (grooves) and frog. This prevents trapping of debris, and allows air to dry the tissue and reduce thrush. I spend time teaching caretakers how to use a pick and knife to gently and safely remove excess tissue prior to applying any thrush "remedies". Sometimes I need to encourage farriers or trimmers to be more aggressive at removing this tissue.
Questions Your Vet Might Ask:
  • How often are you picking out your horse's feet?
  • Are you paying particular attention to getting the material out of the grooves and pits in the sole
  • Is the horse limping or lame?
  • How is the horse stabled or managed?
  • How long has the horse been stabled this way?
  • Is there digital pulse or heat in foot or feet?
  • When was the last shoeing?
  • Is the horse shod?
  • What are the results of the Whole Horse Exam (WHE)?

Author: Doug Thal DVM Dipl. ABVP