Bladder Stones In Dogs

An urinary stone (urinary calculus, plural: calculi, also known as a urolith) forms when microscopic crystals precipitate in the urinary system. Clinical signs are similar to those seen in dogs and cats with other bladder disorders and include increased frequency of urination, painful urination, excessive licking at the genitals, and occasionally blood in the urine. Increased thirst, increased volume of urine, and urinary incontinence are rarely associated with bladder stones and are more typical of kidney disease and diabetes.

Urolithiasis

The urinary tract stone disease, also known as urolithiasis, urinary stones, urinary calculi, ureteral calculi, or urinary calculus disease, presents itself in dogs in two forms: cystic (bladder) calculi and urethral calculi. Cystic stones are found mainly in females and appear when urinary tract bacterial infection within the bladder causes a shift in the urine pH, which in turn causes the crystals to form. The two most common types of crystals generated are struvite and calcium oxalate crystals.

Struvite Uroliths

Struvite or magnesium ammonium phosphate uroliths are the most common uroliths in dogs. They also may contain a small amount of calcium phosphate or calcium carbonate. Staphylococcus and Proteus are commonly associated organisms. Struvite uroliths may occur in all breeds; howevere, those commonly affected include Miniature Schnauzers, Miniature Poodles, Bichon Frises, and Cocker Spaniels. The high prevalence of struvite uroliths in Miniature Schnauzers and Miniature Poodles suggests that there is a familial predisposition in this breed.

Calcium Oxalate Uroliths

Oxalic acid is widely distributed in nature where it commonly occurs as its insoluble mineral salts. Plants produce deposits of calcium oxalate which is the calcium salt of oxalic acid. Calcium oxalate uroliths are thought to be caused by increased concentration of calcium in the urine which, in turn, is caused by increased absorption of calcium from the gut, a kidney defect, or an underlying disease (for example, primary hyperparathyroidism). Increased dietary intake of oxalate (for example, vegetables high in oxalates, grass, vitamin C) may play a role in the formation calcium oxalate uroliths.

Urethral stones occur in male dogs and are seldom caused by infections; rather a metabolic disease is responsible for crystal formation. Breeds susceptible to bladder infections that can prompt the formation of small stones are boxers, poodles, dalmatians, dachshunds, German shepherd dogs, pugs, and Irish and cairn terriers.

Clinical Signs of Urinary Stones

Clinical signs of bladder stones in dogs and cats include frequent urination, dysuria, hematuria. Radiographs of the entire urinary system are taken to determine if stones are present in the kidneys, ureters (ducts that carry urine from the kidneys to the urinary bladder), bladder (the most common location for urinary stones), and urethra (a tube which connects the urinary bladder to the outside of the body.)

The infection must be treated (usually with an extended course of antibiotics) in order for crystals and stones to dissolve. To increase urination (which reduces the amount of time crystals can form and remain in the bladder), extra salt can be added to the diet. However, if a kidney or heart disease is suspected or present, adding salt is not advised.

Treatment of Urinary Stones

Treatment depends on the size and location within the urinary tract. Stones that become lodged in the urethra require immediate veterinary medical and surgical intervention. These are usually small and enter the urethra from the bladder where they form. They progress down the urethra until they reach a location where the narrow diameter will not permit further passage. A male dog whose urinary tract is completely plugged by one or more stones requires immediate emergency care. Catheterization is performed in an attempt to dislodge the stones pushing them back into the bladder and freeing up the flow of urine. Most of the time, these stones must then be removed from the bladder surgically. Smaller struvite stones or crystals can often be effectively managed only with special diets designed to dissolve the stones.

While urinary acidifiers can be useful, some doctors discourage their use, as the exact dosage that is safe and effective is often not known. If urinary acidifiers are used for short-term acidification, a natural therapy such as cranberry extract might be preferred to conventional medications (such as methionine).

Diet for Dogs with Bladder Stones

Dietary therapy is useful for treating and preventing struvite stones in pets. Since the struvite stones form in urine with a high pH (alkaline urine), diets should help to maintain a low pH (acidic urine). Diets with animal-based protein sources are most important in maintaining an acidic pH (vegetarian or cereal-based diets are more likely to cause and alkaline urine). Homemade diets are preferred for dogs with chronic bladder disorders such as bladder stones. If processed foods must be fed, most holistic veterinarians prefer canned diets, which contain large amounts of water, rather than dry foods.

Important: Before you start to feed your dog or cat a home-prepared diet, it is strongly recommended that you discuss your decision with your veterinarian or a holistic veterinarian. It is essential that you follow any diet's recommendations closely, including all ingredients and supplements. Failure to do so may result in serious health consequences for your pet.

Prevention of Urinary Stones

Because the rate of recurrence is relatively high even after a successful treatment, preventive measures should be taken to help lower the odds, including special diets. To help prevent bladder infections, make sure the dog is given an opportunity to urinate at least every 6 to 8 hours. The longer urine is retained in the bladder, the more likely it is to become alkaline and to develop infection. Provide plenty of clean drinking water to keep the bladder flushed of bacteria and to encourage frequent urination. Cranberry juice (either mixed in with your dog's food or administered to the mouth) stops certain bacteria from adhering to the bladder wall; ascorbic acid is also helpful for acidifying urine, as well as building up the immune system.

Natural Treatments for Pets with Bladder Stones

Other therapies to consider for the pet with bladder stones include Coenzyme Q10, alfalfa (to alkalinize the urine), dandelion leaf, goldenseal, horsetail, marshmellow, plantain, Oregon grape, uva ursi, yarrow and maitake mushrooms. These therapies can be used in conjunction with conventional therapies as needed. The natural treatments are widely used with variable success but have not all been thoroughly investigated and proven at this time. Consult your veterinarian.

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