Dog's diet can cause stones

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By Dr. John Koch

Question: I stopped by my veterinarian's office the other day to pick up some medication and saw something I could not believe. The doctor was sitting next to a lady in the waiting room whose dog apparently just had surgery. They were looking at a handful of smooth rocks that had been removed from the dog's bladder. There must have been several dozen of these stones. The largest one was about the size of a quarter. The lady was being told the dog would have to stay on a special diet to keep new stones from forming. How does a dog get stones in its bladder and what does diet have to do with it?

Answer: It is normal for dog urine to have mineral crystals dissolved in it. It is also normal for the urine of a dog to be acidic. As long as the urine stays acid this mineral will generally stay dissolved. If the urine losses its acidity and become alkaline, mineral crystals will precipitate within the bladder and over a period of time grow into stones. Stones or cystic calculi, as they are more appropriately termed, generally require surgery to be removed.

Once cystic calculi are removed, a specimen is sent to a laboratory for analysis. This analysis will determine which food can best prevent them from reoccurring. Food is important in two regards. The amount and type of mineral in the diet can be manipulated to decrease the odds of specific calculi formation. These special diets have one other very important characteristic and this is the ability to keep the urine acid. Maintaining urine as an acid solution is a very important factor in preventing most stones.

Infection within the bladder is one of the chief reasons urine changes from its normal acidic state to one that is alkaline. Frequent urinalysis after removal of cystic calculi is advised for early detection and treatment of these infections.

It is also known that for a short period of time after eating there will be a natural flow of alkaline urine. This normal physiological phenomenon can be circumvented with the prescribed diets. Totally preventing cystic calculi in dogs prone to them may not be possible, but careful management of diet can greatly reduce their incidence.

Dr. Koch is a Cape Girardeau area veterinarian.