Does My Horse Drink or Urinate Too Much?

Occasionally horses drink excessive volumes of water for no apparent reason.


By Warwick M. Bayly, BVSc, MS, PhD, WEVA President’s Advisor

The possibility that a horse drinks and/or urinates excessively (termed polydipsia and polyuria, respectively) is a frequent concern among horse owners.

The first step in such situations is to determine whether the concern is justified. The easiest way to do this is by restricting the horse’s movement and measuring his water consumption and urination patterns over a 24-hour period. Depending on their usage and the weather, horses typically drink anywhere from 5 to 30 liters (about 1.3 to nearly 8 gallons) in a 24-hour period.

Polyuria can result from kidney disease, excessive drinking, or eating too much salt or a similar substance; the latter is often a reflection of the animal’s diet or management. These conditions result in increased kidney excretion of nonreabsorbed solute (such as glucose or sodium), either because the kidneys can’t function normally (the more common occurrence) or are overwhelmed by the amount of solute passing through them. In such situations, the kidneys reabsorb less water and an increase in urine volume results.

Occasionally horses drink excessive volumes of water for no apparent reason. These cases are usually young horses kept in stalls for prolonged periods. Less commonly, the urine will appear almost waterlike due to the lack of a hormone essential for production of normal concentrated urine.

Determining what’s going on in these situations can be tricky and might take time. However, with a veterinarian’s help, the cause should be identifiable. And in many cases, a veterinarian can recommend therapeutic and management steps that will result in partial to complete resolution of the problem.

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