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All About Urinary Crystals In Cats

Ensuring your cat’s long-term health demands an awareness of common life-threatening conditions that could affect your pet. The development of crystals in the urine (a condition called crystalluria) can result in blockages that can prevent your pe...

All About Urinary Crystals In Cats

Ensuring your cat’s long-term health demands an awareness of common life-threatening conditions that could affect your pet. The development of crystals in the urine (a condition called crystalluria) can result in blockages that can prevent your pet from excreting urine (and the waste products it contains) from its body. Urinary blockages are potentially lethal, so quick action is required. We’ll review the causes of crystalluria, common risk factors, and speak to Figo's Chief Marketing Officer about her own cat's struggle with the condition.

What Is Crystalluria and How Does It Occur?

In cats, like humans, the kidneys are responsible for filtering wastes from the blood. These waste products then travel from the kidneys via slender tubes called ureters to the bladder, from which they are then excreted. Crystalluria is caused by the shedding of microscopic crystals, which is normal in cats. In some felines, however, highly concentrated urine, given a certain acid-base balance, can crystallize into a gritty substance that can block the tube from the bladder (urethra).

In male cats, the urethra tends to be long and narrow, making them especially susceptible to urinary blockages, whereas female cats have a slightly wider urethra, making them less prone to crystalluria.

So what are these crystals made of? As it turns out, the primary ingredient is minerals consumed as part of the animal’s diet (such as struvite and calcium oxalate). These nutrients are found and used throughout the body, with excess or waste amounts being filtered by the kidneys and expelled by the bladder. Under the right conditions, however, these crystals coalesce into granules that can block the urethra.

Risk Factors for Crystalluria


Diet is a principal risk factor for urinary tract blockage in cats. Cats that consume a diet rich in sodium, calcium, and phosphorus are at an increased risk for urinary blockage. While most cats that eat a mineral-rich diet pass these substances without incident, some cats develop potentially life-threatening blockages.


Certain cat breeds are more susceptible to crystalluria than others. For example, Himalayans, Persians, and Siamese breeds have shown an increased risk for blockages.


A stressed cat may refrain from using the litter pan as often as needed. Withholding urine can cause minerals to precipitate from the urine and collect into grit that can block the urethra.

pH Balance

A high urinary pH (alkaline) state has also been shown to be associated with a higher incidence of urinary blockages in cats.

Behavioral Changes

If your pet is struggling to urinate you may notice some changes in behavior. These include:

  • Straining to urinate

  • Spending time in the litter pan but without urinating

  • Passing very small amounts of urine

  • Standing near the pans and vocalizing

  • Overgrooming of the genital area

If you notice any of these behaviors or see that your cat’s litter is consistently dry, see your vet immediately. Urinary blockages can stress and distend the bladder, cause serious damage to the kidneys, and can in serious cases be fatal. Time is critical, so don’t delay.


Unblocking a feline urethra is paramount to prevent your animal from becoming uremic, a condition where toxins that cannot be eliminated begin to accumulate in the system. In most cases, your vet can sedate your animal and use a catheter to unblock the urethra. Cats that have shown a tendency toward blockages are often put on a canned food diet. Wet food is preferable to dry kibble because it ensures that your pet gets sufficient water to stay hydrated and to prevent minerals from precipitating from the urine.

What Can You Do?

As a pet owner, there are several measures you can take to protect your pet’s health.

1. Make sure your cat gets plenty of water. Cats should have water available at any time of day.

2. Include both wet and dry cat food in your pet’s diet.

3. Observe your pet for signs of staining or inability to urinate.

4. Contact your vet immediately if you notice these signs.

Interview with a Pet Parent of a Cat with Crystalluria

Cat lays on its side in the sun

We sat down with Figo Cheif Marketing Officer, Vanessa Yeh, to learn more about her journey dealing with urinary crystals in her cat Richard Parker.

Q: What were the first signs/symptoms you noticed that made you decide to get Richard Parker checked out?

A: I adopted Richard Parker in 2013. I first started noticing symptoms a year later when he started peeing outside the box and was straining to urinate - squatting and trying his best all around the house. Cats can pee outside the box for any number of reasons, including a change in routine or overall unhappiness with something going on in their lives, so I thought at first it might be a behavioral issue and not a medical one. After two weeks of this with no reprieve, I decided to take him to the vet.

Q: Once Richard Parker was diagnosed, what were the recommendations you got from your vet? Did they involve any major lifestyle changes for him?

A: After he was diagnosed with crystals, we had to start putting him on medicated cat food (Urinary SO). We were told no more treats either as they were likely to have ingredients that aggravated his condition. We were also instructed to try and get him to drink as much water as possible, so we introduced a cat fountain and tried adding water to his cat food. We'd warm it up a little, and turn it into a sort of warm, wet mush. Cats can be very picky, so I'm lucky that he actually liked the taste of Urinary SO cat food.

All seemed fine for another year, but then in early 2015, he started exhibiting serious signs of distress. He again was straining to pee outside the litter box, and then when I went to touch him, he screamed! This was seriously concerning, as Richard Parket is normally such a sweet, quiet cat and not very vocal. I had never heard him cry out like that before. I immediately took him to an emergency vet, where they had to sedate him.

While taking radiographs, they found a bladder stone, which can be caused by crystals joining together to make a bigger,  more dangerous obstruction. They inserted a catheter to flush him out and had to keep him overnight. They then recommended immediate surgery for a cystotomy (removal of part of the bladder) and perineal urethrostomy (basically reroute his urethra - ouch!). Once a male cat gets blocked more than a couple of times, it's very likely it will keep happening and can ultimately kill them. This surgery was the best option to avoid that. 

So, my sweet Richard Parket went under the knife. He had to stay at the vet for about a week to recover and once he was sent home with us, was on a cocktail of medications for a while. There's a whole other part to this story where a negligent vet gave us the wrong medications (pain killers instead of antibiotics) that led to him getting a massive infection around the surgery site, which they then tried to hide from us!. Because of this, he had to stay in LA for an additional month to recover while I moved cross-country to Chicago. He had to be flown out to me later once he was well enough to travel.

Q: Did you notice major improvements once you began treatment? Has the diagnosis affected Richard Parker's life going forward, even after treatment?

A: Since then, he has been mostly fine. Every 8-12 months, he starts exhibiting similar symptoms of peeing outside the litter box. Thankfully, it hasn't been due to more urinary crystals or blockages, but instead to UTIs. In fact, cats who have had that surgery are more susceptible to UTIs, so he'll probably keep getting them forever.

Emotionally, he has mostly recovered, but the surgery and horrible recovery process absolutely traumatized him and turned him into a slightly different cat. He's more skittish and nervous than he used to be, though he's still incredibly sweet and loving. It's also likely that he's constantly in some discomfort. He may not be getting blocked by crystals anymore, but as I said earlier, the surgery was quite intensive. He licks the area that was operated on frequently, more so than he did pre-surgery.

Q: Did you have pet insurance and did it help with this issue?

A: Unfortunately, I did not have insurance at the time. The emergency vet, surgery, and prolonged vet stay probably cost ~$10K back in 2015. His annual (sometimes biannual) rushed visits to the vet after he starts showing symptoms again usually cost between $150-300 at a time, depending on what tests they run and the meds they end up prescribing. With all that in mind, I think it goes without saying that I wish I had gotten it when I first adopted him!

We're glad that Richard Parker had as good of an outcome as one could hope for! If you have a cat, we highly recommend you follow Vanessa's advice. Not only can surgery, exams, special food, etc. cost an excessive amount, but in a young cat, it can truly be life-saving. We never want any pet parent to have to choose between their savings account and their beloved companions. If you're curious how Figo can help protect your pet,get a quote today.

Cecily Kellogg is a pet lover who definitely has crazy cat lady leanings. Her pets are all shelter rescues, including the dog, who is scared of the cats. She spent eight years working as a Veterinary Technician before becoming a writer. Today she writes all over the web, including here at Figo.

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