Horse Side Vet Guide ®

Equine Health Resource

Drainage from Sheath

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    Drainage from the sheath is most commonly smegma, which is usually not a cause for concern. Smegma is a thick pasty material that is composed of mucus, debris and shed cells. Smegma tends to be similar in color to the sheath skin. In most geldings and stallions, it is dark, but it is often reddish in pink skinned horses. Some horses produce more smegma than others.

    The existence of smegma does not mean that the sheath is infected. True bacterial infections of the sheath are rare without some underlying abnormal condition. Drainage from the sheath is also seen in horses with with tumors and abscesses. For breeding stallions, excessive drainage of the sheath can indicate CEM, a reportable disease.


    Evaluate your horse’s sheath and try to determine whether the drainage is a result of accumulation of smegma or another condition. Feel the end of the penis for a “bean” which is a hard accumulation of smegma. Remove it if it is easy to do so.

    Look for swelling of the sheath and pain to the touch. Observe the pink skin for redness. Assess your horse’s general health using the Whole Horse Exam (WHE) and share your findings and concerns with your vet.


    Vets typically tranquilize horses for sheath examination and cleaning. This drops the penis and provides much better visualization of the penis and sheath.

    Periodic sheath cleaning, by a horse owner or especially a vet, encourages visual inspection of the penis and sheath. Problems such as tumors (that affect this region frequently) can therefore be diagnosed and treated early, improving prognosis and lessening treatment costs.

    What Not To Do

    Do not use disinfectant soaps to clean the sheath. It can change the bacterial population, leading to more problems.

    Helpful Terms & Topics in HSVGWritten, Reviewed or Shared by Experts in Equine Health

    Author: Doug Thal DVM Dipl. ABVP


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