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Why is my Horse Urinating so Frequently?

What is normal?

Horses typically urinate every 4 hours or so and produce 5–15 L of urine per day. (The bladder can hold 3–4 L of urine).

Normal fresh equine urine varies over the day depending on diet and exercise. From light to dark yellow and clear to cloudy.


Calcium carbonate crystals sometimes give the urine a milky yellow or cloudy appearance.

Although there can be other reasons for frequent urination, when it occurs in spring and autumn (or ANY time there is a surge in grass growth) the most likely cause is the higher Crude Protein in the grass.

This is particularly so when the pasture contains clover and the horse is also consuming Lucerne/alfalfa (or hay) and/or is being fed large quantities of protein from other sources like rapeseed or soy-bean meal.


All young green plants tend to be high in nitrogen/nitrates (Crude protein).

Did you know the central molecule of chlorophyll is magnesium but each magnesium molecule is surrounded by 4 Nitrogen molecules.

Chlorophyll is essential to the process of photosynthesis. It absorbs light in the violet to red spectrum and reflects green light which gives the characteristic green colour to terrestrial plants.


Protein is broken down into separate amino acids and nitrogen in the digestive tract. These can then be reconstituted into building/repairing tissues and generally utilised. The problems arise when there is too much protein in the diet and supply exceeds needs.

It is critical that the leftover, now free-floating nitrogen, is removed from the body because any excess can be toxic.

Another concern is that excess protein can result in ammonia being produced from leftover amino acids, and this also must be removed from the body.

The liver produces enzymes that convert ammonia into urea, which can then be safely filtered out of the bloodstream by the kidneys.


Hence signs of excessive protein in the diet are increased thirst and more urine production. Sometimes you will see burn patches on the grass at these times of the year.


You can see how feeding too much protein creates unnecessary work for your horse’s metabolism.

Forage and feeds high in protein include green, growing grass, lucerne/alfalfa, clover, as well as soybean and canola meals and peas. Fed in small quantities, protein is an important part of the horse’s diet and will not cause any problems, but there can be a cumulative effect when there are multiple sources.


What to do:

Make sure your horse gets plain grass hay every day so that he consumes less green grass.

Add salt to daily feeds as these forages are devoid of sodium which is very helpful for excreting the nitrate form of nitrogen (as Sodium Nitrate). Horses are not inclined to lick sufficient from salt licks.

Be mindful about what you are feeding in the way of protein.


Brown patches in the grass
You can see the high clover content of the grass the horse was consuming and the resulting killing of the grass where he had urinated.


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