Urolithiasis in cats

Cats with urolithiasis have stones in their urinary tract. This could mean the bladder, urethra, kidneys or ureters. 25% of cats with lower urinary tract disease have bladder stones. Untreated urolithiasis can result in urinary blockages and even death.

Urolithiasis in cats causes bladder irritation, infection and urinary tract blockages (blocked bladder). Uroliths include everything from tiny particles, like sand, to large single stones. And often both together. There are multiple treatment options, depending on the type of stone and location, but the condition often recurs. Always call a vet if your cat shows signs of difficulty or discomfort peeing or has blood in their urine.

Overview

What is urolithiasis in cats?

Urolithiasis is the formation of hard rock-like material from minerals in urine. These minerals originally come from the food your cat eats. Normal urine contains minerals, including calcium, phosphorus, magnesium, chloride and sodium.

Various health, lifestyle and dietary factors can trigger increased crystal formation from minerals in cats’ urine.
Crystals irritate the bladder wall, making it release thick mucus for protection.
The mucus and crystals stick together, getting bigger and harder over time to form stones.
Stones form in anything from a few weeks to months.
Different types of minerals cause different types of stones.
Between 5 and 40% of cats treated for urolithiasis suffer recurrence, depending on the cause and type of stone.
Urolithiasis in cats is a general term. Stones in different parts of the urinary tract also have specific names, for example nephrolithiasis (kidney stones), cystolithiasis (bladder stones). Most stones in cats happen in the bladder and urethra.

There are 2 common types of stones in cats:

Struvite: most common in females and associated with bladder infection.
Calcium oxalate: most common in male cats.


Bladder stone

Causes:

Infection: bacteria release chemicals that reduce acidity of urine, encouraging stone formation
Diet: unbalanced or unsuitable for lifestyle
Stress: a complex response leading to bladder damage and increased mucus production
Lack of exercise and not drinking enough water
Genetics: inherited tendencies
Other illnesses affecting the chemical components and strength of urine

Symptoms

Symptoms of urolithiasis in cats

The symptoms of urolithiasis in cats will vary depending on the location of the stone(s).

Common symptoms:

Difficulty peeing: repeated squatting, passing small amounts or nothing at all
Yowling or vocalising when trying to pee
Blood in urine
Becoming dull or depressed
Eating less
Vomiting
Having a tense, painful tummy
Fever

Risk

Cats at a higher risk of urolithiasis

Certain factors increase your cat’s risk of getting urolithiasis:

Experiencing chronic stress
Being middle-aged and older: except kittens with struvite urolithiasis
Belonging to certain breeds: British shorthair, Burmese, Persian, Ragdoll or Tonkinese – increased risk of kidney stones
Eating an unbalanced diet: food very high in protein and certain minerals – calcium, magnesium, phosphorus
Not drinking enough: concentrated urine irritates the bladder wall; less drinking means less urine passed, so crystals don’t get flushed out when your cat pees
Having other illnesses: chronic kidney disease, diabetes, liver disease
Being obese and not getting enough exercise
Previously having had urolithiasis

Complications of urolithiasis:

Blocked bladder, especially male cats with a narrower urethra
Burst bladder
Kidney damage, even kidney failure
Sepsis

Will my other cat(s) get urolithiasis?

Urolithiasis affects individual cats. It won’t spread between cats or from cats to humans and other pets.

However, cats in the same household with the same risk factors (breed, diet, lifestyle) will have the same risk of getting the illness.

Diagnosis

How do vets diagnose urolithiasis in cats?

To begin with, urolithiasis in cats will look like a simple urinary tract infection. Your vet will need to do more tests to confirm the presence of urolithiasis.

Urolithiasis is diagnosed by:

Urine tests: testing urine components with a dipstick; looking for cells and crystals under a microscope
Abdominal palpation: vets may be able to feel larger bladder stones just by feeling the tummies of smaller cats
X-ray: some stones will show up on standard x-rays or can be outlined with contrast dye
Ultrasound: urate and cystine
Blood tests: general health and specific causes of urolithiasis
Urine culture: checking which bacteria are causing any infection
Endoscopy: exploring the urinary tract with a flexible camera


Bladder stones on an x-ray

Crystals form in urine left around for any length of time and sometimes even in fresh or refrigerated samples. Any sample you take to your vet for testing must be as fresh as possible. Finding crystals in urine is not the same as having urolithiasis. But it may confirm the need for further tests if your cat has symptoms.

Vet treatment

What’s the treatment for urolithiasis in cats?

Some stones can be dissolved using special diets. Others are too large, undissolvable or require immediate removal after causing a blockage. All cats with urolithiasis must be encouraged to drink more while treating the illness and to reduce the risk of it coming back.

Treatments include

Special diets: to alter the acidity and chemical make-up of your cat’s urine; can dissolve some stones, either completely or to reduce size and number prior to surgery
Antibiotics: to treat infection associated with stones
Medicine to control acidity of urine: helps reduce stone formation or encourages dissolving

Procedures and operations for treating urolithiasis

Flushing

Limited to small stones in the urethra
A catheter (narrow sterile tube) is passed through urethra towards the bladder; stones are flushed into the bladder with sterile saline
Usually followed by removal of the stone to prevent recurrence

Endoscopy (cystoscopy) removal

Usually carried out under heavy sedation or a general anaesthetic
The vet passes a fine endoscope (camera) into the bladder through your cat’s urethra. Or via keyhole surgery through their tummy. Individual stones are picked up and removed in pincers or a mini ‘basket’. Or they may be flushed out of bladder
Limited to small stones

Surgery

Carried out while your cat is asleep under a general anaesthetic
An operation to open the tummy and bladder and remove stones directly
Likely option where large stones are causing blockage

Stents

Stents are small mesh tubes used to hold open a vessel
Used for upper urinary tract blockages – the ureters
Placed via keyhole surgery and an endoscope from the kidney
May be passed up from the urethra in female cats
Holds the ureter open to allow urine to get past a blockage

Laser treatment

Breaking up bladder stones using a laser
Only available in specialist hospitals
Works for all types of stones
Carried out via cystoscopy – unsuitable for male cats due to narrow urethra

Treatment for specific types of stones

Struvite:
- dissolved using a special diet like Hills Prescription Diet s/d or c/d
- antibiotics throughout treatment due to ongoing live bacterial release from dissolving stones
- removal if large or causing blockage
Calcium oxalate: cannot be dissolved

Home treatment

How to care for a cat with urolithiasis at home

There are no home cures for urolithiasis. Cats with stones in their urinary tracts risk developing life-threatening blockages. Male cats and small cats are at most immediate risk for this.

If your cat has had sedation, general anaesthesia, endoscope procedure, and/or surgery, follow your vets directions for their specific care.

You can help your cat’s recovery by:

Continuing to encourage them to drink
Feeding the special diet as advised by your vet – with no other foods or treats
Giving any medication at the times and doses prescribed by your vet

Prevention

How to prevent your cat getting urolithiasis

Some cats have an inherited risk of stones. If we know the risks, we can ensure they have a special diet to prevent stones forming. It’s one of the many reasons that it’s a good idea to research the breed before you bring a puppy or cat home for the first time.

General tips for reducing risks include:

Ensuring your cat always has lots of fresh water to drink
Maintaining them at a healthy body weight and condition
Keeping your cat active
Feeding a balanced, healthy diet
Ask a vet for advice before giving any mineral or vitamin supplements

How to reduce the risk of urolithiasis coming back again:

Treating underlying illness
Feeding wet food and/or ideally, a special prescription diet
Supplements for bladder health may help reduce the risk of stone formation
Starting a weight management program if your cat is overweight
Medicine to prevent stone formation – for example, allopurinol to prevent urate stones

Always talk to your vet before giving your cat a special diet or supplements.

When to worry

Seek help from a vet immediately if your cat is: