References
Aflatoxicosis in dogs
Abstract
Aflatoxins are toxic, naturally occurring bisfuranocoumarin compounds produced by certain strains of the moulds Aspergillus flavus, A. parasiticus and A. nomius. Aflatoxin metabolites cause hepatotoxicity by reacting with macromolecules (including DNA and proteins) to cause fatty liver or liver necrosis. Most cases involve dog food or, less commonly, ingestion of mouldy bread. Periodic outbreaks are reported in dogs, most recently at the end of 2020 to early 2021 in the US. Multiple dogs may be involved in incidents and the dogs usually present with gastrointestinal signs, lethargy, melaena and jaundice. Diagnosis is based on a history of possible ingestion and laboratory confirmation of aflatoxin(s) in suspect material. In the liver the typical histological changes are centrilobular necrosis of the liver and bile duct proliferation. Treatment of aflatoxicosis in dogs in supportive, with management of liver failure. Prognosis depends on the severity of liver damage, but mortality rates in dogs with aflatoxicosis are high.
After thousands of ducklings, turkeys, chickens and swine died in England between 1960 and 1961, extensive investigation was undertaken to establish the cause. Suspicion fell on Brazilian peanut meal, which had recently been imported and used as animal feed (Austwick, 1978), resulting in the eventual discovery of compounds known as aflatoxins produced by the mould Aspergillus. The name aflatoxin is a contraction of ‘A. flavus’ and ‘toxin’ (Denning, 1987) and over a dozen have been recognised.
The most common aflatoxins are B1, B2, G1, G2, M1 and M2. Aflatoxins fluoresce on exposure to ultraviolet light and B1, B2, G1 and G2 are distinguished on the basis of their colour (B for blue and G for green). Aflatoxins B2 and G2 are the dihydroxy derivatives of B1 and G1 respectively. Aflatoxin M1 and aflatoxin M2 are metabolites of aflatoxins B1 and B2 respectively, which were originally identified in milk (World Health Organization, 1979). Aflatoxin B1 is the most commonly occurring aflatoxin.
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