Melamine- and cyanuric acid-associated renal failure in pigs in Thailand

A newly observed syndrome characterized by progressive weight loss, pallor, and high mortality was reported in many swine herds across Thailand from February through May 2007. To determine the cause of the new syndrome, 5 pigs, 4-8 weeks of age, were submitted to the diagnostic laboratory for necropsy examination. All 5 pigs were underweight, with pallor and rough coats. The kidneys of all 5 pigs were yellowish and slightly swollen, with precipitation of crystalline material on the cut surface. Histologically, epithelial degeneration and necrosis were evident in proximal and distal tubules and collecting ducts. Round, yellow-brown crystals with radiating striations were diffusely distributed through the lumen of proximal and distal tubules and collecting ducts. Blood urea nitrogen and creatinine levels were elevated. Melamine and analogs, including cyanuric acid, were detected by gas chromatography mass spectrometry. The evidence reported here suggests that melamine- and cyanuric acid-adulterated feed caused renal failure in these pigs.