The study on heritability of calcium oxalate urinary stones in Miniature Schnauzers met with great success. We met our goal with over 100 dogs enrolled in the study; half were affected by calcium oxalate stones while the other half were older stone-free dogs. Through pedigree analysis, we determined that the most likely mode of inheritance is autosomal dominant, though other types of inheritance are still possible. DNA extraction has been completed on all samples to date, and the DNA is being stored at the University of Minnesota Canine and Equine Genetics Laboratory. This DNA will be used in a future genome wide study to determine the genetic basis of calcium oxalate stones in Miniature Schnauzers. One surprising finding of our study was an very high prevalence of bladder stones in older Miniature Schnauzers with no history of stones or urinary symptoms. Of the dogs screened as controls for the study (all over 8 years old), 21% were identified to have stones visible on abdominal X-rays. This prevalence is dramatically higher than the all-breed prevalence of 0.3 – 2% reported in veterinary literature. We plan to report this finding to the veterinary field to improve awareness of the common nature of this problem. The high prevalence also stresses the need for further investigations into the genetic basis of this disease.