Cats' Urinary pH and Their Health

Urinary tract crystals can be deadly for your cat

Close-Up Of Ginger Cat Eating Food At Home
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It is widely acknowledged that a cat's urine pH can be directly related to the health of its urinary tract. Is your cat in danger of developing crystals in his urinary tract? How does his diet affect his urine pH? Here is help in removing the mystery of the desired range of feline urine pH and how these numbers can correlate to a cat's urinary tract health.

The Importance of pH Levels

pH is a measure of acid in any liquid. pH levels in urine–whether human or feline–can mean the difference between health and illness.

Cats are especially vulnerable to pH problems. When pH is too high or low, crystals can form in a cat's bladder and/or urethra (the tube that drains urine from the body). This causes irritation, bleeding, infection and/or blockage. A cat with a blocked urethra has a condition called FLUTD (Feline Lower Urinary Tract Disorder). Complete blockage of the urethra can cause death within 72 hours, if not treated.

The Normal Urine pH Range for Cats

Cats need acidic urine for urinary tract health. Although the higher range may vary under certain circumstances, the expert consensus seems to be from 6.0 to 6.5. (The lower the pH, the more acidic the urine.) A pH above this range can lead to the growth of struvites (magnesium ammonium phosphate crystals). A pH lower than 6.0 can cause the formation of calcium oxalate crystals.

Other Factors That Affect Feline Urinary Tract Health

  • Excess concentration of minerals in urine: Although for years the generic "ash" content of cat food was blamed for what was then known as FUS (Feline Urinary Syndrome), ash is merely the residue from the burning of minerals and doesn't really indicate the kinds of minerals, nor the amounts and types of each. For that reason, the FDA prohibits claims such as "low ash" on cat food labels. Max's House has a great chart showing the various minerals, along with their AAFCO-recommended percentages in cat food.
  • Excess magnesium and phosphorus: Magnesium and phosphorus have more recently been singled out as potential culprits for FLUTD. Also important is the source of magnesium. The highly respected veterinarians at believe that magnesium oxide appears to cause alkaline urine, and magnesium chloride may result in the formation of acidic urine. The desirable phosphorus to calcium ratio is also factored into the AAFCO recommendations.
  • Water intake: Kidneys require water to function, and the urinary tract system requires sufficient fluids to flush extra minerals out of the body. A cat that drinks adequate water will urinate more frequently. As a result, the urine will also be less concentrated, which will help prevent the formation of crystals.

Relationship Between Your Cat's Diet and Urinary Tract Health

The relationship is so important that many of the premium cat food manufacturers now publish the target range for urinary pH for their various formulas. This information is much more important and meaningful than any claim of "low ash" might be.

Here are the targeted pH ranges for two premium cat foods: Innova EVO has a targeted pH level of 6.2 to 6.4.  Wellness CORE publishes a three-point program for urinary health on its website by targeting a urine pH of 6.1 to 6.6, limiting magnesium in the diet, and adding cranberries for urinary tract health.

If the company that provides your own cats' food does not disclose this information on their packaging, you may decide not to purchase their products.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.