Urinary stones in dogs

Overview

Most of the time, the minerals contained in the food a dog eats and the water he drinks pass from his body when he urinates. Sometimes, though, those minerals clump together and form stones in the bladder, urethra, or kidneys. These stones can irritate the urinary tract and, if they grow large enough, can partially or even totally block the flow of urine from the dog's body. Urinary blockage is a medical emergency that requires immediate treatment by a veterinarian, but all urinary stones need a vet's attention.

Symptoms

• Frequent urination
• Straining to urinate
• Urinating in inappropriate places
• Small amounts of urine with each urination attempt
• Blood in the urine
• Loss of appetite
• Lethargy or depression

Prevention

Any breed or mix can develop urinary stones. However, certain breeds of dogs are genetically predisposed to developing certain types of stones. Among these susceptible breeds are Lhasa Apsos, Dalmatians, English Bulldogs, Miniature Schnauzers, Newfoundlands, and Bichon Frises.

To some extent, stone formation may be prevented by making sure a dog has enough exercise, has free access to clean water, and gets plenty of opportunities to urinate (at least three times a day, preferably more). Some veterinarians also believe that giving a dog filtered water can help prevent the formation of certain types of stones, because the minerals that cause the stones to form are removed in the filtering process.

Treatment

Treatment of urinary stones depends on that type of mineral(s) that are forming the stones, the sizes of the stones, and the effect the stones are having on the dog.

To diagnose stones, the veterinarian will want a urine sample to see whether stone-forming crystals are present and, if so, to determine what minerals make up the crystals. He will also probably perform a bacterial culture to see whether an infection is present in the urine. Urinary infections can predispose a dog to forming stones and can prevent complete resolution of the problem if left untreated.  In addition, he may perform an X-ray to pinpoint exactly where the stones are located as well as determine how large the stones are. Depending on what he finds, treatment may consist of one or more of the following options:

• Surgery to remove the stones, particularly if they are causing a blockage or are extremely large or numerous;
• A commercial prescription diet that's designed to dissolve the stones (this generally takes several months and does not work for all types of stones);
• Antibiotics to combat any infection;
• Medications to combat specific types of stones, such as potassium citrate for dogs with stones made of calcium oxalate.

Post-treatment

Post-treatment of urinary stones focuses on preventing recurrences. The veterinarian may prescribe a commercial diet designed to prevent stone formation, or simply a low-protein diet that prevents the formation of uric acid.  Periodic urine cultures and examination of the urine may be needed in your particular dog's case.  Owners should also make sure their dogs receive enough exercise, water, and opportunities to urinate.

References:

Kahn, Cynthia M., ed. Canine Urolithiasis.  The Merck Veterinary Manual, Ninth Edition

McCullough, Susan: Housetraining for Dummies. Wiley, 2002.

Miniature Schnauzer Club of America, An Owner's Guide to Canine Urolithiasis (based on information provided by Hills Pet Nutrition, Inc.).

Primovic, Debra: Urolthiasis in Dogs. PetPlace.com.

Warrak, Alexander El: Urolithiasis (Urinary Stones). American College of Veterinary Surgeons.