Research Biologist, Center for Veterinary Medicine
Food and Drug Administration
Made the scientific breakthrough to identify the cause of the largest pet food recall in history and is currently conducting critical research to guarantee the safety of imported foods.
2007 was the “year of the recall.” More than 30 million pounds of ground beef were recalled due to E. coli contamination. Over 320 million pounds of peanut butter were called back due to Salmonella. Millions of toys from China were recalled because they had lead paint. When hundreds of pets in the United States died, the Food and Drug Administration (FDA) issued the largest pet food recall in history. Dr. Renate Reimschuessel of the FDA was asked to investigate the cause of these illnesses. Within weeks, she discovered exactly why so many animals were getting sick, a discovery that is improving the safety of imported foods for both animals and humans.
The preliminary analyses of the dogs and cats who began dying in late 2006 revealed that they were developing crystals in their kidneys and dying from renal failure. The problem was scientists couldn’t understand why. Some suspected the problem might be melamine, a chemical commonly used to make plastics, which was found in the recalled pet food. But most experts considered it non-toxic, so investigators focused on other possible causes.
Dr. Reimschuessel was eventually brought in to assist in this investigation. During her review of the scientific literature, she noticed instances where melamine was causing small changes in kidneys, a finding that was not referenced in most mainstream articles on the subject.
Within two weeks, she formulated a hypothesis that melamine in combination with uric acid or cyanuric acid induced renal failure in animals. She believed what was happening in the animals was similar to a rare syndrome that causes renal crystals in humans undergoing chemotherapy. She was initially met with skepticism from scientists who believed the crystals were not plentiful enough to cause kidney failure.
Dr. Reimschuessel examined tissues from affected pets and found that over time the crystals dissolve in the chemical used to preserve pathology specimens, explaining why relatively few crystals were found by pathologists. As a result of this finding, FDA recommended changes in the way that veterinarians preserved and submitted specimens to pathology laboratories.
Next, Dr. Reimschuessel decided to test how melamine behaves in fish to try to better understand what had happened to the pets. Her team fed some fish with a dose of melamine, others with cyanuric acid and others with a combination of the two. The fish treated with both chemicals developed kidney crystals that were similar to the crystals seen in the dog and cat kidneys that had been affected by the recalled foods.
Dr. Reimschuessel demonstrated that the combination of the two chemicals caused the crystals, not each chemical on its own, and she confirmed that melamine, with cyanuric acid, was the problem that made pets sick after all. Due to her discovery, the United States has increased surveillance for melamine and related compounds in food ingredients. In an effort to identify potential risks to humans, she is continuing to test the effects of melamine in chickens, pigs and fish, including tilapia, trout, catfish and salmon. Dr. Reimschuessel’s research helped improve the way our government preserves scientific specimens and identified the ability of nontoxic compounds to become toxic when combined. These discoveries helped resolve an immediate crisis, and her continued efforts help guard against ongoing threats to the safety of the U.S. food supply.