The mystery of how two chemicals that are considered non-toxic but have poisoned so many pets may have been solved.
The breakthrough was made at the prestigious Ontario Veterinary College at the University of Guelph in Ontario, Canada.
Scientist Perry Martos mixed together a few drops of melamine and cyanuric acid, the two unauthorized chemicals found in tainted pet food.
In less than a second, they formed a mass of crystals nearly identical to crystals found in the kidneys of sickened animals.
"If you can imagine an instantaneous kidney stone — that's essentially the way I would perceive it," says Martos.
Dr. Kimberly May of the American Veterinary Medical Association says the discovery could end up saving the lives of animals that eat the tainted food. It's very possible that the crystals that are formed may be dissolved by altering the medical treatment somehow, and that is being investigated.
Meanwhile, the Chinese government reportedly has made one arrest in the contamination case. It's believed the chemicals were added deliberately as a cheap substitute for real protein.
In Washington, the Senate voted unanimously to standardize the nutrition labels on pet food and to fine pet food makers who don't report problems right away.
These discoveries come as Menu Foods recalled yet another batch of its products. Menu Foods said the recall was due to possible cross-contamination between melamine-tainted products and other foods made in the same period.
The expansion includes cuts and gravy pet food, as well as other products that were not made with the contaminated wheat gluten supplied by ChemNutra Inc., but were manufactured during the period the chemical-laced gluten was used.
The company based its decision on study results that revealed cross-contamination, as well as one report from a customer.
The recall now includes additional pet food products in the United States, Canada and Europe. It also expands the date ranges of previously recalled products to match the period that melamine-tainted wheat gluten was used in manufacturing plants.
Menu estimates that the additional items added to the recall represent less than 5 percent of all products already recalled or withdrawn.
More than 130 brands of pet food have been recalled since March 16 because they were contaminated with melamine. An unknown number of dogs and cats have been sickened or died after eating chemical-laced pet food.