Water, Water and Water Battles Crystals

Updated: Friday, May 24, 2019 01:53 PM

Published: Saturday, February 26, 2011 03:55 PM

Written by Andrea Tasi, VMD

My 4 year old kitty, Roxy, is a recovering bladder stone survivor. She had 5-6 crystallite stones in her bladder that were removed in January of this year. She has been on a raw cat food diet ever since, exclusively. She eats the quail recipe from Primal Foods. I have noticed, though, that her water intake has gone to zero since starting the raw diet. I have been adding 6-8 teaspoons of water to her raw cat food every serving to make up for it. I also tried a Cat-It water fountain and she will have nothing to do with it.

Is supplementing her daily raw food with 12-16 teaspoons of water enough? She has been tested four times since her surgery, x-rays and urine draw from the bladder with no crystals showing up.

So, we are one year out from Roxy having had calcium oxalate stones removed and so far no recurrences, based on the rechecks which include radiographs and urinalyses. Good job. Your veterinarian is doing the right thing to monitor Roxy carefully and include x-rays as part of that monitoring, as urinalyses alone cannot rule in or rule out bladder stone recurrences.

It is my experience, and that of many other practitioners, that when cats are placed on a meat-based, water-rich, raw, canned or home-cooked, balanced diet, they drink little or no water at all. This is normal for cats, as they evolved as obligate carnivores in a desert environment. Their physiology adapted to obtaining the water they needed via their diet, which naturally consisted of small mammals, birds, even reptiles and the occasional insect, as the desert does not have the puddles, streams, ponds or rivers so common in other types of climates.

Adding extra water to the diet of cats who have had urinary crystals or stones cannot hurt, provided the cat doesn't mind it and is consuming enough of the balanced food to maintain a healthy body weight. Indeed, it may help, as diluting the concentration of the cat's urine will lessen the ability of the most common types of urinary minerals, calcium phosphate and magnesium ammonium phosphate, AKA struvite, to form into crystals or stones. The catchy phrase, "The solution to pollution is dilution!" applies here. This is why dry foods, even prescription dry diets for urinary crystals, are never the best choice, as they contain almost no water at all. When cats are on dry food diets, they will drink water, but they often do not drink enough to keep their bodies optimally hydrated or produce slightly diluted urine.

There are numerous prescription canned foods that veterinarians use to try to control urinary crystals and stones, but often the same thing can be accomplished with balanced raw food or cooked diets, either homemade or commercially prepared. Most prescription canned foods contain fractionated grain products such as corn starch and corn gluten, which, in some cats, are not digested or metabolized properly.¹ We have also learned, the hard way, that by formulating one type of food to prevent one type of crystal or stone, we end up pre-disposing cats to other types of crystals or stones.² Nearly all commercial cat foods acidified their formulas to try to prevent struvite stone formation, and now there is an epidemic of calcium oxalate stones as a result, as they tend to form in more acidic urine. The lesson in all of this is that dietary pH is not the whole answer to the problem.³

It is important to acknowledge that veterinary medicine cannot explain why some cats are prone to developing urinary crystals and/or stones and why some other cats, perhaps eating the same type of diets, even dry diets, do not develop them. There is obviously some individual tendency or susceptibility present in the cats who do develop these problems.

Note: Feline Nutrition provides feline health and nutrition information as a public service. Diagnosis and treatment of specific conditions should always be in consultation with your own veterinarian. Feline Nutrition disclaims all warranties and liability related to the veterinary advice and information provided on this site.

Andrea Tasi, VMD is a graduate of the University of Pennsylvania School of Veterinary Medicine and has been in exclusive feline practice since 1991.

1. Ingredient List, Hill's Prescription Diet® c/d® Multicare Feline Bladder Health with Chicken.

Ingredient List, Pro Plan® Focus Adult Urinary Tract Health Formula Chicken Entrée Canned Cat Food.

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

3. Brigitte H. E. Smith, Abigail E. Stevenso, and Peter J. Markwell, "Urinary Relative Supersaturations of Calcium Oxalate and Struvite in Cats Are Influenced by Diet," The Journal of Nutrition 128, no. 12, December 1, 1998, 2763S-2764S.