There may be an economical boom in China, but do cheap products respect consumers' life? After toxic compounds were found in Chinese toothpaste and so-called "herbal drugs", now the cause of the toxicity of pet food brought from China has been explained by an UC Davis team in a research published in the Journal of Veterinary Diagnostic Investigation: a deadly combination of melamine and cyanuric acid causes kidney failure in cats and dogs.

The two chemicals were encountered in about 60 million packages of recalled pet food in March, 2007.

Melamine is an organic base derived from coal and used in plastics, resins and fertilizers, relatively harmless on its own, while cyanuric acid is employed in swimming pools to slow the decomposition of chlorine. When mixed, the two chemicals form crystals in the animal's liver and kidney, killing it. The two are illegally added in China to wheat and rice gluten to increase nitrogen amounts, used as an indirect indicator of protein content. Until now, this combination has not been checked for its toxicity.

"There were no published reports of toxicity studies examining the combined effects of melamine and cyanuric acid in any animal species," said lead researcher Birgit Puschner, an associate professor of Veterinary Toxicology.

Autopsies made on cats fed with this kind of pet food showed kidneys clogged with crystals.

"The crystals seemed to cause an obstruction in the kidney leading to damage and inflammation. It will make any future diagnosis much more straightforward." said Puschner.

An University of Iowa team carried on a similar research on pigs.

By knowing the exact chemical combination, imported pet food will be better screened. The finding has also great importance in veterinary medicine.

"The results will help veterinarians better diagnose the causes of kidney failures in cats." said Puschner.