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Horses With Excessive Swelling of the Scrotum

| Updated September 26, 2017

Always take swelling or inflammation of your horse's scrotum as a sign that something is wrong. The cause could be as minor as a tick or insect bite, or a serious medical condition such as cancer. Even if your horse is gentle, don't assume he will placidly accommodate a close inspection of his scrotum, particularly if it is painful. Your veterinarian can administer a sedative to safely examine the swollen area and prescribe a course of treatment.


  • If your stallion's scrotum is swollen, the cause could render him infertile, so prompt veterinary attention is important.

Potential Causes of Swelling

In addition to insect bites or ticks on your horse's scrotum, he may have suffered a kick or some other trauma in the area that caused the scrotum to swell. He may also have an anatomical defect that causes inflammation. A stallion still has his testicles, so a testicular infection, or orchitis, can also cause the scrotum to swell. Your horse can get orchitis in just one or in both testes. Untreated, it can impair his sperm motility or even cause him to be infertile. There are numerous sources for this type of infection, including sexually transmitted diseases and parasitic infections. Getting prompt attention and diagnosis for your stallion could preserve his breeding future, as well as prevent the infection from becoming more serious.


  • If you breed your stallion, carefully screening mares will help reduce your stallion's risk of contracting a sexually transmitted disease.

Swelling and Castration

If your horse was recently castrated, which is the removal of his testicles, expect some scrotum swelling in the first five days following the procedure. His scrotum could swell as much as three times its normal size, but any more than that warrants a call to your veterinarian. You should also call your vet if the swelling continues after five days.

Some horses may also develop a hernia following castration, with intestines and other tissues protruding through the incision that was made to remove the testicles. Don't be alarmed, but if you see any tissue or protrusion from the scrotum, it's imperative you contact your veterinarian.

Symptoms That May Accompany Swelling

In addition to swelling on one or both sides of your horse's scrotum, look for an increase in temperature from the normal range between 99 and 101 degrees Fahrenheit. Take his temperature; anything higher than the upper range of normal could indicate an infection. He may be in pain that can affect his walk or getting up from a lying position. In stallions, your veterinarian may detect heat in his testicles. All of these symptoms require medical attention.

Treat scrotum swelling in a recently castrated horse differently than in other male horses. You should lightly exercise your horse 24 hours after castration surgery to help reduce the swelling and promote healthy drainage from the incision sites. Your veterinarian will give you an appropriate exercise regimen for your horse following castration.

General Care of Your Male Horse

Other than concerns about your stallion's reproductive health from an injury or testicular infection, a gelding or a stallion alike should receive the same preventive care and monitoring. Watch for signs of a urinary tract infection, which could include a seeming reluctance to urinate due to pain, or an unusually wide or lengthened stance with his hind legs when urinating. While sheath cleaning isn't typically necessary in a healthy male horse, examine his penis and sheath regularly for signs of tumors or other abnormal growths.

A good time for a regular veterinarian examination is during his regular teeth floating when the horse is sedated; your veterinarian can also determine at this time if his sheath needs to be cleaned.


  • Contact your veterinarian immediately if you notice blood in your horse's urine, as it could be an early indication of prostate cancer.