Primary hyperoxaluria is a rare inherited metabolic disorder affecting Coton de Tulears. Primary hyperoxaluria is characterized by a deficiency in the enzymes that break down the organic compound glyoxylate, a normal part of the metabolic process. As a result, there is an accumulation of oxalate and calcium oxalate crystals, primarily in the kidneys. Affected puppies present around 3 to 4 weeks of life with renal failure due to excessive crystal formation in the kidneys. Symptoms of acute renal failure can include inappetence, vomiting, lethargy, decreased urine production, abdominal pain, blood in the urine and death. Affected dogs typically die or are euthanized within the first two months of life.