Abnormal Sheath Buildup

Q: I have searched the Internet and asked everyone I know about the abnormal sheath buildup on my 17-year-old palomino gelding. Ever since we bought him, we noticed a large, crusty buildup all over him. We have been cleaning him once a month for three years because within four weeks, he is crusty and dirty again. We use a sheath cleaner every six months, and we use Vaseline or baby oil between times as we do not want to use that harsh stuff every time.

Everything I have read says that you do not clean them this much, and nothing I have read tells me why this horse has this abnormal buildup. Can you help me? We think he might be proud cut--could that have something to do with it? I also own a stallion, and he only needs to be cleaned once every six months or so. He also has a raised red area--what might this be? Could it have something to do with the buildup?      Sherry, via e-mail

A: Great questions. I'll try to answer them in the order you presented them.

The amount of normal smegma varies greatly from horse to horse. Not only does the amount vary, but the quality/texture of the smegma will vary as well. Some horses will have dry and scaly smegma residue on their penis shaft, while many others will have moist and sometimes offensively smelling smegma in their prepuce and on the penis itself.

My first recommendation is to seek the advice of a theriogenologist (animal reproduction specialist) whocan identify normals and abnormals for you.

I admire your desire to provide for this horse, but I also must caution you to be careful in providing "too much care." Washing a gelding 36 times in three years is most likely destroying all of the normal and protective bacteria on the penis. Even with soap "made for sheath washing," the death of the normal "microflora" will allow the resurgence of inappropriate and pathogenic bacteria (capable of causing disease). Remember, wild horses live 20 years or more and never have their sheath/penis washed or a "bean" removed.

Your vet can determine by blood tests whether the horse has testicular tissue left in him. However, castrated horses, intact horses, and improperly castrated horses all have similar amounts of smegma.

Three common skin tumors that can appear as raised nodules on the shaft of a penis are squamous cell carcinoma, sarcoids (the most common skin tumor in horses), and "coital exanthema," which is caused by herpesvirus. My question for this horse might be whether the nodular/vesicular skin appearance might have been exacerbated by aggressive washing that might have induced a mild chemical irritation.

It would be very easy to sedate the horse, infuse local anesthesia proximal to (above) the lesion, and acquire a punch biopsy through one of the characteristic lesions you are worried about.

You can search for a veterinarian who has a special interest in reproduction at www.therio.org, and you can search for someone who is board certified in theriogenology at www.theriogenology.org.

About the Author

Benjamin Espy, DVM, Dipl. ACT

Benjamin Espy, DVM, Dipl. ACT (boarded in equine reproduction), has practiced veterinary medicine in Texas and Kentucky. He has been licensed to practice acupuncture for nine years and is on numerous AAEP committees and task forces. Espy serves on the alternative therapy committee for the Texas Veterinary Medical Association, and he's an animal treatment consultant for the Professional Rodeo Cowboys Association.

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