Horse Side Vet Guide ®

Equine Health Resource

Sheath Swelling or Enlargement

Code Red - Call Your Vet Immediately, Even Outside Business Hours

Code Orange - Call Your Vet at Their First Available Office Hours

Code Yellow - Contact Your Vet at Your Convenience for an Appointment

Code Red - Call Your Vet Immediately, Even Outside Business Hours

  • If the swelling is large, painful or growing rapidly.
  • If the results of the Whole Horse Exam (WHE) in the resting horse indicate fever (Temp >101F/38.3C) or heart rate greater than 48 BPM.

Code Orange - Call Your Vet at Their First Available Office Hours

  • If the results of the Whole Horse Exam (WHE) suggest the horse is otherwise normal.
  • If the swelling is mild or moderate, and not increasing rapidly.

Code Yellow - Contact Your Vet at Your Convenience for an Appointment

  • If you consider this a chronic and relatively mild problem that is not changing rapidly.
  • If the results of the Whole Horse Exam (WHE) suggest the horse is otherwise normal.

The sheath is made up of soft and loose folds of tissue that allow the penis to drop and retract. Because of its many loose folds and its location on the lowest part of the body, it swells readily as a response to many conditions. The sheath also often becomes very fatty in overweight and insulin resistant horses. Sometimes distinguishing between a fat sheath and a swollen sheath can be difficult.

Sheaths also swell as a result of being “dirty.” Horses with large beans (accumulations of secretions at the end of the penis) and large accumulations of sheath smegma (normal pasty secretion) often swell. Horses that urinate into their sheaths tend to have dirtier sheaths and more problems with swelling. Trauma, skin allergy and irritation as well as insect stings are examples of conditions that cause sheath swelling by irritation to the outer skin.

Sheath and penis skin infections and tumors cause swelling by irritation of the internal, hidden tissues. Commonly, injuries to the abdomen and even the upper limbs can cause local swelling that spreads over a distance through tissue planes and ultimately fills the sheath. Finally, the sheath is an indicator of general disease states such as low blood protein and vasculitis (inflammation of blood vessels that allow them to leak fluid into the tissues).

WHAT TO DO

Assess your horse’s general health using the Whole Horse Exam (WHE), paying attention to attitude and appetite, as well as the outside of the sheath in an attempt to determine the general cause of the problem. Pay particular attention to the appearance of the penis when the horse drops to urinate. Look for masses and reddening. Talk to your vet about symptomatic treatment you might administer until they can determine the underlying cause.

WHAT YOUR VET DOES

Sheath swelling can indicate local sheath problems like trauma and smegma accumulation, but it can also be a sign of body-wide disease. For that reason, your vet will probably start by determining your horse’s general health with a careful physical exam. With body-wide (systemic) disease severe enough to cause sheath swelling (conditions like heart disease and vasculitis), there should also be other signs of disease detected on the physical exam. Keep in mind that your vet may want to use tranquilization to drop the penis to allow a thorough exam of the penis and sheath.

POSSIBLE TREATMENTS or TherapiesTo Lessen or Resolve the Sign

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

Author: Doug Thal DVM Dipl. ABVP

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