A normal horse produces a strong urine stream that rapidly empties the bladder. Difficulty urinating can be caused by a number of conditions affecting the bladder or the urethra, the tube that carries urine out from the bladder. Urethral problems are more common in male horses because their urethra is much longer and more likely to be blocked by stones or growths. Occasionally, either sex will urinate very small amounts of urine, or appear to strain.

A horse having difficulty urinating might have a weak and turbulent stream. They might stretch out with little urine voided, or groan when they are urinating. Horses that are ill from other causes, especially conditions causing abdominal pain (colic), may appear to be having difficulty urinating.

Horse owners are often confused by this behavior in horses demonstrating abdominal (colic) pain. If the posturing to urinate is a result of abdominal pain, the sign will improve when the underlying intestinal condition resolves or is corrected. Straining to urinate can also be caused by a blockage due to bladder stone, blood clot, or pressure from a mass on bladder or urethra, any of which can be a veterinary emergency.