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November 2009: Struvite and Calcium Oxalate Urinary Stones and Crystals

B-Naturals Newsletter – November 2009

Struvite and Calcium Oxalate Urinary Stones and Crystals

By Lew Olson, PhD Natural Health

There are a variety of stones and crystals that can affect our dogs. I often get inquiries on how to treat stones when diagnosed during a veterinarian visit. The first question I ask is, “What type of crystal or stones was found?” Each type of crystal or stone is addressed in two very different approaches.

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These are most commonly caused by urinary tract infections. Bacteria in the urine cause alkaline urine (high pH) which creates the perfect environment for struvite crystals to develop. When struvite crystals are found in a urinalysis done at your veterinarian’s office, the next step is to have your vet do a sterile urine culture and sensitivity test. This test is done in house at the vet’s office.  The urine is collected in a sterile manner and sent off to a lab to grow and identify the bacteria that is present. This provides the information on which antibiotic would be the best choice. Usually the antibiotic is given for a month and then another culture is done when the dog has been off the antibiotics for ten days to make sure the infection is gone. Once the infection is gone, the urine returns to a normal pH and the problem is resolved. Keep alert to any symptoms that a UTI has returned.  The symptoms could include frequent urination, blood seen in the urine or pain upon urination. Always take your dog to your veterinarian should any of these symptoms occur.

Diet changes aren’t helpful for this problem, as most often the struvites are responding to bacteria in the urinary tract.

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Calcium Oxalates

These are most common in dogs over five years old and most frequently seen in males. It is common in certain breeds, such as Miniature Schnauzers, Miniature Poodles, Yorkshire Terriers, Bison Frises, Lhasa Apsos and Shih Tzus. It is thought this may be a genetic condition that causes a lack nephorcalin, which inhibits calcium oxalates from developing.

Steroids can aggravate a calcium oxalate former which can create more calcium excretion in the urine. Cushing’s disease may also lead to calcium oxalate stone formation, as the increased cortisol production causes calcium excretion. Other medications to avoid for dogs prone to calcium oxalates besides steroids include furosemid, also known as lasix.

Symptoms can include difficulty in urinating, blood in the urine, inability to urinate in a steady flow or even increased urination. With any of these symptoms, please have a complete check up on your dog by your veterinarian.

Unlike struvites, diet changes can be helpful for dogs prone to oxalates. The primary foods that contain oxalates are grains and vegetables. Since dog foods are primarily grains, the best way to achieve a good diet is to offer a homemade diet. In this way, the ingredients and quality of the foods can be monitored.

Foods to avoid would include barley, corn, brown rice, wheat, soy, most beans, potatoes, sweet potatoes, spinach and nuts.

Foods that can be fed include all meat, dairy (no flavoring or sweeteners, NOT soy based), eggs, Brussels sprouts, cauliflower, white rice, canned pumpkin, and meat and fish broths. Some sources can vary on assessing the oxalate content of food, so compare several lists. Some charts of low oxalate vs. high oxalate foods are listed here:



A good proportion to feed would be approximately 65% to 75% animal protein, and 25% to 35% carbohydrate (vegetables listed above or white rice). Approximate feeding amounts are 2% to 3% of the dog’s body weight daily. On average, a 100 lb. dog would get 2 to 3 lbs. of food daily (approximately 4 to 6 cups), a 50 lb. dog would get 1 to 1 to 1-1/2 lbs. daily (2 to 3 cups) and a 25 lb. dog would get 8 oz. to 12 oz. daily (1 to 1 ½ cups). You would also need to add calcium carbonate, at a rate of about 900 mg per pound of food served.

Calcium can be another issue for calcium oxalate formers.  While it is uncertain whether or not calcium will create problems, it is know that calcium excretion in the urine can form crystals and stones, so it is suggested to avoid foods that are high in calcium.  Additionally, the medications listed above that can cause calcium excretion in the urine should also be avoided. You may add some yogurt or cottage cheese, but only as a small part of the diet, not as main ingredient. You will need to add calcium to diet, but use a calcium carbonate supplement WITHOUT vitamin D. Vitamin D increases the intake of calcium.

A sample diet for a 25 lb. dog for one day (divided into two meals) might be:

¾ cup cooked hamburger

2 eggs

1 tablespoon yogurt

4 oz steamed and mashed cauliflower

Another sample diet might be:

¾ cup cooked chicken breast

4 oz chicken heart

1 tablespoon cottage cheese

4 oz white rice

You may use meat portions for these recipes that your dog enjoys. The same would apply for the smaller ratio of carbohydrate choices. Be sure to use variety foods and avoid getting ‘stuck in a rut’ using the same type of meat or carbohydrate over and over.

Meat suggestions include ground beef, ground chicken, ground turkey, ground pork, baked white fish, beef, chicken, pork or turkey heart and lamb.

Carbohydrates to use include white rice, Brussel Sprouts, canned pumpkin, green peas, white cabbage, zucchini, acorn squash, Bok Choy, melon and egg noodles,  Do COOK (boil, not steam) all vegetables (and the rice) before serving. Cooking is thought to reduce some of the oxalate content, and raw vegetables contain a higher oxalate value on most oxalate food level charts.

Additional supplements would include EPA fish oil capsules, at one per ten lbs of body weight daily, and a B complex vitamin.

Additional Methods to Help Resolve Crystals and Stones

Both struvite and calcium oxalates prevention require having water available around the clock and a moist diet to help flush the crystals. This would include offering water around the clock, giving treats of beef or chicken broth and allowing the dog many opportunities to urinate during the day. All of this helps to flush the crystals and keep the dog hydrated. Holding urine or water can cause increases of crystal formation, leading to stone formation.

B Vitamins are thought to help fight crystal development and EPA fish oil (omega 3 fatty acids) are renal protective.

Treats can be offered in the form of baked liver, hard boiled eggs and jerky treats. Do avoid grain laden dog treats if your dog is prone to calcium oxalates.

Continuous monitoring of your dog’s health in regard to crystals and stones is needed in both conditions to insure your dog is infection free and that stones are not developing.

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Copyright Lew Olson 2009

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