On the last day of April, several dozen epidemiologists, laboratory diagnosticians, clinical nutritionists, toxicologists, pathologists, and other veterinary specialists held a conference call to provide a forum for discussion of the animal health aspects of the pet food adulteration and recall.
Participants were primarily from the Food and Drug Administration, American College of Veterinary Internal Medicine, American Association of Veterinary Laboratory Diagnosticians, and Veterinary Information Network. The call was arranged by AVMA staff to facilitate dialogue among these principals, and to identify any new guidance that could be offered to veterinary practitioners treating patients that became sick after eating adulterated pet food.
Although no new treatment protocols were recommended, several important points were underscored for communication to veterinary practitioners. In particular, the participants agreed that the standard treatment for renal failure, consisting of fluid therapy and supportive care, seems to be effective in many affected animals. Also, there currently is no evidence that acidifying or alkalinizing the urine will help to dissolve the crystals in vivo.
Dr. Neal Bataller, director of the Division of Compliance, FDA Center for Veterinary Medicine, characterized the problem as resulting from a triazine- or melamine-related compound. The current thinking is that a combination of chemicals—each alone, seemingly nontoxic—forms polymers in the animal, and the resulting crystals do physical or other damage, primarily to the kidneys. Melamine and cyanuric acid-related compounds have been shown to cause crystal formation in vitro and perhaps in vivo, Dr. Bataller said, but further studies may identify additional substances as well.
Besides recognizing the type of crystal involved, veterinarians should be aware that formalin dissolves these crystals. Therefore, formalin may not be the best fixative for samples collected from affected animals, although preservation of tissues in formalin for overnight delivery to a laboratory may be acceptable, and some samples should be preserved in formalin for other pathologic studies. The AAVLD provides suggestions for sample collection on its Web site; go to www.aavld.org, click on News and then "Protocol for suspected pet food associated nephrotoxicity."
One of the sites where veterinarians can view images of the crystals in urine is the University of Guelph Laboratory Services at www.labservices.uoguelph.ca/urgent.cfm#crystals.
Veterinarians were also encouraged to participate in the AAVLD online survey on cases related to adulterated pet food. The survey is accessible to AAVLD laboratories on the members-only area of the Web site. Nonmembers can enter case data via the public area by going to www.aavld.org; click on News and then on AAVLD Pet Food Toxicity Survey.
Another point that Dr. Bataller clarified is that recall of a particular pet food does not necessarily mean that food has been associated with any animal harm. The FDA considers a pet food as adulterated if either compound—melamine or cyanuric acid—is found at a quantifiable level, regardless of any association of the pet food with reports of possible animal injury.