February 2006
From the State Vet's Office

AFLATOXIN

An Old Adversary Makes an Appearance

by Tony Frazier

Aflatoxicosis is discussed in the 1955 First Edition of the Merck Veterinary Manual under the heading, "Moldy-Corn Toxicosis." At that time, it was described as a hemorrhagic disease of swine and cattle that have ingested moldy field corn. The disease was said to be caused by an unidentified species of the fungus, Aspergillus, and a strain of Penicillium rubrum, another fungus. The toxicosis was said to have been observed mostly in the Southeast in parts of Alabama, Georgia, and Florida. The toxin caused clinical and pathological symptoms in cattle, swine, and mice. The producer often lost between 5 to 55% of the animals that had ingested the moldy corn. The clinical symptoms caused severe damage to the liver.

Fifty years later, in 2005, the Ninth Edition of the Merck Veterinary Manual reports that aflatoxins are produced by certain strains of Aspergillus flavus and Aspergillus parasiticus on peanuts, soybeans, corn and other cereal grains. It is possible for the fungus to exist on the grain and not produce aflatoxin. The two things that are required are high moisture content and constant day and night temperatures of greater than 70° Fahrenheit. The toxic response and disease by mammals and poultry vary greatly due to several factors. Some of these factors include species, age, sex, nutritional status of the animal, and the level of aflatoxin contamination in the feed. In addition to affecting a number of farm animals such as poultry, pigs, pregnant sows, and calves, it also affects dogs. Generally, adult cattle, sheep, and goats are relatively resistant to the acute form of the disease in which death occurs in a short period of time. Over longer periods, even the adults can be affected.

If you have been paying attention to the news recently, you may be aware that Diamond Pet Foods announced a voluntary recall of certain lots of their pet food. Information abut the recall may be obtained at their website, www.diamondpet.com. The recall was because of aflatoxin found in the food.

Mid-December through Mid-January our Alabama Department of Agriculture and Industries Veterinary Diagnostic Laboratory has had four cases in which dogs had died of acute liver failure, which is consistent with aflatoxicosis. Of the four premises represented in those cases, two were accompanied with samples of dog food which tested positive for the presence of aflatoxin. General clinical in dogs are dose dependent and include unthriftness, weakness, anorexia, vomiting, diarrhea and sudden death.

Because of the testing done on shipments of grain, aflatoxicosis is seen much less often than it was years ago. Grain that is used commercially is tested for the presence of aflatoxin; however, in a large shipment, there could be one area where the toxin is located that is not tested. It may be like finding a needle in a haystack.

According to Dr. George D’Andrea, a toxicologist at our diagnostic laboratory, you cannot look at corn and tell if aflatoxin is present or not. In his experience, sometimes corn that has the most mold on it will test negative for the toxin, while some corn that looks cleanest to the naked eye will have a high level of contamination.

We are fortunate to have the staff and personnel that we have at our veterinary diagnostic laboratories in Alabama. They provide tremendous expertise to the agriculture and companion animal community. We often think of their importance in detecting foreign animal diseases such as Avian Influenza, but they also provide a valuable service in helping the practicing veterinarian diagnose diseases such as aflatoxicosis in pets.