Struvite Stonesstruvite stones

Struvite crystals only form when the pH (acidity/alkalinity) of urine is over 7 — if you’ve read about oxalate stones you will understand what a narrow range we have to try to keep our dog’s urine within for best health!  Pharmacies and health food stores sell urine dip sticks that check for this.  The strips can also check for blood in the urine, bacteria, glucose (sugar), specific gravity (concentration of urine).  The urine tested should be the taken first in the morning before any ingestion of food and checked within 5 minutes of collection.  Only a few drops of clean urine are required — you can try the suggestions for urine collection I have mentioned in my post about oxalate stones or you could tape a dipstick to a wooden stick and dangle it below your dog as he/she urinates.  This is the trickiest part since your dog will be unsure what you’re trying to do and is not likely used to you standing so close as he/she urinates!  But keep trying!!  🙂

Struvite bladder and kidney stones are also called triple phosphate stones, infectious stones and urease stones.  They are made of magnesium, ammonium and phosphate.  These stones are most common in Miniature Schnauzers, Cocker Spaniels, Beagles, and Dachshunds.  These stones occur when your dog develops a chronic urinary tract infection – or “cystitis” with certain bacteria that have the effect of making the urine less acidic.  These bacteria have the ability to convert urine into ammonia because of a certain enzyme that they contain called “urease.” The most common bacteria that do this are Staphylococcus, Proteus and Klebsiella bacteria.  Ammonia in the urine changes its odor.  Ammonia is also toxic to bladder cells and causes the urine pH to shift detrimentally toward stone formation.  Once the stone formation process begins, the bacteria live within the stone itself where they are protected from the dog’s natural defenses and the effects of antibiotics.  These stones are rough (as in above picture) causing abrasion of the lining of the bladder and leading to discomfort as well as blood in the urine.  They can grow quite large and the size alone might limit the amount of urine the bladder can hold causing a frequent or continuous need to urinate.

The troublesome bacteria normally reside in the bowel where they cause no problems but when they move up the urethra and into the bladder, the body has few ways to control them.  Because the urethra of females is much shorter than males, this condition is often seen in female dogs.  Constipation can also predispose the body (humans or dogs!) to cystitis as the bacteria working on fecal matter in the colon can become more numerous and spread to other areas in the body.

Many dogs with bladder stones show very few symptoms.  A Veterinarian can often discover these stones through palpation of the abdomen of dogs during a routine physical exam.  But most owners will notice an increased frequency and straining from their dogs or an abnormally pink/red urine.  Some dogs will itch and/or scoot along their bottoms.  Occasionally, dog owners will find small pea-sized stones on their carpet.

To determine if the stones are struvite, they must be analyzed by a lab, although the pH of the urine of the dog will be a strong indicator of the type of stone.  Bladder and kidney stones are porous and bacteria living inside them are very safe from antibiotics.  Of critical importance in treating struvite stones is an antibiotic sensitivity test of the bacteria found in the dog’s urine.  This is the only way that the proper antibiotic and dose of the antibiotic can be chosen for the dog.  The best suggested plan of treatment that I’ve come across is to give the antibiotic for at least one month — and best to see that x-rays show no remaining stones.  Some even suggest that antibiotics should be given for one month after x-rays show no remaining stones to help prevent a new occurrence anytime soon.

In some cystitis cases, a “broad spectrum antibiotic” may be prescribed for an extended amount of time but although this will protect against many different bacteria in the short term, the long-term resistance to many bacteria is significantly reduced for the pet (as in humans!).  So if your dog has had their first struvite stone, please do not jump on the use of broad-spectrum antibiotics to prevent the time/effort/cost of determining which antibiotic would be best suited to your dog’s needs at the time.  The broad-spectrum antibiotic would best be saved as a “back-up” treatment for recurrent cystitis situations.

Other factors that can increase a dog’s susceptibility to struvite stones include:

Not drinking enough water:  The specific gravity or dilution of your dog’s first-morning urine should be 1.018 or lower.  Some urine dip sticks test specific gravity but they are not very accurate.  Better is a tool called a refractometer — which looks and sounds complicated, but is not.  Urine specific gravity is stable so the urine can be kept cool and tested when it is convenient.  A less accurate but somewhat useful way is to just look at the colour of your dog’s urine.  The less intense the yellow colour, the better!

Urine too alkaline:  Remembering that struvite crystals only form when the pH of the urine is over 7 (alkaline).  Check your dog’s urine with a dipstick every so often — maybe once a month or once every few months if you are getting good readings.  Remember to test first-of-the-morning urination and test pH within 5 minutes of collection.  You can tape a urinary dipstick to a wooden stick and dangle in below the dog as he/she urinates.  A less accurate but also somewhat accurate measure can be taken on litmus paper which is available in many craft stores.  Diets very high in grain and vegetables produces alkaline urine which allows the formation of struvite stones — this is when a commercially prepared diet may be more useful.  If possible, feed the canned form of the diet instead of the dry since most dogs rarely drink enough water after eating dry kibble and the canned foods will contain more moisture/water content.  But make sure you take time to brush your dog’s teeth regularly in these cases as canned foods are linked with more dental concerns.

Occasionally, bacterial infections in dogs are due to an anatomical defect in the dog causing urine pooling in the kidneys, ureters or bladder where bacteria can live.  Sometimes these are genetically inherited defects or caused by prior surgery such as spaying.  A contrast-dye x-ray study would detect such defects but such a study would not likely be performed unless standard treatments fail.

The average age when dogs develop struvite bladder stones is about 2 to 3 years.  So what can you do to help prevent these?   Try these ideas:

1. Increase fibre in your dog’s diet through things like raspberries, brown rice, green leafy vegetables, apples, pears, carrots, broccoli, beans, legumes and flax seeds.raspberries

2. As with prevention of any bladder stones, increase your dog’s water intake!  Either keep his/her food moist (home-made foods contain more moisture than dried kibble), or encourage your dog to drink from his/her water dish regularly.  Always have a fresh water dish available for your dog to drink from through the day (even if no one is home) and have several dishes available if you have more than one dog.

Soccer/Football Caesar3. Exercise your dog daily!  Exercise seems to help prevent cystitis.  Female dogs that are overweight also have an increased risk of cystitis because the vaginal area remains damp between voiding which allows bacteria to survive for longer.  (note that dogs that are spayed too early will often have infantile vaginas that will make them more susceptible to cystitis).  So make sure your dog has regular exercise daily to help prevent weight as well as bladder concerns!  Think about a minimum of 30 minutes of continuous moderate exercise per day but aim for one-hour of moderate exercise per day — this will be good for both the pup and human!

4.  Nutrition:

Specialty Diets: are formulated to maintain proper urine pH.  With time, these diets are often sufficient to dissolve struvite crystals.  If one brand doesn’t work, try another since each dog handles foods differently and a different brand of food might be more useful for your dog than the one that worked for your friend’s dog’s bladder stones.  Some of these diets are not recommended for indefinite use because they are so low in mineral content.  Some have been reformulated to help prevent oxalate crystals as well.  Despite labels warning against long-term use of these diets, in some cases there is little choice but to continue with long term feeding to save a pet’s life.  Since some of these diets are very high in fat, Miniature Schnauzer owners especially (and several other breed owners) need to be particularly sensitive to this information since prolonged intake of high fat can lead to pancreatitis which is a predisposition for this breed (see pancreatitis post I wrote earlier).

Proteins do acidify urine — safe choices include  turkey, chicken, beef and rabbit — note that shellfish (shrimp, crab, lobster, scallops) are contraindicated and thus, NOT safe for the prevention of stones.  Removing grains from the diet seems to help prevent infections.

Adding cranberries (fresh or frozen) to your dog’s diet can aid in acidifying the urine.  Adding Vitamin C to your dog’s diet can be very useful for preventing cystitis to begin with, so this can be a useful option, but too much vitamin C in the diet has been linked in the production of oxalate stones!  So find out the best dose for your dog through a qualified Holistic (if possible) Veterinarian.

One of the dangers of putting your dog on a specialty diet which helps reduce struvite stones is that the size of the stones reduce so much that they pass into and block the urethra — so one must always be on the lookout for a sudden inability to urinate.  Ironically, diets that help prevent/treat struvite stones by making the urine more acidic can lead to the other type of stones commonly found in dogs with an overly-acidic urine (oxalate stones) — ah, pH strips are wonderful for helping you keep your dog’s urine in a healthy range whenever possible.  Especially important to monitor pH regularly if your dog has had a history of bladder stones of any kind.asparagus

I have to tell you that Traditional Chinese Medicine would encourage the use of barley for kidney health as well as celery andasparagus.  If my baby had stones, I would certainly want to increase his intake of these ingredients.  Since he’s good right now, I believe I will add even more of these helpful ingredients into his home cooked meals to encourage prevention!  I hope this has encouraged you to do something new/different and helpful for your dog(s) too!

Remember: “An ounce of prevention is worth a pound of cure.”
— Benjamin Franklin


Dr. Menen



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