All along, experts were saying that they didn't think Melamine alone could do the kind of damage they were seeing in animals. Apparently, there are other toxins involved:
http://www.pittsburghlive.com/x/pittsburghtrib/news/s_503671.html"Researchers also have identified three other contaminants in the urine and kidneys of animals sickened or killed after eating the recalled foods, including cyanuric acid, a chemical commonly used in pool chlorination, three researchers told the Pittsburgh Tribune-Review. Cyanuric acid is what most likely sickened pets, one researcher said."