Crystals, Bladder Issues, FLUTD
By Dr Elizabeth Hodgkins, DVM, Esq
Former Director of Technical Affairs for Hill’s Pet Nutrition

After obesity, bladder disease, also called urinary tract inflammation (UTI) or cystitis, is
the most common nutritionally caused problem in the adult cat. For years veterinarians
have struggled with this seemingly mysterious problem, with very limited success. The
affected cat strains to urinate, may have blood in his urine, and can even become
blocked and unable to urinate at all. The becomes a life threatening emergency
situation that requires immediate veterinary attention.

Why Do Cats Develop Urinary Tract Problems?

Cats are a very successful and naturally healthy species. Left to feed themselves, cats
generally do not have major urinary tract problems. Yet, in the 1970’s and 80’s,
veterinarians began to see very large numbers of cases of cystitis (bladder inflammation
and infection), bladder cyrstal and stone formation, and urinary blockages in thier feline
patients. Many cats died when their blockage caused acute renal failure and treatment
arrived too late. Veterinary surgeons even developed a new surgical procedure, called a
perineal urethrostomy, in which the male cat’s urethra is amputated to better allow for
chronically affected cats, but painful and disfiguring. Unfortunately, this surgery, and
other less dramatic medical treatments were not always effective over the long term.
Sadly for millions of cats, the analysis the experts applied to this problem was flawed,
and the solution faulty. The rise of urinary tract diseases in the cat coincided exactly with
the increasing use of dry kibble to feed cats. In fact, in previous times,when cats
consumed meat-based diets, commercial or otherwise, they simply did not develop UTI.
Scientists at the pet food companies studied the problem and concluded that it was the
magnesium in commercial pet foods that caused UTI. They concluded this simply
because the major type of crystals formed in affected cats were made up of magnesium
salt. The experts reasoned that teh amount of magnesium in the foods of affected cats
must be too high, causing magnesium levels in the urine to be too high. Thier theory
went that high magnesium in the bladder caused stones to form. The experts failed to
consider that the natural prey diet of cat also contained significant magnesium but was
composed of entirely different types of ingredients.
The pet food scientists did notice a key difference in the urine of dry food fed cats. The
urine of such cats was alkaline in its pH, rather than acid. Magnesium crystals form in
alkaline urine, not acid urine. They reasoned that if they added acid to teh food of these
cats and removed the magnesium, the problem would go away. Many different
“prescription-type” foods appeared on the market and were available through
veterinarians as treatment or prevention of UTI. This approach was only partly
successful, however. Many cats with UTI that were managed with these diets still had
recurrences of their disease. Worse, some of them developed a different type of
crystals, made of a calcium salt (calcium oxalate), because their urine had become too
acidic. For these cats, the cure was as devastating as the original disease.

Dry diets also cause UTI because of their very low moisture content as compared to wet
foods. Even healthy cats that eat dry diet and have access to plenty of fresh water have
consistently more concentrated urine than those that eat wet foods. Although dry food
fed cats drink extra water, they do not make up for the lower moisture of their food by
drinking enough free water. This situation is likely the result of evolutionary origins in the
desert and other types of acid environments. The cat’s thirst drive for nondietary water
is not strong. It never needed to be strong when the animal was eating high moisture
foods. When we deprive the cat of dietary water, we invariably cause a state of relative
dehydration, with disasterous results.
The studies that were done to find a cat food that would eliminate the UTI problem never
included a low-carbohydrate, meat based wet food as one of the options to be studied.
The test diets in these studies were usually low moisture, carbohydrate based foods with
different levels of highly acidifying ingredients and different levels of magnesium. The
role of high levels of highly processed carbohydrates in dry form was never questioned
or studied in the nutritional research into this disease. We have seen this oversight
before in the studies involving diets for diabetic and obese cats.
In those studies, the scientists looked for ways to modify cereal based foods to make
them effective in managing these medical conditions. They did not, however, even
consider that meat based, wet foods might provide the best solution for the problems.
Their conclusion that high carbohydrate foods with indigestible fiber were more effective
in dealing with obesity and diabetes than carbohydrate based foods without indigestibe
fiber might have been correct as far as it went, but it certainly did not solve those terrible
problems in cats because it never included the real dietary solution.
Similarly, when research to solve the problem of UTI in cats also failed to even consider
that the cat’s natural nutrient profile might be the logical solution, it failed to solve the
problem. The artificial urinary tract disease fighting diets that were developed are costly
for the pet owner, often do little to provide relief from the disease, and may even cause
other diseases. In fact, cats began developing UTI in epidemic numbers purely and
simply because their carnivorous metabolic requirements were being met by feeding a
diet suited for herbivorous/ omnivorous animals.
So Where Are We Now?

For the past 25 years, no additional progress has been made in dealing with UTI in cats.
Veterinarians and cat owners have resigned themselves to the existence of this common
and very serious problem, with nothing available to prevent it or cure it satisfactorily.
Every week I see new patients that have been on special diets for this problem without
success. Although the numbers of cats that must have the painful and mutilating surgery
for UTI have decreased, this surgery is still recommended for many cats that continue to
relapse on their diets of expensive “prescription-type” dry cat foods. Many of these cats
are diagnosed with a form of UTI called idiopathic cystitis, which means “bladder
inflammation with no known cause.” Veterinarians reason that if the special diets cannot
control the problem, then the cause must be complex and mysterious, beyond
understanding and solution.

Ironically, the means to eradicate UTI from the feline population has always been right in
front of us. Plant-based cat foods, specifically dry cat foods with their very high amounts
of processed cereal and low moisture content, cause UTI, pure and simple. Even the
special, additive-containing foods for UTI cats can, and do, continue to promote this
terrible condition. On the other hand, cats eating meat-based wet foods simply do not
develop UTI. The problem is not, and has never been, the level of magnesium in the diet
of UTI cats. The problem is the extremely low-moisture, alkaline urine-producing,
high-processed-carbohydrate formulas of dry cat foods.

How Do Plant-Based Cat Foods Cause Urinary Tract Disease?

As we have discussed in previous chapters, cats are obligatory carnivores, adapted over
millions of years to the consumption of meat, not plant materials. Because predators like
the cat consume plenty of bone along with meat, the metabolites of the carnivorous diet
include lots of minerals, including magnesium. Magnesium in the cat’s diet is not, and
never was, the problem. The problem is dry cat foods because:
1. The urine of carnivores consuming meat is acid (below a pH of 7.4), not alkaline
(above a pH of 7.4). Dry cat foods, with their high plant content, cause a very
alkaline urine pH. This is an unnatural environment in the cat’s bladder, leading to
inflammation. The consumption of meat creates a healthy bladder environment.
2. Dry cat foods provide almost no moisture, whereas a natural prey diet provides
75 to 80 percent moisture. The cat has low thirst-drive to consume free water
because of its evolutionary origins. Thus, the dry-food-fed cat is usually
subclinically dehydrated, and its urine is very concentrated. The unnaturally high
concentration of minerals and other constituents in the urine, along with an
alkaline pH, leads to UTI.
3. When a cat consumes a wet, meat-based diet, the resulting urine has a natural
acid pH and is more dilute than the urine of dry-food-fed cats. These conditions
do not allow the formation of crystals and stones, and eliminate inflamations.
As I explain to my clients, if you put the wrong fuel in any engine, you can expect poor
performance. If you own an automobile with a gasoline-burning engine, and you put
diesel fuel in that engine, the system will run very badly. This is exactly what we do when
we feed plants to a cat. We are putting the wrong fuel in the cat’s engine, and the engine
does not run normally. Had the pet food companies understood that plant-based foods
were the wrong fuel for cats, there might have made a better decision about how to solve
the emerging problem of UTI.
Just as it would be foolish for you to try to rectify the problem of diesel-fuel in your
gasoline engine by pouring additives into the tank along with the diesel fuel, it was
foolish to try to provide corrective additives to dry cat food to make it “work” in the cat.
The simple and complete solution to the problem was to back up and feed the cat a diet
of natural ingredients in a natural form.
I know this simple solution works, and works extremely well, because I have treated
without any special diets whatsoever every single UTI cat I have seen in my clinic. Here
are some examples of such cases:

Missy Forbes

Missy was a two-year-old spayed female domestic short-haired calico cat with previously
perfect litter-box habits. She was in a good body condition at nine and a half pounds.
Her diet was a “premium” brand dry cat food with occasional “treats” of wet canned food,
which she loved. A week before I saw Missy, she had started to have “accidents” outside
the box, and her owners were understandably distressed about this. There were no
obvious new stress factors in her life, and her basic physical exam was normal in all
respects. Missy’s complete blood count and chemistry panel were also normal. We
performed a urinalysis, and discovered that Missy had a small amount of blood and
protein in her urine, with a urine pH level of 8.0. Her urine was quite concentrated with a
specific gravity of 1.055. This is a highly concentrated and alkaline urine for the cat.
There were no crystals in Missy’s urine, and no bacteria. We concluded that she had a
urinary tract inflammation secondary to the concentrated high urine pH. Missy’s bladder
lining was not designed to handle such alkaline urine, and it was becoming quite
inflamed as a result of this abnormal condition.
We immediately changed Missy’s diet to an all-wet, meat-based commercial cat food
with no corn, potato, carrots, or fruit ingredients. Her owners were instructed to allow no
dry cat food whatsoever. Missy herself was very happy with this change. We also
prescribed a short course of an anti-inflammatory drug to help reduce the urinary tract
inflammation and give Missy relief from the irritable bladder sensations that were making
her urinate frequently and indiscriminately. Within three days, Missy was back to her old
perfect litter-box habits, and two weeks later when we rechecked her urine, there was no
trace of blood or significant protein, and her urine pH was 7.0. The specific gravity of her
urine was 1.036. A month later, Missy’s pH was 6.5, a very acceptable level of acidity.
Missy has done extremely well, and has been normal now for over a year on nothing
more than an exclusively wet-food diet of over-the-counter commercial cat foods.

Roger Bowman

Roger was a six-year-old, neutered male domestic long-haired cat with a history of
recurrent UTI. Roger’s first episode of bladder problems started when he was three
years old. He had been fed a diet of grocery store dry cat food exclusively up to that
point. His previous veterinarian had prescribed a special acidifying diet for treatment of
UTI after that first episode, and Roger had been on that diet ever since. About every six
to eight months, Roger would develop blood in his urine and start to strain to urinate in
the litter box. His owners knew what this meant, and each time this happened, Roger
would go to the veterinarian for treatment. Fluid therapy and antibiotics seemed to
resolve the UTI episodes for a time.
Roger came to us because his owners had moved from their previous residence in
another state. After the move, his UTI flared up again, and his owners sought help for
the problem, once again. Roger was overweight at sixteen pounds at presentation. He
showed painfulness in his bladder area during his physical exam, but was otherwise
normal physically. Roger’s baseline blood work was normal, but his urinalysis showed
significant blood cells and protein, an acid pH of 5.5, small numbers of calcium-salt

crystals in his urine, and a concentrated urine with a specific gravity of 1.052. There
were no bacteria in his urine.
We treated Roger as he had been treated before, with fluids and antibiotics, and added
anti-inflammatory drug therapy as well. The most important thing we did for Roger was to
educate his owners about the role of the acidifying cat food in the recurences of his
disease. They were confused because they believed that the special diet they were
feeding was supposed to prevent the crystals from forming in Roger’s urine. We
explained that Roger’s urine was actually too acid now, because of the diet he was
eating. The amount of acidifying ingredients added to that diet caused Roger’s urine pH
to become too low, and a new type of crystal was forming there in the concentrated urine
caused by the low-moisture of the dry diet. We instructed them to feed Roger any wet,
meat-based commercial food without high carbohydrate ingredients from plants. This
woud naturally correct the problems Roger had been experiencing.
Because he had been on dry foods all his life, Roger resisted this change for a few days.
His owners offered him a number of different canned and pouched foods, and found
some that he liked well enough to eat at least 3 to 4 ounces per day. Within a week,
Roger was eating 7 to 8 ounces of wet cat food per day and his UTI signs were gone.
We rechecked Roger at two weeks, four weeks, eight weeks, and six months. Within a
month, he had lost almost a pound of his excess body weight and had no blood, protein,
or crystals in his urine. His urine pH was 6.5 and had a specific gravity of 1.035. At six
months, Roger had lost over four pounds and looked like a new cat. His activity level had
never been higher, his owners were delighted. Eighteen months after his diet change,
Roger has no new recurrences of his UTI, and his urinalysis rechecks have been normal.

Morris Cassidy

Morris was a ten-year-old domestic short-haired neutered male cat. Morris’s owners
reported that he had been acting lethargic for several days and refused to eat his normal
dry cat food, a “premium” brand, for the last two days. On a physical exam. Morris was
moderately dehydrated, and his bladder was large and very hard to the touch. He was
painful in the abdominal area around his bladder. We determined immediately that the
flow of urine out of Morris’s bladder was completely blocked. He was in a life-threatening
crisis. We immediately passed a catheter into Morris’s bladder and began to empty very
bloody urine out of it. We drew blood for testing and began to give Morris intravenous
fluids.
Morris had a large amount of blood, protein, and magnesium-salt crystals in his urine.
His urine pH was 7.5 with a specific gravity of 1.060. He was in acute kidney failure as
well, because he had been blocked for a few days at least. This had caused all of the
toxins the kidney normally filters from the blood to accumulate in the body. Fortunately,
once the flow of urine from Morris’s body was restored and his dehydration was
corrected with intravenous fluids, all of the signs of kidney failure resolved quickly and he
even began to have an interest in food again. Because of the large amount of crystals in
his urine, though, we had to leave Morris’s urinary catheter in for four days after his initial
treatment began to make sure that he did not become reblocked. His urine remained

very bloody for several days. Ultrasound exam of Morris’s bladder showed a markedly
thickened, “angry” bladder wall, in reaction to the constant irritation of alkaline pH and
concentrated urine full of crystalline “sand.”
Once Morris was eating the regular commercial wet cat food we offered him, his urine
pH dropped to 6.5 and the amount of urinary crystals in his urine samples dropped to low
levels. Within six days, his urine no longer had visible blood; only trace amounts were
detected on the urinalysis. One week after presentation, Morris went home a much
happier cat than we had seen seven days earlier. We rechecked Morris every few days
after that, to make sure he continued to do well. Eight months after his brush with death,
Morris was healthy with no signs of a recurrence of his blockage or permanent kidney
problems. He now eats only commercial canned or pouched cat foods with no
carbohydrate-containing ingredients such as corn, rice, potato, sweet potato, carrots, or
fruit of any kind. I know that I will never see Morris again in my clinic with this problem as
long as his owners feed him like a cat!

In domestic cats, true UTI is a disease with a nutritional basis. Rarely, we see cats in our
clinic that have stress-caused litter-box problems that do not resolve with a diet change.
These cats do not have the typical changes in their bladder environment that we see
with real UTI. The problem in such cats is behavioral, not physical. Overcrowding,
aggression among cats, significant changes in the cat’s environment, and the like can
trigger urine marking or spraying outside the box. Such cats are “acting out” in response
to psychological stressors.
In such cases, although a change from dry to wet food is still appropriate, it will also be
necessary to identify the source of the stress that is causing the misbehavior. If at all
possible, the owner must alleviate that stress. In those cases where the owner cannot
resolve the environmental problem entirely, there are drug therapies that may help to
reduce the affected cat’s anxiety level enough for normal behaviors to return. These drug
therapies may not need to be lifelong. In some cats, a few months of treatment may be
enough to change the bad habits. In others, longer-term but low-dose therapy may
provide good management. Your cat’s veterinarian can determine if your cat has a
behavioral problem rather than a purely physical one, and suggest an approach for
dealing with the behavioral issue. There are also a number of good resources for
information on this subject (see www.sniksnak.com/cathealth/marking.html)