Each horse has a different pattern of urination — when, where and how much he pees.
Normal urine production is typically 15-30 ml/kg daily, which for an average 500kg horse totals around 15 litres. Measuring urine output is not easy, in practical terms, but this equates to a horse peeing around five or six times per day, with a normal stream of urine lasting 30 seconds.
A healthy bladder holds 300-400mls of urine. We have to assume that a horse with a full bladder will feel uncomfortable