Clues to Cat Deaths Found in UCD Study
By Carrie Peyton Dahlberg, The Sacramento Bee, Calif.
Nov. 14–Further clarifying the role that a pair of chemicals played in the deaths that prompted massive pet food recalls earlier this year, UC Davis researchers have shown that cats died only when fed two chemicals in combination.
To test what was suspected but not yet confirmed last spring, UC Davis veterinary toxicologists purchased four cats from a research facility and fed them different combinations of chemicals.
All four cats survived various doses of either melamine or cyanuric acid, two chemicals that regulators suspect may have been slipped into pet food to help a cheaper ingredient masquerade as a costlier one.
Yet the three cats that were fed pet food laced with both chemicals at once sickened within 12 hours, vomiting, losing their appetites and showing signs of kidney failure.
They were killed after 48 hours, and their tissues had the same kind of kidney damage detected in animal necropsies during the pet food recall.
The remaining cat — which had gotten melamine at one point and cyanuric acid later, but never the two together — appeared healthy and its necropsy showed undamaged kidneys.
"The data will make pet food ultimately safer because now we know what to look for," said Birgit Puschner, lead author of the study and a UC Davis professor of clinical veterinary toxicology.
"We had to make some sacrifices, but I hope a large population of pets will benefit from it," Puschner said.
She added that during her 12 years at the Davis toxicology lab, it is the first time she has done a study that involved the deaths of anything other than guinea pigs, rats or mice.
"It was very difficult," Puschner said, but "we needed that data. … We always reminded ourselves of the possibly thousands of animals affected by the recall."
When the study began in April, researchers still didn’t know whether melamine alone was responsible for a nationwide outbreak of pet deaths estimated to reach into the thousands.
As word came that a lab in Canada had found crystals of melamine and cyanuric acid, combined, in the bodies of dead pets, the Davis researchers began testing that combination.
Roughly around the same time Procter & Gamble, whose pet food brands include Iams, was doing similar tests with rats, said Steven Hansen, a veterinary toxicologist and vice president of the American Society for the Prevention of Cruelty to Animals.
Those rat results have not been published and were only discussed with a small group of experts at an invitation-only conference, Hansen said, but the results were similar. It took both chemicals, ingested together, to damage kidneys.
Hansen gave the Davis research team "a lot of credit" for keeping the number of cats it used so small. But he added that in general, when studies must be done that end in animal deaths, the SPCA encourages choosing the "lowest level" animals.
"We’d prefer to see it done in rodents and then stop," Hansen said.
People for the Ethical Treatment of Animals condemned the study, saying it showed a "lack of compassion."
Bruce Friedrich, a PETA vice president, said, "None of us would volunteer our own cats for research because we know trading in lives is immoral."
But Jay Griffiths, a Fair Oaks veterinarian whose six Sacramento-area clinics treated victims of tainted pet food, said research like that done at Davis is sad but necessary.
"At least these cats were able to potentially help future pets down the road," Griffiths said. "There are so many animals euthanized on a daily basis out of humanity’s neglect for them." In comparison, he said, the number of animals euthanized for science "is minimal."
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