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Urine Acidification

Feline Urine Acidification with Sodium Bisulfate Pet™

Formation of struvite crystals in the lower urinary tract is a common cause of lower urinary tract diseases. In some cases, complete obstruction occurs. Urine acidification can dissolve existing crystals and prevent the formation of new crystals. A urine pH of 6.0 to 6.5 is an acceptable range to prevent the formation of crystals. Studies prove that sodium bisulfate significantly lowers feline urine pH.14 The mode by which it affects urine pH is twofold. The cation-anion balance of the diet affects urine pH of healthy cats.2 The more negative the balance, the greater the acidifying potential of the diet. Sodium bisulfate has a cation-anion balance of -1 which causes the urine to be acidified. Compounds that result in the absorption of hydrogen ions produce acidic urine.6 The addition of sodium bisulfate to the diet results in the absorption of hydrogen ions therefore lowering urine pH.

Urine Acidification Research Results-

Summit Ridge Farms – 1998

In 1998, a urine pH study was conducted at Summit Ridge Farms, Susquehanna, PA. Ten adult cats were placed on a diet that contained 0.9% sodium bisulfate for seven days. On the seventh day urine samples were obtained by cystocentesis. The test was performed in triplicate with the following results: The urine pH of the diets that contained sodium bisulfate were significantly lower than the control diet.

University of Illinois – 2002

A 2002 study at the University of Illinois evaluated sodium bisulfate as a urinary tract acidifier for cats. Dr. George Fahey, Chris Grieshop and Julie Spears designed and conducted a study comparing the effectiveness and duration of sodium bisulfate and phosphoric acid for lowering urinary pH. Eighteen cats were utilized in the study that covered a four week time period. A basal urine pH was determined for a commercially available diet. After meal consumption, urine pH rose as high as 6.89 and remained above the recommended level of 6.5 for 8 hours.

When pH rises above 6.5, struvite uroliths can form. Three test diets containing sodium bisulfate and three containing phosphoric acid were made where the only difference between the diets was the acidifier added and the concentration. Cats were acclimated to the test diets for 6 days. On day 7 urine samples were collected at 0, 4, and 8 hours post-feeding via cystocentesis. For all of the test diets, urine pH remained in the range that prevents struvite formation, between 6.0 and 6.5. They concluded that sodium bisulfate and phosphoric acid generally behave in similar fashion when incorporated into a dietary matrix formulated for cats.

Urinary Tract Health Update 2016

Reduce the risk of urinary tract disease from struvite and calcium oxalate stones with sodium bisulfate:

A Healthy Alternative

Struvite stones (magnesium ammonium phosphate) were the most common urolith in cats during the 1980s and has recently returned to being the most prevalent (Osborne et al. 2009). Lowering urine pH, reducing levels of dietary magnesium and phosphorus, and increasing urine volume can help control the formation of struvite. Sodium bisulfate eectively lowers urine pH, does not add phosphorus to the diet, and helps promote increased water consumption, making it a healthy alternative to reduce the risk of urinary tract disease.


2. Buffington, C.A., 1999. Effects of Diet on Lower Urinary Tract Disorders in Cats. Petfood Industry, Nov.Dec. 1999: 57-63.
5. Handbook of Chemistry and Physics, 1997-1998. 78th edition, CRC Press Inc.
6. Izquierdo, J.V., et al, 1991. Effect of Various Acidifying Agents on Urine pH and Acid-Base Balance in Adult Cats. J Nutr 121:S89-S90.
8. Lewis, et al, 1987. Small Animal Clinical Nutrition, 3rd edition. Mark Morris Associates, Topeka, Kansas, USA.