In vitro immunotoxicity of important mycotoxins detected in commercial dry dog and cat food in relation to internal exposure.

A screening of commercial dog and cat foods revealed considerable variation in metabolite profiles across feed categories, with standard feeds generally showing higher concentrations of Fusarium metabolites, phytoestrogens, and plant metabolites than specialized senior or intestinal diets. Concentrations of aflatoxin B1 (AFB1), deoxynivalenol (DON) DON, zearalenone (ZEN), ochratoxin A (OTA), fumonisin B1 + 2 (FB1 + FB2), and T-2/HT-2 toxins remained below existing guidance values and maximum limits. In vitro assays using peripheral blood mononuclear cells (PBMCs) from dogs and cats demonstrated marked interspecies differences in mycotoxin sensitivity. Feline PBMCs were more susceptible to proliferation inhibition by DON and especially ZEN than canine PBMCs, consistent with known species-specific differences in xenobiotic metabolism. The potency ranking of tested compounds in dogs was in line with reports from other species, with T-2 toxin showing the highest cytotoxicity (EC50 < 0.1 µM). Analysis of feed and blood samples indicated that systemic exposure to DON and ZEN under practical feeding conditions was several orders of magnitude below in vitro EC50 values, suggesting limited direct cytotoxic risk. Nonetheless, the presence of multiple mycotoxins in all feed categories underscores the need for continued surveillance and further studies linking feed composition, toxin occurrence, and toxicological thresholds to better inform companion animal health risk assessments.