Urolithiasis (Native American Indian Dog Type) is an inherited condition of the urinary system in dogs. Dogs with two copies of the associated APRT gene Mutation are predisposed to elevated levels of an insoluble compound called 2,8-dihydroxyadenine (2,8-DHA) in the urine. Increased urinary 2,8-DHA, places dogs at high risk for crystal or stone formation throughout the urinary tract including the kidneys, ureters, bladder, and/or Urethra. Dogs with this form of urolithiasis can present at nearly any age with symptoms of recurrent urinary tract inflammation, which include frequent urination, blood in the urine, and straining to urinate. They may also have loss of appetite, lethargy, weakness, vomiting and pain. Urinary stones in the bladder can cause urinary tract infections or more seriously, blockage of the urethra. In addition, blockages of urine flow at any location in the urinary tract place dogs at risk of kidney damage. Both male and female dogs can be affected, but obstruction of urine flow is more common in males due to differences in anatomy. Not all dogs with mutations in both copies of the APRT gene will have symptoms of disease, though they will have increased 2,8-DHA excretion in the urine. Feeding of a specialized diet may be helpful in preventing stones in affected dogs.