San Bruno Pet Hospital 1111 El Camino Real
San Bruno, CA 94066
Phone: (650) 583-5039
Fax: (650) 763-8620

Hospital Hours
M-F: 7:30a-6p
Sat: 8a-5p
Appointment Hours
M-F 8:30a-5:30p
Sat: 8:30a-4:30p

After Hours Emergency
Emergency Clinic

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NOTE: These are offered
as general information
only and NOT a substitute
for a visit to your
veterinarian. If you feel
that your pet has a
problem that may require
urgent attention
call us at (650) 583-5039
immediately. If after hours,
contact the emergency
clinic (650) 348-2575.
Why is My Cat Peeing so Much (Polyuria)?
If you have any questions or concerns, you should always visit or call San Bruno Pet -- they are your best resource to ensure the health and well-being of your pets.

As more and more cats live exclusively indoors (where they’re safest) more and more are also using the litter box. One of the best things about a litter box is that it allows owners be more aware of their cat’s urine habits. You may notice, for example, that you’re cleaning the box more often.

If there is more urine in the litter box, it can sometimes be a bit difficult to tell if a cat is peeing larger volumes or just more often; however, it’s important to differentiate increased frequency from increased volume since they indicate completely different potential problems. There are conditions that cause increased frequency of small amounts of urine, conditions that result in large volumes of urine and conditions that cause increased attempts to urinate. You may need to keep a close eye on your cat to know for sure.

It will also be important to know what is normal for your cat so that changes will be noticeable. One study, reported by DVM 360, indicated that cats produced an average of 28 ml/kg of urine every 24 hours. That means about a cup of urine a day.

In general, what goes in must come out. Although minute water losses include tear flow, saliva flow and fluids contained in stools, the majority of water leaves the body of animals as urine.

Is your cat peeing a lot or just often?

Increased urine frequency: If your cat is urinating small volumes frequently, she is not peeing too much; in fact, she may not be peeing enough. This condition is called Oliguria and refers to decreased urine formation by kidneys or decreased elimination of urine from the body. Frequent small volume is most often a sign of bladder inflammation associated with infection, cystitis, bladder stones or obstructions. Alternatively, increased frequency of a normal volume or increased attempts to urinate are serious signs of urinary problems and inflammation that may indicate a sense of urgency associated with an inability to empty the bladder because of some form of blockage. These conditions should be treated as an emergency and must be evaluated by a veterinarian as soon as possible.

Increased volume: If your cat is urinating larger than normal volumes, it’s called polyuria. Most of the time excessive urinating is a result of the body’s inability to regulate urine formation. Excess blood glucose for instance leaves the body through urine and carries a lot of water with it. Kidney diseases often results in an inability to retain fluids and so urine forms more rapidly than normal. Some hormonal diseases result in poor urine concentrating ability, causing too much water to be excreted as urine. Whatever the cause, the result is increased water intake in an effort to balance this excess urine output.

How will my veterinarian at San Bruno Pet decide why my cat is peeing excessively?
Your veterinarian will always start with a thorough physical examination, but blood and urine tests are needed to evaluate organ function.

What should I do if my cat seems to be peeing more than usual? Many of the causes for increased urination can be very serious and life threatening. The sooner your cat is diagnosed, the greater the chances of success.

If you have any questions or concerns, you should always visit or call San Bruno Pet -- we are your best resource to ensure the health and well-being of your pets.