Miniature Schnauzers are one of the dog breeds that has an increased susceptibility to the development of bladder stones. Other dog breeds with an increased risk include: Miniature Poodles, Bichon Frise, Shih Tzus, and Yorkshire Terriors. Notice that these are smaller dogs and they are more likely to produce oxalate stones, but they are also gaining popularity so vets are seeing these more often in practice which could make it look like they are more susceptible. Larger dogs may have a genetic advantage, or may actually be more likely to have more exercise outdoors with more opportunities to urinate which also helps decrease the development of bladder stones. Either way, if you have a dog (and especially a miniature schnauzer), this blog entry should be good information for you.
Understanding Bladder Stones and Development:
Bladder stones are a fairly common occurrence in domestic animals such as dogs and cats. For simplicity, we can think of urinary crystals as minerals, and a concentration of these minerals into a mass becomes a bladder stone. The stones form in the urinary bladder and can vary in size and number secondary to infection, dietary influence and genetics.
Stones can form in any part of the urinary tract in dogs but unlike in humans, kidney stones are less common and do not often cause significant disease although they can contribute to infected kidneys and chronic renal (kidney) failure. Types of bladder stones include struvite, calcium oxalate, urate, cystine, calcium phosphate and silicate. Since struvite and calcium oxalate stones are by far the most common, that is what I will elaborate about here.
Is this an Emergency?
It can be. Remember that dogs always need to be able to urinate. If the tubes from the kidney to the bladder or from the bladder to the urethra are blocked by a stone, your dog’s health will deteriorate rapidly. Remember that dogs rely on urination to regulate their body’s water and electrolyte balance. The ability to urinate is critical to maintaining their proper blood acidity and in eliminating the waste products of metabolism. The biggest crisis occurs in male dogs that have a bladder stone enter the ureter that gets stuck — if you have ever heard of a man going through the pain of passing a stone through their urinary tract, you might already know that this is often described by men as an excruciating experience.
For a dog, if this blockage lasts more than even just a day, one of their electrolytes (potassium) that is normally excreted through urine can reach dangerously high levels which then effects the heart rhythm and function. Obstructed dogs will become depressed, weak, and they often experience nausea and vomit. If partially or fully obstructed dogs are left untreated, the abnormally high pressure of urine behind the obstruction can rapidly destroy their kidney function.
So prevention is always the best medicine!!
Symptoms in Your Dog with Possible Bladder Stones:
Symptoms of dogs with bladder crystals or stones include straining to urinate, dribbling urine, urinating only drops or small amounts at a time, depression, vomiting, or blood in the urine. A check-up for these symptoms is strongly recommended and should include a palpation of your dogs bladder, urinalysis and a lab culture of the urine. Urinalysis will determine if there are red blood cells and/or white blood cells in the urine and the culture will determine what kind of infection (if any) is present for the right medication to be recommended. The lab culture is very important since if the wrong antibiotic is given, an infection will continue to harm your dog. If crystals are seen in the urine or stones are suspected from palpation and/or an x-ray of the bladder, this will also determine the best treatment choices.
As one of the readers of this blog mentioned in a question to me earlier, statistics seem to show that calcium oxalate stones are most common in male dogs and struvite stones are most common in female dogs. I believe that both male and female dogs are very sensitive to dietary and lifestyle factors that will produce various stones, so it’s good to work with prevention of either in either your male or female dog. These 2 types of stones account for approximately 80-90% of the bladder stones found in dogs, so it’s a good idea to know what to watch for.
These stones only form in urine that is acidic (pH is less than 7). Dogs love meat and meat is acidic. Ideally, you will want to keep your dog’s urine between 6.6 and 7 (best range varies slightly between veterinarians but oxalate stone problems seem to be associated with dog urine pH that is less than 6.5). Too basic urine (pH more than 7) has its own challenges. Urine pH is a test that you can easily perform at home using urine dipsticks or colour-indicator strips of paper that you can find in health food stores and/or pharmacies. Urine pH varies during the day. The best sample to check is from the first fresh urination in the morning before he/she eats anything. After your dog has eaten breakfast, their urine pH will begin to rise from his/her nighttime levels. Now “catching” the urine is the challenge! If you wear a plastic/disposable glove, you can just try to aim your dipstick or paper in the stream of your dog’s urine to “catch” a sample and stay clean while doing this! If you need to bring a sample to your Vet for analysis, this was an interesting suggestion I read from a Vet’s site: the urine sample should be free of contamination, refrigerated or chilled and brought to the Vet as quickly as possible. A foam cup, taped to a broomstick helps in collection. You do not need much — a tablespoon full will do. You can also attempt to get your dog to pee on a layer of Saran Wrap and transfer what you can to a cup. Cover the sample with a (new) piece of saran wrap held in place with a rubber band or ask your Vet for a urine collection vial/cup prior to collection. If you are monitoring your own dog’s pH, you may not be successful in keeping his/her pH within the ideal range, but it seems that dilute urine is better than concentrated urine for health!!! This means that it is more important to keep your dog’s urine dilute than to raise his/her pH.
Things You Can Do for Prevention or Bladder Stone Management:
1. Increase Water Intake!!
Increased water consumption leads to dilute urine! From what is known about calcium oxalate, it is very unlikely to crystallize into discrete, urinary tract stones when a dog’s urine is dilute – even if oxalates are present at the time. There are several ways to increase your dog’s water intake including feeding him/her only home-cooked diets as they are higher in water content, or using only frozen or canned foods. Increasing salt in a dog’s diet will encourage drinking fluid (though I’m not sure that this is an ideal choice) and in some cases, diuretic medications may be prescribed which encourage frequent urination and likely, increased thirst (again, not my first choice, but necessary in some cases).
Do not attempt to increase your dog’s water intake by pouring water on dry dog food in hot weather or when the food will stand for more than an hour. Bacterial growth in the mixture can cause digestive upsets. The same can happen if you leave opened canned food at room temperature for long periods.
Dogs also need easy access to fresh and clean water throughout the day and multi-dog families should have multiple bowls available. Since the most important thing you can do to prevent urinary stones from developing or recurring in your dog is to keep him/her well hydrated and to ensure their urine is as dilute as possible, this should be monitored as well. The dilution of urine is monitored through something called “specific gravity.” The lower the specific gravity, the more dilute the urine sample is. Aim to keep your dog’s specific gravity below 1.025. Urine dipstick strips can help determine specific gravity, but a device called a refractometer is quite specific to accurate readings of specific gravity. Although I have not used this device, I understand that it is not a difficult tool to use and I would especially recommend getting one for anyone who has a dog with a history of oxalate stones.
2. Frequent Opportunities to Urinate
Dogs that are free to urinate when they wish appear to be less susceptible to oxalate stones than dogs that need to wait for their owners to return from long hours away from home. This is not possible for many dog owners, but fewer urinations have been found to be associated with greater risk for oxalate stone production.
3. Frequent Feeding
The acidity (pH) of your dog’s urine fluctuates through the day. it is usually lowest through the night and slowly rises after his/her morning meal. Thus, having many chances to munch during the day should give your dog a less acidic urine which would be less conducive to oxalate stone formation. Give your dog his/her last meal shortly before you go to bed. Just make sure the total amount that you feed your dog does not increase since weight gain has it’s own health issues/concerns associated.
4. Periodic Blood Work
It is always important to check standard blood chemistry panels at your Vet’s office from time to time. This is especially true when oxalate stones remain in your dog’s kidneys or when there was any prior elevation of “BUN” (blood urea nitrogen) or creatinine levels (both measure kidney function). There are some dogs that develop oxalate stones because their blood calcium levels are abnormally high (hypercalcemia) and some of these dogs have underlying hyperthyroid concerns.
5. Radiographs (X-Rays)
Periodic x-rays are useful for detecting new stones that may form and in determining the size, growth and position of stones that have not been removed. When stones are discovered early, it may be possible to remove them from the bladder through a process called “urohydropropultion” or to extract them in what’s called a retrieval basket through the urethra or a small abdominal and bladder incision.
Medications for Oxalate Stones:
Veterinarians have traditionally given potassium citrate solutions to dogs with oxalate stones. The thought is that when the citrate passes to the dog’s urine, it will tie up the urinary calcium which would make it unavailable for calcium oxalate formation. It is also hoped that the citrate will keep the urine less acidic. Studies show conflicting results about the usefulness of this treatment. We do know that to have a continuous effect, postassium citrate would have to be given many times during the day; or it might be best to give the whole daily dose at bedtime since night time conditions are the most conducive to stone formation.
Hydrochlorothiazide is often used to make a dog thirstier and to urinate more, but I wouldn’t recommend this diuretic choice unless significant dietary changes and increased fluid intake measures have failed. If your dog is on a thiazide diuretic like hydrochlorothiazide, please monitor their electrolytes regularly (an imbalance can be created which can lead to what could have been an avoidable emergency).
Special diets will not likely dissolve calcium oxalate stones that have already formed. But dogs that have had an episode of calcium oxalate bladder or kidney stones do have special needs. They shout NOT be fed dry dog food again and they should NOT eat a diet that contains plant products that are high in oxalates.
Many foods can be purchased from your Vet that have been designed (theoretically) to reduce the formation of calcium oxalate tones. They are formulated to provide as little dietary oxalate as possible, provide no more than the necessary amount of calcium and they attempt to keep your dog’s urine pH and specific gravity in acceptable ranges. You still need (or should) monitor through urinalysis if these foods are producing the desired results for your dog. If they are not, I would suggest you think of making meals for your dog yourself. Mini Schnauzers are not big dogs, so you don’t need to make a lot of food (although I make larger batches and freeze containers for use through the week), and I have to say that if you have a bigger dog (schnauzer or other) I would still encourage making your own dog food for the health benefits for your furry family member… but that is a whole different discussion. This is the only way that you can truly know what is going into your dog. I am of the opinion that a dog’s diet should be based on meat (although I do know of some friends that have significantly improved their dog’s health through using purely vegetarian diets). If your dog has a risk for an oxalate stone, use moderate amounts of low-oxalate vegetables, and do add supplements such as vitamins and minerals (but ask a holistic practitioner for amounts that would be best for your dog). There is contradictory information about benefits of protein restriction for the prevention of calcium oxalate stones.
Low amounts of calcium in your dog’s diet will increase their chances of forming calcium oxalate stones. They can benefit from some calcium in the diet to bind oxalate in the intestines. This helps reduce the amount of oxalate being absorbed by the body, so stones are less likely to form. Calcium-rich foods (low fat cottage cheese for example) or the supplementation with calcium-citrate may be helpful. Oxalate is an end product of Vitamin C (ascorbic acid) metabolism. Large doses of Vitamin C may increase the amount of oxalate in your dog’s urine, increasing the risk of oxalate stone formation. Small amounts found in foods or some supplementation should not be a concern.
Foods to avoid/restrict if your dog has a history of oxalate stones: high-oxalate foods include beets, spinach, rhubarb, swiss chard, strawberries, nuts (almonds, peanuts and their butters are quite high in oxalates) , organ meats (like liver – because much of the oxalate formed in the body is produced in the liver), wheat bran, buckwheat, miso, tahini, and all dry beans (fresh, canned, or cooked), excluding lima and green beans (which are safe).
Do not feed your dog products that contain soy or yellow corn or ingredients that are derived from soy or corn. Soybean and corn-derived products have the potential to be very high in oxalates. Many pet foods – both dry and canned are full of yellow corn products and corn gluten isolates to boost the label’s protein content. Besides being potentially high in oxalates, corn glutens have the potential to also increase the acidity of your pet’s urine.
Safe foods: these would be the low-oxalate foods such as cabbage, broccoli, cauliflower, cucumbers, endive, water chestnuts, peas, coconut, flax seeds, sunflower seeds, asparagus, lima beans, canned pumpkin, apples, apple sauce, bananas, lemon juice, melons, nectarine, pear, papaya, oat bran, white rice, wild rice, red meat, chicken and turkey.
The internet has many resources of food lists of high and low oxalate foods so my lists above are a general idea of safe/unsafe foods. For the lists you might find on the internet remember that suggestions might differ from one site to another and most lists are for humans (so do think carefully if the “safe” foods/low-oxalate foods are really safe for your dog).
Also note that boiling high-oxalate foods and then discarding the water used to cook them greatly reduces the amount of absorbable oxalate in vegetables and grains 🙂
Every day do something that will inch you closer to a better tomorrow.