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.

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.

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 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

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.

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

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.

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

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

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:

• Is unable to pass any urine, despite repeated attempts

• Has a suspected stone and starts vomiting

• Has a tense, painful or distended tummy

Call a vet if your cat is:

• Squatting more than usual or vocalising

• Passing smaller amounts of urine than normal

• Passing cloudy-looking urine or urine with blood in it

• Is using their litter tray more often or peeing outside the litter tray

Joii can help with advice on:

• Recognising signs of urolithiasis

• Suitable diets for cats of all ages and lifestyles

• Managing weight

• Encouraging your cat to drink

• Safe and effective urinary supplements