Preventing Urinary Crystals in Cats

There is a saying among the veterinary profession "The solution to pollution is dilution" to explain how to prevent urinary crystal and stone formation in cats. Despite claims of specialized or prescription diets, time, observation, and numerous independent studies have shown that there are no magical diets for solving this problem and that water consumption is the key to a healthy urinary tract.

There are two types of crystals and stones that form depending on whether the urine is acidic or alkaline. Special or prescription diets limit certain minerals and also manipulate the ingredients to create a urine pH that is unfavorable to the formation of crystals and stones. Many cat owners have had multiple surgeries on their cats to remove bladder stones and then feed a specialized diet to prevent the reformation of stones or crystals. However, many owners are frustrated with the limitations of these diets and the answer to that is water and more water. Many cats are notorious for only drinking enough water to hydrate themselves, but not enough to properly flush out their organs. Just like with a woman who gets repeated urinary tract infections, the doctors tells the patient to "push the fluids."

My question is: If our human doctors are prescribing water to prevent urinary tract infections, why has the veterinary profession, as a whole, not stepped on the bandwagon and adopted this same approach for our cats instead of so-called special diets that are very expensive? The more dilute the urine is, the less likely minerals can clump together forming crystals and stones, no matter what the urine pH. This fact is extremely important for cat owners, but it is also a problem for them.

The problem lies in the fact that cats are extremely thirst tolerant, and they are capable of conserving body water by concentrating their urine to a greater degree than dogs or humans. They were engineered that way because of evolutionary adaptations of the carnivore in a dry, desert climate. In the wild, cats obtain most of their water from their prey which is 60% water! Because of the evolutionary makeup of a cat, they are much less likely to seek out sources of water even when their body needs it. The fact that the household cat drinks less water than their wild cousins is the main reason they are more susceptible to urinary crystals and stones. Most woman who has suffered frequent bouts of urinary tract infections know that the more concentrated the urine, the more likely minerals can become crystals and eventually stones.

Urinary tract crystals and stones in cats are the major reason that pet food companies came up with special diets. However, these specialized diets have variable results which have been proven through studies over and over again. These diets are still being prescribed by veterinarians to cat owners. Specialized dry diets only contain about 10% water! Read the label if you do not believe me. Furthermore, if you look at the ingredients in Hill's Science Diet Urinary Care (c/d Multicare) Dry which are: chicken, whole grain corn, corn gluten meal, whole grain wheat, brewers rice, ... The second and third ingredients are CORN! On Royal Canin Veterinary Diet Urinary SO Dry Cat Food (dry) the ingredient list is as follows: Chicken meal, brewers rice, corn gluten meal, corn, … In this food, the third and fourth ingredients are CORN! I would hope by now that we all know that corn is used as a filler and is not very digestible to cats! Both of these foods are very, very expensive. For a 17.6 pound bag of the Royal Canin, it is $75. For a four-pound bag of Hill's Prescription Diet c/d it is $40.

The question remains: How do you get your cat to drink more water? Well, you can't. However, you CAN make some changes to their diet to get that extra water into the diet.


  • Feed Canned Food - you can feed canned food to a cat and only canned food, but regular dental check-ups are recommended.
  • Add water to the canned food
  • Feed smaller meals of the dry food and add water to that

Feeding canned food is important to a cat's urinary tract health, and it is more important than feeding a specialized diet. More water equals dilute urine which is more important than the urine pH and ash content of the diet. In fact, the ash content in modern day cat food is low and therefore, it is an irrelevant concern to a cat's urine pH.

If you take anything away from this article, it should be this: Add more water to your cat's diet. You can do this in two ways: add water to the canned food you are feeding, and add water to the dry food. Adding water to the dry food will necessitate the feeding of two or more small meals a day because you do not want the dry food to get rancid.

An article for further reading, Feline Urinary Tract Diseases, by Lisa Pierson, DVM

A couple of interesting points that Dr. Pierson makes in the above-referenced article:

...."Urethral obstructions cause tremendous pain and suffering... "Many of these cats, understandably, develop litter box aversions secondary to associating the litter box with their pain. This results in house soiling and cases of abuse when the poor cat is punished."

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 {emphasis added by Pelaqita Persians}.

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

Dr. Pierson is adament that the "prescription diets" (which are usually dry kibble diets) are not good for cats as they do not contain the necessary ingredient for optimum urinary health .... WATER!! Furthermore, Dr. Pierson indicates that she does not use "prescription" diets except in RARE cases as noted in her article. In fact, Dr. Pierson states the following:

"I only consider the temporary use of Hill's canned s/d if I know that the patient has urinary tract stones...."

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