The sheath of the male horse is a pocket of skin that houses and protects the penis when the horse isn’t breeding or urinating. It’s lined by glands that secrete a thick, waxy/oily substance called smegma. When the penis is relaxed and inside the sheath, there are many folds of skin along the interior where dirt and smegma collect (straw or plant material may collect, too).
A stallion has an erection often several times a day even without the stimulation of a mare, year round. When this happens, all the folds in the interior of the sheath are pulled tight, dislodging any trapped material. The head/glans of the penis also swells, popping out any collections of smegma in the recess around the opening of the uretha.
A gelding is a different story. Most never have erections or fully extrude their penis and the smegma collects inside the sheath. Hard collections called ”beans” can also form in the recess around the urethra, interfering with the flow of urine. A buildup of smegma is irritating to the tissues and can cause small breaks in the tissue, predisposing to infection. For these reasons, a gelding’s sheath should be cleaned about twice a year.
Although not absolutely necessary, especially if the horse is already used to have his sheath touched and hosed, mild tranquilization greatly facilitates the sheath-cleaning process by controlling any anxiety and also relaxing the penis, making it easier to fully extend it.
Always stand facing the back of the horse with a competent handler on the head, if this is his first time or he is uncomfortable with the process. Even a tranquilized horse can kick in earnest. If necessary, twitch the horse.
Begin by directing a stream of warm water up into the sheath for several minutes. This will loosen and even flush out some of the material. A hose works best for this, but a large syringe can be used as well. Next, wearing gloves, grasp the penis gently but firmly behind the glans (head) and pull it out of the sheath. Any remaining large clumps of material can be removed by hand if not tightly adherent to the tissues. Release the penis and fill the palm of one hand with a generous amount of sheath cleaner.
Putting gentle traction on the penis again, work the sheath cleaner around all surfaces of the penis and interior of the sheath, including the recess on the head of the penis, but try to avoid forcing it into the urethtral opening. Work up a gentle lather if the product lathers (see chart). Leave the cleaner in contact with the tissue for at least five minutes. See chart for times that worked best for us with various products. Rinse thoroughly, then extend the penis to check for completeness of cleaning and rinse again. If necessary, repeat the process.
The concept of sheath cleaning comes as quite a shock to a horse who has no experience with this area being touched. There are some simple steps you can take that will result in the horse being less defensive, making sheath cleaning both easier and safer. When grooming, be sure to include the inner thighs when using a soft body brush, both the inner thighs and the outside of the sheath when toweling. When hosing the horse off, direct a stream of (preferably warm) water between the sheath and the thighs and directly into the opening of the sheath itself. When the horse is accustomed to this, it makes formal cleaning infinitely easier. Routinely flushing the sheath between formal cleanings also slows buildup by removing loose debris.
Very dirty sheaths: Horses with heavy buildups may benefit from pre-cleaning treatments, especially if the penis is irritated and material is tightly adherent to the penis and sheath. Rinse as above to remove the loose debris, then coat heavily with either K-Y jelly or aloe vera gel (both water-soluble). Leave on for 10 to 20 minutes, rinse and proceed with cleaning as above. These two products are very gentle to the tissues and won’t cause any irritation like soaps or even herbals can. Mineral oil or petroleum jelly are sometimes recommended for pre-cleaning softening, but these are messy and difficult to wash off.
Infections: If the sheath is swollen and hot, or you find the penis and inner sheath are inflamed, cleaning is the first step. Be careful to make certain the entire sheath, including the deepest portions, is examined closely for any foreign material like small sticks. A thorough cleaning often resolves the problem. If the swelling and heat do not resolve, consult your vet.
We’ve found that a few days treatment of filling the sheath with dilute Betadine solution and holding it shut for 5 minutes before allowing it to drain will clear most persistent infections. Use plain or distilled water, pour out about 5 ounces from a gallon jug and replace with 5 ounces of 3 to 5% Betadine solution.
No Water Available: If you don’t have warm running water and the horse won’t tolerate cold (not that we’d blame him!), try applying a thick layer of K-Y jelly or aloe vera gel, wait 10 minutes then wipe off with moistened paper towels (do NOT use cotton, the fibers will stick). This can work well when buildups aren’t heavy, but for very dirty sheaths you may need to repeat several times. Any residue left behind will also eventually dry up and flake.
Sensitive to Tea-Tree Oil: All the commercial cleaners contain tea-tree oil, which helps with softening collections and is both antifungal and antibacterial. However, some horses are sensitive to it. If so, try cleaning with Dawn dish soap, baby shampoo or a gentle shampoo, like Corona, instead. Put a small amount in the palm of your hand and work into a lather before applying. Also be sure to rinse well with plenty of warm water.
Insulin Resistance And Swollen Sheaths: For reasons that aren’t clear, geldings with insulin resistance often develop large, swollen sheaths and heavy accumulations of smegma. The swelling in most cases is fat, which may lead to more folds in the sheath to catch smegma or it may be that they overproduce it. In any case, the sheath swelling won’t resolve with cleaning, but once the insulin resistance is brought under good control it’ll go down to normal size.
Commercial sheath-cleaning products are inexpensive and a wise purchase because they do a better job at loosening greasy/waxy buildups than plain soap. Our top performers for cleaning were Excaliber and Triple J. Excaliber is the Best Buy, but Triple J gets our first-choice nod due to its easier rinsing and better moisturizing. If your horse is easily irritated or dried by soaps, try Equispa.