Bladder stones in cats

Bladder stones are also known as urinary bladder calculi or uroliths. They can occur in many companion animals, but only cats will be discussed in this article. Their presence in a cat’s bladder causes local irritation to the bladder wall and they can pass through to the urethra (outflow of the bladder) and lodge here, resulting in a life-threatening situation where the cat can no longer urinate. It is important to understand how to recognise the early signs of bladder stones as well as how to prevent them.

What Causes Bladder Stones?

Bladder stones form when there is a particular environment created in the cat’s urine. There are a few different varieties that can form and they rely on the appropriate pH (acidity), concentration, chemical components as well as the presence of infection. Some breeds are more predisposed to forming stones and often cats fed cheaper supermarket brand foods are more likely to have trouble with bladder stones.

The most common sort of bladder stone seen in the cat is made up of what are called struvite crystals. For these to form there needs to be strongly concentrated and alkaline urine as well as higher levels of magnesium, ammonium and phosphate. The struvite crystals start to form and then start to clump together to form stones.

Another bladder stone seen in cats is calcium oxalate. These are more likely to form in acidic urine and when there is an excessive amount of calcium lost in the urine.

What Problems Can Bladder Stones Cause?

There are numerous problems that a bladder stone can cause, the earliest usually being bleeding and discomfort. This occurs when the precursors of the stones ie crystals, along with the bladder stones scrape the bladder wall. If the stones lodge in the urethra then the bladder can become blocked. The urine builds up in the bladder causing both back pressure damage to the kidneys and eventually resulting in a ruptured bladder.

What are the Signs or Symptoms of a Bladder Stone?

Your cat may exhibit some of the following signs:

  • Blood in urine
  • Straining to urinate with little or no urine being produced
  • Frequent trips to the kitty litter
  • Behavioural changes ie more vocal, hiding
  • Uncomfortable or swollen abdomen
  • Increased thirst
  • Lack of appetite
  • Licking at genitals
  • Vomiting
  • Urinating outside of the kitty litter
  • Weakness
  • Depression

How are bladder stones diagnosed?

After gaining a thorough history about what your cat has been doing at home, with their diet and so on, the Vet will then thoroughly examine your cat. Sometimes a stone can be felt when the bladder is palpated, but more often a painful or over-distended bladder is detected. To confirm the presence of a stone often imaging is required such as an abdominal ultrasound or an x-ray. A urine sample is useful to assess the pH, concentration, presence of infection and crystals that help to increase the suspicion of a stone being present. A blood test may be recommended to assess your cat’s kidney health as well as the levels of calcium and electrolytes. It is also advisable to have a blood test to ensure your cat would be a suitable candidate for surgery if required.

What treatments are available?

Once a stone has formed it is very difficult for them to dissolve, in particular the calcium oxalate ones. Surgery is usually required to remove them from the bladder. Sometimes, dietary changes, treatment of any infections with antibiotics and an increase in water intake can help to dissolve them, but more often than not these are put in place to prevent a recurrence of crystals and stones. Anti-inflammatories are often prescribed to reduce the irritation and discomfort of the bladder wall.

How Can I prevent Bladder Stones?

There are a number of things that can be done including ensuring your cat drinks water frequently, or alternatively feeding them more wet food as this has a high proportion of water in it. It is important to visit the vet if you notice any clinical signs suggestive of stones or urinary tract infections as prompt treatment of urinary problems help to prevent stone formation.

Feed good quality or prescription foods that are specifically designed to dissolve crystals and ensure the pH is optimised.

If a bladder stone is detected and removed surgically then it is important that it gets sent off for assessment to determine what sort of bladder stone it is. This helps in guiding treatment to put in place preventative measures to ensure this particular stone does not form again.

What should i do? 

It is really important to get your cat checked if they exhibit any of the clinical signs suggestive of bladder stones. The possible problems associated with stones are very serious, whereas early intervention and adjustments to your cats diet and other factors can ensure that these are avoided. If you have any questions or concerns regarding bladder stones, please contact your vet or make an appointment to have your cat examined.