Cystine stones in dogsCystine stones in dogs

Cystine stone analysis is becoming more and more common as we learn how to test for and treat these uncommon but potentially very serious stones in dogs and cats. They account for less than 1% of kidney or bladder calculi, yet they cause a disproportionate number of deaths due to the difficulty in treating them. Unlike struvite crystals that are usually seen with urinary tract infections or ammonium biurate crystals typically associated with ruptured bladders, cystine crystals are not affected by infection or inflammation. The formation of cystine stones requires insufficient water consumption (usually due to previous episodes of acute blockage) combined with insufficient urine production over time resulting in an increased concentration of cystine in the urine. The dried urine then acts as a nidus for stone formation, and therefore recurrence of cystine stones is high unless they are treated.

When cystine crystals precipitate out of solution they can bind together to form a visible mass that may be seen by your veterinarian during an ultrasound exam or filling the bladder with contrast material for radiographs (x-rays). A urinary pH greater than 8.0 typically inhibits cystine crystal growth and precipitation (the reason for this is not known) so keeping your pet’s urine alkaline will make it difficult for these stones to form. This can be accomplished by feeding less protein and salt and supplementing sodium bicarbonate, which creates more alkaline urine. These steps alone will not dissolve preexisting stones, but they make the pet much less likely to form new ones and can help decrease urinary tract infections that contribute to cystine stone formation.

Treatment options for cystine stones

Treatment of cystine urolithiasis is a challenge due to their resistance to dissolution and recurrence once formed. Before a diagnosis is made, it must be determined if the size of the crystals being passed warrants intervention by your veterinarian. If so, your pet may benefit from one or more procedures designed to break up or remove stones from the urinary tract before they pass into the urethra and possibly cause serious damage. Cystotomy (surgical incision into the bladder) is required to achieve these goals, but it is important that your cat or dog be adequately anesthetized before the bladder is opened because irritation from urinary leakage can lead to development of cystitis (inflammation of the bladder).

Treatment options for cystine stones
Treatment options for cystine stones

Once a diagnosis has been made, dietary management is first-line therapy. Feeding a diet designed for pets with calcium oxalate stones will decrease urine calcium and increase urine volume, both of which help prevent new stone formation. Feeding a food that contains moderate amounts of protein and salt as well as sodium bicarbonate supplementation may help dissolve existing stones. In some cases, dissolution diets are started immediately after surgery as a means to buy time until more definitive measures can be taken.

In cases where stones cannot be dissolved, but cannot be removed safely either, a percutaneous nephrostomy tube may be inserted in the kidney to bypass any blockages and allow drainage into a plastic bag that can be emptied periodically. This procedure must be carefully monitored to ensure that the cat or dog does not develop an infection from leakage of urine back up through the ureter, which is why it should only be performed under general anesthesia. In cases where medical management is considered too risky or there are too many stones for dissolution diets to help, urinary diversion surgery may become necessary.

In cases where surgical treatment has been unsuccessful in removing all calculi (stones), a more permanent solution such as a cystotomy with a pyeloplasty or a cystotomy as a component of a ureterostomy (surgical creation of an opening from the urinary tract to the outside) can be considered. These surgeries divert all urine flow away from the affected kidney and out through another tube into an externally attached bag or catheter with no possibility for back up into the system.

While medical therapy is often successful in resolving cystine stones, they occasionally need additional help either from surgical removal or urinary diversion surgery

What can I feed my dog with cystine stones?

Can’t afford much. I can tell you that cystine stones are extremely rare, so much so that many vets don’t even know about them. My vet was very much in the dark but he is learning. Your dog needs to be on a low protein diet (no red meat), no corn, rice or anything like potatoes/sweet potatoes. You can feed her any veggies and fruits, lean proteins such as eggs and poultry, maybe some fish but stay away from fatty meats like pork. But most importantly, he needs to be drinking A LOT of water!!! At least 50 ounces a day, if not more. Good luck!

Can cystine stones be dissolved dogs?

Yes, there are many products that dissolve or break down uroliths. Some are harsher than others with side effects. Epsom salts is the mildest and safest to use. Feeding a healthy low protein diet may help too. There are lots of safe foods you can try. Good luck! 🙂

What food causes bladder stones in dogs?

Most commonly in dogs it is due to bacteria. You can feed any food you want to prevent bladder stones, but it is also important that the dog drinks plenty of water so they are not dehydrated. Make sure they have access to clean fresh water at all times! If the bladder becomes damaged from crystals or stones over time this will cause kidney failure. It is important to keep the bladder clean, and if they develop stones you can feed low protein foods like rice and chicken, or you can use any medication that uroliths (stones) dissolve in the bladder. However this should only be used as temporary measure until it completely resolves itself.

Cystinuria (cystine stones in dogs)

Basics: Cystine stones are rare in the general dog population.  They form in dogs with cystinuria, an inherited defect of amino acid metabolism that leads to recurring urine stasis and infection, high concentrations of cystine (an abnormally large amount of a normal amino acid), and formation of urinary calculi (stones).

My dog has cystinuria and I was wondering what kind of diet would help dissolve the stones?

A: My preference is to put pets on a species-appropriate, low-protein renal food which is much easier on their system than trying to feed them human foods. There are also some veterinary prescription diets that can be useful. For dogs with cystinuria, I would recommend trying C/D or SD canned renal food , or B/D dry renal diet . If you have questions about other options that may work for your dog, please feel free to call us at 1-800-213-6740 and we’d be happy to help you.

Are cystine stones dissolvable?

Are cystine stones dissolvable?
Are cystine stones dissolvable?

A: I can’t say for sure without knowing what kind of stone your dog has. Some types of cystine stones are more likely to dissolve than others. Minerals or crystals that aren’t stones (such as struvite and calcium oxalate) do not require a special diet and will often dissolve if given enough time. We often recommend a low-purine diet for pets with stones, as purines can increase the amount of uric acid in your pet’s urine. If you have any questions about what type of stone your dog has or what diet is best for them, please feel free to call us at 1-800-213-6740 and we’d be happy to help you.

What type of food can dissolve cystine stones?

A: There are many types of urinary diets that dissolve or prevent stones, but most artificially acidify the urine. Please see our handout on diet for more information on this topic. A low protein renal diet with modified calcium is always my preference in cases where there is any pre-existing renal disease, but there are many choices that may work for your pet. If you have questions about other options that may work for your dog, please feel free to call us at 1-800-213-6740 and we’d be happy to help you.

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