If your cat has been displaying symptoms of urinary tract disease and
has been diagnosed with crystals, you are likely very keen to know what
treatment options are available. Well, the treatment will depend on which type
of crystal is involved, as the options are really quite different for each
crystal type.
It is important to know if we are dealing with crystals alone, or if the
crystals have developed into stones. In some cats, the stones that form are so big
that they can actually be felt when the bladder is pressed on, though this is
quite rare and most stones will be smaller than this. To determine if they are
present or not, the vet will need to run a few more tests.
Typically, an ultrasound of the entire urinary tract (including kidneys,
ureters and bladder) will be carried out. Most (though not all!) cats are
tolerant enough for this to be done while they are awake, though they do need
to have a large portion of their belly fur clipped. An ultrasound is a painless
and simple procedure that rarely takes longer than ten minutes and can be
performed in most general vet clinics.
Certain stones will show up better on an X-ray than an ultrasound and
many cats will also have abdominal X-rays performed. Most kitties are too jumpy
and nervous to have X-rays performed
conscious so will either be given a sedation or an anaesthetic. X-rays are
particularly good at showing up ‘radiopaque’ stones and the vet will get a good
idea of how many stones are present and how large they are.
Finding out what type of stone is present can be a real challenge.
Though it would be reasonable to think that if the cat was proven to have
struvite crystals on their urine exam that any stones present would also be
struvite, this is not always the case. Depending on the crystals present and
other factors, such as the urinary pH, we can make an educated guess as to
which types of stone are present. In reality, the only way to know for sure is
to remove a stone and have it examined by a laboratory.
Struvite crystals and stones are typically treated conservatively. Any
underlying infection would need to be treated with a course of antibiotics (which
have been based on culture and sensitivity) and the urine should be re-analysed
when the course is finished to ensure the infection has been eliminated and is
not grumbling on.
As soon as struvite crystals have been diagnosed, a prescription diet
should be started. It is critical that this diet be the only source of food, as
supplementing it with a different brand of kibble or some yummy treats will
only negate the benefits. This can mean that cats who normally have access to
the outdoors need to be kept in for a while as if they were to find something
to munch on outside, they could delay the effects of the treatment. Similarly,
if there are other pets in the household, they will need to be fed separately.
This may mean the use of ‘microchip feeders’ in multi-cat households.
While urinary diets are available in wet and dry forms, most vets will
recommend feeding the wet form if the cat will accept it. This is to encourage
further dilution of the urine, ensuring more crystals do not form. Luckily,
most cats prefer the taste of wet food.
Owners are also advised to encourage as much water drinking as possible,
which may mean the purchase of water fountains. Water can be mixed in to the
diet, even if it is already a wet diet.
One of the best-known diets used for eliminating struvite stones and
crystals is called Hill’s C/D. This food is the preferred treatment choice of
many vets and is nutritionally balanced but limited in the ingredients that can
cause crystal formation, such as Magnesium, Phosphorous and Calcium. It is
designed to keep urinary pH at optimal levels, preventing it from becoming too
acidic or too alkaline. Many vets will monitor this over time, ensuring the urinary
pH is staying where it should. You can read more on catcareadvices.com
Once the diet has been started, struvite crystals may dissolve in as
little as a few weeks, though often it will take several months for them to
completely disappear. The general consensus is that the diet should continue
for at least one month after the stones no longer show up on X-ray, and many
recommend feeding it life-long.
Dealing with Calcium Oxalate crystals and stones can be a little more of
a challenge. Interestingly, these crystals used to be extremely rare but now
account for roughly half of feline urinary crystals. Many believe that this is
due to cats eating commercial foods that acidify the urine. If the crystals
form in to stones, diets are not effective at dissolving them and they require
more drastic intervention.
If the stones have formed within
the bladder, the surgery is relatively straight forward and consists of making
an incision and removing the offensive material. However, sometimes the stones
can be sitting in the kidney or ureter, which can be a real issue. In these
situations, cats may be referred to specialist surgeons with more experience in
complicated cases.
In some patients, stones will lodge in the urethra and cause a dangerous
blockage. Cats will be unable to produce urine or will only produce it in very
small amounts. Some of these stones that have lodged may be small enough that
they can be guided back into the bladder safely, relieving the blockage and
allowing the cat to urinate once again.
Vets can perform a technique called ‘retro hydropulsion’, whereby the
stones are encouraged to move back into the bladder via pressure and the use of
saline under high-power. As this can be quite uncomfortable, it is either
performed under a heavy sedation or general anaesthetic. Once the stones have
been moved from the riskier place to the bladder and the cat can pass urine
again, the stones can then be dealt with. So, if the stones are calcium
oxalate, a surgery will still be on the cards. Surgery to remove stones from
the bladder is far safer than one which involves making an incision in the
small urethra. If the stones are struvite, this procedure can mean that a
surgery to remove the blockage is unnecessary and we have now bought some time
for the diet to work.
More recently in the veterinary world, there has been a lot of interest
in ‘Lithotripsy’, a method that is used a lot in human medicine. Sound waves
are applied externally in order to break up the stones. Sometimes, laser lights
and electricity are also involved. Most GP vets will not have access to this
treatment, though several specialist centres are now able to provide it. This
may be a useful option in cats that are not good surgical candidates.
Another technique that may be available in some specialist centres or
universities is stone retrieval via cystoscopy. This is a sterile procedure
that requires a general anaesthetic and is usually performed by a vet with
special training. No incision is required, so the recovery time is very quick
and the risks involved are minimal. A long instrument called a cystoscope is
passed into the urethra and up into the bladder, collecting the small stones
and removing them, without the need for an invasive surgery. During this
procedure, vets also have the ability to visually assess the inside of the urinary
tract, which can provide some useful information. Sometimes, anatomical
defects, strictures or masses are found, so this can also be a useful
diagnostic procedure. Vets have the option of taking a biopsy of any unusual
tissue, which can be a very useful way of telling the difference between
chronic inflammation and neoplasia.
In male cats in particular, this procedure is particularly tricky as
they have such narrow tubes, but it is possible with very small instruments.
Sometimes, a laser will be used at the same time as this procedure so that the
stones can be broken up, allowing for easier removal.
It is well-known that cats who have formed crystals and stones in the
past are likely to form them again. Due to this, owners are encouraged to be
pro-active in their prevention at all times. Our next (and final) article in
this series focuses on how to keep crystals and stones away for good.
