“Sheath cleaning is an important task associated with owning male horses that cannot be overlooked,” advised Douglas Novick, DVM, an equine veterinarian in the San Francisco Bay area of California. “Annual cleanings will help owners remove the ‘bean’ and examine the penis and surrounding tissues to ensure there are no abnormalities.”

The “bean” is an accumulation of smegma (a natural lubricating substance produced by the horse) and other debris in the urethral diverticulum, located in the head of the penis, just above the opening of the urethra (which is the where urine comes out).

“If the bean is not removed, it can in some cases grow to the size of a golf ball or bigger,” Novick said. “A bean of that size can press down on the urethra making it difficult to urinate. Occasionally it can get so big that a horse will not drop and will urinate on himself.”

Novick suggested the following tips to consider when preparing to clean your gelding’s or stallion’s sheath:

• Clean the sheath thoroughly once or twice per year. If you are unable to do this yourself, your veterinarian can perform the cleaning. A good time to do it is while the horse is being sedated for another procedure (such as dental work);
• Use a mild dish soap (such as Ivory or Palmolive) to clean the sheath and penis;
• Proceed with cleaning gently and slowly, especially if the horse is not sedated; and
• Don’t assume the last person who owned your horse cleaned his sheath regularly—many owners forget to include sheath cleaning in their regular veterinary care.

Additionally, sheath cleaning provides a time for owners to check for potential health problems that might not be readily observable on a day–to-day basis, including:

• Tumors (such as melanoma, squamous cell carcinoma, or lymphosarcoma);
• Cutaneous habronemiasis (a skin disease caused by stomach worm larvae that emerge from flies feeding around the genitalia);
• Lesions associated with coital exanthema (a disease caused by equine herpesvirus-3 that’s characterized by painful wartlike lesions on the shaft of the penis) and balanoposthitis (inflammation of the penis and prepuce); and
• The presence of foreign bodies, such as stallion rings, misplaced rubber bands from malfunctioning artificial vaginas, and organic matter (e.g., bedding).

If you detect anything abnormal during sheath cleaning, it’s advisable to seek veterinary attention.

And finally, despite pictures that might suggest the contrary, Novick advises, “Wear gloves. Smegma is smelly and it takes a while for the smell to go away.”