Aflatoxicosis is a form of mycotoxicosis arising from toxin ingestion of spoiled feed contaminated with Aspergillus spp fungus characterized by acute hemorrhagic enteritis, coagulopathy and sudden death.
Aflatoxins are often associated with groundnuts (peanuts) and corn, but they also have been found in other grains and nuts. Aspergillus spp fungi can proliferate in improperly stored grain that has a moisture content of greater than 14%, relative humidity greater than 70%, and temperature greater than 200C. These fungi also can invade grains in the field, especially when there is drought stress, insect damage, or mechanical damage.
The toxins involved include aflatoxin B1, B2 and G1, cyclopiazonic acid and ochratoxins A and B. Toxic levels > 50 ppm are capable of inducing disease. These toxins are produced as metabolic byproducts of fungal metabolic waste products and are hepatotoxic as well as highly carcinogenic. Within the body, aflatoxins are metabolized by the liver to a reactive epoxide intermediate or hydroxylated to become the less harmful aflatoxin M1.
Large outbreaks can occur on farms where corn-meal are fed to dogs, or where they gain access to stores. Aflatoxicosis has also occurred from contaminated commercial dog food. Outbreaks can occur as acute, subacute or chronic based on duration of exposure and volume ingested.
Affected dogs usually present within 24 hours of ingestion of contaminated meal with acute-onset anorexia, polydipsia, icterus, hematemesis, hematochezia, melena and bleeding of the skin, eye, ear and mouth. Death ensues rapidly in many cases.
On postmortem, a consistent, very characteristic finding was the presence of a blue-grey granular material within the bile ducts. Other features include hepatocellular fatty degeneration, bile ductule proliferation and mucoid degeneration or segmental atrophy of the larger intrahepatic bile ducts.
A presumptive diagnosis is based on historical exposure to contaminated feed, presence of aflatoxins in food sources, vomitus, intestinal contents and characteristic histological findings.
A differential diagnosis would include anticoagulant rodenticides.
Supportive intravenous fluid and oxygen therapy may assist recovery.
The active toxin, aflatoxin B1 causes a dose-related hepatocyte fatty degeneration, biliary duct hyperplasia, cholestasis and, in the chronic case, hepatic fibrosis.
Despite aggressive treatment, the mortality rate with aflatoxicosis in dogs approaches 70%, suggesting that dogs with this condition have poor prognosis.
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