Urinary Crystals in Cats: Treatment Options

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.