Fatal poisoning of Old Polish ducks with Amanita muscaria

Amanita muscaria (fly agaric) is a poisonous mushroom containing ibotenic acid (IBA) and muscimol (MUS), two neuroactive alkaloids capable of causing severe or fatal intoxication. While human poisoning is well documented, information on fatal intoxication in birds is limited. This report presents the first documented case of fatal poisoning of Old Polish ducks following ingestion of A. muscaria, confirmed by anatomopathological and toxicological analyses. Post-mortem specimens, including blood, heart, brain, kidney, liver, lung, pectoral and femoral muscles, and gastrointestinal contents, were subjected to LC–MS/MS analysis for the determination of IBA and MUS. Tissue samples were homogenized, extracted, derivatized, and quantified using multiple reaction monitoring. Mushroom caps and stems collected from the environment were analyzed using the same analytical approach. To exclude alternative toxicological etiologies, liver, muscle, kidney, and gastric contents were screened for rodenticides, pesticides, mycotoxins, and other chemical toxicants by LC–MS/MS. Viral infections were excluded by PCR and RT-PCR assays targeting DNA and RNA viruses commonly affecting waterfowl. In addition, comprehensive bacteriological, mycological, and parasitological examinations were conducted. Post-mortem examination revealed lamellar mushroom fragments in the glandular stomach and congestion in the caeca and brain. Ibotenic acid (IBA) concentrations across tissues ranged from 4 to 1987 µg/kg, while muscimol (MUS) ranged from 2 to 66 µg/kg. In gastrointestinal contents, IBA and MUS concentrations ranged from 16.2 to 1110.5 µg/g and from 2 to 41.3 µg/g, respectively. Analysis of environmental mushroom material showed higher toxin levels in caps (871.7 µg/g IBA; 197.5 µg/g MUS) than in stems (206.6 µg/g IBA; 15.3 µg/g MUS). Screening of liver, muscle, kidney, and gastric contents excluded the presence of rodenticides, pesticides, mycotoxins, and other chemical toxicants, while PCR/RT-PCR and comprehensive bacteriological, mycological, and parasitological examinations ruled out viral, bacterial, fungal, and parasitic infections. The presence of IBA and MUS in all organs confirms A. muscaria poisoning as the cause of death. This case highlights the toxicological risk of fly agaric ingestion in waterfowl and indicates that meat and tissues from affected birds are unsafe for consumption.