The urinary tract is a vital system that should never be taken for granted; if a problem develops, it can rapidly become a crisis

(Editor’s Note: Contributing to this article was Hal Schott, DVM, PhD, Dipl. ACVIM, associate professor in the Department of Large Animal Clinical Sciences at Michigan State University.)

The body produces many wastes and byproducts of energy production that must be regularly eliminated. The lungs dispose of gaseous wastes and carbon dioxide, and the digestive tract takes care of the solid wastes from feed. The urinary system excretes the liquid wastes containing nitrogen, salts, excess sugars, and other substances that are filtered out of the bloodstream.

Urinary tract problems can range from fatal (kidney failure, bladder rupture, etc.) to minor (irritations that clear up on their own, or an infection that can be readily treated). The kidneys filter the blood and kidney damage can result in impaired filtering function, which might be life-threatening, depending on the extent of damage. A bladder stone might pass, and the horse will be fine, or it might plug the urethra, prevent urine from passing, and cause eventual rupture of the bladder. The main signs of urinary disease include abnormality in urine output, pain or discomfort, and difficulty urinating.

Overview of the Tract

The body functions in a sea of fluids. Blood acts as the transportation system, taking oxygen and nutrients to all cells and bringing back waste products to be eliminated. The kidneys constantly filter the blood, removing some substances, absorbing some that shouldn’t leave the body, and collecting wastes. The portion of fluid–and its concentrated waste products­–filtered out by the kidneys becomes urine