My cat was forming crystals in his bladder so for the rest of his life I'm to feed him urinary health cat food. My vet had me feed him Royal Canin® Urinary SO Cat Food but after a few bags of it I recently decided to go with Purina Focus Adult Urinary Tract Health Formula dry cat food. Hopefully it will do just as well.

Meanwhile, my two cats CRAAAAVE wet cat food, I was giving it to them as a daily treat, until I realized that mixing it in their diet completely eliminates the benefits of the urinary tract health formula food I've been giving them. So I decided to feed them the treat twice a week--Wednesday evenings and Sunday evenings. Because of this change I give them some of the best stuff I can find (Fancy Feast Elegant Medleys), and not a lot, just half a can for each cat, so one can on "treat night" for the two of them. So now every day they just sit around moaning at me begging me to give them the treat that is typically days out.

I'd like to know how I can "tune" for their happiness better, without compromising their health.


1 Answer 1


Cats have a naturally low thirst drive and it's important for them to be fed wet food regularly to reduce the specific gravity (i.e. concentration) of their urine. It's better that you feed a cat with urinary issues wet food (any brand/variety, but preferably high in meat/protein content) than to continue feeding them prescription dry food.

Lisa A. Pierson, DVM, says specifically of cats who have been diagnosed with crystals in their urine

Always keep in mind that water flowing through the urinary tract system is the most important factor in keeping it healthy. That said, please do not make the mistake that so many people make when they state "but my cat drinks plenty of water!"


Unfortunately, many of these people and their veterinarians have missed the point of water...water...water and have continued to put the cat in danger by feeding/prescribing a dry food diet - including any and all of the prescription dry diets.

It is highly counter-intuitive to label any water-depleted (read: DRY) food as a "urinary tract diet."

Generally speaking, the basic diet recommendation for the average cat with urinary tract issues is a high protein/low carbohydrate canned food with added water.

Her web page is highly educational, and I recommend it.

Prescription diets are high in starch and fiber compared to a quality wet food diet with a high level of protein. This quality can make your cat more susceptible to struvite crystals.

Starch and fiber in diets potentially stimulate formation of struvite crystals. Hence, reducing dietary carbohydrate is desirable to prevent struvite urolith formation. In addition, a net loss of body calcium, phosphorus, and magnesium during feeding of the fiber diet suggests that dietary inclusion of insoluble fiber could increase macromineral requirements of cats.

Am J Vet Res. 2004 Feb;65(2):138-42. Evaluation of effects of dietary carbohydrate on formation of struvite crystals in urine and macromineral balance in clinically normal cats. Funaba M1, Uchiyama A, Takahashi K, Kaneko M, Yamamoto H, Namikawa K, Iriki T, Hatano Y, Abe M. Web Abstract

Prescription diets tend to have less protein than a quality wet food diet. This quality can make your cat more susceptible to struvite crystals.

Our results indicate that compared with dietary supplementation with NH4Cl, the high-protein diet is preferable as a urine acidifier for the prevention of struvite crystal formation in clinically normal cats.

Am J Vet Res. 2003 Aug;64(8):1059-64. Effects of a high-protein diet versus dietary supplementation with ammonium chloride on struvite crystal formation in urine of clinically normal cats. Funaba M1, Yamate T, Hashida Y, Maki K, Gotoh K, Kaneko M, Yamamoto H, Iriki T, Hatano Y, Abe M. Web Abstract

Acidification of urine can decrease the risk of struvite crystals, but can increase the risk of oxalate crystals.

Manipulation of urine pH through dietary means has proven an effective tool for the management and prevention of struvite urolithiasis; acidification of urine, however, may be a risk factor for calcium oxalate urolithiasis, which now appears to occur with approximately equal frequency in cats. Prediction of urine pH from dietary analysis would thus be a valuable tool, but considerable further research is required before this can be achieved with commercial canned foods. With the growing importance of urolith types other than struvite, alternatives to the measurement of urine pH are required to assess critically the likely beneficial (or detrimental) effects of manipulation of nutrient profile. ...Recent observations suggest that recurrence rates of signs in cats classified as having idiopathic lower urinary tract disease may be more than halved if affected animals are maintained on high, rather than low moisture content diets

J. Nutr. December 1, 1998 vol. 128 no. 12 2753S-2757S The Effect of Diet on Lower Urinary Tract Diseases in Cats. Peter J. Markwell, C. Tony Buffington, and Brigitte H. E. Smith Web Abstract

Credit to Cat Centric for finding the scientific studies.

  • But what does the "specific gravity" or concentration of urine have to do with its acidity, which is specifically what these dry diets are engineered to affect?
    – stimpy77
    Commented Apr 3, 2015 at 1:39
  • @stimpy77 it's more effective to simply clear the bladder/urinary tract out of any material that will irritate it, instead of trying to modify the pH (which only works on one of the two types of crystals anyway)
    – Zaralynda
    Commented Apr 3, 2015 at 11:38

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