Cysteine Stones … Everything You Need to Know

At My Pet Nutritionist, we often get enquiries about dogs suffering with urinary crystals or bladder stones. One of the types of crystal often diagnosed, is the Cysteine crystal.

What are Cysteine Stones?

There are 4 main types of bladder stone/crystal; Struvite, Calcium Oxalate, Urate, and Cysteine.

Cysteine stones are uroliths (solidified lumps of crystalloids) which can form in the bladder, urinary tract, or kidneys. Of the four stones, Cysteine stones are incredibly rare, with only around 1% of diagnoses being Cysteine. While these stones can happen in female dogs, they are most common in males.

Learn more about the different types of stone in our blog here!

How are Cysteine Stones Formed?

The amino acid, Cystine, is made by the body after synthesis of methionine. Cysteine can also be found in some higher protein foods. It is reabsorbed by the kidneys, but when the kidneys are unable to absorb it, a condition called cystinuria occurs. When this happens, the cystine becomes very concentrated in the urine, which causes the formation of Cysteine bladder or kidney stones.

As with each type of urinary stone, there are some unique characteristics associated with it; these stones only form in acidic urine. Dogs with more alkaline urine will not form this stone. The risk of cysteine stones forming, may also be down to genetic abnormalities.

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Symptoms of Cysteine Stones

Though similar for other stone types, some symptoms your pet may show are:

  • Frequent, sometimes bloody urine
  • Painful urination
  • Excessive drinking
  • Nausea and vomiting

Breed Predisposition

Some breeds of dog are genetically predisposed to Cysteine stones, and may require regular treatment, as this type of stone is often a recurrent issue.

Breeds predisposed to Cysteine stones include:

  • Basset Hounds
  • Dachshunds
  • Newfoundlands (unusual female cases have been recorded in this breed)
  • Bullmastiffs
  • English Bulldogs
  • Irish Terriers

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What Can the Vet Do?


Often required for those with larger stones, surgery is a very common path to take when battling Cysteine stones. The surgical procedure is called a Ureteroscopy, during which a very small instrument is passed through the bladder and up the Ureter, pushing the stone out in the process.

Alternatively, the pet may be opened up, and large stones causing blockages will be removed by hand.

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Non-Surgical Removal

There is a non-surgical option available for those with very small cysteine stones; this procedure is known as urohyrdopropulsion.

This procedure is usually most successful on medium to large dogs, and involves two catheters being placed in the dog; one up the urethra, and the other in the urethral lumen. A finger is inserted into the rectum to push against the urethra, causing a build up of pressure and a tight seal. Once a tight seal is made, saline water is flushed through the catheters, and the bladder is palpated, flushing the small stones out.

Although this method requires anaesthesia, it is preferred for smaller stones as it is much less invasive than surgery.

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How Can we Support the Body?


Diet plays a huge role in the prevention of Cysteine stones. With these stones, its advisable to feed a normal amount of calcium, but slightly lower protein, and also low salt (to avoid water retention/dehydration).

As well as these specific nutrient requirements, it is imperative that your dog’s diet includes as much moisture as possible! Moisture in the diet will help flush the bladder; feeding a dry food would dehydrate the dog, and could worsen the issue. Feeding a fresh food is very much recommended for any bladder stone, including Cysteine!

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Find our recipe suitable for dogs suffering from cysteine stones here!


Omega 3 in the form of Alpha Linoleic Acid (ALA) is thought to inhibit cysteine crystal formation, due to it’s anti-inflammatory, and antioxidant properties. ALA can be found in leafy greens, nuts (avoid peanuts, and macadamia nuts), and animal fat.

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Selenium has been proven to reduce the volume of cysteine crystal formation. When looking for a supplement, ensure it is as pure as possible.

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Bonus Factoid: Cystinuria Type 3

Cystinuria Type 3 is a cysteine based, androgen dependent disease which means it only affects entire males. Bulldog breeds are particularly prone to this condition. The veterinary treatment is the same as standard cysteine stones, regarding urohyrdopropulsion, however in order to stop this painful condition from recurring regularly, the only method of prevention is castration. Neutering should be discussed with your veterinarian, and performed at the right time if your dog is a frequent sufferer of Cystinuria Type 3 flare ups.

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If your dog has been suffering with recurring cysteine stones or crystals, consider booking in with one of our team!

Team MPN x  

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